Term of Award

Spring 2016

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

J. Checo Colón-Gaud

Committee Member 1

Tavis Anderson

Committee Member 2

Lance Durden

Committee Member 3

Alonso Ramirez

Abstract

Variation in long-term temperature and precipitation patterns will likely influence the decomposition and export of benthic organic matter and influence aquatic macroinvertebrate consumer communities. Tropical systems are relatively understudied; therefore basal information is urgently needed. As part of an ongoing long-term study, we monitored macroinvertebrates in two shrimp-dominated and fishless headwater streams within the Luquillo Experimental Forest in Puerto Rico from 2009-2010. We combined growth rates with yearly biomass data to calculate secondary production and examined gut contents to develop quantitative food webs. Macroinvertebrate assemblages were dominated by a few insect taxa, with similar biotic composition across streams and habitats, but different structure amongst habitats. Biomass and abundance were generally greater in pools, suggesting that pools may provide habitat stability and shelter. Alternatively, shrimp may provide secondary benefits by removing fine sediments given their high density of in pools. Overall, aquatic insects had low biomass; therefore, their production was relatively low as is the case in most tropical areas. However, their turnover rates were not as high as expected. Secondary production appears to rely more on amorphous detritus and allochthonous organic matter rather than algal resources. These data are an important first step towards predicting the long-term effects that expected changes in rainfall and discharge will have in tropical stream communities.

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