MEPS 177:133-146 (1999)  -  doi:10.3354/meps177133

Annual pattern of calanoid copepod abundance, prosome length and minor role in pelagic carbon flux in the Solent, UK

A. G. Hirst*, M. Sheader, J. A. Williams

School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, Empress Dock, Southampton SO14 3ZH, United Kingdom
*Present address: Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, Scotland, United Kingdom. E-mail:

ABSTRACT: Investigation of the calanoid copepods at a coastal station in the Solent, UK, over a 14 mo period revealed a numerical dominance by species of the genus Acartia (comprising A. bifilosa, A. clausi, A. discaudata and A. margalefi), and the species Temora longicornis and Centropages hamatus, with sporadic appearances of Paracalanus parvus and Pseudocalanus elongatus. There was clear seasonality in the abundance of calanoids, with total numbers being highest from May onwards, and low after October. Stage-specific prosome lengths varied with season, and in most cases were negatively correlated with temperature. Individual weights and abundance of the copepods, together with measures of temperature, were used to predict weight-specific growth and production rates using a published empirical relationship. Comparisons of annual copepod production with previous measures of annual primary production and production of bacteria and ciliates at this same site were made, and a carbon flow diagram was constructed. Calanoid copepod annual production was 32.2 mgC m-3 yr-1. This represents only 0.5% of the total annual primary production, and 0.6% of the annual primary production of algae >3 µm. Ciliate annual production was almost 2 orders of magnitude higher, and constituted 33% of the total annual primary production. In other neritic studies (with water column depths <200 m) annual production by copepods has varied between 21 and 177% of annual ciliate production, whereas at this Solent site the value was only 1.5%. It is suggested that the low biomass (and production) achieved by calanoid copepods was the consequence of population loss through high local flushing rates, unfavourable feeding conditions resulting from high suspended particulate matter, and high levels of hydrocarbon contaminants in the area.

KEY WORDS: Calanoid · Copepodite stage · Prosome length · Abundance · Production · Solent

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