Abundance and distribution of large marine gastropods in nearshore seagrass beds along the gulf coast of Florida.

摘要

Local abundance was estimated and distribution determined for selected large gastropod species based on observations made during underwater visual surveys at 10 sites along the Gulf coast of Florida each summer from 2009 through 2012. The total number of tulip snails (Fasciolaria spp., including the true tulip, Fasciolaria tulipa, and banded tulip, Fasciolaria lilium), lightning whelk (Busycon sinistrum), and horse conch (Triplofusus giganteus) were counted at 190 stations (each 600 m2) each year in shallow-water seagrass beds. Tulip snails were observed most frequently, with a mean density of 1.93+or-3.56 snails/600 m2, with substantially fewer lightning whelks (0.29+or-1.04/600 m2) and horse conchs (0.10+or-0.37/600 m2) observed. Horse conchs were distributed more evenly across the 4 Gulf coast regions studied: Panhandle, Big Bend, Nature Coast, and South. Tulip snails were most abundant in the Panhandle and the South, whereas lightning whelks were found predominantly in the South. Snail counts peaked in 2010 and were greatest at the Pine Island Sound site, although mean density was greatest in Sarasota Bay (2.2 snails/600 m2). Snails were observed most frequently at the St. Joseph Bay site, where they were present at 74 of the 80 stations surveyed. Statewide commercial fisheries landings data were examined for years 1994 through 2011 and totaled 130,710 true tulip snails (banded tulip snails were not included), 72,230 lightning whelks, and 33,087 horse conchs. The total number landed of both lightning whelks and horse conchs was greater on the west coast of Florida, whereas the total number of true tulip snails landed was greater on the east coast.