Carbon stable isotopes suggest that hippopotamus-vectored nutrients subsidize aquatic consumers in an East African river
View/ Open
Date
2015Author
McCauley, Douglas J.
Dawson, Todd E.
Power, Mary E.
Finlay, Jacques C
Ogada, Mordecai
Gower, Drew B
Caylor, Kelly
Nyingi, Wanja D
[et al.]
Language
enMetadata
Show full item recordAbstract
The common hippopotamus,
Hippopotamus amphibius
, transports millions of tons of organic
matter annually from its terrestrial feeding grounds into aquatic habitats. We evaluated whether carbon
stable isotopes (
d
13
C) can be used as tracers for determining whether
H. amphibius
-vectored allochthonous
material is utilized by aquatic consumers. Two approaches were employed to make this determination: (1)
lab-based feeding trials where omnivorous river fish were fed a
H. amphibius
dung diet and (2) field
sampling of fish and aquatic insects in pools with and without
H. amphibius
. Lab trials revealed that fish fed
exclusively
H. amphibius
dung exhibited significantly more positive
d
13
C values than fish not fed dung. Fish
and aquatic insects sampled in a river pool used for decades by
H. amphibius
also exhibited more positive
d
13
C values at the end of the dry season than fish and insects sampled from an upstream
H. amphibius
-free
reference pool. Fish sampled in these same pools at the end of the wet season (high flow) showed no
significant differences in
d
13
C values, suggesting that higher flows reduced retention and use of
H.
amphibius
subsidies. These data provide preliminary evidence that
d
13
C values may be useful, in certain
contexts, for quantifying the importance
H. amphibius
organic matterThe common hippopotamus,
Hippopotamus amphibius
, transports millions of tons of organic
matter annually from its terrestrial feeding grounds into aquatic habitats. We evaluated whether carbon
stable isotopes (
d
13
C) can be used as tracers for determining whether
H. amphibius
-vectored allochthonous
material is utilized by aquatic consumers. Two approaches were employed to make this determination: (1)
lab-based feeding trials where omnivorous river fish were fed a
H. amphibius
dung diet and (2) field
sampling of fish and aquatic insects in pools with and without
H. amphibius
. Lab trials revealed that fish fed
exclusively
H. amphibius
dung exhibited significantly more positive
d
13
C values than fish not fed dung. Fish
and aquatic insects sampled in a river pool used for decades by
H. amphibius
also exhibited more positive
d
13
C values at the end of the dry season than fish and insects sampled from an upstream
H. amphibius
-free
reference pool. Fish sampled in these same pools at the end of the wet season (high flow) showed no
significant differences in
d
13
C values, suggesting that higher flows reduced retention and use of
H.
amphibius
subsidies. These data provide preliminary evidence that
d
13
C values may be useful, in certain
contexts, for quantifying the importance
H. amphibius
organic matter
Citation
McCauley, D. J., Dawson, T. E., Power, M. E., Finlay, J. C., Ogada, M., Gower, D. B., ... & Brashares, J. S. (2015). Carbon stable isotopes suggest that hippopotamus-vectored nutrients subsidize aquatic consumers in an East African river.Publisher
University of Nairobi