An Assessment of Human Impacts on Benthic Invertebrate Communities, with an Emphasis on Polychaetes

Abstract

Various human activities such as trampling through shallow waters and organic enrichment can alter benthic invertebrate communities. To examine the impact of human activities to shallow-water invertebrate communities on Oahu’s south shore, sediment samples were collected from depths of 0.1 m, 1.0 m, and 3.0 m, from an area frequently perturbed by humans, and an area that experiences little or no human activity. Multiple samples were collected from six stations, and all invertebrates were identified and preserved in ethanol. The members of the class Polychaeta were identified to family, and grouped in guilds based on motility and trophic categories. Overall, the stations that experience human perturbation displayed less taxa abundance, were predominantly composed of nematodes (an indicator of organic enrichment), and had very few amphipods (a crustacean sensitive to disturbance). The polychaete communities at stations frequently visited by humans were dominated by detritivores, and contained low numbers of suspension-feeding and tubicolous individuals and families, indicating perturbation. In contrast, the stations that experience little or no human activities yielded higher taxa abundance, high individual tallies, were composed mostly of amphipods, and displayed higher percentages of suspension-feeding and tubicolous polychaetes. Since the grain size of each sample site was the only physical parameter taken into consideration, a more thorough study must be performed to conclusively tie human activities to alterations in benthic invertebrate communities.