Abundance, composition and diversity of zooplankton in the area of Cojimíes - Manabí, during the months of may - october 2018

Investigation article

Abstract

Abstract

Zooplankton occupies the second level in the marine aquatic food web, transferring energy between producers, like the nano- and phytoplankton, towards higher consumer levels, for their ability to filter out microscopic particles. A greater abundance of zooplankton in the marine environment is an indicator of high productivity, as a result, it is important know the abundance, composition and diversity, and their asociation with environmental parameters. Studies were conducted in the coastal area facing the estuary of Cojimies during May to October 2018. Day and night biweekly trawls were made in the first meter of the water column with a net of 300 µm mesh, with the objective of determining the abundance, composition, and diversity of the zooplankton and its association with environmental parameters. Samples were collected during daytime (07:00) and evening (20:00) and sea surface temperature (SST) as well as the Secchi depth and pH were measured. The SST showed small variation between June and Sep.-October, with average of 24.9±0.2 ° C, and short duration pulses of 26.0±0.9 ° C in May and July. A synchrony was observed between SST variations, zooplankton and phytoplankton abundance in the study area. A Diversity (H’) was similar in day and night samples, and showed greater values in July, September and October, and a decrese during August when abundance was the lowest. Copepods dominated the zooplankton community (54.7%) while other crustaceans accounted for other 24%. The night zooplankton abundance maintained similarity with the daytime. Fourteen families of zooplankton were found being Paracalanidae, Oithonidae and Acartidiidae the most representative among the copepods. Among the 17 genera identified, Arcatia sp., Paracalanus sp., Oithona sp. and the cladoceran Evadne sp. were the most abundant.

Keywords: environmental parameters, diversity, abundance.