Abstract

This study examined distribution patterns of larval fishes in La Parguera Bay and adjacent oceanic waters in Southwestern Puerto Rico, an area of extensive coral reef development. Larval fishes were sampled at the surface with 202 and 750 :m mesh conical plankton nets at five stations along an inshore-offshore gradient. Stations included a shallow mangrove channel off the shoreline, back-reef and fore-reef areas, the shelf-edge reef and one offshore station located two miles off the shelf-edge. A total of 40 families and, at least, 43 species of larval fishes have been identified. The offshore station had the highest number of species, (19 species), most of which were oceanic types. Relatively higher abundance of pre-flexion larvae was found inshore, at the fore-reef and back-reef stations (means : 45.2 and 40.2 0Ind/100m3, respectively). Conversely, more post-flexion larvae was found offshore (mean : 6.30 Ind/100m3). This trend was influenced by the relatively higher abundance of beloniform taxa (flyingfishes, ballyhoo, needlefishes) offshore, which only hatch as post-flexion larvae. Patchiness, occurring at time scales of shorter duration than the monthly sampling interval, appeared to be the dominant feature of temporal variability in total post-flexion and pre-flexion larval abundance. Peaks of significantly higher abundance were observed during different months at each station. There was a synchronized peak of larval fish abundance at the shelf-edge and offshore stations during August. This patch was multispecific in taxonomic composition (11 families), and included a wide range of ontogenetic stages (pre-flexion and post-flexion) of oceanic, as well as reef associated species. The high relative abundance of oceanic taxa in this patch (Exocotidae, Gempylidae, Macrorhamphosidae, Scombridae, Istiophoridae, Nomeidae) suggests an offshore origin. Co-occurrence of reef associated taxa as well (Hemiramphidae, Pomacentridae, Carangidae, Ostracidae) may be indicative of high larval survival in a physically driven offshore retention zone.

PDF Preview