Biotic interactions can strongly shape community composition. These interactions are often exaggerated during times of ecological stress, such as isolation in streams from lack of flow. Many streams in the eastern Ozark Highlands are characterized by spring-fed headwaters that have connected pools in the upper reaches and isolated pools in the mid-reaches before becoming perennial. Within isolated pools, macroinvertebrate densities and richness can become lower, limiting food resources for fishes. The objective of this study was to examine effects of pool isolation on fish diet. We wanted to answer three questions: if food resources were different or reduced in isolated pools compared to connected pools, were fishes more selective and did they increase resource partitioning in isolated pools, and would individuals exhibit increased gastrointestinal tract (GI) length in isolation to aid in nutrient absorption. Sampling was conducted during March, May, and July 2011 in a headwater tributary of North Sylamore Creek. During each sampling date we collected total available aquatic macroinvertebrates (9 orders; 45 families) and ten individuals of each target fish species (Chrosomus erythrogaster, Semotilus atromaculatus, and Etheostoma spectabile) at each pool for gut analysis in both isolated and connected pools. Non-metric multidimensional scaling (NMS) was used to determine differences in community structure. Benthic macroinvertebrate density and richness was significantly lower in isolated pools compared to connected pools (MRPP, P= <0.0001). We found that fish became more selective and partitioned resources more in isolated pools. All three species showed an increase in GI tract length in isolated pools compared to connected pools. We have shown that when food resources become reduced, these fishes have the adaptive ability to respond and continue to survive.
|Commitee:||Adams, Reid, Entrekin, Sally|
|School:||University of Central Arkansas|
|School Location:||United States -- Arkansas|
|Source:||MAI 51/02M(E), Masters Abstracts International|
|Subjects:||Zoology, Animal sciences, Aquatic sciences|
|Keywords:||Chrosomus erythrogaster, Diet, Etheostoma spectabile, Fish, Intermittent stream, Plasticity, Semotilus atromaculatus|
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