Mesozooplankton abundance and community structure in vembanad-kol wetland ecosystem, kerala, India

Abstract

Abundance and community structure of mesozooplankton were studied (March 2012-February 2013) in the context of prevailing environmental parameters in the Vembanad estuarine system, a Ramsar site on the southwest coast of India. Of the sixteen taxa of mesozooplankton, 16 calanoid copepods and 26 rotifers were identified upto species level. Copepods was the most dominant taxon where calanoids (63%), followed by rotifers (23%), copepodites (2 %), amphipodes (2%), crusteacean naupli (1.5 %) and others contributing in minor proportions. Freshwater diaptomid species, including Heliodiaptomus cintus and Allodiaptomus mirabilipes contributed around 52 % of calanoids in the southern stations (1, 2 and 3) and Bestiolinas imilis (19%) and Acartia southwelli (12.3%) formed the major share of calanoid copepods in northern stations (8, 9 & 10). Seasonal distribution of zooplankton showed bimodality, with a primary peak in premonsoon (av. 25073 ind. m-3) followed by secondary peak in post monsoon (av. 21093ind. m-3) coinciding with maximum of copepod species. Multi-Dimensional Scaling analysis reveal 80% similarity in abundance of plankton between southern (1 to 7) and northern stations (8, 9 and 10). Phosphate, nitrite, temperature, dissolved oxygen, and salinity best determined the abundance and distribution of mesozooplankton in Vembanad estuary based on multivariate BIOENV analysis.