Page:Biodiversity Assessment of the Fishes of Saba Bank Atoll, Netherlands Antilles.pdf/1

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Jeffrey T. Williams ; Kent E. Carpenter ; James L. Van Tassell ; Paul Hoetjes ; Wes Toller ; Peter Etnoyer  ; Michael Smith

Abstract

Biodiversity surveys were conducted on Saba Bank, Netherlands Antilles, to assess ichthyofaunal richness and to compare with published surveys of other Caribbean localities. The primary objective was to estimate the total species richness of the Saba Bank ichthyofauna. A variety of sampling techniques was utilized to survey the fish species of both the visually accessible megafauna and the camouflaged and small-sized species comprising the cryptic ichthyofauna. Based on results presented herein, the number of species known on Saba Bank is increased from 42 previously known species to 270 species. Expected species-accumulation curves demonstrate that the current estimate of species richness of fishes for Saba Bank under represents the actual richness, and our knowledge of the ichthyofauna has not plateaued. The total expected fish-species richness may be somewhere between 320 and 411 species. The Saba Bank ichthyofaunal assemblage is compared to fish assemblages found elsewhere in the Caribbean. Despite the absence of shallow or emergent shore habitats like mangroves, Saba Bank ranks as having the eighth highest ichthyofaunal richness of surveyed localities in the Greater Caribbean. Some degree of habitat heterogeneity was evident. Fore-reef, patch-reef, and lagoonal habitats were sampled. Fish assemblages were significantly different between habitats. Species richness was highest on the fore reef, but 11 species were found only at lagoonal sites. A comprehensive, annotated list of the fishes currently known to occur on Saba Bank, Netherland Antilles, is provided and color photographs of freshly collected specimens are presented for 165 of the listed species of Saba Bank fishes to facilitate identification and taxonomic comparison with similar taxa at other localities. Coloration of some species is shown for the first time. Preliminary analysis indicates that at least six undescribed new species were collected during the survey and these are indicated in the annotated list.

Introduction

Saba Bank is the largest atoll in the Atlantic Ocean Basin and one of the three largest atolls on earth. Located in the Dutch Windward Islands about 250 km east of Puerto Rico, it is a flat-topped seamount rising 1800 m from the surrounding sea floor. Except for the fact that it does not break the water surface, Saba Bank is a classic atoll consisting of a submerged mountain crowned at the summit with a ring of actively growing coral reefs. Saba Bank is relatively free of the problems that are degrading many Caribbean reef systems, and the few problems it faces include anchoring and abrasion by oil tankers maneuvering off the petroleum transshipment facilities on St. Eustatius, potential petroleum spillage and subsequent use of dispersants, general vessel passage in a zone of high maritime traffic, possible overfishing for certain species, and exploration for petroleum reserves (so far unsuccessful). Saba Bank's fisheries and dive operations are economically significant to the small community on Saba Island (about 1500 residents) that has direct responsibility for its management.

The known fish fauna of Saba Bank prior to our survey consisted of 42 fish species. Most of these species were taken during fishery bottom-trawl surveys on Saba Bank, including two M/V Oregon stations in 1958 and nine stations in 1959, and two trawl hauls taken in 1969 by the R/V Pillsbury. Although four of these trawls were taken on or near the top of Saba Bank, nine were on the deep outer slopes. The habitats sampled during these surveys were restricted to relatively soft-bottom habitats due to the exclusive use of trawling techniques. These trawl samples provided valuable records of fishes living on soft bottoms and on the outer slopes of Saba Bank. PLoS ONE