Multivariate Analysis of Gorgonian Habitats on Saba Bank, Netherlands Antilles
The second Saba Bank Expedition in October 2008 aimed at improving the knowledge of the gorgonacea by generating a comprehensive species list for shallow and deep water species with georeferenced in-situ photographs and voucher specimens for each sample taken.
Gorgonian species were common and conspicuous at all sites surveyed, except perhaps in some deep water (~60m) rubble flats south of Poison Bank. A total of 47 species were collected, including two new species in the genera Pterogorgia and Lytreia. Pterogorgia n. sp. was collected twice from 20m depth in the D zone. Lytreia n. sp. was collected twice from 50m depth near the A zone. The total number of gorgonian species collected from shallow water was 39. The number of gorgonian species from deep water (>50m) was 12. There was some overlap in the zones, with 4 shallow water species (Muriceopsis flavida, Eunicea clavigera, Pseudopterogorgia acerosa, and Ps. bipinnata) occurring below 50m. The species accumulation curve for shallow water species indicates the slope of the fitted line decreases with effort, but the line shows no clear asymptote. The species accumulation curve for deep water collections is still climbing. The line could be interpreted as a linear rise in deep-water species richness. There is no indication we have collected all the gorgonian species from the Saba Bank
The survey results add 38 species to the list of gorgonacea known to occur on Saba bank. The discovery of a new species of Pterogorgia was surprising because a) the discovery was made in shallow, easily accessible water depths and b) the new species was collected from the relatively depauperate reef flats in the “D zone”. This suggests the reef flat area in the interior of the Bank may be largely unexplored and the true diversity of the reef flat areas may be somewhat underappreciated.