Environmental influences on patterns of larval replenishment in coral reef fishes

Spatial and temporal patterns of larval replenishment to the San Blas Archipelago were measured using 3 light traps in each of 3 habitats (exposed, lagoon and back-reef) over 18 lunar months from December 1996 to June 1998. Traps were sampled for 19 consecutive nights centred on the new moon in each month. The effects of environmental variables (wind speed and wind direction, tidal range, rainfall, solar radiation and water temperature) on catches were examined both in the days immediately prior to settlement and during the entire larval phase using 2 approaches. Firstly, time-series analyses were used to compare night-to-night patterns in light trap catches of 11 species (Astrapogon puncticulatus, Eucinostomus melanopterus, Lutjanus apodus, L. mahogani, Ophioblennius atlanticus, Stegastes dorsopunicans, S. partitus, S. planifrons Synodontidae spp., Thalassoma bifasciatum and an unidentified blenny) with environmental variables. Secondly, modified correlation analysis was used to examine the relationships between environmental variables, averaged over larval durations, and light trap catches of 6 of these species. Time-series analysis detected significant correlations between catches of 8 species and wind direction; however, correlations were often weak and variable in direction. Similarly, there were weak correlations between day-to-day catches of all but 3 species and water temperature. Modified correlation analysis also found that water temperature was correlated with catches of 4 species (Lutjanus mahogani, Stegastes dorsopunicans, S. partitus and S. planifrons). Catches of the remaining species, Ophioblennius atlanticus and Thalassoma bifasciatum, were not correlated with environmental variables in these analyses. Multiple-regression analysis could not detect any combined effects of environmental variables on patterns of light trap catches, although this analysis also identified weak correlations (R2 = 0.08 to 0.29) between catches of Lutjanus mahogani, Ophioblennius atlanticus, Stegastes dorsopunicans, S. partitus, S. planifrons and Thalassoma bifasciatum and water temperature.