Temporal and spatial variability of ichthyoplankton assemblages in the Eastern Tropical Pacific off Colombia

Abstract

We investigated the spatiotemporal variability of the ichthyoplankton assemblages along the northern Pacific coast of Colombia. This region is characterized by high biodiversity and important artisanal fisheries, yet knowledge of the dynamics of the early life history of fish is scarce. Three sites (north: 6.3°N, central: 5.7°N, south: 4.9°N) were sampled every other month for a year, covering a gradient of varying coastal geomorphology along ∼240 km of the coast. Fish larvae abundances were significantly higher at the southern site (LMEM, p < 0.05), and showed positive relationships to chlorophyll-a (Chl-a), mesozooplankton biomass, and surface temperatures, and a negative relationship to surface salinities (LMEM, p < 0.05). Species richness was similar at the three sites (106–117 spp.), but evenness was lower at the southern site due to the dominance of Cetengraulis mysticetus (39–82%) most of the year and one unidentified Labrisomidae in March (92.7%). At the central and northern sites, C. mysticetus was also abundant, although not as dominant, in conjunction with Eucinostomus sp. Besides these two species, Stellifer sp.1 and Auxis rochei drove differences in assemblages at the central site, whereas two Pomacentridae (Abudefduf troschelii, Pomacentridae sp.), Sphyraena ensis, Caranx sexfasciatus, and two Scombridae (Euthynnus lineatus, Katsuwonus pelamis) differentiate the assemblages at the northern site. Multivariate analyses suggest that fish larvae assemblages were significantly different among sampling dates (PERMANOVA, p < 0.05), and that temporal changes in Chl-a, mesozooplankton biomass, and surface salinities were correlated with assemblage variability. Our study highlights the important effects of seasonal changes in water column hydrographic conditions on the spatiotemporal variability of ichthyoplankton assemblages in coastal sites of the Eastern Tropical Pacific.