ASSESSING HABITAT CONDITION THROUGH BENTHIC INVERTEBRATE ASSEMBLAGES WITHIN A PARTIALLY RESTORED ESTUARY

East Harbor is a back barrier salt marsh lagoon located in Truro, Massachusetts within the Cape Cod National Seashore. East Harbor was tidally restricted until 2002, when a small amount of tidal flow was reintroduced after being sealed for over a century from Cape Cod Bay. This partial tidal restoration has allowed for recolonization of several species, suggesting that the water quality of the area has greatly improved after decades of low salinity, growth of invasive vegetation, and other stressors. Benthic invertebrates are indicators of pollution, as the tolerance of certain species for poor conditions is well documented. To evaluate composition and subsequent habitat quality of areas in East Harbor, benthic sampling was conducted in 2017 and 2018. Stations were sampled using a ponar grab, sorted for invertebrates, and all specimens were identified to species level. Organisms were then classified using the AZTI Marine Biotic Index (AMBI) protocol, a method used to categorize benthic species based on their tolerance of degraded environmental conditions. AMBI analysis yielded site quality classifications based on the invertebrate assemblages present. Most stations within East Harbor fell into the slightly disturbed site classification. Each station had species falling into classes II (indifferent) and III (tolerant). Most sites had a small presence of class IV (opportunistic species), while class I (sensitive) and V (pollution indicating) species were each present in roughly half of the stations. As expected, the percentage of species in either extreme (class I or V) most influenced the outcome of the AMBI site classification. This analysis delivers promising evidence that most of East Harbor is suitable for a wide range of species. Based on the invertebrate compositions, East Harbor was classified as a slightly polluted ecosystem. However, not too much can be assumed solely from this small study.