Murviel-lès-Montpellier, France
Murviel-lès-Montpellier, France

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Highfield J.M.,Plymouth Marine Laboratory | Highfield J.M.,University of Plymouth | Eloire D.,Plymouth Marine Laboratory | Eloire D.,Laboratoire Ecosysteme Lagunaire | And 4 more authors.
Journal of Plankton Research | Year: 2010

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.


Eloire D.,Plymouth Marine Laboratory | Eloire D.,Laboratoire Ecosysteme Lagunaire | Somerfield P.J.,Plymouth Marine Laboratory | Conway D.V.P.,Marine Biological Association of The United Kingdom | And 3 more authors.
Journal of Plankton Research | Year: 2010

Zooplankton community composition and diversity have been analysed for the period 1988-2007 at the coastal station L4 off Plymouth in the Western Channel. The seasonal cycle of the total zooplankton was characterized by two peaks. The total zooplankton abundance did not show any long-term trend and its interannual variations were not directly related to changes in environmental conditions. However, different periods of change in total zooplankton abundance were observed that appeared to be consistently related to changes in sea surface temperature (SST) and wind. The number of taxa (22) contributing 80-90 of the total zooplankton abundance was consistent over the 20 years and their cumulative contribution to the community showed only small interannual variations. A significant long-term increase in species richness of the copepod community was detected and its maximum annual value was significantly related to annual average SST. There was evidence of long-term changes: numbers of Oncaea spp., Cirripede larvae, Calanus helgolandicus and Chaetognaths have increased, whereas numbers of Pseudocalanus elongatus, Temora longicornis, Acartia clausi, Evadne nordmanni, Appendicularians, Podon spp. and Ctenocalanus vanus have decreased. The use of indicator species to monitor hydroclimatic changes in the Western Channel is discussed. © The Author 2010. Published by Oxford University Press. All rights reserved.


Widdicombe C.E.,Plymouth Marine Laboratory | Eloire D.,Plymouth Marine Laboratory | Eloire D.,Laboratoire Ecosysteme Lagunaire | Harbour D.,Plymouth Marine Laboratory | And 2 more authors.
Journal of Plankton Research | Year: 2010

Over a 15-year period (1992-2007), weekly water samples were collected from the L4 time-series station in the Western English Channel and analysed for phytoplankton community structure and abundance. The data produced have been analysed to identify seasonal patterns, inter-annual variability and long-term trends in the composition of the seven main functional phytoplankton groups. Phyto-flagellates numerically dominated accounting for on average ca. 87 of the phytoplankton abundance while diatoms, Phaeocystis, coccolithophorids, dinoflagellates and ciliates contributed 13 of abundance. Distinct seasonal and inter-annual changes in the abundance and floristic composition of the functional groups were observed. Significant long-term changes in abundance showed that, over the study period, diatoms and Phaeocystis decreased while coccolithophorids, the dinoflagellate Prorocentrum minimum and some heterotrophic dinoflagellate and ciliates increased in abundance. These changes highlight the importance of long-term observations for the understanding of natural temporal variability in plankton communities. Such shifts in the community composition at L4 could have important consequences for ecosystem function. © The Author 2010. Published by Oxford University Press. All rights reserved.

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