VARIABILITY IN THE ABUNDANCE OF LARVAE OF CRUSTACEANS AND POLYCHAETOUS IN BAHÍA MÁLAGA, COLOMBIAN PACIFIC (JANUARY-JUNE 2010)

Abstract

This research presents the taxonomic composition, diversity, relative abundance and spatial distribution of the crustaceans and polychaetous larvae from superficial waters collected during six months in Bahía Málaga, Colombian Pacific. The sampling was taken monthly using a superficial dredge, between January and June 2010. Physical-chemical variables (salinity, temperature, and dissolved oxygen) were registered in every station, simultaneously. They were identified 58 morphotypes of larvae of crustaceans belonging to 30 families and 24 morphotypes of larvae of polychaetous belonging to 14 families. 38720 ind/m3 (SE ± 84.7) of crustacean larvae in different typical larval stages (cypris, nauplio, protozoea, zoea and mysis) grouped in seven infraorder and/or suborder: Brachyura, Caridea, Balanomorpha, Anomura, Penaoidea, Thalassinoidea and Stomatopoda were found. Brachyura was the most abundant infraorder (42%) in all the stations and months, followed by Balanomorpha (20.4%) and the infraorder Caridea (11.7%). The most abundant family was Balanidae of the suborder Balanomorpha with 6421 ind/m3. On the other hand, 1019 ind/m3 larvae of polychaetous (SE ± 1.68) represented by nectochaeta of the order Spionida (62% of total composition) and Phyllodocida (4.7%), trochophore of the order Sabellida (26%) and postlarvae of the order Terebellida (6.8%) were found. The distribution of crustacean larvae is heterogeneous along the bay, with oceanic stations presenting significant differences with regard to other stations (p < 0.001), while the distribution of the larvae of the polychaetous was similar along all points of the estuary (p = 0.0918). In regard to the temporal variation, the abundance of crustacean and polychaeta larvae presented a significant increase in April, when rains are more intense and the superficial temperature of the sea increases, compared to January-March, when rains are less intense. Salinity and dissolved oxygen showed significant differences between the outer and inner areas of the estuary (p < 0.05). Different rainfall intensities through months generated variations in temperature and surface salinity (p < 0.05).