ICHTHYOPLANKTON ASSEMBLAGES IN THE GULF-OF-NICOYA AND GOLFO-DULCE EMBAYMENTS, PACIFIC COAST OF COSTA-RICA

Ichthyoplankton surveys were conducted in December (rainy season), 199 3 and February (dry season), 1994, during the RV Victor Hensen German - Costa Rican Expedition to the Gulf of Nicoya and Golfo Dulce, Costa Rica. Samples from the inner, central, and outer areas of each gulf we re collected in oblique rows with a bongo net of 0.6 m mouth diameter, 2.5 m long and 1000-mu m mesh. A total of 416 fish larvae of 22 famil ies were sorted out of 14 samples. Stations of both the maximum (11) a nd the minimum (1) family richness were located in Golfo Dulce. Mean t otal larval abundances were 124.9 and 197.2 individuals 10 m(-2) for t he Gulf of Nicoya and Golfo Dulce, respectively, while mean larval den sities ranged from 95.3 larvae 10 m(-2) in December to 236.7 larvae 10 m(-2) in February. However, no statistical differences between gulfs or seasons were detected, due to the high within-group variability. Cl uster Analysis, Multi-Dimensional Scaling (MDS), and non-parametric te sts showed two well-defined major groups: (1) the Gulf of Nicoya nerit ic assemblage, represented by Engraulids, Sciaenids, and Gobiids (inne r and central stations), and (2) the oceanic assemblage, dominated by Myctophids, Bregmacerotids, Ophiidids, and Trichiurids (outer stations off the Gulf of Nicoya and Golfo Dulce). A third, although less defin ed group, was an Ophichthid-dominated assemblage (typical in areas nea rby coral or rocky reefs). These assemblages closely resemble the clus ters based upon adult fish data of the beamtrawl catches of the same c ruise. This publication is the first to report on the ichthyoplankton community of Golfo Dulce.