A Case for Developing Long-Term Macroinvertebrate Assemblage Datasets in Headwater Streams at the LUQ-LTER, Puerto Rico

Predicted variation in long-term temperature, precipitation, and discharge patterns will likely have direct and indirect effects on consumer communities. Tropical systems are relatively understudied; therefore basal information is urgently needed in order to fully assess the potential effects of climate change on stream consumer communities. As part of an ongoing long-term study, we assessed benthic macroinvertebrates and organic matter standing stocks at two headwater streams in the Luquillo Experimental Forest, Puerto Rico. Benthic samples reflect an assemblage dominated by leptophlebiid mayflies, chironomid midges, and oligochaetes, in addition to the known dominance of shrimps and crabs. Mean monthly abundance 625.4±193.6ind/m2 and biomass 687.9±387.7 mg/m2 estimates indicate a variable system with a community dynamics likely explained by changes in discharge and organic matter. The observed importance of discharge and organic matter in controlling invertebrate assemblages agrees with available information from other tropical systems. These types of studies are needed to uncouple the natural variations due to seasonal patterns from large scale variations that may be due to climate change.