Seasonal dynamics of meroplankton assemblages at station L4

Abstract

Zooplankton data from 20 years of weekly sampling were used to determine inter- and intra-annual patterns of meroplankton community change at Station L4, off the coast of Plymouth, UK. From these data, abundances were calculated for five groups; Cirripedia, Decapoda, Polychaeta, Echinodermata and Lamellibranchiata. This taxonomic level of analysis was chosen to minimize the potential effects of variation in taxonomic expertise over the 20-year period. Analyses showed that while there is some annual variability, it is seasonal variation that accounts for the major changes in the meroplanktonic community composition throughout the time series. Cirripedia are the most abundant meroplankton in March and April, followed by Echinodermata in August, and Lamellibranchiata in September and October. Abundance is low during the winter period. The average monthly contribution of the meroplankton community as a percentage of the total zooplankton abundance is highest in spring, when meroplankton (predominantly Cirripedia) can account for up to 42.5 of the total zooplankton community following spawning events linked to phytoplankton blooms. Little evidence was found for any major trends of change in the meroplankton community (at the taxonomic level examined here) at Station L4 over the 20-year period. © The Author 2010. Published by Oxford University Press. All rights reserved.