SETTLEMENT-PATTERNS OF CARIBBEAN SCLERACTINIAN CORALS ON ARTIFICIAL SUBSTRATA ALONG A EUTROPHICATION GRADIENT, BARBADOS, WEST-INDIES

Artificial substrate settlement plates (terracotta tiles) were set out on 3 fringing reefs for a period of 12 mo to study settlement patterns of juvenile scleractinian corals along a eutrophication gradient on the west coast of Barbados, W.I. A total of 716 coral planulae settled on 120 experimental plates after 12 mo of exposure. Statistically higher (p < 0.05) average number of juvenile corals per plate (XBAR = 9.2 +/- 3.3; N = 40) was recorded on a less eutrophic reef compared to 2 more eutrophic reefs (XBAR = 6.9 +/- 3.1; N = 40 and XBAR = 1.9 +/- 1.3; N = 40). Differences in juvenile coral settlement between reef zones, within each reef, were dependent on the reef's position along the eutrophication gradient. Statistically higher number of coral planulae (XBAR = 7.2 +/- 4.5; N = 60) successfully settled on vertical plates compared to horizontal plates (XBAR = 4.8 +/- 3.3; N = 60). Coral planulae did not settle on upper surfaces of horizontal plates. In terms of relative abundance, the most common coral species in the juvenile population on the experimental plates were Porites astreoides Lamarck which accounted for 42% of the settled planulae, followed by Agaricia spp. (23%); and P porites (Pallas) (19%). Juveniles of Montastrea annularis (Ellis & Solander), Siderastrea spp. and Diploria spp., while present at 2 northern reefs, were absent from the most eutrophic reef.