Macroinvertebrate Trophic Composition and Processing of Four Leaf Species in a Mississippi Stream

ABSTRACT

The benthic invertebrate community associated with leaf packs of four taxa of deciduous leaves was examined along with changes in community composition occurring during leaf decomposition. Dogwood leaves were processed most rapidly, followed by tulip poplar, hickory, and oak, with average decay coefficients (k) of 0.059, 0.046, 0.026, and 0.021 d⁻¹, respectively. Twenty-five taxa of macroinvertebrates were collected from the leaf packs, and most were insects. Trichoptera were the most commonly collected organisms and were dominated by Lepidostoma sp. The majority of the taxa occurred on all leaf species and in similar numbers. Among the collected taxa were eight shredders, five collectors, nine predators, and two scrapers. Invertebrates colonized leaf packs two days post-introduction, suggesting that shredders did not require pre-conditioned leaves. Attempts to correlate the number of invertebrates with percent leaf material remaining were unsuccessful. The greatest macroinvertebrate abundance and diversity occurred on oak leaves. There was no discrimination between leaf species by the majority of the colonizing invertebrates, with over 96% of the invertebrate taxa found on all four leaf species. The results suggest that invertebrates in warmwater streams are able to exploit allochthonous resources over a longer time period than invertebrates in higher latitude streams.