Channel and marina dredging/restoration of bayside sediment processes: Sailors Haven ecological monitoring report

Landers, Lisa; Soucier, Chris; Kuroiwa-Bazzan, Kristine; Brewer, Keith; Thyberg, Krista

Ecological monitoring was conducted by Cashin Associates, P.C. (CA) to evaluate the impact of creating a feeder beach adjacent to Sailors Haven Marina (Fire Island, New York) on nearshore nekton community compositions and abundance. Tetra Tech provided oversight, management and technical support through GSA Contract No. GS-10F-0268K. A total of eight monitoring events were performed by CA from 2014 to 2017, two pre-construction (fall 2014 and fall 2015) and six post-construction events (spring, summer and fall of 2016 and 2017). Sampling was conducted by seining at triplicate random locations within each pre-defined project reach (transect) to characterize pre- and post- feeder beach finfish and invertebrate species composition and abundance. Nearly 11,900 specimens were captured, measured, and released during the eight sampling events, consisting of 35 species of finfish, shrimp, and crab. The dominant finfish species captured was Menidia menidia, accounting for 50.8% of all finfish captured, followed by Anchoa mitchilli (44.1%). The species richness differed substantially by season, with the highest number of species captured in summer 2017. The data appeared to indicate that seasonal variability is a dominant factor in determining species richness and abundance. Community composition and abundance were compared between years and among project reaches using the Analysis and Similarities (ANOSIM) procedure. Species composition and abundance were not found to differ significantly from pre-construction (2014, 2015) to post-construction years (2016, 2017), nor by sampling reach (transects extending east and west of the construction zone). Differences in abundance did exist between years, but there is no clear indication that these differences are a result of construction activities, particularly because no significant differences were observed from 2014 (pre-construction) to the post-construction years (2016, 2017), and significant differences were observed between post-construction years. ANOSIM analyses also indicated that significant differences in abundance were observed between seasons. For pair-wise comparisons that were significant (i.e., communities were different) the proportion of the overall dissimilarity that was contributed by individual species was calculated using the Similarity Percentage analysis (SIMPER) procedure which utilizes the Bray-Curtis similarity measure. The species which contributed most to the dissimilarity for all significant year comparisons were Menidia menidia, Crangon septemspinosa, Ovalipes ocellatus, and Anchoa mitchilli. For season, M. menidia, Anchoa mitchilli, and Crangon septemspinosa contributed substantially to the seasonal dissimilarity.

Channel and marina dredging/restoration of bayside sediment processes: Sailors Haven ecological monitoring report

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