File:American malacological bulletin (1988) (18153066202).jpg

Title: American malacological bulletin
Identifier: americanmal6719881990amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
58 AMER. MALAC. BULL. 7(1) (1989) Table 1. Coordinates and mean depths of benthic stations. Mean depth Station Coordinates* (m) I 27"21.3'N, 80°14.1'W 8.4 II 27°21.6'N, 80°13.2'W 11.2 III 27°22.0'N, 80°12.4'W 7.1 IV 27"20.7'N, 80°12.8'W 10.9 V 27022.9'N, 80°13.9'W 10.8 *U.S.C.G.S. Chart No. 1247, dated 1969. south of Station II; sediments were very similar to those at Station II (type 2), but sands were slightly less coarse; large shell fragments also were present. Station V, another trough station, was located north of Station II; sediments were very coarse, poorly sorted, slightly muddy, calcareous sandy-shell gravels (type 4). Samples were preserved in 10% buffered formalin when collected and then were washed through a 0.71 mm U.S. Standard Sieve screen. Materials retained on the screen were preserved in alcohol, sorted to higher taxonomic categories using a binocular dissecting microscope, and transferred to specialists for identification and enumeration. I examined all mollusks from the samples and prepared a technical report on species composition and abundance (Lyons, in press). The specimens are deposited in the FDNR Marine Invertebrate Collection at St. Petersburg, Florida. Species were designated as characteristic of the study site based upon occurrence during at least 6 of the 12 sampl- ing periods. Interstation similarities of the fauna were deter- mined using Czekanowski similarity coefficients (Clifford and Stephenson, 1975) derived from raw bimonthly abundances (Q mode) of the characteristic species at each station (five replicate grabs pooled) during each of eight sampling periods when sediments were analyzed. Station sediments likewise were examined for similarity using percentages by weight of particle sizes (0) of the samples during each of the same eight periods. Resultant dendrograms of similarity based on fauna and on sediments were compared for evidence of faunal affinity for sediment types. RESULTS One hundred thirty-six molluscan species comprising 4135 living specimens were collected with the benthic grab. Station I, which yielded only 40 specimens in 16 species dur- ing 11 sampling periods (one atypical sample excluded), was eliminated from further analyses. Station III, the shoal station, yielded 697 specimens in 23 species. Greatest abundance and diversity occurred at the trough stations: Station 11—1139 specimens, 72 species; Station IV—841 specimens, 79 species; Station V—1418 specimens, 70 species. By class, 54 bivalve species contributed 75.5% of all specimens, followed by 78 gastropods (18.4%), 3 polyplacophorans (5.2%), and 1 scaphopod (0.9%). Identities and abundances of all species were reported elsewhere (Lyons, in press). Only 33 of the 136 species (24%) were collected dur-
Text Appearing After Image:
Fig. 1. Location of offshore benthic sampling stations at Hutchinson Island, central Florida east coast; depth contours in meters. ing at least 6 of the 12 sampling periods, but those characteristic species contributed 90% of all specimens ob- tained during the study. The characteristic species, which in- cluded 16 bivalves, 13 gastropods, 3 polyplacophorans, and 1 scaphopod, contributed greater proportions of the total fauna at Stations III and V than at Stations II and IV (Table 2). Czekanowski similarity coefficients derived from abun- dances of the characteristic species were used to construct a dendrogram of relationships among samples collected at Stations ll-V during eight sampling periods (Fig. 2). Three groups were evident: one group contained all of the Station III samples, one contained six Station II samples and seven

Note About Images