7 research outputs found
Recommended from our members
Carbon stable isotopes suggest that hippopotamusāvectored nutrients subsidize aquatic consumers in an East African river
Ā© 2015 McCauley et al. 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 (Ī“13C) 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 Ī“13C 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 Ī“13C 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 Ī“13C values, suggesting that higher flows reduced retention and use of H. amphibius subsidies. These data provide preliminary evidence that Ī“13C values may be useful, in certain contexts, for quantifying the importance H. amphibius organic matter
Recommended from our members
Carbon stable isotopes suggest that hippopotamusĆ¢ļæ½ļæ½vectored nutrients subsidize aquatic consumers in an East African river
Recommended from our members
Carbon stable isotopes suggest that hippopotamusāvectored nutrients subsidize aquatic consumers in an East African river
Ā© 2015 McCauley et al. 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 (Ī“13C) 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 Ī“13C 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 Ī“13C 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 Ī“13C values, suggesting that higher flows reduced retention and use of H. amphibius subsidies. These data provide preliminary evidence that Ī“13C values may be useful, in certain contexts, for quantifying the importance H. amphibius organic matter
Disruption of an ant-plant mutualism shapes interactions between lions and their primary prey
Mutualisms often define ecosystems, but they are susceptible to human activities. Combining experiments, animal tracking, and mortality investigations, we show that the invasive big-headed ant (Pheidole megacephala) makes lions (Panthera leo) less effective at killing their primary prey, plains zebra (Equus quagga). Big-headed ants disrupted the mutualism between native ants (Crematogaster spp.) and the dominant whistling-thorn tree (Vachellia drepanolobium), rendering trees vulnerable to elephant (Loxodonta africana) browsing and resulting in landscapes with higher visibility. Although zebra kills were significantly less likely to occur in higher-visibility, invaded areas, lion numbers did not decline since the onset of the invasion, likely because of prey-switching to African buffalo (Syncerus caffer). We show that by controlling biophysical structure across landscapes, a tiny invader reconfigured predator-prey dynamics among iconic species