Effectiveness of Artificial Plants in Subsurface Exclosures as a Substrate for Hydrilla-Dwelling Macroinvertebrate Communities

We examined the efficacy of plastic plants in mesh exclosures as artificial substrates for sampling hydrilla (Hydrilla verticillata) beds. Macroinvertebrate densities standardized by surface area were compared between plastic plants and natural hydrilla stands once a week for five weeks, and between three mesh-size treatments and hydrilla for the final experimental week. Macroinvertebrate community structure on the artificial plants most closely resembled hydrilla communities on week five. Only cladocerans differed between substrates and were more abundant on the plastic plants, probably due to exclosure design and vertical migration patterns. Macroinvertebrates inhabiting exclosures with the largest mesh size were most similar in species composition to hydrilla-dwelling communities. This work indicates that these exclosures should be deployed for a minimum of five to six weeks to yield representative macroinvertebrate communities in finely dissected macrophytes such as hydrilla.