Page:Biodiversity Assessment of the Fishes of Saba Bank Atoll, Netherlands Antilles.pdf/34

 combination of visual surveys, ichthyocide sampling using SCUBA, and various fishing techniques must be employed to effectively assess fish-species richness in marine habitats shallow enough to be accessible to SCUBA divers.

Table 1. Number of fishes recorded at well sampled sites in the Greater Caribbean. 10.1371/journal.pone.0010676.t001

The number of fish species living on Saba Bank is undoubtedly higher than 270 as indicated by Chao2 and Jack1 estimators. As most parts of Saba Bank are deeper than 25 m, sampling with ichthyocides using SCUBA is limited by the reduced bottom time at these depths. As a result we focused primarily on the rim (shallowest parts) of the submerged atoll to maximize bottom time for collecting. Future sampling with ichthyocides applied by divers utilizing rebreathers, supplemented with trawl and dredge sampling would allow collecting from the outer slopes and would certainly yield additional new and interesting species of fishes from this submerged atoll.



Methods

The NMNH/SI Animal Care and Use Committee approved the methods and procedures utilized during the course of this biodiversity assessment project. All Saba Bank projects had collecting permits through the Convention on Trade in Endangered Species (CITES, where necessary) and the Saba Conservation Foundation (where CITES was not required).

Roving surveys were completed using SCUBA and lasted 60 minutes, bottom time permitting. All species encountered were listed on a slate while swimming in a haphazard pattern covering all bottom depths possible down to a maximum of 38 m. Other visual surveys are described in Toller et al. Collecting methods follow Collette et al. Species were photographed in aquaria after the fins were pinned out and brushed with formaldehyde solution. Tissue samples were taken from fresh specimens and the voucher specimens were preserved in a formaldehyde solution diluted with water to 3.75% formaldehyde. Large specimens were also injected with 37.5% formaldehyde before being soaked in the 3.75% formaldehyde solution.

After arrival at the Museum Support Center (MSC), National Museum of Natural History, specimens were transferred sequentially through water-diluted solutions of 25% ethanol, 50% ethanol, and finally into 75% ethanol for permanent archival storage. Specimens were then processed and cataloged into the USNM at the MSC in Suitland, MD.

To generate species-accumulation curves, a data matrix of presence/absence was constructed from 38 combined roving surveys, rotenone collections, and fish-habitat transects using species as variables and dives as observations (Table 2 provides details for each survey and collecting station). The matrix was employed for actual and expected species-accumulation curves (Mao Tau) in EstimateS v.8.0 software. Total expected richness was estimated using Chao2 and Jack1 estimators.