Summary of Abstract Submission

Abstract Submission No. IO50-09-0054PresentationPoster

SEQUENTIAL RESPONSE OF MESOZOOPLANKTON TO THE HYDROGRAPHICAL TRANSFORMATIONS IN THE MUD BANK REGION OFF ALAPPUZHA, SOUTH WEST COAST OF INDIA

Jagadeesan, L.,*1, Jyothibabu. R.,1, Arunpandi, N.,1, Karnan, C.,1

1 CSIR- National Institute of Oceanography, Regional center, Kochi , India

ABSTRACT :

Mud banks are littoral areas along the Kerala coast with a relatively high concentration of suspended sediments during the Southwest Monsoon (SWM), facilitating remarkable damping of the incident waves and creating a calm sea environment conducive for fishing activities. In this paper, we present the results of a zooplankton ecology study conducted off Alappuzha where mud banks occur during the SWM. Altogether 18 field observations in three locations (M1, M2 and M3) within the study domain were carried out from Spring Intermonsoon (SIM) to late SWM. The characteristics of mud banks, such as relatively high suspended sediments and calm sea conditions, were found in M2 by early July. The most striking hydrographical feature observed was the coastal upwelling process by the onset of SWM. Zooplankton biomass and abundance were high during the peak and late SWM compared to the SIM and onset of SWM. Zooplankton abundance was contributed chiefly by copepods (>70%) and the number of larger zooplankton carnivores (medusae, siphonophores and chaetognaths) was found to be low (<5%). Altogether 43 species of copepods were recorded in which Acartia danae, A. erythraea, and Centropages orsini dominated during the SIM. Temora turbinata was the most dominant species during the onset of SWM, and Oithona similis dominated during the peak of SWM. Temora turbinata, Pseudodiaptomus serricaudatus, and Centropages tenuiremis dominated during the late SWM. This copepod dominance pattern was similar in all locations, indicating the major influence of coastal upwelling on the zooplankton community in the study domain.