v
<
c
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Estimation of the Halogen Content of
the Marine Alga Nereocystis
luetkeana over the Growing Season
By: J.N.C. Whyte and J.R. Englar
FISHERIES AND MARINE SERVICE
SERVICE DES PECHES ET DES SCIENCES DE LA MER
T ECHNICAL REPORT No.
RAPPORT T ECHNIQUE N°
1975
561
1+
Environment
Canada
Envitonnement
Canada
Rsheries
and Marine
Service
Service des peches
et des sciences
de la mer
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Research and Development Directorate
Developpement
TECHNICAL REPORT NO.
RAPPORT TECHNIQUE NO. 561
561
(Numbers 1-456 in this series were issued
(Les numeros 1-456 dans cette serie
as Technical Reports of the Fisheries
furent utilises comme Rapports
Research Board of Canada.
Techniques de l'office des recherches
The series
name was changed with report number 457)
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Le nom
de la serie fut change avec Ie rapport
numero 457)
Estimation of the Halogen Content of the Marine Alga
Nereocystis luetkeana over the Growing Season
By
J.N.C. Whyte and J.R. Englar
This is the twenty third Technical
Ceci est Ie vingt troisieme Rapport
Report from the Research and
de la Direction de la Recherche et
Development Directorate
Developpement, Laboratoire de
Vancouver Laboratory
Vancouver
Vancouver, B.C.
Vancouver, (C.-B.)
1975
ii
TABLE OF CONTENTS
Page No.
ABSTRACT
iii
GENERAL INTRODUCTION TO THE ALGA
1
COLLECTION AND PREPARATION OF SPECIMENS
5
THE HALOGEN CONTENT OF NEREOCYSTIS
6
(i)
(ii)
(iii)
Introduction
Methods of analysis
6
7
(a) Ion selective electrode apparatus
(b) Fus i on of alga for hal i de anal ys i s
(c) Attempts to determine iodide directly
(d) Attempts to estimate chloride, bromide and
iodide in the same solution
(e) Procedure for iodide and chloride estimation
(f) Assessment of bromide content by spectrometric
analysis
7
8
8
Results and Discussion
REFERENCES
TABLE 1
10
13
14
15
19
Halogen content of the fronds and stipes of
Nereocystis luetkeana over the growing season
21
FIGURE 1 Seasonal variation in the percentage freeze dried
wei ght
3
FIGURE 2 Seasonal variation in the total and insoluble ash
contents
4
FIGURE 3 Electrode response to the titration of a solution
of chloride, bromide and iodide with aqueous silver
nitrate
11
FIGURE 4 Seasonal variation in the chloride content
22
FIGURE 5 Seasonal variation in the iodide content
23
iii
ABSTRACT
A general introduction including habitat and life cycle of
the brown alga Nereocystis luetkeana is presented together with the
determination of the seasonal variation in the halogen content of the
alga over the growing season.
Specimens of the alga were collected monthly from April to
October and the frondsand stipes of the alga analyzed for chloride,
iodide and bromide content. The use of ion selective electrodes to
estimate these halogens was investigated and a procedure developed
for the determination of chloride and iodide which involved prior
fixation by alkaline fusion followed by titration with standard aqueous
silver nitrate using an iodide selective electrode as a hypersensitive
equivalence point detector. As a result of a coprecipitation
phenomenon the bromide content of the alga could not be determined by
this procedure. However the assessment of the bromide content was
performed by a spectroscopic technique for which a threshold detection
level was determined.
The chloride content of the stipes ranged in value from 15.1
to 26.9% and provided a seasonal average of 19.3% whereas a lower
chloride content was exhibited by the fronds which ranged from 12.7
to 17.0% over the season and afforded an average concentration of 17.0%.
Similar to the chloride content, the highest level of iodide was
provided by the stipes which contained 826 to 1548 ppm over the season
and averaged 1163 ppm in contrast to the fronds which contained an
average 914 ppm iodide and a seasonal range of 529 to 1423 ppm. No
bromide above the threshold detection level could be ascertained in
either segment of the alga throughout the season.
iv
,
,
RESUME
Les auteurs presentent une introduction generale comprenant une
discussion de l'habitat et du cycle evolutif de l'algue brune Nereocystis
Luetkeana, ainsi qu'une determination des variations de la teneur en halogenes
au cours de la saison de croissance de cette algue.
Des echantillons de l'algue en question ont ete recueillis
chaque mois, d'avril
a
a
octobre, et la fronde et Ie pedoncule ont ete analyses
pour leur teneur en chlorures, iodures et bromures.
Les auteurs ont etudie
la possibilite d'utiliser des electrodes ioniques specifiques pour evaluer
la concentration de ces halogenes et ont mis au point une methode pour la
determination du chlorure et de l'iodure, methode comportant une fixation
prealable par fusion alcaline puis un titrage avec une solution etalon de
nitrate d'argent aqueuse au moyen d'une electrode specifique pour Ie dosage
des iodures comme detecteur hypersensible du point d'equivalence de la
reaction.
a
La teneur en bromures n'a pu etre determinee par cette methode
cause d'un phenomene de coprecipitation.
Cependant, elle a pu l'etre par
un procede d'analyse spectroscopique pour lequel Ie seuil de detection a ete
determin~.
La teneur en chlorures des pedoncules variait entre 15.1 et 26.9 %
pour une moyenne de 19.3 % pour la saison.
soit de 12.7
a
CelIe des frondes etait inferieure,
17.0 % pour une moyenne de 17.0 %.
Les pedoncules contenaient
egalement une plus haute teneur en iodures que les frondes, leur concentration
se situant entre 826 et 1548 p.p.m. pendant la saison pour une moyennede 1163
p.p.m. comparativement aux frondes dont la teneur etait de 529
pour une moyenne de 914 p.p.m.
a
1423 p.p.m.
Pendant toute la saison, la teneur en bromures
dans les deux parties de l'algue n'a pas depassee Ie seuil de detection.
- 1 -
GENERAL INTRODUCTION TO THE ALGA
Nereocystis 1uetkeana (Mertens) Postels and Ruprecht is a
member of the family Lessoniaceae of the order Laminaria1es, which is
indigenous to the North East Pacific where its distribution ranges
t
from the coast of Alaska to California (Drueh1, 1970).
The alga is
commonlyknown as "bull kelp", "sea onion", "bladder kelp", "ribbon kelp",
IIsea otter's cabbage", or "sea whip" and is the dominant giant kelp
on the coast of British Columbia.
It is essentially an annual plant
which starts as a young sporophyte in the early part of the year and
is usually torn loose by storms or disintegrates by the late autumn
of the same year.
Hence it constitutes a renewable resource on the
coast of British Columbia estimated to exceed 370,000 tons annually
(Scagel, 1961).
The plants that do persist through the winter are
heavily covered by epiphytes and epifauna by the following summer.
The
alga is secured to rocks in the upper subtidal level and to a depth
of several fathoms by a profusely branched ho1dfast from which a
cylindrical stipe emerges.
The stipe up to 25 m long is terminated
by a pneumatocyst (15-17 cm in diameter) which bears two clusters of
fronds (up to 15 cm broad and 10 m long) normally about 3.5 times
heavier than the stipe.
The mature plant has an average weight ranging
from 7-18 lbs in the waters of British Columbia.
The mature alga produces dark brawn spore patches, "sori"
on the fronds which drop away when mature and the sporangia after meiosis
liberate biflagellate zoospores which germinate to yield multicellular
filamentous sexual plants.
From the antheridia of the male plants
- 2 -
motile sperm
arer~eased
female plants.
to fertilize the eggs in the oogonia of the
After syngamy the zygote formed undergoes mitotic
division and growth to yield the young sporophyte which is conspicuous
in the early part of the year.
In a previous report (Whyte et al., 1974) on the inorganic
cationic components of Nereocystis luetkeana the dry matter of the
fronds and stipes of the alga ranged from 5.89-9.63% and 7.53-9.60%
of the fresh weight respectivelY,Fig. 1.
The dry matter in the fronds
was assessed to contain over the growing season from 35.9-48.0% ash,
Fig. 2,providing an average 40.2% ash content comprised of approximately
19% water soluble cations in the form of alkali metals.
Similarly the
stipes of Nereocystis over the same period exhibited a range in total
ash of 46.5-60.6%, Fig. 2, with an average 51.3% content comprised of
approximately 25% water soluble cations, which like the fronds were
composed principally of the potassium and sodium ions.
This present report affords a continuation of the assessment
of the chemical composition of Nereocystis luetkeana and describes the
methods researched and subsequently employed to obtain the chloride,
iodide and bromide content of the alga over the active
considered to be from April to October.
growing season
- 3 -
Fig. 1
Percentage Freeze Dried Weight
10.0
A
9.0
- - - t:. -
Fronds
- - - 0 - Stipes
6.0
A
5.0------..,......--..,.....--....oor----.,.---....----"""""P----,..~I~P.
0 ~. ,.,.L.
May
Aug.
Jun.
Jul.
Apr.
'-JV
.-~...,
- 4 -
Fig. 2
Ash Content
70
Total
60
50
40
30
- 0 - Stipes
- l l - Fronds
20
Insoluble
10
A______ ___--o----
& __----A~~~~~-~~-£-----
Apr.
May
Jun.
-<:J--___. __-
Jul.
Aug.
Sep.
Oct.
- 5 -
COLLECTION AND PREPARATION OF SPECIMENS
The samples examined for halogen content were those
analyzed for cation components (Whyte et al., 1974).
Specimens of Nereocystis luetkeana were collected from
selected kelp beds off Stanley Park in Vancouver in the middle of the
months April through October.
This period was considered to be most
representative of the active growing season for Nereocystis since
severe deterioration of the alga was noted in November.
To avoid
enzymatic and microbiological degradation the specimens collected in
plastic bags were transported to the laboratory cold room in insulated
coolers filled with ice.
The fronds and stipes (including pneumatocysts)
were separated and freed from extraneous epiphytes and epifauna and
surface water was removed by blotting lightly with paper.
Fresh water
was not used to wash the alga since it had been demonstrated with other
algae (Young et al., 1958) that alkali metal salts were readily leached
by this treatment.
Specimens after being frozen at -31 0 C were freeze
dried and ground with a porcelain mortar and pestle to 20 mesh size.
Each lot analyzed contained portions from at least 10 plants collected
at the same time and for the analytical determinations the ground
samples were stored in the freeze dryer to ensure anhydrous conditions
at all times.
- 6 -
THE HALOGEN CONTENT OF NEREOCYSTIS LUETKEANA
(i)
Introduction
The occurrence of halogens in ocean seawater has been reported
as 18,980 ppm chloride, 65 ppm bromide, 0.05 ppm iodide and 1.4 ppm
fluoride (Sverdrup et al., 1946) and of these elements only fluorine
is not accumulated to any appreciable extent in benthos algae (Young
et a1., 1958).
Lodine is the only halide of commercial importance in marine
algae from which it was universally isolated until the middle of the
twentieth century (Chapman, 1970).
However the industrial utilization
of kelp as a source of iodine is practised to a limited extent only in
Russia and Japan at the present time (Levring et al., 1969).
The
mother liquor of Chile saltpeter which contains iodine in the form of
sodium iodate is the major source of this element today.
The seaweeds containing iodine still find recognition as a
dietetic supplement, as a pharmaceutical grade seaweed meal, to
eradicate diseases resulting from iodine deficiency such as goitre,
myxeodema and cretinism.
In an increasingly iodine deficient agricultural environment
the use of seaweed meal in agriculture and horticulture has considerable
practical advantages (Jensen, 1972).
Although part of the iodine in
algae is considered to exist covalently bonded in the form of iodo-amino
acids (Scott, 1954) the majority of the iodine is present as inorganic
iodide.
Nevertheless the iodide in seaweed meal appears to be strongly
chelated as it is stable for years in contrast to mineral rich animal
feedstuffs which lose inorganic iodides quite rapidly (Jensen, 1972).
- 7 -
The estimation of halogens by standard procedures (Official
methods A.O.A.C., 1970) are time consuming and tedious and in an
effort to expedite these analyses techniques using ion selective
electrodes were researched.
Unlike most substrates examined by ion
selective electrodes the marine algae, on a dry weight basis, contain
a considerable proportion, approximately 50%, of inorganic salts which
furnish high ionic strength solutions and adversely affect the
electrode potential responses.
Alternate procedures from those generally
practised had therefore to be developed to overcome these problems
inherent in algal analyses.
(ii)
Methods of Analysis
Ion selective electrode apparatus
(a)
An Orion Research Ionalyzer model 801 digital pH/mv meter
with a range from +999.9 to -999.9 millivolts (mv) for the measurement
of specific ion electrode potentials was coupled to an Orion 94-53A
iodide electrode and a double junction reference electrode model
90-02-00 with the outer compartment filled with 10% potassium nitrate.
The interference threshold of the iodide electrode for the chloride and
bromide ions, expressed as a ratio of the concentration of iodide ions
was 10 6 and 5 x 10 3 respectively. Thus if the concentration ratio of
these two interfering halides exceeded these values then erroneous
readings of the electrode would result.
The Ionalyzer was interfaced
with a printer which facilitated the recording of the electrode
potentials.
- 8 -
(b)
Fusion of alga for halide analysis
A sample of the dry alga (2.5 g) was mixed with sodium
carbonate (5 g) in a nickel crucible and moistened with ethanol to form
a homogeneous paste.
Aqueous sodium hydroxide (5 ml, 50%) was added
and fusion commenced spontaneously on mixing.
The mixture after
heating on a hot plate at maximum temperature for 20 min. was completely
fused in a muffle furnace for 15 min. at 500oe. After cooling the
crucible, water (25 ml) was added and the contents boiled for 10 min.
using a watchglass to cover the crucible.
The resulting solution was
filtered and the filter pad with residue was returned to the crucible
for a further extraction with boiling water (25 ml).
The residue
remaining on the filter paper was then washed with boiling water
(4 x 15 ml), nitric acid (4 x 5 ml, 15%) and again with boiling water
(2 x 10 ml).
The resultant solution on cooling was adjusted to pH 4.2
(bromocresol green indicator) with nitric acid using an ultrasonic
cleaner to expedite the mixing and neutralization.
The volume of the
solution was then adjusted to exactly 250 ml to afford the stock solution.
(c)
Attempts to determine iodide directly
Standard solution of sodium iodide were prepared and a
calibration graph drawn of concentration versus electrode potential
response.
The electrode response to an aliquot (100 ml) of the stock
solution was then determined but as a result of steadily declining
potentials no constant equilibrium values could be obtained.
The
values recorded were equivalent to iodide concentrations of approximately
10- 6 M, a level at which the electrode was hypersensitive to changes in
the total ionic strength of the solution.
In an attempt to swamp the
- 9 -
total ionic strength of the fused sample ionic strength adjusters in
the form of 2 Maqueous barium nitrate, nitric acid and potassium
nitrate were added separately to the standard sodium iodide solutions
and the stock solution prior to recording the electrode potentials.
Using these swamping agents the results obtained were reproducible to
on 1y 2=. 10%.
Another procedure for estimating iodide directly was the
"known addition method".
The total concentration of an ion in a
solution can be calculated directly from the change in potential when
a known amount of the ion is added to the sample.
The concentration
of the ion is calculated by the following equation:
CoVo
1
-Co = - = ----:--;:::--CLl
Co
VaMa
(anti 1og Ll~ - 1)
= concentration of iodide in original solution.
CLl = change in iodide concentrations of additi ve.
Vo = original volume of solution.
Va
= volume of additive.
Ma
=
LlE
= change in potential on addition of additi ve.
S
molarity of additive.
= slope of electrode response.
The change in potential was measured when 1 ml of 10- 2 M
sodium iodide was added to 100 ml of a stock solution prepared from a
kelp sample of known iodide content.
The calculated value was 1000 ppm
in contrast to the value of 830 ppm which had been determined by the
Elmslie-Caldwell method (Official method of A.O.A.C. 1970 (b)).
- 10 -
The drift in the electrode potential in the initial readings, as a
result at the low iodide concentrations in a high ionic strength
background, was assessed to be the major factor affecting the accuracy
of this procedure.
(d)
Attempts to estimate chloride, bromide and iodidein the same
solution
Apart from the direct potentiometric measurements the halides
in a solution can be determined by silver nitrate titrations using the
iodide selective electrode as an extremely sensitive endpoint detector.
As iodide and bromide are associated with brown and red algae, the use
of this technique in their assessment in addition to the ubiquitous
chloride ion offered considerable analytical advantages.
To assess the utility of the procedure a solution (100 ml)
containing the sodium salt of the three halides, each in 2 x 10- 3 M
concentration, was titrated with 0.100 Msilver nitrate solution with
the electrode potential being recorded after equilibrium had been
attained following each addition of titrant.
The results are
graphically displayed in Fig. 3 where the equivalence points of the
iodide, bromide and chloride were determined, by using Gran's plot
graph paper (Orion Research Inc. 1970), to be 2.00,2.17 and 1.83 ml
of silver nitrate respectively.
When using an iodide selective
electrode the endpoint determined from Gran's plot graph paper
required that the upper portion of the titration curve be used for
chloride and bromide equivalence points (change in silver ion
concentration) and that the lower portion of the curve be used for the
+400
Fig.3
- 11
-
Solution, 100ml containing;
2 x 10
-3
M NaCI
-3
2 x 10 M NaBr
2 x 10 -3 M Na I
+300
Chloride
•
+200
1
>
E
+100
Bromide
o
Read at equi Ii brium
Iodide
-100
•
-200
~~--r---~~--~~--~----~----~----~-----r----~
1
2
3
4
5
- - ml O'10M Silver Nitrate
6
7
...
8
~:}
- 13 -
but failed to yield any results for the bromide admixed with chloride.
!twas concluded therefore that the coprecipitation phenomenon between
the silver bromide and chloride made impractical the determination of
parts per million of bromide in the presence of a high percentage of
chloride anions.
Nevertheless the above titration procedure was shown
to be simple, accurate and rapid for the estimation of small amounts
of iodide admixed with a high chloride concentration.
(e)
Procedure for iodide and chloride estimation
An aliquot (100 ml, or 50 ml diluted to 100 ml depending on
concentration of halides) of the stock solution was titrated with
0.001 Msilver nitrate solution.
The ionic potential was recorded after
each addition of titrant at the potentiometric endpoint range previously
ascertained from the titration of standard solutions of iodide, usually
-120 mv to -60 mv.
Using volume corrected Gran's plot graph paper the
equivalence point for the iodide was determined which optimally was
found to range from 2-5 ml of titrant.
The concentration of iodide
was calculated as follows:
0.001 Mtitrant x 317.26
pp m Iodide = X ml weight
sample (g)
An aliquot
(for 250 ml stock
solution and
100 ml aliquot)
(5 ml) of the stock solution was diluted to 100 ml
and titrated with 0.100 M silver nitrate solution with potentiometric
data being collected in the predetermined millivolt range, usually from
+345 mv to +400 mv.
With the aid of Gran's plot graph paper the
equivalence point of the titration was determined which optimally was
observed to be from 2-5 ml of titrant.
calculated accordingly:
The chloride content was
- 14 % Chloride
= X ml
0.10 M titrant x 17.727
weight sample (g)
(for 250 ml
stock solution
and 5 ml aliquot
diluted to 100 ml)
A sample of Nereocystis analyzed in triplicate by the above
procedure afforded average values of 514 ppm iodide and 21.3% chloride
compared to the corresponding values obtained by alternate chemical
methods (Official methods of AOAC, 1970) of 471 ppm iodide and 21.6%
chloride respectively.
The iodide results by titration were slightly
higher than those provided by the Elmslie-Caldwell method, however this
discrepancy was considered acceptable in view of the errors inherent in
the latter more indirect and laborious method.
(f) Assessment of bromide content by spectrometric analysis
Although the qualitative tests for bromide (Vogel, 1964)
failed to indicate the presence of this halide in Nereocystis the
following procedures were used to quantitate the detectable levels of
the bromide ion by employing spectrometric techniques.
To standard aqueous solutions of sodium bromide (5 ml),
sulphuric acid (16 N, 5 ml) and chloramine-T (1.5 ml of a solution
containing 15
g/~)
werp added and the mixture thoroughly shaken.
The
resulting mixtures were then treated dropwise with chlorine water
(stock solution 100 ml 5% sodium hypochlorite with 10 ml 16N hydrochloric
acid) to oxidize any iodine to iodate thereby transferring the iodine
to the aqueous phase.
The chloroform layer was then separated and a
spectrum recorded which exhibited strong absorption for bromine at
410 nm. It was demonstrated that a solution containing 5 x 10- 3 M
bromide afforded a chloroform solution exhibiting clear absorption at
- 15 -
that wavelength, however no absorption in the organic phase was presented
from a solution of 1 x 10- 3 M bromide. Thus the former was taken as the
threshold level of spectrometric detection of bromide by this technique.
The algal samples were analyzed as follows.
The dry alga
(25 g) was fused by the procedure previously outlined and the resultant
alkaline solution evaporated to dryness.
To concentrate the alcohol-
soluble bromide salts the residue was extracted several times with a
mixture of methanol: ethanol (v:v; 1 :1,5 x 100 ml) and the filtered
combined extracts evaporated to dryness.
To the residue enough water
was added (approx. 40 ml) to make a saturated solution of these salts
and the bromide content of this solution assessed by the spectroscopic
procedure previously described.
The threshold level of spectrometric detection
= (5 x 10- 3) (5 x 10- 3 ) moles Br
= 2.5 x 10- 5 moles BrHowever 25 g of alga was sampled.
The threshold level of detection in the alga by this procedure
= 2.5 x 10 -5 x 79.9 x 100 %
25
(iii)
==
0.00799 %
=
79.9 ppm
0
Results and Discussion
Prior to the assessment of halogens in Nereocystis all samples
of the dry alga were fused with alkali before ashing as a preventative
measure against loss of bromine or iodine originating from organically
bound and potentially volatile halogen components.
- 16 -
The standard methods for estimating halogens are laborious
and time consuming, therefore in an effort to expedite halide determinations use was made of ion selective electrode techniques.
The direct
measurement and "known addition method" for determining iodide with
the iodide selective electrode failed to provide reproducible and
accurate results.
This failure resulted from the low intrinsic
concentration of iodide in the alga necessitating the use of the
electrode in a sensitivity range which was adversely affected by the
inherently high ionic strength of the algal solution.
The high ionic
strength was further compounded by the necessity for alkaline fusion of
the sample prior to analysis.
The use of the iodide selective electrode to detect the
equivalence points of halides titrated
wit~
standard silver nitrate
solutions proved to be rapid, accurate and convenient only for chloride
and iodide estimations.
The estimation of bromide in parts per million
admixed with a high concentration of chloride ion proved to be impossible
due to a coprecipitation phenomenon which could not be resolved even by
altering environmental conditions.
The use of Gran's plot graph paper
to determine the endpoint of the titration curve greatly facilitated
the chloride and iodide determinations.
As bromide could not be detected
by the electrode procedure a spectrometric technique was devised to
enable a content in excess of 79.9 ppm to be ascertained.
The results of the halide evaluation for Nereocystis over the
growing season are presented in Table 1.
The chloride content of the
stipes with an average of 19.3% and a range of 15.1 to 26.9% was
considerably greater than the 15.1% average and 12.7 to 17.0% range
exhibited by the fronds.
The exceptionally high value 26.9% recorded
for the chloride content of the stipes in April declined rapidly to
- 17 -
the lowest value 15.1% by the following month and thereafter steadily
increased through the remainder of the season, Fig. 4.
Less extreme
fluctuations in the chloride content of the fronds were evident with
the lowest value recorded in mid season and the highest in September,
Fig. 4.
The range of chloride content in Nereocystis, 12.7 to 26.9%,
was markedly greater than that reported, 3.6 to 5.2%, for the content
of chloride in dry Norwegian seaweed meal, Ascophyllum nodosum, which
is utilized as an animal feed (Jensen et al., 1968).
The effects, if
any, of feeding animals with Nereocystis meal containing this high
proportion of chloride is presently under examination.
The iodide content of the stipes generally fluctuated throughout
the season and ranged from 826 to 1548 ppm with an average value of
1163 ppm, Table 1.
An upward trend in the iodide content of the fronds
from June at 529 ppm to October at 1423 ppm provided the total range
registered for the fronds which contained a seasonal average of 914 ppm,
Fig. 5.
The iodide content, similarly to the chloride content, proved
to be greater in the stipes than the fronds of Nereocystis and
corroborated the higher ash content to be found in the former segment
of the alga.
The values for the iodide in Nereocystis, 529-1548 ppm, are
considerably lower than the corresponding values of 0.1 to 1% reported
for Laminariales in Scotland (Black, 1949) where observations indicated
that iodide concentration was directly proportional to the depth of
immersion of the algae.
Thus the lower values provided by Nereocystis
may be a function of the relative proximity of the actively growing
plants to the surface of the sea.
Still, the values for iodide content
- 18 -
of dry Norwegian seaweed meal 824 to 1412 ppm (Jensen, 1971) fall
comfortably within the range afforded by Nereocystis.
The bromide content of the alga throughout the growing season
did not exceed 79.9 ppm, the level detectable by the spectrometric
procedure employed.
Bromine has normally been associated only with
aromatic bromo-compounds in red algae (G10mbitza et a1., 1972; Craigie
et a1., 1967) but recently the occurrence of similar compounds in
brown algae has been reported (Pedersen et a1., 1975).
Gas liquid
chromatography - mass spectrometry and neutron activation analyses
(Lunde, 1973) have been required as detectors in the analyses since
the levels of bromine inclusion in these brown algae have been
estimated at less than 600 parts per billion.
At this level it is
feasible that some of the bromo-compounds are not originating from the
algae but from associated epiphytes or epifauna.
Nevertheless it is
unlikely that Nereocystis is assimilating bromide since the threshold
level of detection at 79.9 ppm is slightly higher than the bromide
content of ocean seawater at 65 ppm.
In conclusion, the relatively high halide content in Nereocystis
1uetkeana compared to the conmercially utilized seaweed meal from
Ascophy11um nodosum could possibly be a limiting factor in the high level
inclusion of this meal into animal feed.
However,this facet of live-
stock feeding with Nereocystis meal is currently under examination and
preliminary results with high levels of seaweed inclusion in the feed
appear to have had little if any detrimental effects on the animals but
conversely appear to have stimulative effects on the process of digestion.
- 19 -
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Black, W.A.P.
1949.
Seasonal variations in chemical composition of
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Part II, J. Soc.,
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,
Chapman, V.J.
1970.
Seaweeds and their uses.
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p. 24.
Craigie, J.S., and Greunig, D.E.
1967.
Bromopheno1s from red algae.
Science 157, 1058.
Drueh1, L.D.
1970.
The pattern of Laminariales distribution in the
northeast Pacific.
Phycologia~,
237.
Glombitza, K.W., Stoffe1en, H., Murawski, U., Bie1aczek, J. and Egge, H.
1974.
Antibiotica aus algen 9.
Rhodomelaceen.
Mitt. Bromphenole aus
Planta Medica 25, 105.
Jensen, A., Nebb, H., and Saeter, E.A.
1968.
The value of Norwegian
seaweed meal as a mineral supplement for dairy cows.
Norwegian Institute of Seaweed Research, Report No. 32, 35 pp.
Jensen, A.
1971.
animals.
The nutritional value of seaweed meal for domestic
Proc. Intll. Seaweed Symp. I, 7.
Levring, T., Hoppe, H.A. and Schmid, O.J.
of research and utilization.
Lunde, G.
1973.
1969.
Marine algae, a survey
Cram, De Gruyter and Co., p. 347.
The presence of volatile, nonpolar bromo organic
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Granls plots and other schemes.
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Pedersen t M. and Fries t L.
1975.
Bromophenols in Fucus vesiculosus.
Z. Pflanzenphysiol. 74 t 272.
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Scagel t R.F.
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11th Edition (a) p. 45 (b) p. 134.
Marine plant resources of British Columbia.
Bull. Fisheries Res. Board of Canada t 127 t 39 pp.
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Observations on the iodo-amino-acids of marine algae
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Elemental composition of the
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- 21 -
TABLE 1
Halogen Content of the Fronds and Stipes of
Nereocystis 1uetkeana over the Growing Season
Month
Chloride
(% Dry Weight)
Iodide
(ppm Dry Weight)
Bromide
(ppm Dry Weight)
Fronds
Stipes
Fronds
Stipes
Fronds
Stipes
April
15.6
26.9
733
826
ND
ND
May
15.9
15. 1
721
1548
ND
ND
June
14.2
16.5
529
946
ND
NO
July
12.7
16.2
988
1322
NO
ND
August
15.2
18.5
1018
1246
ND
ND
September
17.0
19.6
979
1309
ND
ND
October
15.2
22.0
1423
947
ND
ND
NO
= None
detected above 79.9 ppm (detectable level)
- 22 -
Fig.4
Chloride Content
Frond.
- - - C-Stip••
- - - 6. -
~
o
15
10~--~----~-----r----~------~-----r-----r-
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
- 23 -
Fig.5
Iodide Content
8
1500
1
E
C-
o.
_ _- - - A _ _ _ _ _
A-
A
m.
Fronds
0 - Stipes
- - - !:J. -
......
Apr.
---...,.....,-_.
Sep.
Oct.
--.----...---~----.---..,.....--·-'---r-t
May
Jun.
Jul.
Aug.