A comparative study of the invertebrate community and its longitudinal diversity

Abstract

Inputs into riverine ecosystems are highly variable with respect to longitudinal location within the system. These inputs help to shape the animal community within the river or stream, and have been hypothesized to be correlated with invertebrate diversity and community composition (Rosi-Marshall and Wallace 2002). In order to test this relationship, we sampled the benthic invertebrate community from three reaches of the Mississippi River near and within Itasca State Park, Minnesota. These samples were used to quantify invertebrate diversity and functional feeding group types (FFG). Significant differences were found between the community composition of each site with the Headwaters site showing the highest levels of invertebrates which feed upon allochthonous material, and the Downstream site showing the highest amount of invertebrates which feed upon autochthonous material (p=1.84*10-12). The Headwaters site also demonstrated the highest levels of community diversity, due to the myriad of niches created by varying river conditions. The results of this study suggest that the invertebrate community composition is dependent on the primary inputs into the system, whether from allochthonous or autochthonous sources.