Invertebrate Assemblages Associated with Water Hyacinth (Eichhornia crassipes) Roots in the Waccamaw River, South Carolina

Invasive macrophytes can play several key roles in ecosystems, possibly creating new areas for refuge, colonization, and feeding by invertebrate species. This study examined aquatic macroinvertebrates associated with water hyacinth (Eichhornia crassipes) roots in the Waccamaw River, SC. Ambient water hyacinth roots, defaunated water hyacinth roots, and artificial substrates were secured to frames placed around permanent water hyacinth mats. Plants and artificial substrates were collected every two weeks for two months and invertebrates were identified and measured. The top five colonizing taxa ranked by importance were Oligochaeta, Cladocera, non-Tanypodinae Chironomidae (Diptera), Talitridae (Amphipoda), and Tanypodinae (Diptera: Chironomidae). Abundance and taxa richness of macroinvertebrates were greater on roots compared to the artificial substrate. Collector-gatherers were the dominant functional feeding group in terms of abundance across all treatments, with the greatest cumulative abundance on the artificial substrate. Macroinvertebrate abundance on plant treatments exhibited a fairly even distribution of functional feeding groups. Predators dominated the invertebrate assemblage biomass of all treatments, and were greatest on the artificial substrate. Shredder biomass was greater on the plant treatments compared to the artificial substrate. Colonization of defaunated roots began within two weeks. Invertebrate assemblages found on the artificial substrate did not mimic that of the water hyacinth roots. Also, abundance, taxa richness, and biomass of macroinvertebrates found on hyacinth roots far exceeded that found on native moss and cutgrass species. These data suggest that water hyacinth roots can provide an important habitat for aquatic macroinvertebrates in the Waccamaw River, which was previously not provided by native aquatic plants