MARINE BIVALVES OF THE FLORIDA KEYS: A QUALITATIVE FAUNAL ANALYSIS BASED ON ORIGINAL COLLECTIONS, MUSEUM HOLDINGS AND LITERATURE DATA

摘要

Marine bivalve biodiversity in the waters surrounding the Florida Keys, an island archipelago off southern Florida, including the Florida Keys National Marine Sanctuary, was studied from ten years of original collections as well as from a critical review of museum specimens and literature data. A database of more than 12,000 records representing 389 species (half of which were ranked as abundant or common) was assembled and analyzed, resulting in a 139% increase of the known bivalve fauna of this region compared to the most recent prior (1995) checklist. Of the 389 species, 42% have not been positively recorded as live-collected, and 12.5% are represented only as singletons or doubletons. Using multivariate non-metric statistics and a priori geographic groupings along the island chain (Upper, Middle, Lower Keys; Dry Tortugas) and across the island chain (Florida Bay, shallow Atlantic waters [ < 35m], deeper Atlantic waters [35-300 m]), the data showed distinct differences in benthic community structure across several spatial gradients. A pronounced northeast-to-southwest gradient was found on the Florida Bay-side of the island chain, although none was evident along the oceanside in either shallow or deep depth zones. Although they shared dominant species, the shallow-water communities of bayside and oceanside differed significantly in the percentage distributions of co-occurring species. In contrast, the deeper oceanside community differed substantially from both shallow-water groups in supporting a different set of species. A comparison of the bivalve fauna of the Keys with other well-documented faunas of the western Atlantic indicated that the Florida Keys fauna groups more closely to the Gulf of Mexico and Cuba than to eastern peninsular Florida, Yucatan, or the Bahamas. The impact of the heterogeneous nature of the dataset (live-specimen, dead-shell; and original collections, museum, and literature) is discussed and compared to analyses based on live-only data: the latter resulting in less spatial resolution but the same general patterns. In a comparison of data sources (original collections, museum records, gray literature and traditional literature), original collections were least effective (51%) in capturing the total species list despite representing approximately half of the total records. Literature was most successful (90%) in capturing the list but only when gray literature was included. Rapid assessment methods contrasted against the long-term results showed effectiveness when based on a range of sample types and habitats.