Annls
Limnol.
25 ( 2 ) 1989 :
107-120
A longitudinal study of zooplankton along the L o w e r Orinoco River
and its Delta (Venezuela)
E. V a s q u e z
J.
1
Rey2
K e y w o r d s : O r i n o c o River, O r i n o c o Delta, zooplankton abundance, zooplankton
composition.
Z o o p l a n k t o n s a m p l e s c o l l e c t e d a t l o w a n d h i g h w a t e r i n 14 a n d 21 s t a t i o n s r e s p e c t i v e l y a l o n g s o m e 900 k m o f t h e O r i n o c o a n d i t s D e l t a , r e v e a l e d the p r e s e n c e o f 100 r o t i f e r a n d 48 c l a d o c e r a n t a x a . O f t h e s e , o n l y 13 r o t i f e r a n d 8 c l a d o c e r a n
s p e c i e s w e r e f r e q u e n t a n d n u m e r i c a l l y i m p o r t a n t , m a i n l y Keratella
americana,
Lecane proiecta,
Ploesoma
lenliculare,
Polyarthra
vulgaris,
Bosmina
tubicen,
Bosminopsis
deitersi,
Diaphanosoma
birgei a n d Moina
minuta.
Nauplii w e r e domin a n t a m o n g the c o p e p o d s . A t l o w w a t e r , r o t i f e r s w e r e b y f a r the m o s t a b u n d a n t g r o u p ( m e a n 4 9 o r g . / l ) f o l l o w e d b y c l a d o c e r a n s ( m e a n 2.8 org/1) a n d c o p e p o d s (1.5 org/1). A t h i g h w a t e r , r o t i f e r d e n s i t i e s d e c l i n e d t o a m e a n o f 3,5 org/1, f o l l o w e d
b y c o p e p o d s ( m e a n 3.4 org/1) a n d c l a d o c e r a n s ( 1.2 org/1). M e a n z o o p l a n k t o n d e n s i t i e s at l o w w a t e r w e r e e i g h t t i m e s h i g h e r
than at h i g h w a t e r . A t l o w w a t e r , l o n g i t u d i n a l z o o p l a n k t o n d e n s i t i e s s e e m e d t o b e i n f l u e n c e d by t r i b u t a r y r i v e r w a t e r s .
At h i g h w a t e r , d e n s i t i e s w e r e g e n e r a l l y l o w u p to the D e l t a w h e r e a l o n g i t u d i n a l i n c r e a s e w a s o b s e r v e d . A h i g h p r o p o r t i o n
o f e g g c a r r y i n g c l a d o c e r a n s , p a r t i c u l a r l y B. tubicen,
B. deitersi a n d M. minuta,
w e r e o b s e r v e d at l o w w a t e r a l o n g t h e s a m p l i n g s i t e s , s u g g e s t i n g an a b i l i t y o f t h e s p e c i e s f o r g r o w t h a n d r e p r o d u c t i o n in the
river.
Klude longitudinale du zooplancton du Bas O r é n o q u e et de son Delta (Venezuela)
Mots clés : Fleuve Orénoque, Delta Orénoque, zooplancton, abondance,
composition.
L ' é t u d e l o n g i t u d i n a l e de l ' a b o n d a n c e et d e la c o m p o s i t i o n du z o o p l a n c t o n , e n p é r i o d e d e b a s s e s et d e hautes e a u x d a n s
14 et 21 s t a t i o n s r e s p e c t i v e m e n t d e l ' O r é n o q u e et d e son D e l t a , a r é v é l é la p r é s e n c e d e 100 t a x a d e r o t i f è r e s et d e 48 t a x a
d e c l a d o c è r e s . S e u l s 13 r o t i f è r e s e t 8 c l a d o c è r e s s o n t f r é q u e n t s et n u m é r i q u e m e n t i m p o r t a n t s : p r i n c i p a l e m e n t
Keratella
americana,
Lecane proiecta,
Ploesoma
lenticutare,
Polyarthra
vulgaris, Bosmina
tubicen,
Bosminopsis
deitersi,
Diaphanosoma birgei et Moina minuta.
L e s c o p é p o d e s s o n t e s s e n t i e l l e m e n t r e p r é s e n t é s p a r d e s n a u p l i i . A b a s s e s eaux, l e s r o t i f è r e s
c o n s t i t u e n t le g r o u p e l e p l u s a b o n d a n t (49 o r g / l en m o y e n n e ) , s u i v i p a r l e s c l a d o c è r e s (2.8 o r g / l e n m o y e n n e ) et l e s c o p é p o d e s (1.5 o r g / l ) . A h a u t e s e a u x , l e s r o t i f è r e s c h u t e n t à 3.5 o r g / l e n m o y e n n e , s u i v i s p a r l e s c o p é p o d e s ( m o y e n n e : 3.4 o r g / l )
et les c l a d o c è r e s (1.2 o r g / l ) . L a d e n s i t é m o y e n n e du z o o p l a n c t o n est d i m i n u é e d'un f a c t e u r 8 à h a u t e s eaux. L o n g i t u d i n a l e m e n t , à b a s s e s e a u x , l ' a b o n d a n c e d u z o o p l a n c t o n s e m b l e ê t r e i n f l u e n c é e p a r les e a u x d e s t r i b u t a i r e s . A h a u t e s e a u x , l e s
densités sont g é n é r a l e m e n t f a i b l e s j u s q u ' a u D e l t a o ù l'on o b s e r v e un a c c r o i s s e m e n t l o n g i t u d i n a l . U n e forte p r o p o r t i o n
d e c l a d o c è r e s o v i g è r e s , p r i n c i p a l e m e n t B. tubicen,
B. deitersi et M. minuta,
o b s e r v é s à b a s s e s e a u x t o u t au l o n g d e s s i t e s
é c h a n t i l l o n n é s , s e m b l e i n d i q u e r q u e c e s p o p u l a t i o n s p e u v e n t se r e p r o d u i r e e t s e d é v e l o p p e r d a n s l e f l e u v e .
Introduction
t h e f a c t t h a t t h e s e r i v e r s a r e , in m o s t c a s e s ,
H y n e s (1970) a n d W e l c o m m e (1985) h a v e
pointed
out the scarcity o f z o o p l a n k t o n studies f r o m
cal
rivers. T h e study of these communities
V e n e z u e l a n r i v e r s o f the O r i n o c o B a s i n has
received much
tropifrom
recently
attention. This interest stems
from
cal w a t e r c o u r s e s w i t h n o o r scarce h u m a n
rivers offers the opportunity
tions
established
their
floodplains.
between
to study the
the
tropi-
interven-
tion. S i m i l a r l y , t h e study o f zooplankton f r o m
these
interac-
watercourses
and
T h e first study w h i c h i n c l u d e d analysis o f z o o p l a n k 1. Fundacion La Salle de Ciencias Naturales, Estaciôn Hidrohiologica de Guayana. Apdo. 51, San Félix, Edo. Bolivar, Venezuela
2. Laboratoire d ' H y d r o b i o l o g i e , Université Pau I-Saba tier, UA
695 du C N R S , 118, route de Narbonne, 31062 Toulouse Cédex,
France.
ton c o l l e c t e d in the O r i n o c o f l o o d p l a i n w a s t h a t o f
H a u e r ( 1 9 5 6 ) . M o r e recent
Vâsquez
& Sanchez
studies include those o f
(1984) w h o studied
f r o m t h e L o w e r O r i n o c o a n d an a d j a c e n t
plankton
floodplain
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
Article available at http://www.limnology-journal.org
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
or http://dx.doi.org/10.1051/limn/1989011
https://doi.org/10.1051/limn/1989011
108
lake and Saunders & L e w i s (1989) w h o carried
an e x t e n s i v e study o f z o o p l a n k t o n f r o m the
out
Lower
O r i n o c o a n d s o m e tributaries. V â s q u e z (1984 a) and
R e y & V â s q u e z ( 1 9 8 6 a ) c a r r i e d o u t t a x o n o m i c stud i e s o f rotifers a n d c l a d o c e r a n s f r o m the L o w e r Orinoco
(2)
E. VASQUEZ. J. REY
and
some
of
its
tributaries
lakes. Dussart (1984) studied
rent lotie and
and
floodplain
copepods from
lentic habitats of the
diffe-
R i v e r ) , a n d S a u n d e r s & L e w i s ( 1 9 8 8 a, b ) , ( C a u r a
by Sanchez
and
so
patterns
o f a b u n d a n c e , c o m p o s i t i o n and biomass. T h i s information
m a y also be of value to establish
compari-
sons with other neotropical floodplain rivers
such
as t h e A m a z o n a n d t h e P a r a n a w h e r e r i v e r z o o p l a n k t o n is w e l l d o c u m e n t e d
Robertson & Hardy
(José de P a g g i
1978,
1983,
1984).
T h e present study w a s carried out
longitudinal
abundance
and
to survey
composition
of
the
zoo-
plankton along the mainstream o f the O r i n o c o River,
margins
o f the r i v e r c h a n n e l and
n o c o d i s t r i b u t a r i e s in the D e l t a
s o m e of the Oriregion.
1. Study A r e a
6
2
T h e O r i n o c o B a s i n d r a i n s a s u r f a c e o f 1.1 x I 0 k m
s h a r e d b y V e n e z u e l a ( 7 0 %) a n d C o l o m b i a ( 3 0 %) ( F i g . 1).
F r o m t h e n o r t h a n d w e s t , t h e O r i n o c o r e c e i v e s the w a t e r s
o f rivers d r a i n i n g t h e V e n e z u e l a n a n d C o l o m b i a n A n d e s
as w e l l as the alluvial plains o f the L l a n o s l o c a t e d b e t w e e n
the A n d e s and the G u a y a n a Shield. R i v e r s d r a i n i n g f r o m
t h i s p o r t i o n o f t h e w a t e r s h e d c o n t r i b u t e the g r e a t e s t q u a n t i t y o f s e d i m e n t s t r a n s p o r t e d by the O r i n o c o f o r w h i c h t h e y
a r e u s u a l l y r e f e r r e d t o as w h i t e w a t e r rivers. T h e y a l s o p r e s e n t h i g h a m o u n t s o f e l e c t r o l y t e s ( M e a d e e t a l 1983). F r o m
t h e south, the O r i n o c o receives p r i m a r i l y b l a c k w a t e r s o f
r i v e r s d r a i n i n g the G u a y a n a Shield w h i c h consists o f lithologically complex Precambrian rocks (Gibbs & Barron
1983). B l a c k w a t e r s a r e c h a r a c t e r i z e d by a v e r y l o w cont e n t o f n u t r i e n t s and d a r k c o l o r c a u s e d by a h i g h c o n t e n t
o f dissolved organic matter. Electrolyte content m a y also
b e l o w ( V e g a s - V i l a r r û b i a et al 1988). T h i s g r o u p o f b l a c k w a t e r rivers i n c l u d e s the m o s t i m p o r t a n t w a t e r c o u r s e s o f
t h e basin w i t h r e g a r d to length a n d a v e r a g e annual disc h a r g e . W i t h i n this g r o u p the C a r o n i c o n s t i t u t e s the o n l y
m a j o r river r e g u l a t e d in the w a t e r s h e d .
W o r l w i d e t h e O r i n o c o r a n k s t h i r d in t e r m s o f a v e r a g e
w a t e r d i s c h a r g e (36 0 0 0 m ' / s ) a n d its s u s p e n d e d l o a d h a s
b e e n e s t i m a t e d a t 2 0 0 x 1 0 t o n s / y e a r ( M e a d e e t al. 1983).
73 % o f t h e O r i n o c o f l o w r e a c h i n g i t s m o u t h o r i g i n a t e s
from
the basin a b o v e the A p u r e R i v e r . T h i s
river
6
i n late A p r i l o r e a r l y M a y ( F i g . 2). T h e n a r r o w
f l o o d p l a i n o f the O r i n o c o p r e s e n t s n u m e r o u s
fringing
temporary
a n d p e r m a n e n t f l o o d p l a i n l a k e s o f v a r i o u s s i z e s a n d shap e s ( V â s q u e z 1988).
studied
& al. (1985). I n f o r m a t i o n g e n e r a t e d
far has been valuable to establish seasonal
the
type w i t h a high w a t e r phase extending from
M a y to N o v e m b e r . M i n i m u m w a t e r l e v e l g e n e r a l l y o c c u r s
b y V â s q u e z (1984 b) (Caroni
A p u r e rivers). Other minor tributaries w e r e
T h e h y d r o l o g i c a l r e g i m e o f the b a s i n b e l o n g s t o
contrasted
basin.
Z o o p l a n k t o n f r o m the major tributaries o f the Orin o c o has been studied
contributes 7 % of the O r i n o c o f l o w w h i l e the Caura and
C a r o n i r i v e r s c o n t r i b u t e 9 % a n d 11 % r e s p e c t i v e l y ( L e w i s
1988). O v e r m o s t o f its 2 0 6 0 k m l e n g t h the O r i n o c o f l o w s
t h r o u g h l o w l a n d s f o r m i n g a b r a i d e d c o u r s e w i t h b a n k s and
i s l a n d s . I n the l o w e r O r i n o c o s l o p e is w e a c k , w a t e r v e l o c i t y is s l o w (1-2 mis) a n d f l o w is h i g h ( M . A . R . N . R . 1979).
T h e O r i n o c o D e l t a is s i t u a t e d b e t w e e n the n o r t h e r n c o a s tal range o f V e n e z u e l a and the G u a y a n a S h i e l d m a r g i n to
t h e s o u t h , w i t h an e x p a n s e o f s o m e 22 500 k m . T h e d e l t a i c p l a i n is f o r m e d b y v e r y l o w l a n d s ( s l o p e < I % a n d e l e v a t i o n a.s.l. < 10 m ) . T h i s r e g i o n is d r a i n e d b y 9 m a j o r dist r i b u t a r i e s and m a n y i n t e r c o n n e c t i n g s m a l l e r canals, all
o f w h i c h a r e l o c a l l y k n o w n as « c a n o s » , r e s u l t i n g in n u m e rous islands and t e m p o r a r y and p e r m a n e n t lakes (van
A n d e l 1967, M . A . R . N . R . 1979). M e a s u r e d f r o m the a p e x o f
t h e D e l t a the m a j o r c a n o s a r e : R i o G r a n d e (270 k m ) , M a c a r e o (21 1 k m ) , a n d M â n a m o (236 k m ) . A s a d i s t r i b u t a r y the
R i o G r a n d e d i s c h a r g e s 84 % o f the O r i n o c o f l o w . V a n A n d e l
(1967) c o n s i d e r s that t i d a l r a n g e in the D e l t a is r e l a t i v e l y
small c o m p a r e d to d i f f e r e n c e s b e t w e e n high and l o w
w a t e r s o f t h e r i v e r . A t h i g h w a t e r the D e l t a is a l m o s t c o m p l e t e l y f l o o d e d . W i l b e r t ( 1 9 8 6 ) d i v i d e d the O r i n o c o D e l t a
i n t o a p r e l i t t o r a l z o n e , c o v e r i n g the r e g i o n n e a r t h e a p e x
w i t h a m e a n e l e v a t i o n o f 3-4 m . a . s . l . ; a l i t t o r a l z o n e
(10-30 k m w i d e ) w h i c h c o m p r i s e s a c o a s t a l s t r i p o f m a n grove forest, palm forest, and savannas permanently flood e d by tidal w a t e r s ; a n d an i n t e r m e d i a t e z o n e , w e d g e d betw e e n t h e p r e v i o u s t w o a n d u n d e r the i n f l u e n c e o f t h e t i d e s .
2
2. Methods
Z o o p l a n k t o n s a m p l e s w e r e c o l l e c t e d at h i g h w a t e r (18-26
September
1985) a n d l o w w a t e r (3-10 A p r i l 1986).
— A t h i g h w a t e r , c o l l e c t i o n s w e r e m a d e a l 21 s a m p l i n g
s i t e s ( F i g . 1), w i t h i n an a p p r o x i m a t e s t r e c h o f 9 0 0 k m .
— A t l o w w a t e r , s a m p l e s w e r e c o l l e c t e d in 14 s a m p l i n g
sites w i t h i n a s t r e c h o f s o m e 7 5 0 k m .
In 9 o f t h e s e s i t e s l o c a t e d b e t w e e n S a m a r i a p o a n d the
a p e x o f t h e D e l t a , c o l l e c t i o n s w e r e m a d e in t h e m i d d l e o f
t h e r i v e r a n d in its t w o s h o r e s . I n the D e l t a , c o l l e c t i o n s
w e r e t a k e n o n l y in the m i d d l e ( T a b l e I ) . A t e a c h s i t e , 80
liters o f subsurface w a t e r was collected and filtered
t h r o u g h a 45 ^.m m e s h net. F o r r o t i f e r s a n d c o p e p o d s 5 m l
s u b s a m p l e s w e r e e x a m i n e d ; they g e n e r a l l y a l l o w e d the
i d e n t i f i c a t i o n o f at least 100 o f t h e m o s t a b u n d a n t t a x a .
I n c a s e s o f l o w d e n s i t y the e n t i r e s a m p l e w a s e x a m i n e d .
H o w e v e r , f o r c l a d o c e r a n s , the e n t i r e s a m p l e w a s a l w a y s
counted. Rotifers and crustaceans demanding detailed
t a x o n o m i c s t u d i e s w e r e m o u n t e d in p o l y v i n i l a l c o h o l a n d
glicerine alcohol, respectively.
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
F i g . 1. T h e O r i n o c o R i v e r B a s i n a n d l o c a t i o n of s a m p l i n g s i t e s .
T a b l e I. N u m b e r a n d n a m e o f s a m p l i n g sites a n d n u m b e r o f s a m p l e s c o l l e c t e d .
LOCATION
SITE
ORINOCO RIVER
Samariapo
Puerto Ayacucho
El Burro
Caicara
Las Bonitas
Las Majadas
Ciudad Bolivar
San Félix
Barrancas
ORINOCO DELTA
Cano M a c a r e o
Rio Grande
Cano Nabasanuca
Caho Orejana
NUNBER
1
2
3
4
5
6
7
8
9
10-14
15-18
19
20-21
Shore a
Middle
Shore c
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
110
E. VASQUEZ, J. R E Y
(4)
F i g . 2. S t a g e h e i g h t in t h e O r i n o c o R i v e r ( A n g o s t u r a ) , (1985-1987).
3. Results and Discussion
f r o m Brazil, Paraguay, a n d Argentina (José de P a g g i
&
3.1.
K o s t e 1 9 8 8 ) . Pioesoma
species
Zooplankton composition
in o u r
lenticulare,
samples,
was
an
abundant
previously found
in
S o u t h A m e r i c a in B r a z i l a n d A r g e n t i n a ( H a u e r 1965,
I n this p a p e r , c o p e p o d s are c o n s i d e r e d as a w h o l e .
T h e inventory of rotifers and cladocerans are
repor­
t e d in T a b l e I I .
b e l o n g t o t h e g e n u s Brachionus,
to
Trichocerca.
22 % t o Lecane,
Over 50 %
o f the
and
identified
organisms w e r e planktonic or semiplanktonic
cies.
%
spe­
13 r o t i f e r s p e c i e s a r e n e w r e c o r d s f o r
Vene­
z u e l a . T h e r e c o r d a n d d e s c r i p t i o n o f B. variabilis
was
p u b l i s h e d e l s e w h e r e ( V â s q u e z & K o s t e 1988). O t h e r
n e w brachionids
tata
bidentata,
cornis
f o r the country
B. caudatus
diversicornis.
i n c l u d e B.
vulgatus,
Lecane
biden-
andB.
lunaris
diversi-
perplexa
was
1973).
C o n c e r n i n g c l a d o c e r a n s 48 taxa w e r e identified :
45.8%
100 r o t i f e r t a x a w e r e i d e n t i f i e d o u t o f w h i c h 25
15 %
Paggi & José de Paggi
were Chydoridae,
Daphniidae,
16.7%
Sididae,
1 0 . 4 % B o s m i n i d a e , 8.3 %
12.5%
Macrothri-
c i d a e , a n d 6.3 % M o i n i d a e . T h e n u m b e r o f c l a d o c e ­
rans
found
in
the
Orinoco was
higher
than
that
r e p o r t e d f o r the P a r a n a (José d e P a g g i 1980) as w e l l
as f o r A f r i c a n r i v e r s s u c h as t h e S o k o t o ( G r e e n 1962),
the O s h u n ( E g b o r g e
1972) a n d the W a r n
(Egborge
1987).
Among
cladocerans,
Bosminopsis
brandorfji
(a
n e w s p e c i e s d e s c r i b e d b y R e y et V â s q u e z 1989) col­
lected
from
the
Nhamundâ
River
in t h e
Amazon
f i r s t l y r e c o r d e d in S o u t h A m e r i c a b y J o s é d e P a g g i
(Brandorff
& K o s t e ( 1 9 8 8 ) in t h e S a l a d i l l o R i v e r B a s i n . T h e p r e ­
p l i n g s i t e s o f t h e O r i n o c o . Diaphanosoma
sence of this species
rare form, only reported from Thailand, China, Aus­
in the O r i n o c o s u p p o r t s
o b s e r v a t i o n s o f these a u t h o r s w h o c o n s i d e r that
Parana River carries southwards
or
subtropical
Guyana-Brazilian
Lecane
amazoniana
origin
the
fauna of tropical
therefore
subregion
the
further
extending
to the
had previously been
the
south.
recorded
et ai. 1982), w a s p r e s e n t
in m a n y
sam­
volzi,
a
t r a l i a ( K o r o v c h i n s k y 1981) w a s o b s e r v e d at s i t e
a t l o w w a t e r . Diaphanosoma
polyspina
(from
z o n B a s i n ) w a s a g a i n r e c o r d e d in t h e O r i n o c o .
minopsis
negrensis
1,
Ama­
Bos­
w a s o b s e r v e d at h i g h w a t e r f r o m
s a m p l e s c o l l e c t e d at site 3 (El B u r r o ) . D e s c r i b e d b y
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
T a b l e I I . List o f r o t i f e r and c l a d o c e r a n
taxa.
ROTIFERA
Anuraeopsis
fissa
Anuraeopsis
navicula
fissa
Asplanchna
Lecane
navicula
brightwelti
Asplanchna
sieboldi
Bdelloidae
ind.
Brachionus
angularis
Brachionus
pseudolabratus
bidentata
Brachionus
calyciflorus
Brachionus
amphiceros
calyciflorus
caudatus
Brachionus
austrogenitus
caudatus
caudatus
Brachionus
caudatus
f.
Brachionus
caudatus
f.
Brachionus
caudatus
Brachionus
insuetus
personatus
vulgatus
diversicornis
Brachionus
diversicornis
dolabratus
Brachionus
falcatus
forficula
Brachionus
gessneri
Brachionus
gillardi
Brachionus
mirus
f.
Brachionus
patulus
Brachionus
patulus
Brachionus
angustus
patulus
Brachionus
urceolaris
Brachionus
quadridentatus
urceolaris
Collotheca
campanulata
sp.
Conochilus
dossuarius
Epiphanes
dossuarius
macrourus
Euchlanis
Euchlanis
dilatata
meneta
longiseta
Filinia
longiseta
Filinia
longiseta
pejleri
Lecane
luna
Lecane
lunaris
Lecane
lunaris
Lecane
ludwigi
luna
lunaris
perplcxa
melini
Lecane
papuana
Lecane
proiecta
rhenana
Lecane
signifera
Lecane
stichaea
Lecane
ungulata
ploenensis
stichaea
ungulata
patella
f.
patella
collinsi
ventralis
Platyias
quadricornis
macracantha
remata
vulgaris
vulgaris
sp.
mucronata
Testudinella
ohlei
Testudinella
patipa
Testudinella
patina
bic ris ta ta
Trichocerca
gracilis
Trichocerca
inermis
Trichocerca
pusilla
lenzi
Kera
tropica
Lecane
Lecane
tella
sp.
aegana
lenzi
tropica
elongata
flagellata
brasiliensis
Keratella
capucina
elongata
intermedia
Trichocerca
bic ris ta ta
chattoni
intermedia
cochlearis
amazonica
capucina
Trichocerca
americana
dendradena
patina
tridentata
intermedia
cochlearis
hauerensis
ohlei
sp.
Hexarthra
Keratella
ruttneri
Trichocerca
similis
grandis
Trichocerca
similis
similis
Trichocerca
Trichotria
.
sp.
Hexarthra
Keratella
quadricornis
lenticulare
Polyarthra
Trichocerca
collinsi
sp.
Mytilina
Trichocerca
oblonga
patella
Monommata
Trichocerca
pejleri
levistyla
ludwigi
Trichocerca
opoliensis
Filinia
Lecane
Trichocerca
limnetica
leontina
levistyla
Testudinella
dilatata
Filinia
Lecane
Testudinella
campanulata
Colurella
hornemanni
Synchaeta
sp.
curvicornis
leontina
Ptygura
mucronata
Collotheca
cornuta
hastata
Polyarthra
voigti
Cephalodella
curvicornis
styrax
Ploesoma
variabilis
Brachionus
Lecane
Lecane
bulla
Macrochaetus
quadridentatus
rubens
cornuta
Lepadella
macracanthus
Brachionus
Lecane
Lepadella
havanensis
Brachionus
bulla
Lecane
fakatus
Brachionus
Lecane
Lecane
f.
calyciflorus
Brachionus
bulla
Lecane
budapestinensis
Brachionus
amazoniana
Lecane
stylata
tetractis
tetractis
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
112
E. VÂSQUEZ, J. R E Y
(6)
T a b l e I I . (suite)
C L A D O C E R A
Alona
sp.
Alona
Diaphanosoma
exirnia
Alona
guttata
Alona
monacantha
Alona
poppei
Alona
intermedia
Biapertura
bicen
deitersi
Latonopsis
negrensis
Macrothrix
sp.
Ceriodaphnia
cornuta
sp.
spinifer
australis
spinosa
Moina
micrura
Moina
minuta
Moina
eurynotus
Notoalona
Chydorus
nitidulus
Oxyurella
gessneri
macrops
Diaphanosoma
sp.
globulosa
sp.
Pseudosida
bidentata
Scapholeberis
sp.
Scapholeberis
sp.l
Diaphanosoma
B r a n d o r f f ( 1 9 7 6 ) f r o m m a t e r i a l c o l l e c t e d in t h e A m a ­
Robertson & Hardy
z o n e , B. negrensis
gessneri
by
w a s firstly recorded for Venezuela
F. W e i b e z a h n
(pers.
comm.)
negrensis
(pers.
has
f r o m the
blackwater
comm.).
collected
but
E. Z o p p i d e
not
Roa
reported
B.
m o u t h of the A t a b a p o River,
tributary of the Orinoco. Based upon
Interesting to note
s e n c e o f Daphnia
in the
gessneri
spe­
the O r i n o c o B a s i n t o
A m a z o n ( W e i b e z a h n e t a l , in
a
the
p r e v i o u s findings, the distribution range o f the
c i e s is e n l a r g e d t o i n c l u d e
the
press).
River (Infante
was
the
first
is r a r e a n d
Mean
serrulatus
1984), in t h e O r i n o c o s y s t e m
r o t i f e r s p e c i e s r i c h n e s s ( F i g . 3) w a s 7.2
h i g h w a t e r a n d i n c r e a s e d t o 2 2 . 9 at l o w w a t e r .
n u m b e r o f c l a d o c e r a n s p e c i e s w a s 4 . 2 a n d 5.4 a t
and
low water
the
pre­
o b s e r v e d at s i t e 2 ( P u e r t o
f o r r e s e r v o i r s in the
Caroni
1984, R e y & V â s q u e z 1986 a ) a n d
t i m e t h a t it w a s o b s e r v e d
in the
D.
scarce.
at
Mean
high
respectively (Fig. 4.).
Longitudinally,
rotifer
species
r i c h n e s s at
high
w a t e r w a s h i g h e r i n t h e D e l t a t h a n in t h e O r i n o c o .
A t l o w w a t e r , the n u m b e r o f species w a s
samples was
A y a c u c h o ) at l o w w a t e r ( d e n s i t y 0.01 o r g . / I ) . T h i s s p e ­
cies had been reported
kingi
Simocephalus
2
*
reticulata
Chydorus
Dadaya
testudinaria
llyocryptus
Bosminopsis
Daphnia
tridentatus
occidentalis
Craptoleberis
n.sp.
Bosminopsis
Chydorus
hybridus
Euryalona
bàandofi&fa
Camptocercus
triserialis
Ephemeroporus
hagmanni
t
sp.
Ephemeroporus
verrucosa
Bosmina
volzi
dadayi
Echinisca
Biapertura
Bosminopsis
spinulosum
Echinisca
sp.
Bosmina
polyspina
Diaphanosoma
Disparalona
rustica
Biapertura
brevireme
Diaphanosoma
Diaphanosoma
quadrangularis
Alona
birgei
Diaphanosoma
relatively
s i m i l a r a l o n g the sites. N u m b e r o f species o f c l a d o ­
c e r a n s at b o t h h i g h a n d l o w w a t e r , w a s h i g h e s t
the
in
river.
3.2.
Overall zooplankton
density
this
Ori­
—
A t high water, mean zooplankton density (Fig.
n o c o w a t e r s . I n c o n t r a s t w i t h the A m a z o n w h e r e this
5 a ) w a s 5.6 o r g . / l a l o n g s h o r e a, 2.1 o r g . / l a l o n g s h o r e
species
c. M e a n d e n s i t y
is
reservoirs
frequent
and
and
sometimes
floodplain
lakes
abundant
(Arcifa
in
1984,
in the
Cano Macareo was
m i d d l e of the
river and
in
12.6 o r g . / l .
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
S T U D Y OF Z O O P L A N K T O N A L O N G T H E O R I N O C O
35
RIVER
T
1
2
3
m
2
3
a
4
4
•
b
5
5
5
•
6
a
7
9
1 0 1 1 1 2 1 3 1 4
Stations
c
7
8
3
10
' 1
"2
! 3
14
: 5
1ô
: 7
11
1 9
20
2i
Sîaiicns
F i g . 3. R o t i f e r s p e c i e s r i c h n e s s at h i g h w a t e r (a) a n d l o w w a t e r ( b ) .
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
114
E. VÂSQUEZ. J. REY
1
2
3
32
4
5
§3
6
a
•
7
b
•
8
(8)
9
1
0
1
1
1
2
1
3 1 4
Stations
c
F i g . 4. C l a d o c e r a n s p e c i e s r i c h n e s s at h i g h w a t e r ( a ) a n d l o w w a t e r ( b ) .
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
S T U D Y OF Z O O P L A N K T O N A L O N G T H E O R I N O C O R I V E R
(9)
1011
115
1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9
20
21
Stations
F i g . 5. Z o o p l a n k t o n d e n s i t y at h i g h w a t e r ( a ) a n d l o w w a t e r ( b ) .
—
At l o w water, zooplankton density
marked
increase
with a mean
showed
o f 59.1 o r g . / l
a
along
s h o r e a, 5 6 . 9 a l o n g s h o r e c a n d 4 7 . 5 a l o n g t h e m i d d l e
sites ( F i g . 5 b) : a m e a n
than at h i g h
density
eight time
1981) w h o p o i n t e d out
zontal
distribution
River and
a fairly homogeneous
of zooplankton
in s o m e o f its
in t h e
tributaries.
higher
water.
Considering each zooplankton group
An
inverse
hori­
Parana
relationship
between
discharge
and
plankton density in the O r i n o c o h a d p r e v i o u s l y b e e n
3.5 o r g . / l
reported
3.4 o r g . / I ;
(Vâsquez &
Sanchez
1984,
Saunders
&
separately,
at h i g h w a t e r , r o t i f e r a b u n d a n c e s h o w e d a m e a n o f
(43,1 % ) f o l l o w e d
41.8 % ) a n d
by
copepods
cladocerans
(mean
(1.2 org./l ;
L e w i s 1989). T h e r e s u l t s a l s o i n d i c a t e that, p a r t i c u ­
15.1 % ) ( F i g . 6 a ) . A t l o w w a t e r r o t i f e r s w e r e b y f a r
l a r l y at l o w w a t e r , d e n s i t i e s a l o n g the s h o r e s w e r e
the most abundant zooplankton g r o u p w i t h a
not m a r k e d l y d i f f e r e n t f r o m m i d d l e s i t e s in s p i t e o f
d e n s i t y o f 49 org./l (92 % )f o l l o w e d by
ihe fact that these r i v e r i n e sites m a y present
( 2 . 8 o r g . / l ; 5.2 % ) ,
more
and
mean
cladocerans
c o p e p o d s ( 1 . 5 o r g . / l ; 2.8 % )
favorable conditions for zooplankton growth. A simi­
(Fig. 6 b). At both high and l o w water, c o p e p o d abun­
lar o b s e r v a t i o n w a s r e p o r t e d b y José d e P a g g i (1980,
dance
was primarily due to nauplii
stages.
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
116
(10)
E. VASQUEZ, J. R E Y
®
©
F i g . 6, R e l a t i v e d e n s i t y o f c o p e p o d s , c l a d o c e r a n s a n d r o t i f e r s at h i g h w a t e r ( a ) a n d l o w w a t e r ( b ) .
3.3.
L o n g i t u d i n a l patterns o f density
Ceriodaphnia
cornuta,
many Chydoridae, and
insect
l a r v a e ) . O n the c o n t r a r y in the D e l t a r e g i o n , the z o o ­
a)
Overall
—
A t h i g h w a t e r ( F i g . 5 a ) , at a l l r i v e r s i t e s ,
longitudinal
zooplankton
distribution
plankton
of zooplankton
did
d e n s i t y w a s h i g h e r t h a n t h a t o b s e r v e d in
the
the O r i n o c o , with a m a r k e d
not
along the distributaries,
tendency
to
increase
probably due to organisms
density
flushed f r o m the vast f l o o d e d a r e a s to the c a n o s . In
o f o r g a n i s m s w a s l o w e x c e p t in site 5 ( s h o r e a) w h e r e
this p e r i o d , z o o p l a n k t o n g r o u p s s h o w e d o s c i l l a t i o n s
a
in their r e l a t i v e densities a l o n g the
s h o w a defined pattern oi abundance. T h e
high density
was observed (mainly
s u c h a s Bosminopsis
deitersi,
Bosmina
cladocerans
hagmanni,
water-courses.
R o t i f e r s , h o w e v e r , w e r e m o r e a b u n d a n t in m o s t of
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
(11)
S T U D Y OF Z O O P L A N K T O N A L O N G T H E O R I N O C O R I V E R
t h e sites e x c e p t in s i t e 5 w h e r e , a s m e n t i o n e d ,
cla­
117
period, dominant bdelloid rotifers showed a certain
d o c e r a n s p r e v a i l e d t h e o t h e r g r o u p s , a n d in sites 11,
f r e q u e n c y a l o n g the first sites. W i t h r e g a r d to cla­
1 9 , 2 0 , 21
docerans, the f o l l o w i n g succession o f frequent d o m i ­
in t h e
Delta, w h e r e copepods (nauplii)
represent 70 % to 90 % o f the zooplankton (Fig.6 a).
In this p e r i o d a p p e a r e d
also drifting
organisms
s u c h as insect l a r v a e , n e m a t o d e s , a n d o t h e r s ,
very
s c a r c e at l o w w a t e r , a n d w h i c h w e r e p r e s e n t in
the
samples
the
as
the
mainstream
floodplain
—
result
of being
flushed
into
f l o w f r o m the river b o t t o m and
other
areas.
n a n t s p e c i e s w a s o b s e r v e d : Moina
1-2), Bosminopsis
tubicen
a l o n g shore a a n d in the m i d d l e o f the r i v e r increa­
s e d l o n g i t u d i n a l l y in t h e s t r e t c h b e t w e e n s i t e s
1-5
and then decreased up to the apex of the Delta (site
9 ) . I n C a n o M a c a r e o ( s i t e s 10-14) t h e r e w a s a s l i g h t
oscillating increase
in a b u n d a n c e w i t h o u t a
clear
p r i m a r i l y in t h e
At l o w water, dominant
a l o n g the studied
proiecta.
dossuarius
sites
(sites
Bosmina
P. vulgaris
sites
and
falcatus,
w e r e frequent
lenticulare
3-6. A t t h i s p e r i o d ,
minuta
frequent
americana
D o m i n a n t Brachionus
and
cladoce­
Delta.
rotifer species
s e c t i o n w e r e K.
1-3, w h i l e Ploesoma
between
Moina
reticulata
( s i t e s 3-9), a n d
( s i t e s 15-21). T h e r e s t o f d o m i n a n t
rans w e r e present
Lecane
At l o w w a t e r (Fig. 5 b), zooplankton abundance
deitersi
C.
between
was
frequent
B. deitersi
w e r e dominant and frequent
and
among
the c l a d o c e r a n s u p t o site 6 f r o m w h e r e t h e y w e r e
r e p l a c e d b y B.
tubicen.
p a t t e r n . D e c r e a s e in a b u n d a n c e o b s e r v e d at sites 6
and 8 w a s p r o b a b l y d u e t o the dilution effect
d u c e d b y the b l a c k w a t e r s o f the C a u r a a n d
pro­
Caroni
Rivers. In both these rivers, zooplankton abundan­
c e s are c o m p a r a t i v e l y m u c h l o w e r than in the
n o c o ( V â s q u e z 1984 b, S a u n d e r s & L e w i s
Ori­
1988 a ) .
A l o n g s h o r e c, a b u n d a n c e d e c r e a s e d b e t w e e n
sites
1-3 a n d t h e n i n c r e a s e d p r o b a b l y b e c a u s e o f t h e r e l a ­
tively higher
suspended
load
transported
by
the
M e t a R i v e r . T h e l o w e s t t r a n s p a r e n c y (25 c m ) o f all
s t u d i e d s i t e s w a s o b s e r v e d at t h e m o u t h o f t h i s r i v e r .
During
important
courses,
this p e r i o d ,
rotifers m a d e up
the
most
g r o u p o f z o o p l a n k t o n a l o n g the
exhibiting
relative
abundances
water­
between
81.8 % a n d 97 % ( F i g . 6 b ) . C o p e p o d s , s c a r s e b e t w e e n
sites
1-6, t h e n s h o w e d a s l i g h t
R e y & V â s q u e z (1986 a) c h a r a c t e r i z e d
whitewater
b o d i e s b y t h e s p e c i e s a s s o c i a t i o n M. minuta,
nuta,
B. tubicen
a n d B. deitersi.
C.
cor­
Dominant cladoce­
ran a s s e m b l a g e in the O r i n o c o w a s s i m i l a r t o
the
p r e v i o u s c h a r a c t e r i z a t i o n . S o m e o f these s p e c i e s o r
r e l a t e d o n e s a r e a l s o d o m i n a n t in t h e
ton of others
potamoplank-
tropical rivers : South America (José
d e P a g g i 1980 and
1981, R o b e r t s o n & H a r d y 1984),
Sri L a n k a ( F e r n a n d o 1980).
T h e presence of a typical freshwater
zooplankton
a s s e m b l a g e in sites o f t h e D e l t a u n d e r the
influence
o f t i d e s c a n b e e x p l a i n e d b y the fact that o u r
sam­
ples w e r e c o l l e c t e d superficially. A t high w a t e r , rela­
tively
little m i x t u r e
o f fresh
and
marine
waters
o c c u r s s u p e r f i c i a l l y u p to a d i s t a n c e of s o m e 7 0
increase.
km
off the Delta coast. At l o w water, this limit
recedes
zooplankton
to s o m e 50 k m o f f the coast. F o r instance,
in M a y
of identified species
1987, d u r i n g the r i s i n g - w a t e r p h a s e , s u p e r f i c i a l sali­
of rotifers and c l a d o c e r a n s , o n l y 9 taxa o f rotifers
n i t y a t 5 0 k m o f f s h o r e w a s 0.2 % (J. M o n e n t e , p e r s .
a n d 7 s p e c i e s o f c l a d o c e r a n s s h o w e d at h i g h
water
c o m m . ) . E g b o r g e ( 1 9 8 7 ) f o u n d in t h e W a r r i R i v e r a
d e n s i t i e s e q u a l o r h i g h e r t h a n 10 % ( T a b l e s I I I , I V ) .
l i m i t o f s a l i n i t y f o r c l a d o c e r a n s b e l o w 0.25 % , w h i c h
b)
Dominant
species
of
In spite of the high n u m b e r
Similar observations have been reported for Ama­
zon w a t e r b o d i e s w h e r e , despite a large n u m b e r
rotifer
species,
few
(Robertson & Hardy
are
numerically
of
dominant
1984). At l o w w a t e r the
num­
b e r o f d o m i n a n t r o t i f e r t a x a i n c r e a s e d t o 14 a n d t h a t
of
cladocerans
groups
to
showed a
semiplanktonic
8.
In
all
cases,
predominance
however,
s p e c i e s a m o n g the
tella
americana
and
dossuarius
Polyarthra
or
dominants.
At high w a t e r the most frequent dominant
s p e c i e s w a s Conochilus
both
of planktonic
vulgaris.
In
Kera­
this
the
A m o n g t h e d o m i n a n t c l a d o c e r a n s in t h e O r i n o c o ,
a high proportion of egg carrying females w a s obser­
v e d at l o w w a t e r a l o n g t h e s a m p l i n g sites ( T a b l e V a )
which suggests
that these species
may be able
g r o w and reproduce along the river. This w a s
t i c u l a r l y t h e c a s e f o r B. tubicen,
rotifer
followed by
is a l i m i t t h a t m a y b e f o u n d s u p e r f i c i a l l y a l o n g
c o a s t of t h e O r i n o c o D e l t a .
B. deitersi,
to
par­
and
M.
minuta.
A t h i g h w a t e r a l a r g e set of e g g c a r r y i n g
females
was
observed mainly restricted
to site
5
w h e r e cladocerans w e r e abundant (Table V b ) . I n the
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
118
(12)
E. VASQUEZ. I . R E Y
T a b l e I I I . D o m i n a n t r o t i f e r a n d c l a d o c e r a n s p e c i e s at high w a t e r ( % ) :
• : 10-19 ; o : 20-29 ; * : 3 0 - 3 9 ; + : 40-49 ; + I : > 50.
l.pAùiteJtA
P.uuZiJilAii
r jjAaocttj
C. ÙOIAUXJL
U. m.nuXa
T a b l e I V . D o m i n a n t r o t i f e r a n d c l a d o c e r a n s p e c i e s at l o w w a t e r ( % ) :
• : 10-19 : o : 20-29 : * : 30 39 ; + : 40-49 ; + + : > 50.
la lb le 2a 2b 2c 3a 3b 3c 4a Ub 4c 5a 5b 5c 6a 6b 6c ?a 7b 7c 8a 8b 8c 9a 9b 9c 10 11 12 13 1U
Bdelloida ( i n d e t . )
0
*
R. budapeAiA.ne.mAJ.
E.
•
caZycÂiZoïui
•
B. ^o-tcaMi&
*
C. campanuùrfa.
•
*
0
0
•
F. £<jng,^*e-ta
•
•
M. intejw>e.cU.a
i.
P.
** 0
m
«
0
piale.<Ua
tenticutane.
zlong.a£a
T.
§>w<UZù,
B.
hagtnanni
B.
-tukeeen
B. dtÀJtzAil
C
co-'inu-ta
0.
bOlQZi.
M. .ie.tccu.taZa
0
*
0
o
«
0
•
•
•
0
c
•
•
*
»
*
0
0
0
*
*
•
+
•
0 *
•
•
++++++*
•
•
* 0
•
0
•
•
*
m
V. ipÀJUktomm
M. minuta.
*
•
P. va£ga/LÙ
T.
•
•
C. donucvULià
K. ajnejU.cana.
«
•
*
*
m 0
.
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
(B)
STUDY OF ZOOPLANKTON ALONG T H E ORINOCO
119
RIVER
T a b l e V . P e r c e n t a g e o f e g g c a r r y i n g c l a d o c e r a n s ; a : at l o w w a t e r ; b : at h i g h w a t e r ( d o m i n a n t s p e c i e s ) .
1
B.
2
3
4
5
6
7
14
12
15
16
17
19
19.0
24.0
31 . 0
12.5
19.O
19.0
21.0
25.0
hagmanni
27.0
B.
tubicen
B.
deitersi
C.
cornuta
D.
birgei
D.
polyspina
M.
minuta
M.
reticulata
B.
hagmanni
27.3
35.0
25.5
22.0
14.0
100
98.0
6.7
100
14.3
17.3
1
®
2
3
4
5
6
7
B.
tubicen
66. 7
50. 0
58. 3
25. 0
33. 3
18. 8
20. 0
B.
deitersi
48. 3
9. 2
27. 8
26. 5
27. 7
55. 3
19. 2
14. 3
C.
cornuta
birgei
D.
spinulosum
M.
minuta
M.
reticulata
23. 7
9. 9
20. 0
8
9
2 1 . .9
13. 6
1 4 .. 5
9..3
10
12
13
16. 7
9. 1
D.
25.0
100
7.1
8. 8
12. 2
11. 3
9. 1
28. 0
23. 8
52. 0
39. 7
17. 2
9. 1
5C .u
10. 5
24. 7
20. 0
8 .5
7. 9
T a b l e V I . M e a n n u m b e r o f e g g s in o v i g e r o u s f e m a l e s
(dominant species).
Mean number of eggs carried by ovigerous fema­
les is i n c l u d e d
in T a b l e V I . In g e n e r a l , n u m b e r o f
e g g s w a s l o w ( m e a n : 2 . 6 ) w i t h h i g h e s t v a l u e s f o r B.
B.
B.
B.
hagmanni
tubicen
deitersi
3.6
3.3
2.8
C.
cornuta
2.6
D.
birgei
25
D.
polyspina
2.7
D.
M.
spinulosum
minuta
2.0
2.5
M.
reticulata
2.0
D e l t a a c e r t a i n p e r c e n t a g e o f B. tubicen
gei
hagmanni
period.
This l o w fertility supports
populations
of B o s m i n i d a e f r o m the m o u t h o f A m a z o n e (Stingelin ( 1 9 0 4 ) a n d f r o m a f l o o d p l a i n l a k e of t h e O r i n o c o
(Rev
& Vâsquez
1986 b ) .
Acknowledgements
a n d D.
egg carrying females was also observed
the high w a t e r
a n d B. tubicen.
t h e o b s e r v a t i o n s p r e v i o u s l y n o t i c e d for
bir­
during
One a u t h o r ( E . V . ) thanks Dr. W a l t e r K o s t e for his conti­
n u o u s c o l l a b o r a t i o n in the i d e n t i f i c a t i o n of r o t i f e r s . W e
a l s o thank M s . M a r i a L a u r a M e d i n a a n d Mr. G a r y B r a v o
f o r t h e i r m o s t v a l u a b l e a s s i s t a n c e in t h e field a n d l a b o r a ­
t o r y w o r k . D r . W e r n e r W i l b e r t p r o v i d e d us i n f o r m a t i o n
o n t h e O r i n o c o D e l t a a n d h e l p e d us in t h e c o m p u t e r e l a ­
boration of graphs.
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011
120
E. VASOUEZ, J. R E Y
References
Andel ( T H . van). 1967 — T h e Orinoco Delta. J. Sed. Petrol., 37 (2) :
297-310.
Arcifa (M.S.). 1984. — Zooplankton composition of ten reservoirs
in southern Brazil. Hydrobiologia, 113 : 137-145.
B r a n d o r f f ( C O . ) . 1976. — A new species of Bosminopsis (Crustacea, Cladocera) from the R i o N e g r o . Acta Amazonica,
6:
109-114.
Brandorff ( G O ) , Koste ( W . ) & Smirnov ( N . N . ) . 1982. — The composition and structure of rotifera and crustacean communities
of the L o w e r R i o N ham un da. Amazonas, Brazil. Stud. Neoirop.
Fauna and Envir., 17 : 69-121.
Dussart ( B ) . 1984. — Some Crustacea Copepoda f r o m Venezuela.
Hydrobiologia,
113 : 25-67.
E g b o r g e (A.B.M.). 1972. — A preliminary check list of zooplankton
organisms of the R i v e r Oshum in the Western State of Nigeria. Nig. J. Sci, 6 : 67-71.
E g b o r g e (A.B.M.). 1987. — Salinity and the distribution of Cladocera in W a r r i River, Nigeria. Hydrobiologia,
145 : 159-167.
Fernando ( C H . ) . 1980.— The freshwater zooplankton of Sri Lanka,
with a discussion of tropical freshwater zooplankton composition. Int. Revue ges. HydrobioL, 65 ( 1 ) : 85-125.
Gibbs ( A . K . ) & Barron ( C ) . 1983. — The Guiana Shield reviewed.
Episodes, 1983 ( 2 ) : 7-14.
Green (J.). 1962. — Zooplankton of the River Sokoto. T h e Crustacea. Proc. Zool. Soc. Lond., 138: 415-453.
Hauer (J.). 1956. — Rotatorien aus Venezuela und Kolumbien. Erg.
Dt. Limnol. Venezuela Exp. 1952, 1 : 277-312.
Hauer (J.). 1965. — Zur Rotatorienfauna des Amazonasgebietcs. Int.
Revue ges. Hvdrobiol., 50 (3) : 341-389.
Hynes (H.B.N.). 1970. — The Ecology oj Running Waters. University of T o r o n t o Press, Toronto.
Infante ( A . ) . 1984. — A note about Daphnia in Venezuelan waterbodies. Hydrobiologia,
119 : 81-82.
José de Paggi (S.). 1978. — First observations on longitudinal succession of zooplankton in the main course of ihe Parana R i v e r
between Santa Fe and Buenos Aires harbour. Stud.
Neotrop.
Fauna and Environ., 16: 185-199.
José d e Paggi (S.). 1980. — Cam pana I imnolôgica Keratella I en el
rio Parana M e d i o : zooplankton de ambientes lôticos. Ecolo
gia (Argentina) 4 : 69-75.
José de Paggi (S.). 1981. — Variaciones temporales y distribuciôn
horizontal del zooplancton en algunos cauces secundarios del
rio Parana Medio. Stud. Neotrop. Fauna and Environ., 16 :
185-199.
José de Paggi (S.). 1983. — Estudio sinôptico del zooplancton de
los principales cauces y tributaries del valle aiuvial del rio
Parana : t r a m o Goya-Diamante, I parte. Rev. Asoc. C'tenc. Nat.
Litoral, 14: 163-178.
José de Paggi (S.) & K o s t e ( W ) . 1988. — Rotifera from Saladillo
river basin (Santa Fe province, Argentina). Hydrobiologia, 157 :
13-20.
Korovchinsky ( N . M . ) . 1981. — Taxonomic and faunistic revision of
Australian Diaphanosoma (Cladocera, Sididae). Aust. J. mar.
Freshwat. Res., 3 2 : 813-831.
L e w i s ( W . M . ) . 1988. — P r i m a r y production in the flowing w a t e r s
of the O r i n o c o R i v e r in relation to its tributaries and floodplain. Ecology, 6 9 : 679-692.
M e a d e ( R . H . ) , Nordin ( C F . ) , Pérez Hernandez (D.), M e j i a ( A . ) & Perez
Godoy (J.M.). 1983. — Sediment and water discharge in R i o Orinoco, Venezuela and Colombia. Proc. Second Internal. Symp.
River Sedimentation.
Water Resources and Electric Power Press
(Beijing, China): 1134-1144.
(14)
Ministerio del Ambiente v de los Recursos Naturales Renovables
(M.A.R.N.R.). 1979.— Alla* de Venezuela, Direction dc C a n o
graffa Nacional, Caracas, 331 p.
Paggi (J.C.) & José de Paggi (S.). 1973. — S o b r e algunos rotfferos
nuevos para la fauna argentina. Rev. Asoc. Cienc. Nat. Lit., 4 :
49-60.
Rey (J.) & Vâsquez (E.). 1986 a. — Cladocères de quelques cours
d'eaux du bassin moyen de l'Orénoque (Venezuela). Annls Limnol., 22 (2): 137-168.
Rey (J.) & Vasque?. (E.). 1986 b. — Bosminopsis macaguensis n. sp.
et Alona ovata n. sp. (Crustacea, Cladocera), Cladocères nouveaux du Venezuela. Annls Limnol., 22 (3) : 219-229.
Rey(J.) & Vâsquez (E.]. 1989. —Bosminopsis brandorffi n. sp. (Crustacea, Cladocera), une nouvelle espèce de Bosminidae des systèmes Amazone et Orénoque. Annls Limnol., 25 (3) : à paraître.
Robertson (B.A.) & Hardy ( E . R ) . 1984. — Zooplankton of Amazonian lakes and rivers. 337-352. In H. Sioli (Ed.). Vie Amazon.
Limnology and Landscape Ecology of a Mighty Tropical river
and Its Basin. Dordrecht, Junk Publishers, 763 p.
Sanchez (L.), Vâsquez (E.) & Blanco (L.). 1985. — Limnological investigation of the Rivers Uracoa, Yabo, Morichal Largo, and Claro
in the eastern plains of Venezuela. Verh. Internat. Vere'in. Limnol, 2 2 : 2153-2160.
Saunders (J.F.) & Lewis (W.M.). 1988 a. — Zooplankton abundance
in the Caura River, Venezuela. Bioiropica, 20 (3) : 206-214.
Saunders (J.F.) & Lewis (W.M.). 1988 b. — Zooplankton abundance
and transport in a tropical white-water river. Hydrobiologia,
162 : 147-155.
Saunders (J.F.) & Lewis (W.M.). 1989. — Zooplankton abundance
in the Lower Orinoco River, Venezuela. Limnol. Oceanog r. : In
press.
Vâsquez (E.). 1984 a. — Estudio de las comunidades de rotfferos
del Orinoco Medio, Bajo Caroni y algunas lagunas de inundacion. Mem. Soc. dene. Nat. La Salle, 44 (121) : 95-108.
Vâsquez (E.). 1984 b. — El zooplancton de la secciôn baja de un
rio de aguas negras (rio Caroni) y de un embalse hidroeléctrico
(Macagua), Venezuela. Mem. Soc. Cienc. Nat. La Salle, 44 (121) :
109-129.
Vâsquez (E.). 1988. — Morfometria de un conjunto de lagunas de
inundaciôn del Bajo Orinoco, Venezuela. Pantepuy, 4 : 31-37.
Vâsquez (E.) & Koste ( W . ) . 1988. — Form variation of the rotifer
Brachionus variabilis (Hempel 1896) from the Orinoco River
(Venezuela). Annls Umnol, 24 (2) : 127-129.
Vasquez(E.)&Sanchez ( L ) . 1984. — Variaciôn estacional del plancton en dos sectores del rio Orinoco y una laguna de inundaciôn adyacente. Mem. Soc. Cine. Nat. La Salle, 44 ( 121 ) : 11-31.
Vegas-Vilarnibia ( T ) , Paolini (J.) & Herrera ( R ) . 1988. — A physicochemical survey of blackwater rivers from the Orinoco and the
Amazon basins in Venezuela. Arch. HydrobioL, 111 (4) : 491-506.
Weibezahn (F.H.), Vâsquez (E.), Zoppi de Roa (E.) & Rey (J.). 1989.
— Bosminopsis negrensis Brandorff 1976 (Cladocera, Bosminidae), en la cuenca del R i o Orinoco, al Sur de Venezuela.
Memor. Soc. Cienc. Nat. IM Salle, 130 : in press.
Welcomme (R.L.). 1985. — River Fisheries. FAO Fish. Tech. P a p ,
(262) : 330 p.
Wilbert (W.). 1986. — Warao Herbal Medicine : A Pneumatic Tfieory
oj Illness and Healing. Ph. D. dissertation, University of California, Los Angeles. University Microfilms International, Ann
Arbor, 821 p.
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 18 Jun 2017 at 13:54:08, subject to
the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.
https://doi.org/10.1051/limn/1989011