Fish assemblages on coral reefs in Guanaja, Bay Islands, Honduras

Abstract

Species composition and relative abundance of ichthyofaunal assemblages on reefs surrounding Guanaja, Bay Islands, Honduras were censused from June through December 1996. Transect and random swim surveys were used to characterize community structure across patch, fringing, barrier, and wall reef types at five permanent study sites (transect surveys) and 24 randomly visited sites (random swim censuses). Overall, 170 species were documented during transect and random swim censuses. One hundred and one species representing 32 families and 23,512 individuals were sighted during 216 transect surveys of reef crest and wall habitats. Four species, masked goby (Coryphopterus personatus), blue chromis (Chromis cyanea), bluehead wrasse (Thalassoma bifasciatum), and fairy bassist (Gramma loreto) represented 54.7% of the individuals recorded during transect surveys. Reef crest transects at permanent study sites yielded 83 species representing 26 families dominated by Families Pomacentridae, Labridae, and Scaridae. Adjacent wall transects produced higher totals (92 species representing 31 families) dominated by Gobiidae and Grammatidae. Wall transects also yielded higher species/census (2 of 4 sites) and individuals/census (3 of 4) sites statistics. Reef type and topographical characteristics (i.e. depth and habitat complexity) were major factors in structuring reef fish assemblages at each of the five permanent study sites surrounding Guanaja. Species totals at respective sites only varied from 66 (Bayman Drop) to 72 (Rainbow Reef); however, differences in community composition were notable across sites. Steep wails and overhangs at Bayman Drop (wall reel) provided preferred habitat for masked goby and fairy bassist, and thus facilitated this site exhibiting peak CPUE (1.48 individuals/m²) recorded among sites. Conversely, lack of habitat complexity at Bayman Drop limited species/census statistics to the lowest across sites. Blacktip Slumberland reef site, in exhibiting increased depth and decreased habitat complexity, yielded the lowest CPUE (0.79 individuals/m²) among all sites. Random swim censuses conducted in conjunction with transect surveys targeted three habitats (wall reef crest, and sandy bottom), and provided a more complete species listing of fishes. One hundred fifty-nine species representing 44 families were sighted at 24 reef sites in 143 daytime random swims, while 79 species from 30 families were observed during 26 nighttime random swims. Day and nighttime random swims revealed 58 species not recorded during transect surveys.