Biological Productivity
of the Southern Beaufort Sea:
the physical-chemical environment
and the plankton
E.H. GRAINGER
Technical Report No. 12a
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B I OLOG I CAL P RODUCT I V ITY OF THE
SOUTH ERN B EAU FORT S EA: THE PHYS I CAL - C H EM I CAL
ENV IRONMENT AND THE PLANKTON
E . H . Gra i nger
Arcti c B i o l o g i cal Stati on
F ish er i es a nd Ma ri ne Serv i ce
Dept . o f the Env i ro nment
P . O . Box 400
Ste . Anne de Bel l evue , Quebec
H9X 3 L 6
Beaufort S ea Tech n i ca l Report #12a
Beau fort Sea Project
Dept . of the Envi ronm ent
512 Federal Bui l d i ng
1230 Government St.
V i ctori a , B . C . , V8W l Y4
Decem ber , 1 9 7 5
Reprinted September,
1976
Price
$1.50
1
1 . SUMMARY
The south Beaufort Sea , i mmense l y mod i fi ed by the o u tfl owi ng
Mac ken z i e Ri ver , co ns i s ts o f a l ayer o f l ow sal i n i ty water of
Mac ken z i e Ri ver ori gi n overly i ng one of h i gher sa l i n i ty , o f o ffshore,
Arc t i c Ocean ori g i n . The vari abl e bal ance between these e l ements
determi nes the extent o f the ri ver pl ume , and therefore the bas i c
b i o l og i ca l composi ti on o f the sou th Beaufort Sea . A chang i ng sea­
i ce cover i nfl uences undersea l i ght and provi des a surface for the
i ce fl ora wh i ch supp l i es a primary food sou rce for wha t appea rs to
be an i mportant troph i c seri es . Undersea l i ght i s a l so i nfl uenced
by parti c u l a te mater i a l i n the water . Li gh t penetra ti on i s sha l l ow
i n the i nshore p l ume wate rs , bec a use o f the-h i gh sed i men t l oad
carri ed to the sea by the o u tfl owi ng ri ver . Nutri ents , m a i n l y
ni tra te and s i l i cate , are added to the sea from the ri ver . Leve l s
rema i n h i gh nea r shore , whe re consumpti o n by p l ants i s consistently
l ow . Outs i de the p l ume , ni tra te i s proba b l y the maj or fa c tor
l i mi ti ng phytopl ankton p roduc t i o n ; wi thi n the p l ume it i s proba b l y
l i g h t , i nh i b i ted by river-contri buted turb i d i ty . A l ow annual
primary pro duc ti on ra te i s i ndi cated for a l l waters of the reg i on,
and especi a l ly for the area of the ri ver p l ume . A l ow secondary
( zoop l ankton ) product i on i s a l so i nd i ca ted , a nd stand i n g s to c ks
a re genera l l y l ow by worl d standa rds .
The two - l ayered , estua r i ne struc ture of the i nsho re waters i s
expected t o encoura ge rap i d s pread of pol l utants through the system ,
e i ther from offshore , from i nsho re o r from terrestr i a l o r ri ver
l ocati ons . Much of th e cha ra cter of the system is determi ned by
ri ver i nfl uences , so much so tha t q uanti tati ve chan ges i n the ri ver
wi l l be expected to a l ter the b i o l og i c a l composi ti on of the south
Beaufort Sea . Even temporary e l i m i nati on of the p l ume wou l d wi pe
out the estua ri ne fa una a nd fl ora . Qua l i tati ve changes wou l d a l so
be expected , a nd pol l u tants from the ri ver wou l d q u i c k l y spread a t
l east t o the l i m i ts of the p l ume . The pri mary and seconda ry producers
p rovi de the bas i s o f a food structure wh i c h supports fishes and
mamma l s, both i n the water co l umn and in asso c i a ti on wi th the sea
i ce cove r . Re l a ti vely s hort food chai ns represen t a reas of the system
of potenti a l l y great v u l nerabi l i ty to o i l .
2
2.
IN TRODUCTION
��o s t of the i nforma ti on p resented i n thi s report was ga thered
over a peri od of a l i ttl e more than two years , i ncl ud i n g the
s ummers of 1 9 7 3 , 1974 and 1975 . A few o bserva t i o n s made earl i e r ,
i n fact a s l ong a go a s 195 1 , a re i n cl u ded to expand both the ti me
and s pa ce range of the s tudy . Fi e l d work done i n 197 1 and earl i er
wa s carri ed out a s pa rt of the regu l ar pro gramme of the Arcti c
B i o l o g i cal Stati on . Stu d i es done i n 197 3 were s up ported by the
Envi ronmen ta l - Soc i a l Pro gra m , Northern P i pel i nes , of the Tas k Force
on Northern Oi l Devel opment , Government of Canada; tho s e i n 1 974
a nd 1975 by the Beaufort Sea Proj ect.
No part of the actua l Beaufort Sea Proj ec t open-water study ,
and th i s appl i es to the wo rk underta ken i n 1974 a nd 1 9 75 , was carri ed
out under favoura b l e c i rcumstances . The s h i p - s u pported s urveys of
the two s ummers fa i l ed so badl y to achi eve the s c hedu l es p l anned for
them , that most of the data s trength of the s tudy or i g i na ted therefore
ei ther i n the year preced i n g i n i ti a ti on of the Bea ufort Sea Proj ect
or through the u s e of hel i copters on the ea rl y s ummer sea i ce cover .
Th i s was l a rge l y the con s eq uence of sea i ce pers i sti ng over areas
where s tud i es from s h i pboard had been p l anned. I t had i mportant
conseq uences to thi s s tudy , a nd i t s howed in a very cl ear way the
fal l acy of underesti mati ng the arcti c by presuppo s i n g a capaci ty
to perfo rm i n i t under a l l cond i t i ons .
The present i n vesti gation di d not a c h i eve i ts expectati ons i n
terms of ra nge of covera ge , ei ther i n s pace o r i n t i me . A n umber
of ra ther el ementary q uestions con cern i ng ba se- l i ne features of th i s
ecosys tem therefore rema i n u nan swered . Such gaps s how the repor t
to b e even more of a prel i mi nary o n e than i t wa s hoped i t wou l d b e
when the pl a n wa s conce i ved .
Abo ut 120 s tat ions \'/ere occupi ed i n a l l ( Fi gures 1 , 2 , 25 , 26 ) ,
nearl y al l of them duri n g the s ummer, a nd mos t of them from s h i p board
i n open water . Informa t i on was ga thered on water temperature , sal i n i ty,
l i ght , di ssol ved oxygen , n i tra te , phosphate , s i l i ca te , chl orophyl l ,
parti cul ate and d i ssol ved organ i c c a rbon , bacter i a and benth i c and
pl an kton i c pl ants and a n i ma l s . The o bj ec t of the exer c i se wa s to
def i ne the p resen t , rel a t i vel y und i s turbed Bea ufort Sea b i o l og i ca l
sys tem , to try to devel op a n unders tand i n g of i ts str ucture , i n
rel a t i o n t o the majo r va ri a b l es of the present ti me , and i n response
to anti c i pated c ha nges of the futu re resu l ti ng from o i l expl o i ta ti on.
Current va r i a b l e s i ncl ude seasonal p henomena cau s i ng va ri a t i o n i n
s uch thi ngs a s sea i ce cover and ava i l a b l e s ubma r i ne l i ght , a nd
al terati ons i n Mac ken z i e ( a nd o ther ) ri ver fl ow a nd con sequent s h i fts
i n the ba l ance between ri ver f l ow on the one hand and offs hore mar i ne
i nf l u ences on the othe r . The s um of these oppos i ng factors seems to
determi ne the pattern of muc h of the b i o l o g i cal s tructure of the south
Bea ufort Sea a t a ny one ti me .
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Fig ure 1 . Stat i ons wh i ch provi ded p hy s i cal and chemi cal data .
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PO I N T
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MASON
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Fi gure 2 . Mason Bay stati ons .
Area shown i n Fi gure 1 .
5
The data on wh i c h thi s s tudy i s based may be found i n two
data reports , one of them on phy s i cal a nd chemi cal oceanography
(Gra i n ger and Lov ri ty 197,5 ) , the other on zoopl an kton (Gra i nger
and Grohe 1975 ) .
3.
CURRENT STATE OF KNOWLED G E
Befo re the i n i t i a ti on of s tu d i es i n the earl y 1970 ' s , the
s ta te of knowl edge of the southea s tern Beaufo rt Sea ecosystem was
di s tres s i ngl y i l l devel oped . Cl earl y t h i s sea , borderi n g on both
Canada and the U n i ted States and the route of whal ers for a hundred
years , had been a l most to tal l y i gno red by oceanographers of a l l
k i nds . The f i rst oceanogra ph i c paper on the regi on a ppears to be
Tul l y ' s ( 195 1 ) in wh i c h data col l ec ted on H. A. Larsen ' s h i sto r i c
fi rst retu rn j ourney through t h e northwe s t passage on the R . C . M . P .
ves s el St . Roche were g i ven . Tul l y s howed that rel ati ve l y col d
( 0 . 2 - 5 . 5°C) and brac k i s h (3-9%0 ) water exi s ted between Po i nt Barrow
and Li verpool Bay , wi th warmer and much s a l ti er water (to 3 1 . 6% 0 )
to the wes t , and s i mi l a r l y col d but aga i n mo re sal i n e water (to
30 . 7%0 ) to the eas t . The rel a t i vel y brac k i s h water i n the mi dd l e
reg i on was of course rel a ted to the outf l ow of the Ma c ken zi e Ri ver .
Cameron ( 1 9 5 3 ) , fo l l owi ng two cru i ses by the Canco l i m I I i n the
Bea ufort Sea , descri bed the net c i rcu l a t i o n i n the south Bea ufort
as anti c l oc kwi se , wi th l ow sa l i n i ty (Ma c kenzi e ) water mov i n g
ea stward a l ong the coa s t , and h i g her sal i n i ty water fol l ow i ng i n
beh i nd i t from the northwe s t to mi x w i th ri ver wa ter i n Mac ken z i e
Bay . Wind wa s gi ven a s the pri mary factor i n i nf l uenc i n g the
d i stri but i on of l ow - sa l i n i ty (Ma c kenzi e ) water i n the south Bea ufort
Sea . Coa s ta l sal i n i ti e s rel eva n t to the Mac kenz i e outfl ow were
offered by Henoc h ( 1969 ) . Deta i l ed i n s hore o cea no gra p hy , ma i n l y
conf i ned to Tuktoya ktu k harbour , wa s d i scus sed by Ba rber ( 1968 ) .
A n umber of tempera ture and sal i n i ty mea s urements i n shal l ow ,
i n s hore waters immed i a tel y adj acent t o t h e Mac kenzi e del ta were
gi ven by Bru n s k i l l , Ro sen berg , Snow , Va s co tto and Wagemann ( 1973 ) ,
and a fa i rl y detai l ed d i s cu s s i on of ma i nl y off s ho re p hys i cal
oceanogra p hy was contri b uted by O ' Rou rke ( 1974 ) .
No account of i no rgan i c n u tri ents i n a ny part of the south
Bea ufort Sea p receded the sympos i um on Bea ufort Sea coa s t and
s hel f researc h hel d in San Franc i s co ea rl y i n 1 974 . From th i s
there appeared a ccounts of n u tri ents f rom the so utheast Beaufort
Sea (Gra i nger 1 974 ) a nd f rom the Co l v i l l e Ri ver and i ts e s tuary
off northern Al a s ka ( Hufford 1974; Hami l ton , Ho and Wal ke r 19 74;
and Schel l 1974 ) . Gud ko v i c h ( 19 5 5 ) , Engl i s h ( 196 1 ) a nd Ki nney ,
Arhel ger and Burrel l ( 1970 ) had prev i ous l y gi ven nutri ent data from
the Arcti c Ocean for north of the Beaufo rt Sea , and thei r i nformati o n
may b e compared wi th the p resent study . Mackenz i e Ri ver n utri ent
i nformati on has come f rom Reede r , Hi tchon and Lev i nson ( 1972 ) .
6
Ava i l a b l e works on p hytopl a n kton o f the regi on appear to be
l i mi ted to Mann ' s ( 1925 ) report on d i a toms o f the Cana d i an Arctic
Exped i ti on o f 1 9 1 3 - 1 8 . Later , Bursa ( 19 6 3 ) d i scu s sed genera l
phytopl ankton of north Al a s ka , to g i ve the on l y eco l ogical data on
these pl ants i n the Beaufort Sea reg i on . Benth i c pl ants (al gae )
were cons i dered by Col l i ns ( 19 2 7 ) , and the pauc i ty o f data ,
es peci a l l y i n the wes tern Canadi a n a rctic , wa s brought out qu i te
recentl y by Lee ( 1973 ) . Gra i nger ( 1974 ) descri bed chl orophyl l
d i stri buti on i n the vic i n i ty o f the Mackenzi e del ta . For benthic
a n i ma l s a few sca ttered co l l ecti ons were made a l on g the north coa s t
o f Al a s k a a n d cl os er to t h e Mac k en z i e before MacGi n i t i e's ( 19 5 5 )
excel l ent account o f the ma ri ne i nvertebra tes o f north Al a s ka . The
mos t notab l e amon g the earl i er works were severa l papers ari s i ng
from the Canad i a n Arctic E xped i ti on , in wh ich a few col l ecti o ns o f
severa l taxonomic groups o r i gi nat i n g i n the a rea o f i nterest here
were descri bed . Al most no q uanti ta ti ve data were a s semb l ed on the
benth i c fauna , however, and no i nforma t i o n was ava i l a bl e for the
assessment of s tocks or producti on rates unti l the reports by
Wacasey ( 1974 ) and Carey , Ruff , Co sti l l o and Di c k i n son ( 1974 ) .
Zoopl an kton wa s somewha t better covered , and a s many a s 27 p a pers
pertai n i ng to the Bea ufort Sea were reported by Shi h , F i guei ra and
Gra i nger ( 19 7 1 ) . Zoopl an kton from the v i c i n i ty of the Macken z i e
del ta was desc r i bed by Gra i n ger ( 1974a ) .
The reports from 1974 were the fi rs t b i o l ogical contri buti ons
wh i c h had real rel evance to the object i ves of the p resent study .
The ba s i c pa ttern o f a n i mal d i stributi on and dependence upon the
estuari ne sys tem off the del ta , and the fea tures o f the regi me whi ch
control pl ant produc t i on were i n d icated a t that t i me . Subsequent
wor k has tended to confi rm and refi ne the earl i er concl u s i on s .
4.
STUDY AREA
4. 1
The south Bea u fort Sea
The central part of the so uth Beaufort Sea i s characteri zed
by fa i rl y warm and l ow- sa l i n i ty water i n shore , and cool e r , more
sal i ne water offs hore . It i s i n many ways typ i cal of s ea a reas
off l a rge r i ver mouths everywhere , havi ng ri ver-con tri buted
features s pread i n g seawa rd o ver deeper ocean i c i n fl uences bel ow .
Ri ver fl ow i s domi nant i n gi v i ng the south Bea ufo rt Sea i ts
i d enti ty . Ri ver fl ow and varyi ng wi nds a re proba b l y mos t
i mportant i n bri ngi ng abo u t vari a t i o n s i n t h e di s tri buti on of
o ffshore features o f the Bea u fort Sea in the reg i o n of the
Mac kenzi e del ta . It i s an a rctic ma ri ne regi o n , a nd i t i s
ice-bound duri ng much of the year . Th i s means l i ght penetrat i on
and vertical mi x i ng a re restricted and that produc ti on i s
l i mi ted to a fa i rl y bri ef peri od o f the year .
P l ace names are s hown i n F i g ure 3 .
7
4.2
Ma son Bay
Th i s i s a s pec i a l i zed i n s hore area l a rgel y separated
both on hori zontal and vertical pl ane s from the ma i n body o f
the Beaufort Sea , a n d comb i n i n g coastal a n d o ffs hore Beaufort
Sea feature s wi th l ocal l y deve l oped q ua l i ti e s a s soci a ted w i t h
l and dra i n a ge fro m northe a s tern Richards I sl and . Located
between the e a s te rn and we s tern mouths o f the t�ac kenz ie , Mason
Bay , open i ng to the no rth , probably mi s se s the ma i n thru s t of
the outfl owi ng Mac kenzie Ri ve r under most wi nd cond i t i ons .
Onl y s tron g and fa i rl y prol onged no rthe rl y wi nds wou l d be
expected to tra n s port s i gn i ficant quanti ties o f o u ts i de wate r
i nto the bay . The deepes t parts of Ma son Bay a re sepa ra ted
from the ma i n body of the Bea ufort Sea by a s i l l a t the
entra nce to the bay . I t i s nece s s ary to trave l 25 mi l e s north
from the bay i n o rde r to fi nd wa te r depths i n t he Beaufort
Sea as great as the deepe s t parts of Ma son Bay , o r ( i n s ummer)
to f i n d sal i n i ty as h i gh a s i s fo und i n Ma son Bay .
4.3
L i verpool Bay
Much l arger but a l s o s hal l ower than Ma son Bay , Li verpool
Bay rece i ves ri ver-d i l ute d s u rface water from the Bea ufort Sea ,
bu t l i ttl e of the co l de r , more sal i ne water wh ich i s fo und i n
the deeper pa rts o f Mason Bay . Li verpool Bay rece i ve s rel ati ve l y
l e s s l oca l fres hwate r i nf l uence than Ma son Bay , e ven tho ugh i t
i nc l udes o utput from the adj acent Es k i mo Lake s sys tem . Li verpool
Bay i s the refore more sal i ne a t the s urface and l e s s sal i ne at
t he bottom than Mason Bay .
4.4
Es k i mo La ke s
Th i s reg i on , the subjec t o f a l ong s tudy by the Arctic
Bi o l ogical Stat i on , is refe rred to only briefl y in thi s report .
Con d i t i ons a t the Li ve rpool end of the sys tem a re s i mi l ar to
tho se i n adj acen t Li verpool Bay , and tempera ture tends to i ncrea se
and s a l i n i ty to decrease towards the u pper or sou thern end of t he
sys tem . Dee pe r wate r i s fo und wi t h i n the l a ke s than outs i de
i n Li verpool Bay , mo re than 1 00 mi l e s d i s tant from depths a s
great i n the Bea u fort Sea . Those depths however do not s how
s a l i n i ty as h i gh as i s found i n the bo ttom waters of Ma son Bay ,
or a ny greater than i s fo und i n the much shal l ower b ottom water
of L i ve rpool Bay .
5.
METHODS
5.1
Fie l d techn ique s
8
5.1.1
Shi ps more or l e s s equi pped for oceano g raphy
Four ves s e l s i n thi s ca tegory were used i n carryi n g
o u t th i s study . Mos t effec t i ve wa s the North Sta r of
Herschel I s l and , u sed in l ate July o f 1973 to occupy 1 8
s tati ons , mos t of them fa i rl y cl ose to shore between
Herschel I s l a nd and Cape Dal hou s i e . I n 1 9 74 , the Theta
a nd i n 1975 the Pandora were used for b r i e f voya ges ,
ma i n l y i n the o ffs hore, western part of the Beau fort
reg i on covered by thi s s tudy . Mo s t of the rema i n i ng
open-water o bs ervati ons were ma de from the Sal vel i nu s ,
res earch vessel o f the Arcti c Bi o l o gical Stat i on . The s e
i ncl uded t h e pl anned programme i n 1975 wh i c h wa s part o f
t h e Beaufort Sea Project study of tha t yea r a n d earl i er
col l ecti n g done i n v a r i o u s years a s parts o f the
conti n u i n g f i sheri es s tudy of the Arctic Sta ti on .
Col l ec t i on s obta i ned from a fi fth vessel , whi c h was not
in any way part o f the Beaufort Sea Project s tudy , are
i ncl uded here . Th i s i s the Canco l i m I I , operated i n
1 9 5 1 by the Defence Research Boa rd i n a n ocea no graphic
opera t i o n wh i ch y i el ded some zoopl an kton reported here
for the fi rs t t i me .
5. 1.2
Hel icopters
El even s ta t i o n s were occ u p i ed from the sea ice
s urface , u s i ng hel icopters . Th i s wa s s hown to be a
h i gh l y s ucces s ful techn i q ue when ca rr i ed out wi th
su i tabl e wo rki ng equi pment and by experi enced and
wi l l i n g peopl e . Col l ecti n g by th i s means wa s of course
l i mi ted to vertical l y moved gea r whi c h mea n t that
hori zontal p l an kton net haul i n g , and benthos dredgi ng
and trawl i n g were not pos s i b l e .
5.1.3
Shore s tati ons
Th i s approach was u sed mai n l y in the E s k i mo La ke s ,
whe re stat i o n s cl o s e to shore were v i s i ted e i ther by
smal l boat ( s ummer ) or by snowmo b i l e (wi nter ) . Al l
s tandard l i gh t gear co ul d be u sed from the smal l boat ,
wherea s onl y vertical sampl i ng wa s poss i bl e from the
ice s u rface i n wi nter .
5.1.4
Col l ecti ng me thods
Wa ter s ampl es from bel ow the s urface were col l ected
wi th non -me tal l i c 5 - l i tre Van Dorn bottl es or 1 . 7- l i tre
N i s k i n bo ttl e s . Surface sampl i ng wa s done wi th a pl a s tic
b uc ket . Li ght penetrati on was mea s ured wi th a Secch i di sc .
9
Mos t water temperature s were determi ned u s i ng
cal i brated rever s i n g thermometers . A few water
temperatures and sal i n i t i e s were meas ured in s i tu
u s i ng a Y S I model 3 3 S-C-T meter . Sta ndard pl a n kto n
nets we re used for zoop l an kton . Mos t col l ecti ons
were ma de wi th nets of 30 cm d i ameter open i n g and mesh
of 73� , ha u l ed verti c a l ly . Other mes hes were u sed a s
we l l ( see Gra i nger and Grohe 1975 ).
5.2
Laboratory method s
Mos t sal i n i ty determi nati ons were done u s i ng a Bi s sett
Berman model 6230 l abora tory sal i nometer . Di s so l ved oxygen
sampl es were u s ual l y anal ysed by the Wi n kl er t i trati on method ;
a few were determi ned u s i ng a Y S I model 54 o xygen meter .
Water sampl e s fo r c h l orophyl l were f i l tered i mmed i a tel y after
the i r col l ecti on thro ugh HA Mi l l i pore f i l ters , wh i ch were kept
frozen and dark o ver s i l i ca gel unt i l l a ter extracti o n and
ana l ys i s of chl orophyl l s . The rema i n i n g wa ter for chemi cal
de termi nati ons was kept frozen until l ater anal ys i s .
Ch l orophyl l &, phosphate - p ho s p horu s , n i trate - n i trogen ,
n i tri te- n i trogen , s i l i cate- s i l i con and part i c u l a te organ i c
carbon were determi ned accord i n g to the methods of Stri c kl and
and Parsons ( 1968 ). The s l ower and far more l a bor i o u s ta s ks
of pl ant and ani mal i dent i fi ca ti ons and counts were conducted
( and are sti l l be i n g carr i ed o ut ) under s tanda rd l a boratory
cond i ti ons .
6.
RESU LTS
6.1
Sea i ce cover
Vari a ti ons i n the extent o f the sea i ce cover duri n g
b i ol og i ca l col l ecti ng peri od s i n recent year s a re s hown i n
Fi gure 3. I n 1 9 73 , pe rhaps someth i ng l i ke a "normal " i ce yea r ,
ful l y open water reac hed to a bout 2 5 m i l es o ff Tu ktoya ktu k
Pen i n s u l a and the o uter edge of Hersc hel I s l a nd off Mac kenz i e
Bay i n l ate July . Du r i n g Augu s t , the i c e edge moved fa rther
from s hore . I n 1974 , known far and wi de by now a s an espec i al l y
severe i ce yea r , the extent o f open water wa s somewhat l es s i n
l ate Au gust than i t had been a month earl i er i n 1973. The i ce
edge had been muc h cl oser to s hore earl i er i n 1 9 74 and was i n
the p rocess of mov i n g s eaward i n l ate Au gu s t . I n 1975 , there
was evi dentl y a notabl y ear l y a ppeara nce of o pen wate r
cond i t i o n s o ff the del ta , Mac kenzi e Bay and Tu ktoya ktuk
Pen i ns ul a . By earl y Au gu s t , the i ce edge wa s fa r outsi de the
po s i ti ons s hown i n Fi gure 3 for the two earl i er yea rs . I n
fact , the i ce moved s horeward aga i n wh i l e the bi o l og i ca l
col l ec t i n g wa s under way i n 1975; i t wa s however a yea r o f
exten s i ve o pen water dur i ng the earl y and mi ddl e parts o f the
s ummer .
Approximate extent of
" ope n water"
1913
late Ju Iy
1914-----late Aug.
1975 .. ····· .. ·······early Aug.
710
70 0
-1
134 0
13 6 0
138 0
1 4 00
/
f
.
····· .
·
·
·
·
·
·
. /0
.
·
.. . ..
..
'
'.
.
.. '
...
...
..
.0.
·····
···
·
··
..
·
·
········ ·r
•
·
•
.
. .
.
..
.
..
... . . . .
.. . ...
.
.... ..
..... .
.
····· T ········ ..............·······
. ..
·
..
�
..
..
..
'
III
•
V
1.0
•
L � -/\/
..
o. . ..I.....
.
..
II1II
o
A
•
128 0
13 0 0
132 0
a.
-
1.
I-'
o
.c1
Fi gure 3 . Pos i t i ons of t he i ce edge dur i n g 3 years of i nvesti gati on.
C:::?
IV
\J
11
The b i ol ogy i s d i scus sed i n section 6 . 9 bel ow .
6.2
Li ght
Secc h i di sc read i ngs were made at many o f the stati ons
occu p i ed in open water , a nd res u l ts , as depth o f 1 % o f s u rface
l i ght cal c u l ated from the Secch i d i sc read i n gs , a re s hown i n
Fi g ure 4 . Penetrati o n of 1 % of s urface l i gh t as deep a s 60
metres is s hown at the stat i on s l ocated fart hest from the
del ta . Crui s e stat i ons s i t ua ted farthest from the del ta
s howed 1 % of s urface l i g ht down to 40 metres . In genera l , a
pattern o f l ea st l i ght penetrati on cl osest to Mackenz i e Ri ver
d i sc harge po i nt s ( 1 % of s urface l i ght reac h i n g to l es s than
1 metre bel ow the s urface ) a nd greatest l i g ht penetrat i on
farthest from t he sources o f r i ver water. i s s hown i n Fi gure 4 .
Th e Secch i d i sc mea s u rement s made wou l d a ppear to
i nd icate two ca uses of i n h i b i ted l i ght passage , one the
sedi menta ry l oad o f the waters nea r the delta , i nd ica t i ng
d i rect Mac ken z i e Ri ver contr i buti on to the sea , the other
o rga nic part ic u l a te ma tter , pro babl y ma i n l y pl ant cel l s . These
features are not necessari l y cl earl y d i fferent i ated i n Fi gure 4 .
Mos t o f the near- s hore turb i d ity ( 1 % o f s u rface l i ght penetrat i n g
to 1 metre o r l es s ) i s i nd icat i ve o f ri ver transported sed i ments .
The deep l i ght penetrat i on of the northeas tern pa rt o f t he s tudy
area s hows cl ear waters with mi n i mal quantit i es of pa rticul ate
matter of a l l ki nd s . The s ha l l ower penetrat i on of the northwe s t
s ector may b e a res u l t mai n l y of pl a nt cel l s i n t h e s urface
waters .
6.3
Temperature and s a l i n i ty
Du r i ng the o pen water peri ods the warmest waters , with
s urface temperature more than 1 0 ° C , were fo und adj acent to the
Mac kenz i e del ta , the col dest , with surface temperature cl ose to
O° C , farther off s hore . A pattern wa s a l so revea l ed i n the
sal i nity d i s tr i b uti on , with the l owes t s u rface val ues ( l es s than
2rJ bei ng fou nd i n Mac ken z i e and Kugma l l it Bays and cl ose to the
north s hore of Richard s I s l a n d , and the h i ghest s urface records
comi ng genera l l y from the open -wa ter s tat i on s fa rthest from the
'
Mac kenz i e Ri ver outl ets .
Temperature p rof i l es i n Fi gure 5 s how the h i gh va l ue s
preva i l i n g from s u rface t o bottom i n t h e s hal l ow stati ons cl ose
to shore . C l o s e to Tu ktoya ktu k Pen i n s u l a , sta t i o n 7 3 - 5 30 s howed
l a rge l y uni form h i gh temperatu res from s u rface to bottom and
nea rby stat i on 7 1 - 505 s i mi l ar s urface con dit i o n s but a bottom
temperature 6 ° co l der . An offshore stat i on ( 73-533 ) was
1380
14 0 0
71 0
I
I
7
::'"
6
fI
I
' .....
\,fl.
.
. .'" � ..... ..... .�
.�
.. �
��
'
........
--
/
I
,
I
fI/
0
\'
....
\
\
....
\
\
\
I
I
........
--
"
,. -
• ","
-III
.
.. / lli tr
w I'
­
•
", ...3- -
..
•
6
7
3
I!A
;
,
"
/
I
.
7fl/ ,, '"
1°
0
09
" -- .....
60
128 0
\
•
I
J
70 0
.
Secchi disc
Depth of 1%surface
light
130 0
132 0
1 340
13 6 0
r
I'
/
I11III
I'
"
"
\-
40 II
__ _
.....
....
......
.
"" ....0-1_I11III
......,
N
II1II
rr
"
III
-4
Fi gure 4 . Depths of l i ght penetra ti on beneath t he s urface of the sea.
t::::?
N
\J
-2
oOc
2
4
6
8
10 · 12
71-505
If"
o
0/00 10
30
20
73- 527
11
61-1072
40
60
60:- ',013
Temperature
80
Sal i n ity
1 00
......
w
200
'5-566
4001
600
1
11
75-568
"
75-567
75-567
"
I
Fi gure 5 . Curve s of tempera ture ( l eft ) and s a l i n i ty (ri g ht ) .
--1-----
,------
14
co n s i derabl y warmer a t the s u rface than an offshore stat i on
occup i ed from the fl oa ti ng s ea ice ( 74- 1 2 ) .' The Ma son Bay
stati on 75-607 , warm at the surface , was l e� s than 2° bel ow
about 5 metres . Nearly a l l wa ters between 50 a nd 2 00 metre s
were bel ow O°C , and al l the deep stati on s showed warmi n g to
more than zero between 200 a nd 300 me tres ( t h e Atl a ntic water
l ayer of the a rctic bas i n ) . Stat i on 75- 567 s howed s l i gh t
cool i n g bel ow about 500 me tre s . Stati ons cl ose to s hore and
i n coastal bays showed the l owes t s u rface sal i ni ty ( 73-527 ,
75- 607 ) , but val ues were onl y a l i ttl e l es s than surface
rea d i n g s ta ken duri n g sea ice mel ti ng at the stati ons fa rthes t
from s ho re (74- 12 ) . Stati o n s occup i ed far from s hore i n open
water ten ded to s how the h i ghe s t s u rface sal i n i ty ( 73-533 ) .
Al l s tati ons wi th s uffi c i ent depth showed sal i n i ty greater
than 34%0 bel ow between 2 00 and 300 metre s ( the Atl antic water
l ayer , al so i nd i ca ted by temperature cu rve s i n the same fi gure ) .
The overal l tempera ture - s a l i n i ty fea tures of the water s
sampl ed i n th i s study a re s hown i n a temperature- sal i n i ty
d i a gram ( Fi gure 6 ) . Surface waters from Mac k en z i e Bay to
j u s t off Tu ktoyaktuk Pen i n s u l a a re repre sented by the u p per
l eft pa rt of the fi gure , w i t h i n s ho re waters tendi n g toward s
hi gher temperature and l ower s a l i n i ty , and o ffshore waters
towa rds l ower temperature and h i gher s a l i n i ty . Li verpool Bay
s urface water i s i nd i ca ted by the u pper central part o f the
fi gure and waters from off Cape Dal ho u s i e by the u pper ri ght
secti on of the fi gure , wi t h the s u rface of the l atter s howi n g
hi gher temperature a nd l ower s a l i n i ty , a nd i ntermed i a te water
of the l atter showi ng l ower temperature and h i gher sal i n i ty .
Surface wa ter near mel t i n g i ce i s represented by t he l ower l eft
corner o f the fi gure , i ntermed i a te depths i n Mac ken z i e Bay a n d
towards Herschel I s l and by t h e l ower central part , the l atter a
l i ttl e warmer than i n termed i ate wa ter depths under the i ce .
Al l "deep " water ( about 50 me tres and bel ow ) i s i nd i ca ted by
the l ower , ri ght corner of the fi gure .
The same ,waters , di s t i ngui shed a bove on temperature and
sal i n i ty gro und s , can be sep a ra ted i nto vi rtua l l y the same
categor i e s on the ba s i s of a n i ma l s conta i ned , a s i s s hown i n
a l a ter sect i on o f thi s report . Sal i n i ty and tempera ture , a n d
e speci a l l y the forme r , a r e obv i o u s l y t h e pri nci pa l envi ronment a l
features control l i n g the d i s tri but i o n of s pec i e s o f pl a n kton i n
thi s regi on .
6.4
Ni tra te
Ni trate- n i trogen s howed a pattern of di stri buti on i n wh i c h
the hi ghest val ues i n t h e s u rface waters occu rred i n t h e v i c i n i ty
of the Mac ken z i e Ri ver outl ets , and the l owes t quant i ti e s i n
o
I
16
°c
12
0/00
"".
4
I
8
12
16
I
20
I
24
28
32
!
Inshore
Surface Mackenzie Bay,
SurfaceLiver p o ol Bay
Herschel Island,
8
off Tuk Peninsula
SurfaceOffshore
�
4
Surface- near melting ice
o
'"
Offshore
t->
U1
from
Cape Dalhousie
~
Intermed.
Intermediate depths-
depths
Mackenzie Bay, Herschel I.
Intermediate depths­
under i ce
Fi g u re 6 . Temperature s a l i ni ty d i agram of a l l wate rs o f the s tudy a rea .
16
s u rface waters exi sted at s ta t i o n s fa rthest from the ri ver
mouths ( Fi gure 7 ) . The pattern evi dent i n Fi gure 7 i s fa i rl y
regul ar i n spi te o f the d i fferences i n t i me o f observati ons
i n the vari o u s years except for the Apri l - May sampl i ng of
1975. Quanti t i e s mea s u red duri ng that peri od are shown a s
underl i ned numbers i n the f i gure , and mo s t d o not conform to
the pattern s hown by the o ther val ues . They were h i gher
t han a),l the other numbers i n the fi gure , a t l ea s t partl y
beca u se they were a consequence of wi nter i n s i tu repl en i s hmen t
wh ich too k pl ace duri n g a period of v i rtually�depl eti o n ,
that i s , o f no ut i l i zati on by pl ants . Ob serva t i o n s made j us t
o f f Tu ktoya ktu k Pen i n s ul a i n very s ha l l ow water a l i ttl e l ater
in May , and not i ncl uded i n the f i g ure , s howed n i trate l evel s
a s h i gh a s the Kugma l l i t Bay s ampl es, from Apri l - May , and both
of these s howed l a rger q u a nt i ti e s than were i nd icated by the
Apri l - May sampl es from farther o ff s hore . These o b serva ti ons
i n d i cate that the h i gh wi nter n i trate s were s uppl emented by
Mackenzi e Ri ver contr i buti ons wh i c h were s hown by the h i ghest
l evel s of the enti re s t udy ( a bove 30 metres ) bei ng found i n
the u pper few metres a t the stati ons c l osest to the outfl owi n g
Mackenz i e River .
Fi ve l i ne s of s tati ons a re s hown i n Fi gure 8. From l eft
to ri ght i n the fi g u re they a re : ( 1 ) from Mac kenz i e Bay to
Herschel I sl and ; (2) from Herschel I sl and northwa rd ; ( 3 ) from
Richards I s l and no rthwa rd ; ( 4 ) from Ku gmal l i t Bay toward s Cape
Da l hou s i e , off the Tuktoya kt u k Pen i n sul a coa s t ; and ( 5 ) from
near Ca pe Da l ho us i e northwa rd . In sect i ons 1 , 3 and 4 , s urface
val ues are shown to fa l l al ong l i nes l ead i n g seawa rd from
r i ver mouths. Sect i on 4 , mo st of which represents ri ver­
i nfl uenced wa ters , s hows mo st cl earl y the outfl ow of n i tra te
at the s urface , over l yi ng deep er , n i trate- poor water . Farthe r
o ff s hore , the deepest s tati ons show t h e h i ghest n i trate val ue s
o f a l l toward s the bottom .
Some o f these fea tures a re shown aga i n i n s i ngl e s tat i on
depth curve s i n F i g ures 9 and 10 . I ncrease i n n i trate wi th
depth i s the ma i n trend a p pa rent in Fi gure 9 , at l east i n mos t
o f the o pen-water s tati ons . I n the upper ri ght corner o f the
fi gure , December and Apri l -May observa t i ons in and near
Kugma l l i t Bay s how the h i gh s u rface val ues a s s oc i a ted at l ea s t
partl y wi th Mackenz i e Ri ver outfl ow . I t i s i nteres t i n g that
s ta t i ons 3 and C in the same fi gure , both s amp l ed a l so i n
the Apri l - May period , and both evi dentl y out s i de the ma i n
i nfl uence of the Mackenz i e Ri ver ou tfl ow to the sea , had much
l ower n i tra tes nea r the su rface than the other ear l y spri n g
s ta ti on s . They probably i l l u s trate c l os e to max i mum n i trate
l evel s resul ti ng from i n s i tu repl eni s hment o ver wi nter . Deeper
1 40 0
1380
13 6 0
_ __
7 0 0 -I
1.7
o
,
f)
'.
f)....... -.
/ .
f)' ...
f)
"
I
I f)
,
........ 1.4f),1
�-I'
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17.5
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.... 10- .......
",
,
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....2
If)
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)
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...... f)
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- - .,.; .
tt:> .�
.
I
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1.9
.....
13 0 0
0
0.2
•
•
0.2
0 ·8
0°
13 2
0.2 •
. N03-N
(mg - at /m 2 )
upper 5 metres
• 20 - 27/7/19 73
• 19/7 - 2/8/1914
f) 27/8 - 2/9/1974
26/4-10/5/1975
o 17/6-18/7/1975
7 10
1 340
o
I-'
-.....J
�
•
q;r
-4
C?
N
Fi gure 7 . Ni trate i n the uppe r 5 me tre s . Underl i ne d numbe rs , earl y s p r i n g val ues ,
do not conform to the pa ttern s hown by i some tric l i ne s .
\)
]\
�
540
0 .\
• \
m et res
20l
1974
1973
.
\ ,
542
541
•
\i-�.5=•.:
'- 1
.
, .
\
,
\.,
3
•
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,
40
,
.
\.
.,
556
.
557
.
...
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)
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. 1
. - . --.,.. \
"
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-
,
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CD
.
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. ,.
- 5-- ...., \
, \
•
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/-9 .......
.\
· // .
60
•
80
.
·
9
\
\
\
\
\
,
.
I (-/
•
.
547
548
549
.....
•
•
•
•
1 -�
"
......
.......
\
",
,
-
10 -
/
. ,.
.
,,0,. /
.
.
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8.
.....
"-
......
531
532
533
•
•
•
•
•
•
•
•
•
\
·
/
0 ....
.....
.-
2....;(..
/
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3
,./
/
•
,
531
•
"
......
'"
co
.
\
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\
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,
NO3 -N
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12 •
t
120
Figure
530
I-'
-
•
.
529
528
,
•
100
527
" ...... 2
.
,
•
'
1973
1973
1974
553
554
Nitrate profiles along
5
lines of stations .
19
4
I
6
�
I
74-562
I
564
8
10
I
•
5-562 .
10
B
30
50
567
80
Fi gure 9 . Ni trate curves , s ha l l ow s ta t i ons .
o
o
r
'/
)Jg-at I
2
4
6
10
8
metres
100
"7'l_
• u
12
542
,
,
,
,
,
,
\
200
300
,
\
\
14
\
\
\
NO3 -N
500
r-
�
,-----.,- ----.---
----.
\
\
\
\
\
N
o
\
I
I
,
400
700J
16
--.--
T
--------.--------,-
;
- ........
175-567
/
I
",,/
----.---
Figure 1 0 . Nitrate c urves , deep stations .
/
I
I
I
I
/
�L
21
wa ters ( F i gure 10) show ni tra te rea c h i ng to near 1 6 ug-at/ l .
Max i mum l evel s seem to occur between 100 and 200 metres , wi th
l ower l evel s be ing found i n st i l l grea ter depths .
6. 5
Phospha te
The hori zonta l d istr i but i on of p hosp hate is l ess
satisfactori ly expl a i ned than that of n i tra te , a bove . There
is evi dence of a pa ttern ( F igure 1 1 ) showing h i ghest surface
va lues cl osest to the ri ver outl ets dur i ng the open-water
per i od . At the same t i me , stati ons farthest from the shore
also showed .high l evel s near the surface , wh i l e nearl y a l l
sta ti ons i n between had l ess surface phospha te , many of them
wi thout any measureabl e quanti ty at al l . Ri ver contri buti ons
are ind i cated a t l east i n Jul y and August . However , in Apri l
and ear l y May , a t stati ons near Tu ktoyaktu k , phosphate i n very
sha l l ow coasta l wa ter was l ow i n every sta t i on measured
suggest i ng that ri ver-contri buted phosphate was scarce . At
that t i me , ri ver fl ow was pro babl y a t i ts mi n i mum for the
year , or at a bout 10% of ma x i mum fl ow wh i c h devel ops fa i r l y
qu ickl y in l a te May . However , a t the same ti me , p hospha te
near the surface a t stati ons farther from shore was rel a ti vel y
h i gh (see Figure 1 1 , underl i ned numbers ) . Most of those
stati ons were effecti vel y outs i de the area of rea d i l y
detecta b l e Mackenzi e Ri ver i nfl uence a t that ti me , and must
therefore have gained phosphate in the upper l ayers ma i nl y as
a resu l t of rep l eni shment wi t h i n the sea .
Profi l es of l i nes of sta ti ons (arranged as in Fi gure 8 )
are shown i n Fi gure 12. In this there i s no thing l i ke as cl ear
an indi cat i on of ri ver- contri buted nutri ents as there was for
n i trate at the same stati ons . Ra ther , the ma i n effect of the
figure is to show fa i r l y regul ar i n crease in phosphate wi th
depth . Th i s figure and the next two i l l ustra te the far sma l l er
range of phosp hate found here (mean high val ues around 4 or 5
ti mes the mean l ow val ues ) than of n i trate val ues in the same
waters (a comparabl e rati o of more than 10 to 1).
In F i gure 1 3 , the wi nter and near -shore spr ing stati ons
are shown i n the upper l eft corner , the area of l ow phospha te.
So are o bservati ons from the surface of the Apr i l -May sta t i ons
ta ken just outs i de Kugmal l i t Bay (sta ti ons B and 2 ).
Other
Apri l -May stati ons from farther from shore show muc h h i gher
surfac e l evel s (stati ons 3 and C) .
Deep stati ons show
( Fi gure 14 ) max i mum va l ues of a bout 1 . 6 ug-at/ l between 100
and 200 metres , and a dec l i ne to a bout one ha l f that quanti ty
at 500 to 700 metres .
1380
1400
1300
I
2.70
13 2 0
1340
1360
•
P04- P
710 -U
(mg-at/m 2)
upper 5metres
• 20 - 27/7/ 1973
• 19/7- 2/8/ 1974
f) 27/8 - 2/9/ 1974
26/4- 10/5 11975
o 17/6-18/7/1975
--
01
•
o
70°
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f)
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°3.25
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5 83
.
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-- - 2
.2.10
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--- - - I
05
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---". 43
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f)
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1280
.
•
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,
{- -,
.
2.35 r
�
Go
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(()�!:J:: .
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.
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Fi gure
11.
C?
N
\)
Phosp hate i n the upper 5 metres . Under l i ned numbers , ear l y spr i n g va l ues ,
do not conform to the pattern shown by i sometri c l i nes.
Ole
540
·
·
542
541
*', .
\
.....
.
;0.5_.
metres
20
o
/
/
40
/'
/1 •
•
60-1
80
100
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.
557
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553
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Fi gure
531
.
.....
\.
•
f\
548
0
•
•
0 / 0
•
0
•
0-0-0""
549
1973
1973
1974
1974
1973
12. Phospha te prof i l es a l ong 5 l i nes o f stati ons .
N
w
o
o
0.6
0.8
1.0
10
metres
20
N
.j:::>
30
40
50
P04-P
60
Fi gure 1 3 . Phos p ha te curves , s ha l l ow s tati ons .
o
0 '
1
ug- at
/I 0.2
,
'
0.4
'
0:6
'
,.�
�
0.8
�
___
1.0
1.2
I
I
1.4
I
1.6
I
7 3-542
metres
100
200
"-'�7
P04-P
300
7 5 - 56.6
400
N
U1
75-568
500
�
t
700J
T
--
Fi g ure
l
---r
\
�L
75-567
�- -
T
14. Phosphate curves, deep stati ons .
26
6. 6
S i l i cate
A very clear pattern i s shown i n the hori zontal
d i stri buti on of s i l i cate fo und near the surface of the
south Bea ufort Sea ( Fi g ure 15) . H i ghest values are
proba bly assoc i a ted wi t h Mackenz i e Ri ver flow , lowest w i th
o ffshore waters o u ts i de the area o f pr i mary r i ver i nfluence.
I t i s certa i nly s i gn i fi cant that while the other n u tri ents
measured , especi ally n i trate , were consp i cuously more
abundant i n the wa ters near the surface i n Apr i l and early
May than they were i n s i mi lar depths a t other ti mes o f the
year , s i l i cate i ncreased only sl i ghtly at that ti me ( underli ned
n umbers i n Fi gure 1 5 ) .
Evi dence o f r i ver-contr i buted s i l i c a te to the surface i s
stron gly shown i n Fi gure 1 6 , espec i ally i n secti ons 1 and 4 .
As was shown for n i trate and phosphate , there was a layer o f
mi n i mal values below the surfa ce , below wh i c h q uanti ti es
i ncreased towards the bo ttom . Unlike wha t was fou n d for both
the other n utri ents , however , q uanti t i es i n deep water were
not grea ter than the ma xi mum amo unts found near the sur face .
They were i n fac t cons i derably less . Th i s i s shown i n
Fi gures 1 7 and 1 8 . I n Fi gure 1 7 , late wi nter values near
shore were h i gh , h i g her than at sta ti ons taken progress i vely
farther from the ri ver mouths (stati o ns B and 3 ) , wh i c h
s howed l i t tle d i fference from open-water values of summer .
Ma x i mum values benea th the surface ( Fi gure 1 8 ) of about
40 u g- at/l occurred between 100 and 200 metres a nd were less
tha n the h i ghest s urface f i g ures o b ta i ned . Below 200 metres ,
levels decli ned to a bout 1 0 ug-at/l at 700 metres .
6.7
Oxygen
Dissolved o xygen i n t he south Beaufort Sea (Fi gure 19 )
showed a pattern o f d i str i b ut i on i n wh i c h the lowest values
appeared adjacent to the Macken zi e delta , a n d the hi ghest
farthest from shore i n the upper 5 metres . A ran ge of oxygen
values of 6 . 7 to 7 . 8 mlll i n the u pper 5 metres o f the waters
adjacent to the Macken zi e delta i n la te July i nd i cated low
levels for the t i me o f year . At the same t i me , satura t i on
values were low , all less than 1 00%. I n t he offshore waters ,
a verage quanti ti es i n the upper 5 metres exceeded 9 mlll and
1 1 7% sa turati on . Th i s ra ther ti dy p i c ture was d i srupted
somewha t by the da ta obta i ned i n 1975 ( c ollected and measured
by the Mari n e Sci en ces Di rectora te , V i c tor i a , B . C . , and not
i nclu ded i n Fi g ure 19 ) . Oxygen levels taken at stati ons
north of 70 ° i n early Aug us t , only a very l i ttle la ter by the
calendar than those measured i n 1974 , were found to be much
lower . Average values for the u pper 5 metres ran ged from 7 . 4
1 38°
140°
1 34°
136°
132°
130°
18
Si
(mg- at/m2)
upper 5metres
7 1° -I • 20 - 27/7/1973 • 19/7- 2/8/1974
() 27/8- 2/9/1974
e 26/4-10/5/1975
<> 17/6-18/7/1975
1
<>
70 0
•
16
__
<>
•
() 163
/
<>
() I
100
/"
'.!2!.
e
---1-
-_
37 •
- - 50-- --1- --_ 5
1 -•
()
/
I
()
1-
•
() /....
()
12 8°
,
/ ..!!!.
111
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I()
()
143 '·
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/.146
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.
-100 - -
134
()
.11 02
' -� /
,/
N
-......J
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•
()
-4
Fi g ure
15. S i l i cate i n the u pper 5 metres .
c::?'
N
Underl i ned numbers show early spri ng va l ues .
\)
·• \
•
•
•
•
•
•
553
554
557
556
549
.
,
'30
• 20,.
-'"":::..
-10--_
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-
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I
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120
i
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1--20 :
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o
o
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52 7
529
528
.
.
30-. -20 .­
.....
o
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.
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530
.
i""
( e
-
531
531
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.... -20
e "­
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533
532
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10
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,
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547
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100
/
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548
/e
o
\.
\
I. \
•
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--i
80
•
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e
I
I
..... ,
•
1973
1973
1974
1974
1973
,
\
\
,
\ e
N
co
I
\
\
\
\
\
Si
\
\
0
•
F i g ure 1 6 . Sili cate prof i les alon g 5 li nes o f s tati ons .
o
IJg-at/1 10
L-___._
_ _____
°1� I
�
_
1- _______._____ _
30
20
I
-.-1.._
I
80
70
60
I
1----\./
1
10
50
40
...J..
.I
I
•
563
.,
564
:
;
metres
20-i
I
,
I
I
30
l
\\�
1�
Si
N
�
14
i
40�
I
533
I
I
I
5
I
�
J
--- -.--------,------,-------_._------,.,----
.
--
T--------------,----------�------.
F i g ure 1 7 . S i l i cate curves , s h a l l ow s ta t i on s .
30
o
o
I
J..Ig-at/1 10
1
20
I
30
{
40
I
50
I
100
metres
200
300
400
500
600
700
75- 567
800
,------,- ·-·
-rl------,--r---.
Fi gure 18 . Sil icate curves , deep station s .
1380
1400
I I
OXYG EN
(mean m ljl)
upper 5metres
710 -l-J . 20 - 27/7/1973
• 19/7 - 2 /8/1974
� 27/ 8 - 2/9 / 1974
o 17 / 6-18/7 / 1975
70 0
-I
I
_
0
�
. . ' ....
. ' ' . ' �.. : : :.: . . :.:..>:.
.... ' ', :
� }
/.
....
•
•
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./
/
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9/
•
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.,. ,../ .//
/
/
I
I.
I
I
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I
0
....
,
))
•
.... 10- ....
........ 8-,
/
1280
1300
1 32 0
1340
1360
......
�
�
�
•
/
9'
/
1
I
I
/
•
•
•
.' " /o
/\ 8/
,.. .,. / .J/ •
,
.
W
I-'
,.. '
I...
7,
I1 •
I
I
·f
..t1
c::?
/II
\)
Fi gure 19. Oxygen i n the upper 5 metres.
32
nl1/1, all less than the 9i values found the
year befo re and o n l y a month or so previ ous l y i n the same
ye a r . Qui te apparently these fi gures refl ect the i ce cover
effects of the two summers and the di fferences i n t i mi ng
of oxygen producti on in the s ame two yea rs .
to about 8.5
Vert i c a l pro fi l es o f indi v i dua l s ta t i o n s ( Fi gures 20 and
2 1 ) s how genera l l y depressed s urface quanti ti es and i ncrea s e
i n o xygen wi t h depth t o 10 o r 20 metres ( to 10 ml / l a n d more ) ,
bel ow wh i ch oxygen dec l i nes. Thi s d i mi n i s h i ng trend conti nues
downward to between 200 a nd 300 metres , a nd to between 6 and
7 ml / l . In deeper wa ters , val ues r i s e once aga i n .
6.8
Chl orophyl l
Hi g he s t c h l orophyl l a l evel s were found i n Mac ken z i e
and Kugma l l i t Bays , l owest i n the northea s t sector o f the s t udy
a rea , i n the upper 5 metres ( F i gu re 22 ) . The h i ghes t val u e s
at s i n gl e s ta t i ons were u s u a l l y fo und in t h e upper 5 metres ,
rare l y deeper than 1 0 metres . At 50 metres and deeper , l evel s
were usual l y l e s s than 0 . 1 mg/m3• Val ues at al l depth s were
l ow by northern coastal marine s tandards , and wou l d seem to
denote l ow s tanding stocks of p hytopl an kton ( s ee Beaufort Sea
Project Techni cal Report #1 2b ) .
6.9
Sea i ce b i o l ogy
The con sti tuents of the sea i ce cover o f the Beau fort Sea
were not exami ned , but some wo r k of th i s k i nd wa s done as p a rt
o f a l ong-term s tudy i n the nearby E s k i mo La kes , and some o f
the Es k i mo Lakes find i ng s are presented h ere . A fundamental
di fference be tween the i ce cover of the Esk i mo Lakes and muc h
o f the cover over the south Bea u fort Sea concerns thei r ages
and thi c knesses . The Es k i mo La kes general l y become total l y
free of i c e dur i n g s ummer . The i ce cover therefo re during most
wi nters i s f i rst-year growth , fa i rl y even l y devel oped and w i t h
a rel a ti vel y smooth s u rface . Thi s covers al most the enti re
a rea of the E s k i mo La kes . In contra s t , the Beau fort Sea ,
espec i a l l y a s seen i n 1975 , does not nece s sari l y l ose a l l i ts
i ce i n summer . The i ce pac k , from the p rev i o u s wi nter and
before , may dri ft southwa rd rea c h i ng fa i rl y c l ose to the c o a st
during autumn when new i ce i s fo rmi ng . I f the i n i t i a l wi nter
s urface forms in thi s way , the i c e cover may be compr i sed to
a si gn i fi cant degree o f ol d i ce , rafted , o verturned and th i c ker
by fa r than the i ce of the yea r . I n no way can measurements o f
features i n and o n the l ower s urface o f annual i ce be
extrapol ated to a rea s of o l d and thi c k i ce o f un known h i s tory ,
abou t the b i o l ogy o f wh i c h we know al mos t nothing . The Es k i mo
33
6
0
mill
8
7
9
10
_
J
1
metres
10
20
30
40
60
70
12
542
80
Fi g ure 20 . Oxygen cu rves , shal l ow s tati ons.
34
0
6
mill
7
8
9
10
r
1
metres
I
100
I
I
I
I
I
400
700
75-567
F i g ure 2 1 . Oxygen curves , deep s tati ons .
140 0
710
--+-1-_
138 0
Chlorophyll a
(mg / m 2 )
upper 5metres
II 20 - 27/7/1973
• 19/7-2 /8 /1974
() 27/8 - 2/9/1974
° 17/6-18/7/1975
� 4/8 - 9/8/1975
13 6 0
134 0
132 0
13 0 0
128 0
0.61�
0.38""
0.42
"
"
•
4.29
.......
°
.......
....... 1
....
•
•
70 0
•
--
�
1.08
2.00
�
5-- -
•
-
�
2 .01
II!III
.
/
,/
I
\
/
1.20
..........
/
/
/
I
3.36
/
.
.....
........
1- -
/0 �1.83
--
W
(-',
I
4.96
' .... _!!­
rJ1I'""
1.95.
r
/
I
I
.
..q
Fi gure
22. Chl orophyl l
� i n the upper 5 metres.
I:::?
N
\)
36
o
1
'---___________-..1___________
74-14
_ _ _ _ ___ _
________
74-23
3
2
...L.___ _
--,---- ----------------'
73-527
74-29
10
50
70
74- 9
74- 2 2
Fi gure 2 3. Chl orophyl l � curve s , sel ected s tat i ons.
37
Lakes ice study therefore ca nnot stand in p l ace of a thorough
Bea ufort Sea ice study. It may give us some indication
however of conditions fou nd in the new , first-yea r Beau fort
Sea ice , formed a nd remaining in a fairl y sta bl e position, s ay ,
al ong the outer edge o f Mackenzie Bay o r a few mil es off
Tuktoyak tuk Penin su l a .
In the spring of 197 3 , Eskimo Lakes sea ice reached a
t hickne s s of a bout 170 cm, beneath a s now cover whic h proba b l y
did not exceed 15 cm a l l winter . The snow dis appeared from
the ice surface at abo ut the end o f the firs t week o f June ,
and the ice cover had gone from the Lakes by a bout the beginnin g
of t h e l as t week o f June . I t wa s a fairl y earl y breakup .
Chl orophyl l a wa s measured in t he ice on 24 November , 2 3
February and-19 May (Figure 24) , � n d o n the three dates was
found a s 0 . 3 0 , 0 . 73 a nd 4 . 47 mg/m of ice surfa ce . On the
l a st date of sampl ing , horizo ntal s tra tification had deve l oped
s trongl y , and a concentration equiva l ent to more than 50 mg/m3
wa s found in the l ower 1 0 cm o f ice , a t the same time a s l es s
than 1 mg/m 3 wa s found a t the top o f the ice . During the period ,
c h l orophyl l a was l ow in the water benea th the i ce , p resent as
o n l y a sma l l -frac tion o f the quantity found i n the ice .
Measurements of nitrate , p h o s p ha te a n d sil icate were a l so
ma de on the s ame date s ( Fiqure 24) , and they s howed u l timate
d evel o pment to 1 . 1 mg-at/m2 o f nitra te , 0 . 58 mg-at/m2 of
phosphate and 2 . 5 mg-at/m2 of sil ica te in the ice . Nitrate and
sil icate were increa sing during that time in the water from
which the growing ice formed , and q uantities of both can be
more than a ccou nted for a s having been frozen into the ice a s
i t grew . Pho sphate , howeve r , was fa r l es s pl entiful in the
water than the ice l evel s wou l d sugge s t it s houl d be , and the
buil d-up o f phospha te in the sea ice cannot be readi l y exp l ained
at the present time .
These figures s how a devel o pmen t of c h l orop hyl l in the
ice within an environment containing nutrients and , concl uded
from the ice and s now cover thicknes s at the time of the May
sampl ing , sufficient l ig h t for p l a nt photo synthe sis . At the
time , in the Eskimo Lakes , t he re was no apparent p l anktonic
p l ant p ro duction underway beneath the ice ; that came l ater ,
a fter the rel ease o f the ice-bound pl a nts to the water col umn
as the ice mel ted . We do not have sufficient data from the
Beaufort Sea a t t hat time o f yea r ; it seems l ikel y however , at
l ea s t in the firs t-year ice , that p l ant p ro duction occurs
within the ice , hence tha t the s ea ice supports a vita l fl o ra
which , a s s hown el sewhere , sustain s a n under-ice faun a a nd
enters the s ea a s ice mel ting takes p l ace in l ate s pring or
earl y summer .
24/11/72
o
em
+
(0.30)
+
24111/72
I
---1
::: :::::::8}f:r :::�:; : ::::t:::ii;�;�:�:�t.,Ai:){�:���t:�:�;:.;:Ib)r�\. : : : ;: : : ::::;:,.:.:..::,:::::..:\�{��:�:����
I
+
(0.73)
19/5/73
+
(0. 9 )
(1.1)
I
I
•
(4!47)
I
/
Ch.
(0.3)
.
+
a
/
/
//
1 .....
1 -t.........:
.".,. .... .,
­
.
... ./
_..50-+'"
�.
-=.:;;;...
-
(mg 1m 2 )
N0 3 - N
.;.::::::::::mf:::::�:::::�:�:f�:��@���m���;��{���tm?�I���Ij}� �I��Ij!�fIf�m)m\�����;j��j�m);�;mj j�����j;�f�����rn����=!-�
�;.:.:
23/2/73
..... ---
150
em
__
I
100
o
19/5/73
23/2 / 73
I
+
(0.�4)
t
(0..S8)
•. � ...
._
: :: :
�;.:.:.:.:.:.::::::::: :
(mg-at/m2)
::r:;·:;�r:}?�:::;:r;i��.::)� :;:;.: �:�: .��:� :f�m;(��:t�I?Ir�:=T::::::��:::;8��:,:••
t
(2.S)
(2!6)
100
150
,.,'
........ 1.....+.. . . . ....:
P04 - P (mg-at/m2)
_
Si
..",.
8-f.
..'
."". :-
..
. .
(mg-at/m2)
Figure 24. Diagrammatic sections of the ice and snow cover, Eskimo Lakes, showing chlorophyll
and nutrients as total quantities in the ice (bracketed numbers) and as mg/m3
(unbracketed numbers).
.
w
co
39
6 . 10
Zoopl an kton
Col l ect i ons o f z oop l an kto n reported here or i gi nated at
near l y 100 s tat i ons s hown in Fi gures 2 5 to 26. At l ea s t 92
spec i es are i ncl uded in these co l l ecti ons , and they are
l i s ted i n Tabl e 1 . For zoop l an kton d a ta , s ee Gra i n ger and
Grohe ( 1975 ) .
Number s o f speci es ta ken a t s i n g l e col l ecti on s tat i o n s
are s hown i n Fi gure 2 7 . The s ma l l es t numbers ( 3 a nd fewer)
were found i n the east channel mo uth o f the Mac kenz i e Ri ver ,
i n Kugmal l i t Bay , and j u st north of Ri chard s I s l a nd . Sl i ghtl y
1 arger n umbers were fo und i n Ma c kenz i e Bay and Li verpoo 1 Bay .
I ntermed i a te n umbers were found i n t h e c entre and t h e l argest
number s ( 14 spec i es a nd more) near the wes tern a nd
northwes tern l i mi ts o f the s tudy area . There were a l mo s t
al ways more spec i es found bel ow 50 metres than a bo ve . The
h i gh d i ver s i ty at the s tati o ns farthes t from s h ore appl i e s
onl y to the waters bel ow 5 0 metres at tho se l ocati o n s ;
cons ider i n g the upper 5 0 metres on l y , the offshore s tati ons
fa l l in the same category as the i ntermed i ate ones on the
grounds of spec i es n umber s .
Expres sed a s n umber o f copepod i te spe c i mens per c u b i c
metre o f water samp l ed , t h e resul ts s how a somewhat d i fferent
p i cture . In th i s presentati on (Fi gure 2 8 ) , s tati ons farthest
from s hore and tho s e c l osest to the Mac kenz i e Ri ver s howed the
fewest organ i sms per uni t of water s ampl ed . Hi ghest n umbers
were fou nd o ff Tu ktoya ktuk Peni n s u l a (more than 1 000 organ i sms
per cub i c metre) i n Mason and Li verpool Bays , and i n termed i a te
numbers i n the middl e l a t i tudes .
Combi n i ng the i nforma ti on i n these two fi gures s hows that
the very shal l ow s tati ons cl osest to the Mac kenz i e had the
sma l l es t s tand i n g stocks and the sma l l e st spec i es d i ver s i ty .
Deep s tat i o n s farthe s t from s hore a l s o had smal l stocks
(re l ati ve to water quant i ty sampl ed) but they s howed the
greatest spec i es d i vers i ty , ent irel y bel ow 50 metres .
Stat i ons i n L i verpool Bay and Ma son Bay and off Tu k toya ktuk
Pen i n s u l a s howed the l argest stand i n g s to c ks a nd rather
var i a b l e d i ver s i ty , rang i ng from l ow to med i um (fewer than
3 to at l ea s t 10 spec i es) . Genera l l y , stati ons in the centre
of the study area were i ntermed i a te i n both quanti t i e s .
Stat ions i n deep wa ter farthest from the s hore and the
Mac kenz i e Ri ver i nfl uence s upported the greatest number of
spec i e s . Stati ons i n i n termed i a te depths between the
i nnermos t and o u termos t s tati ons s upported the l argest n umber
of speci mens , and probabl y the l arge s t b i omas s per un i t of
water sampl ed .
1 40 0
710
1 380
1 3 40
1 360
\
\ e12
--f
5 6 70
0570
\
5 72
<)
1 28 0
1 3 00
1 32 0
5 73 �
9
_.! 3 .
5 32 . \\\
7 ei
e 544
e 545 531 . .
�
\
,
034 fC'
38
�
.-"
5�
/
�J013
o
53 5
•
F i g ure 25 . Sta t i ons wh i c h provi ded zoopl ankton data .
�
o
41
... •..
74°
1 7.
B A N KS
1 6.
18
•
14
IS L A N D
•
. " ,:.
A MUNDSEN
GULF
Fi gu re 2 6 . Stat i ons whi ch provi ded zoopl a nkton data .
42
Ta bl e 1 .
Zoopl a nkton specie s repo rted here from the south Beaufort
Sea .
HYDROZOA
Eumedusa birul ai ( Linko)
Sarsia princeps (Haeckel )
Hal itho l u s cirratus Hartl a ub
Euphysa f l ammea ( Li nko)
Obe l ia sp.
Mel icertum octocos tatum (M. Sars)
Tiaropsis mul ticirrata ( M. Sa rs)
Ag l antha digital e ( 0. F. MU l l er)
Aeginopsis l au renti Brandt
Dimophyes arctica ( Ch un)
Mu ggiaea bargmannae Totton
ANTHOZOA
Larvae
CTENOPHORA
Beroe cucumis Fabricius
N EMATODA
Unidentified
MOLLUS CA
Spira tel l a hel icina (Phipps)
Cl ione l imacina (Phipps)
ANNEL I DA
Pe l a gobia sp .
Pol ychaete l a rvae
BRANCH I OPODA
Daphnia sp.
Podon l euckarti G . O. Sars
Bo smina sp.
OSTRACODA
Con c hoecia bore a l i s maxima Brady
&
Norman
43
Tabl e 1 .
( Cont i nued )
COPE PODA
Acartia cl aus i G i e s brecht
Acar ti a l ongi remi s ( Li l l j eborg )
Ch iri d i u s obtus i frons G . O . Sar s
Derj ug i n i a tol l i ( L i n ko )
Ga id i u s ten u i spi nus ( G . O . Sar s )
Ca l anus cr i s tatus Kr¢yer
Cal anus g l aci a l i s Ya schnov
Cal anu s hyperbore u s Kr¢yer
Limnoca l an u s macrurus G . O . Sar s
Di aptomus sp .
Eucal anus bung i i bungi i Johnson
Euchaeta gl aci a l i s Hansen
Heterorhabd u s norveg i cu s ( Boeck )
Metr i d i a l onga ( Lubbock )
Me tr i d i a pac i f i ca Brods ky
Drepan opu s bungei G . O . Sars
t�i croca l anus pygmaeus ( G . O . Sar s )
Pseudoca l anus mi nutus ( Kr¢yer )
Sp i noca l anus l on g i corn i s G . O . Sar s
Scaphoca l an u s brev i corni s G . O . Sars
Scaphoca l an u s magnus ( Scot t )
Scol eci thr i cel l a mi nor ( Brady )
Ep i schura sp .
Eurytemora herdmani Thompson & Scott
Temor i te s brevi s G. O. Sars
Ect i no soma negl ectum G . O . Sar s
Mi crosete 1 1 a sp .
Pseudobradya m i n or ( T . a nd A . Sco tt )
Harpact i cu s s uper fl ex us Wi l l ey
Dan i e l s senia s tefanssoni Wi l l ey
Tach i d i us sp .
Ti s be furcata ( Ba ird )
Cycl ops sp .
Cycl op i na schnei der i Scott
Mormon i l l a pol ar i s G . O . Sars
Oi thona s i mi l i s Cl aus
Oncaea boreal i s G . O. Sars
Oncaea mi nuta Gi esbrecht
Oncaea no topu s Gi e s brecht
Monstr i 1 1 a sp .
C I RR I PEDIA
Naupl i i
Cypr i s 1 arvae
MYS I DACEA
Mys i s l i tora l i s ( Banner )
44
Tabl e 1 .
( Cont i n ued )
CUMACEA
Di a s tyl i s rathkei ( Kr�yer )
I SOPODA
Un i denti f i e d
AMPH I PODA
Apherusa gl a c i a l i s ( Hansen )
Ha l i rages mega l ops ( Bucho l tz )
Gammaracanthus l ori catus ( Sa b i ne )
Pseudal i brotus gl ac i al i s G . O . Sars
Monoc u l odes sp .
Pontopore i a affi ni s L i n dstr�m
Acero i des l a t i pes ( G . O . Sar s )
Acantho s tep he i a mal mgreni ( Go� s )
Acanthostephei a beh ri ngi en s i s ( Lo c k i ngton )
Pontogenei a i nermi s ( Kr�yer )
Metopa sp .
Hyperi a gal ba ( Montagu )
Hyper i a med u sarum ( MU l l er )
Pa rathemi sto a byssorum Boec k
Parathemi sto l i bel l u l a ( Li c hten s tei n )
EU PHAU S I AC EA
Thysanoe s s a i nermi s ( Kr�yer )
Thys anoessa ra s ch i ( M . Sars )
Thys anoes sa l on g i pe s Bra ndt
DECAPODA
Sa b i nea septemcari nata ( Sa b i ne )
Pa nda l u s sp .
CHAETOGNATHA
Eu krohn i a hamata ( MBbi us )
Sa gi tta e l ega n s Verri l l
Sa gi tta max i ma ( Conant )
COPELATA
Fri t i l l ar i a boreal i s Lohmann
Oi l opl eura van hoeffen i Lohmann
ASC I D I ACEA
Larvae
138 0
140 0
I
710
I
1 -3
·
•
•
I,
-I
•
,
4-6
7-9
10-1 3
14 17
> 17
1 340
13 6 ?
I
r
?
I
40
-
•
. re i
I
?
70 0 � ,,�
•
. ..� . : .•(....
�
..
•
u
�
•
/.
0 ""'"
--..
•
•
I
•
•
•
•
..
•
•
,
•
tf
r
r
128 0
...!!.. �
•
�
�
•
•
•
•
•
•
130 0
132 0
I •
,
•
)'� . ' . '
. :. ../
..q
Figure
27 .
Number of species of zooplankton at each station . Paired
circles s how numbers above and below 50 metres dept h .
t1.
:
c:?
IV
\)
�
- . . . . ." I
"
.:-.:.
.j::>
U1
1 380
1 400
•
•
•
710 ,
•
'.
1 280
1 320
1
101
101-500
501-1,000
1,001-10,000
>10,000
•
<
I •
•
•
•
•
•
70 0
•
•
•
•
•
•
•
.. /
•
•
•
••
•
•
•
•
.p
...
•
•
•
•
· · ···: · · :: · ·
�(': .
...�� · .· · I
•
(J!fP
\
\
,
(/
,
/' ,
" �- .q
C;?
N
\J
Fi gure 2 8 . Numbers o f zoopl ankton i nd i vi d ua l s per cubic metre .
.j:::>
m
47
One g roup of zoopl an kters cons i s ted of e s sent i a l l y
fres hwater forms o f the genera Daphnia , Diaptomus , Epischura
and Bosmina . They were fo und wi thi n the ea s t c hannel o f the
Mac kenz i e Ri ver and j u st off the d e l ta ( Fi gure 29 ) , i n water
wh i c h wa s v i rtual l y fresh . These a re al l a n i ma l s of fres hwater
ori gi n wh i c h had entered the s ea wi th ou tfl owi n g ri ver wate r .
Cyclops i s a genus of fre s h a nd estuari ne waters .
I t wa s found
here over a fa i rl y l a rg� area u p to severa l mi l e s from s hore
( Fi gure 30 ) i n sa l i n i ty at l ea s t as hi g h a s 12%0 ( few a n i ma l s )
to l es s than 1 %0 (ma ny ) . Thes e organ i sms were l i ke l y d i s c ha rged
to the s ea i n o u tfl owi ng fre s h water . Mysis ( Fi gu re 31 ) wa s
fo und under s i mi l ar ci rcumsta nces , nearl y a l l i n sa l i n i ty l es s
than 1 2%0 , the l argest col l ecti on i n l es s tha n 6%0 ' Eurytemora
herdmani was another w i t h another range , wi th the l arger
co l l ecti on s comi ng from sal i n i ty of about 2 to 1 5 %0 ' Wi th
perhaps a l i ttl e h i gher sa l i n i ty tol e rance than the o thers
menti oned a bove , E. herdmani has reached i nto Li verpool Bay
and the E s k i mo La kes , whe re i t occ u rs i n l a rge n umber .
Two s peci es wh i c h are c ha racteri sti ca l l y found i n mari ne
waters o f l ow sa l i n i ty , but ev ident l y i n a h i g her m i n i mum
sal i n i ty than the spec i e s above , a re Acartia c lausi and Halitho lus
cirratus ( Fi gure 33 ) , fou nd i n a s l ow a concentrati on as a bout
7%0 and a s h i gh a t l east a s 20%0 , and for H. cirratus at l ea s t
perhaps someti mes cons idera b l y hi ghe r .
A very abundant s pec i e s i s Limnocalanus macrurus , a nother
spec i es found c ha racteri s t i ca l l y i n l ow sa l i n i ty , but wi th a
general l y wider range than the speci es a bove , occurri ng i n
sal i n i ty a s hi gh a s 25%0 ( Fi g u re 34 ). Th i s s pe c i e s and Derjuginia
to l l i ( Fi gure 35 ) outl i ne a pparently q u i te wel l the Mac kenz i e
ri ver p l ume . D . tol li i s s l i ghtl y l es s tol erant than L . macrurus
o f e spec i a l l y l ow sal i n i ty , so i s a b s ent from i nnermost Mac kenz i e
and Kugma l l i t Bays ; both however extend to about the same
sa l i n i ty max i mum .
Severa l spec i es are c ha racteri s t i c of so-ca l l ed Arcti c
Surface water , that i s water wh i c h o r i g i nates a t the s urfa ce
of the Arct i c Ocean , where i t occu p i e s the upper 200 to 300
metres , and wh i c h extend s a rcti c mari ne i n fl uence southward
by fl owi ng amon g the i s l a nd s of the Canad ian Arcti c Arc h i pe l ago
a nd down the east coa s ts of Green l and and ma i n l and North Ameri ca .
These speci es , i l l u s trated here by Ag lantha digitale and Calanus
g lacialis ( Fi gures 36 and 37) , ran ge from the o utermost stati o n s
toward s s hore . They are s e l d om i f ever found i n bays or i n a ny
other l ocati on wi th sal i n i ty l ess tha n a l i ttl e bel ow 20%0 '
Wh i l e al l the s pec i es of l ow sa l i n i ty referred to a bove a re
fo und i n s ha l l ow and s u rface waters , these arc t i c s u rface spec i es
are present near the surface i n o ff s ho re arcti c water s , but they
1400
I
710
70 0
1 380
o Dap h n i a sp.
o
Diaptomus s p.
l:!.
Epischura sp.
1340
1 36 0
1 300
1 320
1 28 0
<> B os m i n a sp.
1
.j:::o
co
t
.p
<?"
AI
c::P"
N
\}
Fi gure 29 . Fres hwater zoopl a nkto n i n the Bea ufort Sea .
1 380
1 40 0
710
70 0
:
" -.,'
-I
1 340
1 36 0
1 300
1 32 0
128 0
I
\1
Il---L---+----;.--- t--23� )
2
•
2
54
-
•
.p
23
•
•
+:>
�
t
r
4
Cyclops sp.
c::7
N
\J
Fi gure 30 . The di stri buti on of CycZops .
1400
710
700
1
-/
1 38 0
13 6 0
1 340
I
I
I
1 280
(.J1
o
-;
•
•
1 30 0
1 320
•
18 ,
tr
•
•
<4
Mys i s s p .
Figure
3 1 . The dis tribution of
<!::7
N
\)
MYsis .
1380
14 00
71 0
�
13 6 0
I
1 340
132 0
I
\
13 0 0
128 0
3
•
70 0
-I
•
(J1
I-"
... l'
.
•
.
' .
14
.
. tt
�
14
c:?
..q IV
E urytemora herd mani
\)
Fi gure 32 . The di stri but i on o f Eurytemora .
1380
1 4 00
7 10
70 0
13 6 0
1 340
1 28 0
13 00
132.0
�
I
-,
h
i
q
"
o
. ',' :.<;;.� .:-
•
..q
Acartia c lausi
Hal itholus c i r ratus •
Fi g u re 33 . The d i stri bution o f Acartia and Halitho lus .
t!::::?
N
'J
\1
71 0
1 360
1 380
14 0 0
I
•
. . . .. · : .·.�
. . . . ':'.:;... . :�
9 19
� 47 .�
•
•
. .
•
•
•
•
rr
. f?
�
•
•
8
28
1 28 0
•
29
175
268
164. r72 39 ·
15
8 107 655
4 93
70 0
1 30 0
1 320
I
I
_I
1 340
<.TI
W
_ ....
.:r
198
4
L i mnocalanus macru rus
Figure 34 . The distribution of LimnocaZanus .
c:?
N
\)
1 380
14 0 0
71°
-f
I
1 36 0
1 340
1 320
I
\
1 30 0
1 28 0
5.
1 .1
9.
1
".
,
2
2
•
•4
��
1
•
•
8•
(J"1
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•
1
•
�
-4
Oerjug i n i a tol l i
Figure 3 5 . The distribution of Derjuginia.
c::?
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\)
1 38 0
1 40 0
2.
i.
7 1 0 --'"
1
•
5•
9 I
•
5•
•
70 0
4.
I
•
•
.����.�
2
•
1.
•
4.
•
1
•
.p
·3
�
•
•
•
3
1 28 0
1 30 0
1 320
1 340
1 36 0
•
•
•
-
1 4•
•
8
•
U'1
U'1
-.
r
-
�
Aglantha d i g itale
Fi gure 3 6 . The d istributi on of AgZantha.
c:::?
N
\j
13 6 0
1380
1 4 00
13 0 0
132 0
1 340
2
710
_1
7
_
I-
4_
.
-
-
15
27
-
1
-
128 0
-\
-
8
-
•
(.J1
CJ\
•
' .
4
-
10
�
Calanus g l acial is
C?
N
\J
Figure 37. The di s tribution o f CaZanus .
57
a re found deeper beneath waters o f l ow sal i n i ty or h i gh
temperature (a bove 8 to 10 ° C ) .
Another group of s pec i es i s c haracteri s ti c of deeper
Arctic Ocean water , the At l ant i c l ayer wh i ch l i es beneath
the Arc ti c Su rface l ayer , extend i ng from 200 or 300 metre s to
around 900 me tres . These s pec i es o f course are not frequentl y
fo und i n coa stal waters , a l though i s o l a ted i nd i v i dua l s do
ri se a bove the At l anti c l ayer . The spec i e s o f th i s grou p
i denti f i ed i n thi s s tudy i ncl ude Chiridius obtusifrons , Gaidius
tenuispinus , Heterorhabdus norvegicus ( Fi gure 38 ) , Spinoca Zanus
sp . , Scaphoca Zanus magnus and Sco Zecithrice Z Za minor ( Fi gure
39 ) . Al l were taken i n sma l l n umbers onl y .
The fi nal gro up i ncl udes Pac i f i c s pec i e s , whi ch are
des cri bed a s enteri ng the Arcti c Ocean through Ber i n g Stra i t
from the Paci fi c . Th ey occur i n the Chukchi Sea and eas tward
i n the Bea ufo rt Sea a s fa r as t he l ocati ons s hown here ( Fi gu re
40 ) . I nc l uded are CaZanus cris tatus , Euca Zanus bungii and
Metridia pacifica . They too, occurred on l y i n smal l n umbers .
7.
D I SCUSS I ON
The coa s ta l waters o f the south Bea ufort Sea s how what i s i n
many ways the typ i cal ri ver mouth s tructure o f wa ter o f l ow sal i n i ty
and of r i ver ori gi n over l y i ng water of h i gher sal i n i ty of offs hore ,
ocean i c ori gi n . The river water i s contri buted by the Ma ckenzi e ,
and the underl yi n g ocean i c water by the Arct i c Ocean . The vari abl e
bal ance between these factors determi nes much of the bas i c b i o l ogi cal
character of the south Beaufort Se a .
One o f the c ha ra cteri sti c fea tu res o f arcti c wa ter s i s the
presence of a sea i ce cover duri ng a l arge part of the yea r . Ice
cover cond i t i on s i n the Beaufort Sea are nota b l y va r i a bl e , and
espec i a l l y wel l i l l us tra ted by cond i t i on s preva i l i n g at var i o u s
ti mes o f t he norma l open -wa ter season duri ng the l as t 3 years . Th e
i mportance of the sea i ce cover on the b i ol ogy of the sys tem i s
a s soc i a ted wi th the e s ta b l i s hment of a 3 -d i mens i onal subs tratum
on and wi th i n wh i c h a number o f events of b i o l og i c a l s i gni fi cance
occur , cul mi na ti ng in the devel opment of an i ce fl ora . It i s al so ,
when snow-covered , a barr i e r to the entry of l i ght to waters
beneath the i ce , hence o ften an i n h i b i tor of pel a g i c p l ant g rowth .
I t i s o bv i ou s therefo re tha t the extent o f sea i ce cover both i n
space and t i me and the nature o f i ts snow cover are hi gh l y i mportant
fea tures of a far northern ma r i ne env i ronmen t , from the poi nt of
v i ew of the b i o l ogy of the sys tem . It wo u l d a ppear to be no l ess
i mpo rtant in t he Bea ufort Sea than el sewhere .
1380
1 4 00
1 340
13 6 0
13 0 0
132 0
128 0
o Ch i ridius obtusifrons
o
71 0
-t
70 0 -I
A
! "'-=A
6
Gaid i u s t e n u i spinus
Heterorhabdus n orveg icu s
-I
I
-
�
o
. {J
�
(J1
o:;J
t
r
..q
Fi gure 38 . The d i s tri buti on of Atl anti c zoopl a n kton s pec i es .
\-
C?
N
\)
1 400
1 380
o
S p i nocalanus
4 �! I
1::..
. . ..-.
1 32 0
1 300
128 0
Spa
�L�Il===ll-+--i
\
--I
1::..
700
1 340
Sca pho ca l a n u s mag n u s
Sco lec ith rice l l a m in o r
o
71 0
1 36 0
1::..
1::..
1::..
o
:
6
�
1
· If
qa
r
I
\
4-
\l
1·
U1
�
�
F i g u re 39 . The d i s tri b u t i on of Atl anti c zoopl an kton s pec i es .
C:?
IV
\)
14 00
o
-
I
71 0 r
700
-I
1380
13 6 0
Cal anus c ristatus
,.
o E ucalanu s bungi i
" Met ridi a pac ific a
1
t>-
.J1 I
1 340
\
. tt
13 0 0
�
_
t
0"1
o
tr
�
Fi gure
128 0
--n
\\
o
A
132 0
40. The d i stri buti on of Paci fi c zoopl ankton s pec i es .
C?
N
\J
61
The t i mi ng o f cyc l i cal events and the ma gni tude o f acti v i ty
o f the bi ol o g i c a l c omponent o f a rcti c seas i s l a rg e l y contro l l ed
by the avai l ab i l i ty o f l i ght and nutri ents . Li ght may be
prevented from penetrati n g the s e a s u rface by a cover of i ce and
snow, var i at i on s i n the d urati on o f whi c h , wi thi n l i mi t s , may
a l ter l i g h t suppl y s uffi c i ent l y to modi fy underwater b i ol ogi c a l
acti v i ty rates . I t i s a l so a pparent t h a t t h e pl ants of arct i c
sea s are adapted to the o s c i l l ati n g l i g ht wh i ch the normal annual
cycl e u nder i ce-co vered seas prov i de s . The i ce fl ora a ppears to
be adapted to a n excepti onal l y l ow quanti ty of l i ght ( Bunt 1964 ;
Apol l on i o 1965 ) . The f i rst p hyto p l a n kton to a ppear i n spri n g ,
often under the i ce , i s ada pted too, to l ow l i ght i n ten s i ty , but
to h i gher l eve l s than the i ce fl ora ( Steeman N i e l sen and Han sen
1959 ; Bursa 1 9 6 1 ) . These s teps i n the appeara nce o f the annual
pl an t bl oom represent a success i on o f pl ant forms adapted to
d i fferent l i ght range s . Progre s s i on thro ugh thi s seri es i s
es s enti a l for the compl eti on o f a normal arcti c s ummer pl ankton
producti on seq uence . The wi nter sea i ce cover wh i c h gradual l y brea k s
u p a n d d i s ap pears by s ummer p l ays a domi nant ro l e i n t h i s succes s i o n .
Ada ptati on to va ri ati ons i n the cond i ti on s o f the i ce cover can be
made by the p l ants to at l ea s t the degree of vari ati on brought
about by na tura l annual fl uctuati ons . Obv i o u s l y there are more
ex treme fl uctua tions p o s s i b l e to wh i c h the p l ant s coul d not a da pt .
Another facto r wh i ch a ffects the penetra t i on o f l i ght bel ow
the water s u rface i s the s u s pen ded parti cul a te ma tter , evi dentl y
ori g i na t i n g ma i n l y from the Mac ken z i e Ri ver and occurri n g i n the
ri ver p l ume i n the south Bea u fort Sea . Thi s i s a conspi cuous
feature o f the reg i on , when s een ei ther from an a i rcraft o r from
the dec k of a s h i p . The s ea i s con s p i cuou s l y brown i s h i n col ou r ,
and vi s i bi l i ty thro ugh i t i s severe l y l i mi ted . Sec c h i d i sc
read i ng s permi t ca l c u l a t i on of l i gh t penetrati on beneath the sea
surface i n terms o f percentage of l i ght reac h i n g the s u rface . It
i s i n d i ca ted by these that under cond i t i on s o f ne utral wi nd effect ,
that i s wi th the ri ver p l ume extend i ng out from the del ta and
veeri n g , as a res u l t of forces other than the wi n d , to the east
al ong Tu ktoya ktu k Pen i ns u l a , a l i ght i nten s i ty a s h i gh as 100 l ux
sel dom reaches to a s deep a s 1 metre bel ow the s urface wi th i n 2 0
to 40 mi l es o f the del ta and Tuktoya ktu k Pen i n s u l a coasts .
Mos t o f the observed phytopl a n kton photo synthes i s i n Fro b i s her
Bay , in the eastern Canad i an arcti c , was s hown to ta ke p l ace at
a bo u t 1000 l ux and h i gher ( Gra i nger , in pre s s ) . The very mi n i mum
l i ght requ i rement for photosynthes i s in the sea i ce wa s s hown to be
66 l ux by Cl a sby , Ho rner a nd Al exander ( 19 7 1 ) . Th e i nd i ca t i on from
these va l ues i s that the i n h i b i t i ng effect o f l ow l i ght on potent i a l
pho tosynthe s i s , regard l e s s o f the l e ve l o f p l ant popu l a t i o n s i n the
pl ume waters , i s very grea t , a nd that acti ve photo synthes i s i s
expected to be res tri c ted to the top few cen t i metres o f the water
col umn at l ea s t i n the i nnermost pa rts of the pl ume .
62
Li ght penetration wa s shown t o i ncrea se gra d ual l y wi th
i ncreas i ng d i s tance from the Mac ken z i e Ri ver mouths ( Fi gure 4 ) .
A fa i rl y abrupt i nc rease i s seen i n t he fi gure however a bout 5 0
mi l es from the ri ver mou ths , beyond wh i ch d i s tance l i gh t
penetration was muc h greater t h a n nea rer t o s hore . Onl y near
those sta ti on s farthes t from s hore was s ub s urface l i ght at a l l
s i mi l a r to what was found rather rout i ne l y i n t he eastern arc t i c
i n Frob i sher Bay ( Gra i n ger 197 1 ) where the depth o f penetrati on
of 1% of s u rface l i ght between l ate June and earl y September
(wh i c h i n cl udes the per i o d of the p hyto p l ankton bl oom) wa s from
abo u t 15 to 25 metres .
The pattern o f ni tra te d i s tri b ut i on i n the waters near the
s u rface ( Fi gu re 7 ) po i nt s to a contri buti on of the nutri ent from
the Mackenz i e Ri ver . Reeder, Hi tchon and Lev i n son ( 19 7 2 ) showed
a ran ge of val ues o ver the Ma c kenzi e dra i nage a rea o f l e s s than
0 . 2 to 12 . 4 ug-at/ l , a nd in the Ma c kenz i e where i t enters the
del ta of 4 . 5 ug-at/l N0 3 - N . These a re fa i rl y hi g h l evel s , a s h i g h
a s the h i ghest i nd i vi dual meas u remen ts made i n the i n ner part of
the pl ume i n s umme r . They are i ntere s ti n gl y hi g her than any
mea surements made i n t he dra i nage a rea o f t he E s k i mo La kes i n
l ate Ju l y ( 0 to 0 . 7 ug-at/ l ) and i n t he E s k i mo Lakes themsel ves i n
s u mmer ( from unpubl i s hed data ) . Hi gher n i trate l evel s were fo und
in May near the s urfa ce i n and nea r Kugmal l i t Bay , where they
reac hed 9 . 9 ug-at/ l . The se were c o l l ected near the end o f the
peri od of nutri ent repl en i s hment o ver wi nter, a per i od when t here
was l i ttl e or no u s e by pl ants . They pro babl y refl ect a comb i nati on
of repl en i s hment wi thi n the sea and contr i buti on from the Mac ken z i e
River. Other May val ues , a l so l arge but not a s great as those
above , were ta ken farther from s hore , and pro babl y s howed red uced
Mac ken z i e Ri ver i nfl uence . The h i ghest n i tra te q ua nt i t i es of al l
were found i n deep waters and reac hed a l most to 1 6 ug-at/l . These
were typ i ca l of deep quant i ti es reported farther north i n the Arcti c
Ocean ( Gud ko v i ch 1 95 5 ; Engl i s h 1 96 1 ; Ki nney , Arhel ger a nd Burre l l
1970 ) . Quanti t i e s near t he s u rface i n the south Be aufo rt Sea were
h i gher however than s urface l evel s fo und at the Arct i c Ocean stati ons .
The general d i s tri buti on o f ni trate a s s hown here i n the south
Beaufort Sea i s muc h l i ke wha t was s hown off Si be r i a n r i ver mouths
by Cod i s poti a n d Ri c ha rds ( 1968 ) . Ri ver-con tri b uted n i trate a l so
was s hown on the north Al a s ka s l ope ( Hufford 1974 ) .
Fi g u re s 7 and 9 s how l owe s t s urface n i trate val ues at the
stations farthe s t from s ho re . Thes e s tati ons , wh i c h were not
s amp l ed at a ny ti me earl y in the year , a re ra the r d i ffi c u l t to
i nterpret . It i s s u gges ted however that l ow to v i rtua l l y exhauste d
n i trates i n t he u pper few tens o f metres i nd i cate a n earl i er
produ ction of p hyto p l an kton i n those depth s . The devel opment of
dens i ty stra ti fi cati on i n s ummer p ro b a b l y effecti vely prevents the
63
ri se o f deeper nutri ents t o the euphoti c l ayers duri ng the
remai nder of the per i od of wa rm water . At such deep stati ons
far from shore , a s i ngl e peri od of drai n on the n utri ents ava i l abl e
i n the u p per l ayers probabl y l i mi ts the produc t i on o f the yea r to
that s uppl y of nour i s hmen t . At the t i me o f sampl i n g these s tati ons ,
chl orophyl l � VJas a l ready fa i rl y l ow , perhaps gra zed fa i r l y q u i c kl y .
Sta t i ons a t i ntermed i a te d i s tances from s hore genera l l y
s howed more va r i a b l e su rface ni trate val ues wi th a greater ra nge
than wa s found farther o ut and cl oser to shore . Many o f the s e
stati on s were var i ab l y i ns i de and outs i de t h e pl ume . I n s i de
the pl ume, nutr i ent enri c hment du ri n g the open water per i od may
ta ke pl ace d i rectl y from the ri ver . J u st outs i de the pl ume , i t
i s suggested that summert i me nutri ent repl en i s hment may occur at
the s urface a s a resu l t of deep wa ter entrai nment by the outfl owi n g
s urface water , a n d the gradu a l ri s e of thOi s towards the surfa ce by
movement al ong the unders i de o f the fre shwater wed ge . Li ght ava i l abl e
be neath the s urface o f these s tati ons duri ng the open -wa ter peri od
al s o was var i a bl e , dependi n g u pon fl uctua ti ons in the extent of the
pl ume . I t was often l ow howeve r , and a s cal c u l a ted a bove for the
stati ons nea rer shore , may sel dom have exceeded 100 l ux bel ow about
3 metre s . Th i s i s s ha l l ow l i ght penetra t i on , and al mo s t certa i nl y
severe l y i n h i b i ts pri mary p roduct i v i ty a s fa r a s 5 0 mi l es from
shore .
Phosphate does not repeat the p i ctu re s hown fo r n i trate . The
range of va l ue s was far l es s and the pa ttern of d i str i b uti on over
the south Beaufort Sea nothi ng l i ke as c l earl y defi ned ( Fi gure 1 1 )
as i t appea red to be for ni tra te . Hi ghest s urface va l ue s were i n
and near Mac ken z i e and Kugmal l i t Bays , b u t they were onl y a l i ttl e
hi gher there than at s tati ons fa rthe st from the ri ver mouths . The
range of P04- P found i n the Mac kenz i e dra i nage area by Reeder ,
Hi tchon and Lev i n son ( 19 7 2 ) wa s l e s s than 0 . 10 to 0 . 95 u g- at/ l , and
at a si n g l e Ma c ken z i e Ri ver stati on a t t he base of the del ta the
pho spha te l evel wa s l es s than 0 . 1 0 u g-at/ l . The l a s t of the s e i s
e s pec i a l l y l ow , and i t and the max i mum quanti ty recorded u p the
ri ver are l e s s than the max i mum s urface quant i t i e s of nea rl y
1 . 5 ug-at/ l fou nd off the ri ver mouths i n the south Bea u fort Sea .
Thi s i s i n contra s t wi th n i trate res u l ts wh i ch s howed s i mi l a r
l evel s i n the ri ver and o ff the mouth s o f the ri ve r i n the s ea .
These fi gure s are not concl u s i ve , b ut i t i s pos s i b l e that the
Mac ken z i e Ri ver may be a more i mportant sou rce of n utr i ent n i trogen
than of phosp horu s , a t l ea s t at certa i n t i mes of the yea r . Thi s i s
fu rther i nd i cated by some earl y May o b servati ons from coa sta l waters
in and near Kugmal l i t Bay wh i ch s howed p hos phate l evel s of 0 . 1 3 to
0 . 1 7 ug-at/l o n l y , at a ti me when n i trate had reached except i ona l l y
h i gh l evel s . Phosphate mea su rements made i n Apr i l and May fa rther
from shore b u t i n the s ame general a rea showed h i g her q uanti ti es o f
phos phate near the s u rface , l evel s s i mi l ar to tho s e fo und i n
64
Kugmal l i t Bay con s i dera b l y l ater i n the season . These data are
not ea s i l y i n terpreted , but they al l ow the s u ggesti on tha t
phosphate repl en i s hment wi th i n the ma ri ne sys tem may be rel ati vely
more i mportant at the same ti me a s the ri ver i s rel a t i vel y l es s
i mportant for p hos pha te than for n i tra te . Add i ti ona l s up port
comes from Huffo rd ( 1974 ) who showed that ri ver-co ntri buted
phosphate was l ow in summer on the north Al a s k a s l ope , wh i l e both
n i trate a n d s i l i ca te we re rel a ti vel y more abundant .
Pho s p ha te i n the surface waters o f stati ons fa rthest from
the ri ver mouths was rel ati vel y h i g h , wh i l e n i tra te at the same
time a nd pl ace was l ow . There was neverthel e s s evi dence of
phosphate depl eti on i n the upper 20 metre s from where ni tra te was
a l mo s t total l y exhausted . Evi dently a res i due of unused phos p ha te
remai ned . At the i n termed i a te s tati ons , phosphate wa s l ow ,
entirely consumed i n the u pper 5 metre s of several of the stati ons
at ti mes when n i tra te exi sted in pos i ti ve and rather vari a bl e
quanti ti e s . Perhaps n i tra te had been rep l eni s hed a t the s u rfa ce by
s uch means a s the entrai nment p roces s , s ugges ted above . Evi den tly
phospha te had not , o r i t had been cons umed q u i c kl y a s it wa s
repl aced . Near the del ta rel ati vel y h i g h val ues of phosphate i n
the s h a l l ow , a l most fresh wa ter probab l y refl ected a t l ea s t some
degree o f Mac kenz i e co ntri buti on . Uti l i zati on by pl ants , as wi th
ni trate , vo/as proba b l y very l ow there beca u s e o f l a c k of l i ght i n
the h i ghl y turbi d wate r s .
The verti ca l s truc ture of phos phate ( Fi gure 14 ) , s howi ng
max i mum q uanti ti es between 100 a nd 200 metres ( reac h i ng to more
than 1 . 6 ug-at/ l ) and a bo u t one hal f max i mum val ues i n deeper
water , i s s i mi l a r to cond i ti ons s hown from farther north i n the
Arcti c Ocean by G ud kovi c h ( 1 9 5 5 ) , Engl i s h ( 19 6 1 ) and Ki nney ,
Arhel ger and Burrel l ( 1970 ) . Compared wi th the data presented by
Cod i s poti and Ri c hards ( 1968 ) from off S i beri an ri vers , the south
Beaufort Sea phos phate l evel s are l ow , a t the s urface and bel ow .
I t i s no teworthy tha t n i trate was fo und i n s i mi l ar quanti ti es off
the Ma cken z i e and o ff the S i beri an ri vers , wh i l e phospha te was
d i s t i nctl y l es s a bundant i n the south Beaufo rt Sea .
S i l i cate-s i l i con i n the s urface waters s h ows a pattern rather
more l i ke tha t of n i trate than o f phosphate . Va l ues i n the
Mac ken zi e p l ume were h i gher than those outs i de i t . Si l i ca te i n
t he Mac ken z i e d ra i nage area ( Reede r , Hi tchon and Le v i n s on 1972 )
ranged from 5 to 127 ug-at/ l . In the ri ver , a t the base o f the
del ta , a quanti ty of 58 ug-at/l Si was reported . These a re h i g her
than the maxi mum l evel s found near the s urface i n i n s hore waters
i n summe r , wh i c h were around 35 ug-at/ l , and they are in fact
h i gher than ma x i mum deep o ffs hore val ues whi ch reac hed to l i ttl e
more than 40 ug-at/ l .
65
The verti cal structure compa res cl osel y wi th data from the
Arcti c Ocean ( Gud kov i ch 195 5 ; Engl i s h 1 96 1 ; Ki nney , Arhe l ger and
Burrel l 1970 ) , i n a l l but va l ues near the s urface , whi c h were
nota bl y h i gher i n the south Beaufort Sea . The Beaufort Sea s ummer
ra nge was s i mi l ar to what Cod i spoti and R i c hards ( 1968 ) found i n
coa s ta l Si beri an waters .
Of the three n utri ents consi dered here , n i tra te i s proba b l y
t h e most i mporta n t , at l ea s t i n t h e waters outs i de the pl ume , i n
l i mi ti ng p l a n t production i n s urface waters . When nu tri ents are
depl eted i n s uc h waters du r i n g the s ummer when verti cal den s i ty
strati fi cati on i s s trong l y devel oped , p l ant producti on must cease
unti l by some means repl eni s hmen t of the req u i red n utri ents i s
brought about . I t i s l i kel y tha t i n s i tu regenera ti on takes pl ace
too s l owl y to have any s i gn i fi cant-effect dur i n g the c o u rse o f a
s i ngl e open-water per i od . I n the ou ter reac hes o f the pl ume ,
obs ervati ons of tota l l y exha u s ted phosphate i n the euphoti c zone
i ndi cate phos pha te as a l i mi ti ng fa ctor there . Th i s i s not however
en t i re l y c l ea r . Just o f f the del ta , a l l nutri ents seem to b e i n
s u ffi c i ent s u p p l y a t al l ti mes of the s umme r . Sure l y n utr i en t
def i c i ency i s n o t a l i mi ti ng factor there , where l i ght i s proba b l y
t h e ma i n factor l i mi ti ng the pri ma ry producti vi ty rate . Si l i cate
evi dently i s not l i mi t i ng anywhere i n the reg i on .
The pa ttern of di s s o l ved o xygen d i s tri b uti on i n waters near
the surface ( Fi gure 1 9 ) s howed a regul ar trend o f l owest va l ues
near the del ta a nd hi ghest l evel s fa rthest from the coas t .
Brun s k i l l , Rosenberg , Snow , Va s cotto and Wagemann ( 19 73 ) gave
di s so l ved oxygen f i g ures for the Mac kenz i e d ra i na ge a rea and
Kugma l l i t Bay , and s howed gen eral l y l ower l evel s i n the ri ver
channel s than off the ri ver mo uths i n the sea . Thi s trend appears
to be extended to the offs hore wa ters .
Oxygen i n the sea i s contro l l ed by p l ant produ c ti o n , ani mal
con s umpti on and exchange a cros s the a i r- sea i n terface . It va ri es
seasona l l y . Thi s i s not bro ught out cl ea rly by the pa ttern i n
Fi gure 19 , but i s s hown by some o f the 1975 data wh i c h were not
i nc l uded in the fi gure . In the offshore area i ndi cated by val ues
h i gher than 9 ml / l i n t he fi gure , observations made in Au gust of
1975 s howed l evel s there reduced to a s l ow as about 7 . 5 to about
8 . 5 ml / l . I n fa c t , earl i er observa t i o n s i n the offshore waters
s h owed va l ues refl ecti n g cond i t i on s earl y i n the s umme r producti on
peri od , whi c h was l a te in 1974 . Happen i ng earl i er in 1 975 , in
accorda nce wi th e arl i er i ce removal , summer p rod ucti on evi dently had
pea ked in the o ffshore waters by Au gust , and oxygen l evel s had
dec l i ned .
The d i s tri buti on o f cons ume rs ( zoopl an kton ) wo ul d s ugge s t more
oxygen cons umpti on outs i de the 8 ml / l l i ne i n Fi gure 19 , that i s
66
i n the outer porti on o f the pl ume a n d outs i de i t , than nearer
the del ta . Hi ghest oxygen val ues i n the same regi on , i n s pi te
o f probably g reater oxygen u s e there , po i nts to greater oxygen
produc t i o n i n those wa ters than nea rer shore . Th i s , of co urse ,
fol l ows the expected pa ttern as s hown by ava i l ab l e l i g h t i n
s u b - s u rface waters .
The verti cal structure o f d i ssol ved oxygen ( F i gu re 2 1 )
shows very c l ose s i mi l ari ty to the c urves from farther north i n
the Arcti c Ocean i n Ki nney , Arhe l ger and Burrel l ( 1970 ) . The
ma i n di vergences from the pattern a re the i n s ho re s ta ti ons of l ow
oxygen s h own i n Fi gure 2 0 .
Quan t i t i es o f pl ant ma teri al and amounts o f photosyntheti c
acti vi ty u nder s i n gl e s q uare metres of .sea s u rface may not
neces sari l y s how a cl ose rel ati ons h i p . There a re several reason s
fo r th i s , among them the ava i l a b i l i ty of l i gh t and n utri en t s .
Large popu l a ti ons of p l a nts may refl ect past rather tha n
contempora ry condi ti ons of growth and destru c t i o n ( gr a z i n g ) , and
s how that fa vourabl e cond i t i o n s preva i l ed formerl y a t l ea s t , but
not necessari l y that they con ti n ued u nt i l the ti me of samp l i n g .
Sma l l popul a t i o n s may mean poo r growth cond i t i ons i n t he h i s tory
of the popu l a t i on , or they may be the conseq uence of heavy graz i ng
on a primari l y l arge popul a t i o n no l on ger abl e to grow rap i d l y
enough to ma i nt a i n h i gh l evel s . Chl o rophyl l a va l ues shown i n
Fi gure 22 may gi ve u s an i nd i cati on o f pl ant quanti t i e s i n t he
s u rface waters o f the s tudy a rea , b ut there a re no good grounds
for us i ng them to i nterpret acti v i ty rates at t he t i mes of
sampl i n g . The oxygen d i stri buti on map ( Fi gu re 19 ) may i n fact
appro x i mate fa r more c l o se l y the tren ds i n s urface water pl ant
production ra te s , and u sed i n conj unct i on wi th Fi gure 22 i nd i ca te
that the rel at i v e l y h i gh c hl o rophyl l l evel s of the del ta waters
do not neces s ari l y s i gn i fy a correspond i ng l y hi g h p hotosyntheti c
ra te . At the s ame t i me , o ffshore waters i n wh i c h chl o rophyl l l evel s
are l ower than nearer to s ho re may be produci n g at a greater rate
than t hose c l oser to the del ta .
I t i s hel d neverthel ess that chl oro phyl l a va l ue s may be
used to i nd i cate s tandi n g s toc k l eve l s , i f not-to refl ect
photosynthet i c rate s , a nd therefore that they may be u sed to
compare p hytopl an kton quanti t i es i n di fferent wa ters . Fi gure 4 1
s hows chl orophyl l a l evel s mea s u red a t vari o u s dates i n the
Beaufort Sea , an d , expressed as mg/m2 i n the u pper 20 metres . The
Beaufort Sea val ues , g i ven by the same symbol s as were used i n
Fi gure 1 , were h i ghest i n l a te June and earl y J u l y , l ower and very
var i a bl e i n l a te J u l y and Augus t . Superi mposed a l ong the s ame
t i me sca l e are curves o f compa rabl e val ues from the adj acent Es k i mo
Lakes and from Frobi s her Bay , the l atter i n the ea stern Canadi an
67
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68
arcti c ( data from Gra i nger and Lovri ty 1975 an d Gra i nger 1 9 7 1 a ) .
The Es k i mo La kes l evel s were not greatl y d i fferent from tho s e
i n the Beaufort Sea , al tho u g h ra ther h i gher i n l a te s ummer .
Quanti ti es i n Fro bi s her Bay however were fa r hi gher i n general
than in the Beaufort Sea , wi th the c urve moved somewhat to the
ri ght al ong the ti me s cal e . The Fro b i s her va l ues are hi gher
than tho se from the Beaufort Sea by a factor of 5 to 10 .
In Fro b i s her Bay an annual p hytopl ankton produc t i on rate
expres sed a s 50 to 100 g ca rbon per m2 per yea r has been
descri bed ( Gra i n ger in p re s s ) . Wi thout tryi n g to rel a te pl ant
s toc k to p hytopl a n kton rate in stri ct n umeri cal terms , it remai n s
rea sona b l e however t o a s s ume a si gni fi cantl y l ower producti on rate
fo r the South Beaufort Sea than for Fro b i s her Bay on the ba s i s
o f compa red stan d i ng s tocks o f primary . producers .
There i s a t the present t i me a v i rtua l l y c ompl ete l ac k of
hard i nforma t i o n on the fl ora of the sea i ce of the south Beaufort
Sea . Certai n i nference s can be made on the ba s i s of i n formati on
avai l a bl e from the E s k i mo Lakes and the i nshore s ea off Po i nt
Barro w , Al a s ka . Cl earl y i t p l ays a ro l e i n the economy of the
Beaufort Sea . Noted i n i ti a l l y i n the a ntarcti c , probabl y the fi rst
reference to the under- i ce fl ora o f the arcti c was Bursa ' s ( 1963 )
from off no rth Al a s ka . Meg u ro , Ito and Fu kus h i ma ( 19 6 6 ) al so
descri bed the i c e fl ora and a s so c i a ted features from north of
Al a s ka . They s howed i t to be a v i tal commun i ty , con s i s t i n g of
d i atoms . Late r , Horner and Al exander ( 1972 ) fo und a more varied
fl ora and a s soci ated fauna . They di s cus sed d i a toms , d i no fl a gel l ates ,
fl agel l ates , c i l i a te s , hel i ozoan s , nema todes , pol ychaete l arvae and
a copepo d , and s howed tha t the cppepod and worms were feed i ng on
other o rgani sms , ma i n l y di atoms .
The re l a t i ons h i p between the i ce fl ora and the s pri n g
p hytopl ankton , wh i c h o ften deve l ops under the i ce , i s not yet
cl ea r . Meguro , I to and F u ku s h i ma ( 19 6 7 ) cl a i med that there was
a d i rect con nection between the rel ease of p l ants from the l ower
s urfa ce of mel ti ng sea i ce and wha t they evi dent l y thou ght to be
the i n i ti a ti on of thi s by the p hyto p l a n kton bl oom under the ice .
Al exander ( 1974 ) cl a i med however tha t the re l ease o f i ce p l ants
to the wa ter was not a tri gger for the phytopl a n kton b l oom , on
the bas i s of d i fferen ces i n the compo s i t i o n of the two fl oras and
the exi s tence o f a ti me l ag between the end o f the i ce bl oom and
the begi nni ng o f the wa ter b l oom . Thi s i s a probl em w h i c h cl earl y
requ i res a sol uti on .
Whether or not the i ce fl ora " seed s " the p hytop l a nkton b l oom ,
i t i s concerned wi th a n i mportant troph i c seq uence i nc l ud i n g the
forms l i s ted by Horner and Al exander a bove and add i t i onal c opepo d s ,
69
amphi pods and fi shes . The a rcti c cod ( Boreogadus saida ) the most
ab undant smal l pel agi c fi sh known from the whol e of the Canad i a n
arcti c , and frequentl y found i n a s so c i a t i on wi th sea i ce , i s
obvi o u s l y bound to th i s trop h i c seri e s whi ch s ta rts wi th i n the
sea i c e .
The numbers of zoopl an kton s pec i e s found i n d i fferent part s
of the study a rea refl ect ma i nl y sal i n i ty- temperature barri ers to
the va r i o u s popu l ati ons a s soc i a ted wi th speci fi c ki nds of
envi ronmen ts . The total numbe r of speci es repo rted ( a t l e a s t 92 )
i s l a rge for an arct i c reg i on of thi s s i ze . In fac t , the study
a rea represents , as wa s p o i nted out i n earl i er secti ons of thi s
report , a two - l ayer estuari ne system. The total sal i n i ty range of
zero to more than 34%0 and the tempe rature range of l es s than - 1 ° C
to nearly 1 8 ° C encompa sses envi ronmenta l cond i t i on s rea c h i ng from
ri ver mouth to Arcti c Surfa ce water , at the s u rface , and to Atl anti c
wa ter at depth .
I n shore s ta t i o n s i n Mason Bay and Tu ktoya ktu k Harbo u r and i n
Li verpool Bay s upported t he grea test n umbe r o f orga ni sms , represented
however by on l y 4 copepod spec i es ( and by o n l y 5 s pec i es o f a l l
groups ) . Acartia c lausi and Eury temora herdmani were very a bu ndant ,
Pseudoca lanus minutus s omewha t l es s so and Limnoca lanus macrurus
next .
Stati ons wi th the next l a rgest n umbers of i ndi vi dua l s were
l ocated off Tuktoya ktuk Pen i n s ul a , and t hey s upported mi xed
popu l a t i ons of estua ri ne and norma l l y more offsh ore s pec i es . The
stati ons fa rthest from shore , and wi th the sma l l es t appa rent stand i n g
s toc ks were the deepest ones . They s howed l ow s tandi n g s toc k s , i n
contra s t wi th the i r l a rge s pec i e s d i versi ty . At those stati ons the
l a rge numbers of spec i e s , most of them at depth , were con s i stentl y
represented by sma l l numbers , and the few s pec i es o f the upper 50
me tre s were al so represented by far smal l er n umbers than were found
i n the mi xed s urfa ce wa ters cl oser to sh ore . Smal l e s t stocks
certai n l y are chara cteri sti c o f the ri ver mo uth reg i o n .
The spec i e s reported here ( Ta b l e 1 ) i nc l ude al l but 4 known
forme r l y from the south Beaufort Sea ( Gra i n ger 1965 ) . They are
the hydrozoa ns Eumedusa birulai ( Li n ko ) and Ptychogena lactea Agas s i z ,
the cten ophore Mertensia ovum ( Fabri c i u s ) and the amphi pod Hyperoche
medusarum ( Kr�yer ) .
The to tal s tand i ng s to c k of zoopl ankton , expressed a s mg/m 3 ,
i s s hown al ong wi th compa rabl e numbers from Frob i s her Bay i n the
eastern Cana d i a n a rcti c ( Frob i s her data from Gra i n ger ( 19 7 1a ) ) i n
Figure 42 . Apa rt from 6 c o l l ecti ons , one i n Li verpool Bay , one
i n Tu ktoya ktuk harbour a nd 4 made i n 1 9 7 1 off the north coast o f
Tu ktoya ktu k Pen i n s u l a , numbers o f i nd i v i dual s were smal l i n the
60 , OOO
l
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1074 .
I n d ividu als
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5o,OOO
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- 526
20,000 1
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0 502
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Frobisher Bay
5,000
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Fi gure 42 . Zoop l a nkton concentrati ons i n the Be aufort Sea and Fro b i s her Bay ,
.
-
Sept.
71
south Bea ufo rt Sea , and very muc h sma l l er than we re found i n
Frobi s her Bay . I nd i cati ve of the nature of the l a rge popu l ati ons
found in the h i g h dens i ty i n s hore sta t i o n s i s the domi nance of
s i n gl e s pec i es a t those s tati ons . At stati on 6 1- 1074 , for i n s tance ,
more than 53000 of the a pproxi mate l y 6 3000 organ i sms col l ected
were Acartia clausi copepodi te s and uni den t i f i ed copepod naupl i i ,
p ro b a bl y mos t of them Acartia . At stati on 7 3 - 52 6 , there were more
than 43000 Cyclops i n a total ani ma l count of a l i ttl e more than
49000 .
The 1 9 7 1 stat i ons may be u sed to i l l u s trate a n i mportant
fea ture of the south Beaufort Sea wh i c h was referred to often
a bove . Th i s i s the fl uctua t i ng bal ance between the Mac ken z i e Ri ver
output to the sea and the counter force o f the offs hore waters .
Contro l l ed ma i n l y by vari ati ons i n t he wfnd a nd i n ri ver fl ow , the
ri ver pl ume c ha nge s cons tantl y , and the ba l ance between brac k i s h
and hi gh-sal i n i ty o rga n i sms s h i fts accord i n gl y . Suc h fl uctua ti ons
in co nd i ti ons i n crease the probl ems of de scri b i n g the envi ronment
sati s factori l y and mea n that bri e f and i nfrequent peri ods of
observati ons may be even l es s u seful in the Beaufort Sea than i n
othe r , more s tabl e regi ons . I n 1 97 1 , for exampl e , s tati ons 502 a nd
5 04 were sampl ed on 18 and 19 J u l y o ff the coast of Tu ktoya ktu k
Pen i n s u l a . In 1973 , s ta t i o n s 528 , 529 and 530 were samp l ed on
22 and 2 3 Jul y . Geograp h i cal l ocati ons and t i me s of the year were
cl ose . Temperature and sal i n i ty data from the two sets of
observati ons a re shown i n Fi gure 43 . The two sets of data
d i ffered wi thout overl a p i n the i r comb i n ed T- S p ropert i e s . The
wa ter i n 1 9 7 1 wa s of h i gh sal i n i ty and cool ; i n 1 9 7 3 i t was of l ow
sal i n i ty a nd on the average, warme r . Ob servati on s made i n 1973
fo l l owed a per i od o f s ettl ed weather , u nder wh i ch t he r i ver p l ume
wo ul d be expected to extend wel l o ff the del ta and the coast of
Tu ktoyaktu k Pe n i n s ul a . Cond i ti ons found in 197 1 s u ggest that
northerly wi nds had i n fl uenced the re g i on before the col l ecti ons
were made , dri v i ng o ffsho re wa ter i n to the o bs erva t i on a rea .
Tab l e 2 s hows the s pe c i e s compos i ti on a t the two groups of
stati ons . The 2 1 spec i es o f 1 97 1 i ncl uded 1 5 not fo und in 197 3 ,
and among the 12 s pec i es of 1973 there were 6 s pec i es not fou nd i n
19 7 1 . Nea rl y al l the s pe c i e s ta ken onl y i n 1 9 7 1 are a s soc i a ted
wi th waters found fa rther from shore at other t i me s , and they are
norma l l y found i n s a l i n i ty and temperatu re cond i t i on s i n di cated by
the l ower ri g h t q uadrant o f Fi gure 43 . I n contra s t , at l ea s t 5 of
the 6 s pec i e s ta ken onl y i n 1973 are a s so c i a ted wi th i ns hore
ri ver-mouth waters and are u s ua l l y fo und i n sal i n i ty and temperature
cond i t i on s i nd i cated by the upper l eft co rner of Fi gure 43 . Spec i e s
common to the two years , o n l y 4 , have general l y wi der T-S tol erance
than the exc l u s i ve 1973 spec i e s , but they are character i s t i c a l l y
a s soc i ated wi th waters o f fa i rl y l ow sal i n i ty .
o
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12
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20
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F i gure 4 3 . T- S d i agram of cond i t i ons off Tuk Peni nsula i n 19 7 1 and 19 7 3 .
73
Ta bl e 2 .
Zoopl an kton s pec i e s ta ken off Tu ktoya ktuk Pen i ns u l a i n
l a te J u l y o f two ye ars .
Stati ons 502 , 505 ( 19 7 1 )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10 .
11.
12 .
13 .
Agl antha d i g i ta l e
Aeg i nops i s l a urenti
mo l l u sc l a rvae
u n i dent i f i ed anne l i ds
Aca rti a c l a u s i
A . l o ngi remi s
Derj ugi n i a tol l i
Cal anus gl a c i al i s
Cal anus hyperboreus
L i mnoca l anus macrurus
Metr i d i a l onga
Mi croca l an u s pygmaeus
Pseudoca l an u s mi nutus
1 4 . Oi thona s i mi l i s
15 . Oncaea borea l i s
1 6 . Copepod naupl i i
17 . Ci rri pede l arvae
18 .
19 .
20 .
21 .
Monocul odes s p .
E u krohn i a hama ta
u n i denti fi ed c haetognaths
Oi l opl e ura vanhoeffe n i
Stat i ons 528 , 529 , 530 ( 1973 )
1 . Hal i thol u s c i rratus
2 . pol yc haeta l arvae
3 . Acart i a c l a u s i
4 . L i mnoca l an u s mac rurus
5 . Pseudoca l anus mi nutu s
6 . Eurytemora herdma n i
7 . Cycl ops s p .
8 . Cyc l o p i n a sp .
9 . Copepod na u p l i i
10 . My si s sp .
1 1 . Di a s tyl i s sp .
12 . Monocul ode s sp .
74
Wha t is shown by the exampl e i s that had on l y the 1973
observati ons been made off Tu ktoya ktuk Pen i n sul a , the waters
there coul d have been i nterpreted a s sup porti n g a s pa rse fauna
of on l y bra c k i s h -water s pec i es . In the s ame way , o bs ervati o n s
made i n 1 9 7 1 coul d have p rompted the concl u s i o n t h a t t h e same
geo graph i cal l oc at i on su pports a ri c h and di verse fa una . What
emerges i n stead , of cou rse , i s that th i s s i te s upports faunas of
bo th k i nds at vari ous t i me s .
8.
CONCLUS I ONS
1 . The b i o l ogi cal nature of the Beaufort Sea i s very muc h
dependent u pon the ba l ance between Mac kenzi e i nfl uences and t hose
of the offshore ma ri ne el ement . The typ i cal ri ve r mou th s tructure
of water o f ri ver ori g i n a nd of l ow sal i n i ty o verl yi ng water o f
oceani c o ri g i n and o f h i g h s a l i n i ty i s s hown i n t h e Beaufort Sea ,
where the bal a nce between these facto rs i s i n a constant state o f
fl ux a n d where va ri ati on s i n the i r ranges determi ne the d i stri buti on
of many of the bi o l ogi ca l e l ements .
2 . The sea i ce cover i s essent i a l for the sys tem . Vari a t i on
i n i ts th i c kness , extent and dura ti on i nfl uence p r i mary and
success i ve l eve l s a ccord i ng l y .
3 . Li ght avai l ab i l i ty to waters beneath the s urface i n the
Mac ken z i e p l ume i s l ow , wi th the compen sation depth probably
occurr i ng wi t h i n a few centi metre s of the su rface . Th i s i s vari a b l e ,
depend i n g o n the pos i ti on and extent o f the p l ume and the sea i c e
cover .
4 . Ni trate-ni trogen i s contr i b u ted to the pl ume a rea from the
Mac ken z i e Ri ver . In shore wa ters a ppear to reta i n a hi gh l eve l of
ni trate , where consumpti on by p l ants i s l ow . Waters fa rthes t from
shore , beyond the ri ver p l ume , s how dep l etion of n i tra te d u r i n g the
s ummer producti ve peri o d .
5 . The Ma c kenzi e Ri ver i s p robabl y n o t as i mp o rtant a source of
phos phate- phosphorus as i t i s for n i trate .
6 . Ni trate s uppl y seems to be the maj or factor l i mi t i n g pri mary
p roducti on i n wa te rs outs i de the p l ume . No a ppa rent mec hani sm
exi sts for rap i d repl en i s hmen t d u ri ng the s ummer growth season .
Wi th i n the outer pa rt o f the p l ume condi ti on s are l e s s cl ea r . Total
e l i mi nati on of p ho sphate s ugges ts it may be the l i mi ti ng nutri ent
t here , but t he ava i l a b l e i nfo rmati on i s i n s uff i c i en t . S i l i ca te i s
o bv i ou s l y i n s u ffi c i ent s u ppl y everywhere i n the s tudy a rea , hence
nowhere a l i mi ti n g factor .
7 . Oxygen d i stri buti on s hows l owes t q uanti t i e s i n a ss oc i ati on
wi th ri ver o utfl ow and i ncrea s i n g amounts seaward from the ri ver
mouths .
75
8. A s i mi l a r pattern is i n ferred for p hotosyn t heti c rate , the
l owe st acti v i ty occu rri ng i n the turb i d waters nea rest to the
ri ver mou ths , and the rate i ncrea s i n g towards the o u te r edge of the
pl ume , mai nl y contro l l ed by the ava i l a b i l i ty of l i ght .
9 . Chl orophyl l l evel s a re l ow i n the so uth Bea u fort Sea ,
compared wi th o ther mar i ne l ocat i ons i n h i g h l a ti tudes . On the
ba si s o f l ow chl orophyl l and general l y l ow l i gh t avai l ab i l i ty , a
l ow annual pri mary produ ct i v i ty rate i s i nd i ca ted , even by a rct i c
mari ne s tandards .
1 0 . Data on the sea i ce fl ora a re al mo s t tota l l y wanti ng from
the Bea ufort Sea . Such a fl ora exi sts however and , from knowl edge
of the fl ora and i ts cond i t i on s of growth a nd rel evance to the
eco system el s ewhere in the arct i c , i t may be i n ferred to be
potent i a l l y i mportant i n the south Bea ufort Sea . I t a l most certai n l y
pl ays a h i ghly s i gn i fi cant ro l e i n t h e troph i c sequence wh i c h
i n vol ves pel agi c fi shes and the i r predators .
1 1 . Zoop l a n kton i s wel l known i n the south Beaufort Sea , and a t
l ea s t 95 spe c i es ma ke up several qu i te d i s t i nct gro u p s , on t h e bas i s
of sal i n i ty- temperature ra n ge s . Incl uded a re the a l mo s t fres hwate r
speci es o f the ri ver mouth a rea s , the brac k i s h s pec i es o f s u rface
waters o f the ri ver p l ume , the offs hore , Arcti c Surface s pec i es , and
the under l y i ng Atl ant i c water s pec i es found on a nd outs i de t he s l ope .
The deep , o ffs hore waters s upport the mo s t d i verse fauna , wh i c h i s
spa rse i n quan ti ty . The mo st dense concentra t i o n s of zoopl a n kton
occur e i ther i n smal l s horel i ne bays or i n the regi on of mi xed s urface
water ( r i ver pl u s offshore el ements ) . The sparsest fauna and the
poores t i n vari ety occurs cl ose to and i n the Macken z i e Ri ver outl e ts
to the sea . Stand i n g s to c ks o f zoop l a n kton i n the south Bea u fort Sea
are general l y l ow by worl d standard s .
9.
I MPL I CAT IONS AND RECOMMENDAT I ONS
The Bea u fort Sea appears to s upport at best a fa i rl y l ow rate
of pri mary and secondary product i on . Th i s i s proba b l y s ubject to
con s i derab l e annual vari a t i on , be i n g i n fl uenced by va ri abl e sea i ce
cond i t i o n s . I t i s al so proba b l y s u bject to vari a ti ons a s soc i a ted
wi th mod i f i cati on i n ri ver outfl ow and i n cl i mat i c , ma i n l y wi nd ,
con d i ti on s . Exh i b i ti ng perhaps more natural vari ati on than many
compara b l e ma ri ne reg i on s , i t i s th erefore al l the more d i ffi c u l t
to defi ne i n terms o f "norma l " s tate .
The pattern of wate r movemen t i n the south Bea ufort Sea , be i n g
governed a s i t i s by an estuari ne c i rcu l a t i o n sys tem powe red by
ri ve r o u tfl ow and by a counte r force from seawa rd , i nvol v i n g hi ghl y
va ri abl e wi nd fa ctors , i s i mportant i n a s s es s i ng i mpac t effects .
One mi ght l oo k , u nder these ci rcumstances , for a greater spread o f
an i mpact effect than wo ul d b e fo und i n a p hys i ca l l y s i mp l er sys tem .
76
Such a spread of a harmful i mpact wo ul d be expected to h ave
e s peci a l l y undes i rabl e effects on a b i o l o g i ca l sys tem l i ke th i s
one , whi c h may be e spec i a l l y v u l nerabl e . I t i s s uggested that
estuari ne b i o l ogi cal sys tems may be in some ways the mos t fra gi l e
of arcti c mari ne systems becau se , al though they have wi de tempera t u re
and s a l i n i ty to l era nce , they a re not to l erant to ful l s ea sal i n i ty
and therefore they are dependent upon conti n ued a nd a l mo s t unal tered
ri ver fl ow . Ri ver fl ow i n thi s regi on i s certa i n l y fa r from
unal tered over the year , a nd the resul ts wou l d be e xpected to show
i n a l a rge annual var i a t i on i n the s i ze a nd extent of the pl ume .
Unfortuna te l y thi s has no t been we l l demons trated beca u s e of the
smal l n umber of observati ons ma de other than i n J u l y and Au gu st .
The e s s enti a l e s tu ar i ne nature o f t he fauna i s dependent u pon there
be i n g a pl ume at al l t i mes , and i ts d i sappearance , for even a short
t i me , wo u l d effec t i ve l y wi pe o ut the s pec i a l fauna o f t he estuary .
The Bea ufort Sea i s a s ump to the Mac ken z i e Ri ver . Therefo re ,
i t i s not on l y i nfl uenced by vari a t i o n s i n vol ume of ri ver fl ow ,
but i t i s vul nera bl e too to q ual i tati ve c ha n ge s i n the ri ver wate r .
Among po s s i b l e harmful add i t i ves to the Mac ken z i e Ri ver i s o i l ,
t he spread o f whi c h o ver the area o f the pl ume coul d be great and
expo s ure to it by al l l evel s of the b i ol og i ca l sys tem i mmense .
Di fferent parts o f the ecosystem wi l l vary i n the i r
vul nera b i l i ty to o i l i mpact, whether the o i l reaches them from
the ri ver or s hore or from fa r off s hore . The p l a n kton are p roba b l y
among the l ea s t v u l nera bl e , i n the sense o f i mme d i a te e ffec ts , o f
al l the b i o l o g i c a l el ements because of thei r 3- d i mens i onal d i stri bution
pa ttern . Th ey may avo i d the u pper s urfa ce of the s ea , the bottom, the
shore l i ne and mos t s u rface s on wh i c h o i l tends to col l ect . Al mo s t
certa i n l y the l ower s u rface of the s ea i ce i s h i gh l y s u scept i bl e t o
the effec ts of o i l . Deteri orati on of the s ubstratum and d i s rupti on
o f the troph i c rel ati on s h i p s a l one wo ul d des croy the b i ol o g i c a l
sys tem beneath t h e i ce , a n d wi th i t t h e farther rea ch i ng eco l o g i ca l
rel evance o f the under-i ce b i o ta .
Al though q u anti tat i vely l ow , the pri mary product i o n i n the water
and i n the i ce serve s a s the base of a foo d s tructure wh i c h supports
fi sh and mamma l popul ati on s . The rel ati vel y s i mpl e pop u l ati on
structure of the i ns hore waters in parti cu l a r s u ggests a rel ati vel y
u ncompl i ca ted food c ha i n , and th i s means fewer but rel ati vel y more
i mportant l i n k s i n the chai n and greater vul nerab i l i ty on the who l e
than one wou l d expect i n a more compl ex we b . Pe rhaps the commone s t
tro ph i c seq uence reac h i ng t h e h i g he s t l eve l s i s d i a tom ( water or i ce )
- c opepod - fi s h - mammal . There a re more compl ex cha i ns t han thi s ,
bu t i t i s probabl e tha t the l i ne s are u s ual l y s hort and have few l i nks
and that the opti ons are few . One o f the ma i n routes of course for
the exten s i on of o i l e ffects through the sys tem i s al o n g food chai n s .
77
Speci fi cati ons of req u i remen ts for the a s se ssment of i mpact
effects u pon an ecosys tem a re i mmensel y d i ffi cul t to present .
Part of the probl em i s a s so c i ated wi th the complex i ty of i ntera c t i o n s
wi t h i n even s i mp l e arcti c sys tems and our l a c k o f deep and detai l ed
knowl edge of most o f the fa cto rs wh i ch ma ke a sys tem l i ke th i s one
go . Th i s i s sl owl y accumu l a ted knowl ed ge , and it i s regrettabl e
that i t i s not be i n g put together a s ra pi d l y a s i t i s req u i red for
i mpa ct a s s e s sments . It i s unfortunate that the present a pproach to
probl ems of thi s k i nd i s not desi gned to bri ng rap i d progres s . The
recent h i story of ma ri ne envi ronmenta l i mpact s tud i e s i n t he
Canad i an arcti c has i nc l uded a seri es of s ho rt- term i nvesti gati ons ,
too b r i e f , too hurr i ed and too restri cted i n funds to a l l ow more
than very s uperfi c i a l a s s e s sments to be made . In the Bea u fort Sea ,
we face the poss i b i l i ty o f exposure of the ma ri ne e co system to o i l .
We know that s ome of the effec t s o f o i l on· b i o l og i ca l components of
the sys tem a re harmfu l . vJe know o f none whi c h are unquest i onabl y
benefi c i a l . We are a very l ong way from havi ng a ny good u nderstand i n g
o f t he overa l l effects u pon the ecosys tem . There i s a great need to
overcome thi s defi c i ency , and i f rea l i s ti c env i ro nmental i mpact
a s ses sments a re to be ma de i t mu st be overcome .
10.
NEEDS FOR FURTHER STUDY
Wi th re spect to i mpact asse ssmen t , we req ui re devel o pment o f
an u ndersta nd i n g , wh i ch we do not ha ve at presen t , of what the
i mpact does to the eco system as a who l e . Th i s i s a
probl em con s i d ered a part from s tud i e s on d i rect effects on i ndi vi dual
components o f the sys tem . The questi on s wh i ch ari se here a re
concerned wi th tota l e ffec ts .
There are many needs fo r further s tudy . The data base shoul d
be expanded i n both t i me and space , to gi ve year-round i nfo rma t i o n
from the ful l ex tent of the study a rea .
The phys i cal s i de of the study shoul d be suppl emented to g i ve
good detai l ed i nforma t i on on water movements a t al l depth s , i n a l l
seasons and under the fu l l ra nge of the pri nc i pa l external forces
wh i ch govern them . I n thi s way , the route of the i mpact may be
pred i cted , the vari abl e pattern s o f nutri ent and pl an kton
di stri but i o n may be descri bed , and the i n teracti ons among them
may be better understood .
Better knowl edge of the i ce cover i s needed , both of i ts
geogra ph i cal extent and i t s stru cture a nd content . The i ce fl ora
and a s soci ated features requ i re exten s i ve exami nat i on over the
fu l l geo grap h i c a l and t i me ran ges .
78
Trophi c re l a ti onsh i p s need to be q ua nti tati vel y de scri bed ,
to take i nto account e s peci al l y the phytopl ankton - zoopl an kton fi s h - mammal , and the i ce d i a tom - zoop l an kton - f i s h - mammal
sequences . The re are req u i rements to know the degree of troph i c
i nterdependance a t al l l eve l s o f the sys tem , the ava i l ab l e o p t i o n s
i n tro ph i c pathways a n d t h e deta i l s of i mpact s pread through the
food cha i n .
79
11 .
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