Epipelagic abundance and distribution of paralarvae (Cephalopoda: Mollusca) in the Colombian Pacific: rainy periods 2001-2004

Abstract

Despite their great ecological and economic importance, information on cephalopods is scarce, especially on their paralarvae, particularly in the Colombian Pacific Ocean (OPC). Therefore, their abundance and distribution in the periods 23.Jun-12.Jul.01, 27.Ago-15. Sep.01, 03-22.Sep.02, 01-21.Sep.03 and 18 .Sep-08.Oct.04 were evaluated. Organims were caught at the surface with a conical net (O = 50cm, length 1.85m, pore 363μm). The temperature and salinity data were obtained with a CTD probe. Ommastrephidae (66.3%), Ancistrocheiridae-Ancistrocheirus lesueuri (14.2%) (first specific paralarval record for the OPC), Cranchiidae (1.5%), Enoploteuthidae, Gonatidae, Octopodidae, Onycoteuthidae, and Pyroteuthidae (≤0.5%) were identified. Newly hatched paralarvae (≤2.0mm) covered the whole OPC, indicating its relevance as a spawning area, especially in neritic waters. The smaller size at hatching could be due to the higher temperatures in the OPC than in other latitudes of the American Pacific. The meso-scalar distribution could be mediated especially by the geostrophic eddy, the Equatorial South Current and the Colombian Current. El Nino-moderate perhaps influenced the exclusive appearance of Ommastrephidae during the period 03-22.Sep.02. The night predominance (83.2 vs. 16.8% day) was attributed to the paralarval vertical migrations. The variability of these findings could be related to the interannual environmental changes framed in the great environmental complexity of the OPC and other unweighted factors, such as food availability and predation.