Effects of a storm-induced barrier breach on community assemblages and ecosystem structure within a temperate lagoonal estuary: A post Hurricane Sandy analysis.

Since the 1800’s, Great South Bay (GSB), NY, has had reduced connectivity to the ocean system, a reduction in filter feeders including oysters, hard clams, and menhaden, a reduction in marine top predators such as sharks and has become dominated by lower trophic level pelagic species. In October 2012, Hurricane Sandy created a breach in Fire Island at Bellport Bay, increasing the exchange between eastern GSB and the ocean resulting in higher salinity levels throughout almost the entire bay. The breach created an opportunity to evaluate whether increased connectivity to the ocean would alter the species assemblage of this lagoon system. We hypothesized that higher salinity in GSB would result in greater occurrence of marine species and increased abundance of migratory finfish and invertebrates. Otter trawl surveys were conducted seasonally (i.e., spring, summer and fall) from 2013 through 2015 throughout GSB from Fire Island Inlet to Bellport Bay. Results indicate an increase in species richness and diversity following the breach in GSB compared with assemblages sampled during 2007 pre-breach. Eight species showed an increase in catch per unit effort (CPUE) following the breach; of these species, five are considered to generally prefer higher salinity habitats, and include Summer Flounder, Windowpane Flounder, Bluefish, Sea Robin spp. and Mantis Shrimp. The higher CPUE of Summer Flounder and Bluefish in GSB is important given their economic importance. Also important to note is the increase in CPUE of Horseshoe Crab following the breach. The most dramatic change pre- and post-breach has been the shift in CPUE of Blue Crab and Lady Crab, with a ~84% decline and a >150% increase in CPUE, respectively, following the breach. Community-wide evaluation indicated that the fish and mobile invertebrate assemblage in GSB in 2007 differed from 2013-2015, with greatest differentiation between 2007 and 2013. The increase in diversity, species richness, and CPUE of higher trophic level predators, such as Summer Flounder, following the breach suggest that the connectivity of GSB with the ocean has increased the trophic complexity, an indication of initial recovery of ecosystem maturity. Many, but not all metrics from our Ecopath model indicate that the breach increased maturity of GSB. However, the species assemblage appears to still be transitioning from the effects of the breach.