JPR Advance Access published online on February 11, 2008
Journal of Plankton Research, doi:10.1093/plankt/fbn016
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Reproduction, growth and secondary production of Pseudocalanus elongatus Boeck (Copepoda, Calanoida) in the southern North Sea
Alfred Wegener Institute for Polar and Marine Research, PO Box 120161, 27515 Bremerhaven, Germany
* Corresponding author: E-mail: Jasmin.Renz{at}awi.de Phone: +49-471-48311042 Fax: +49-471-48311918
Received on October 25, 2007; accepted on January 10, 2008
| Abstract |
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The seasonal cycle of population dynamics and production of the dominant copepod Pseudocalanus elongatus in the southern North Sea was described using for the first time concurrent shipboard measurements of abundance, egg production and stage durations. Biological and physical parameters were measured from February 2004 to May 2005. Highest population abundance (592*103 n m–2) was recorded in June. Maximum egg production rate (EPR) was 9.1 eggs f–1 day–1 in April 2004. High EPR occurred at several stations where chl a concentration was low, suggesting P. elongatus to be able to use alternative food resources like microzooplankton and detritus or to maintain high production rates by using lipid reserves. Stage durations derived from molting experiments ranged from 1 day (CII) in February up to 9.2 days (CV) in April, with fastest development for most stages occurring in April. The increasing temperature in summer did not further shorten developmental times. Therefore food might be an important determinant of development of P. elongatus in the North Sea. Estimated generation times in August based on shipboard measurements of stage durations were 2.3 times longer than predicted from laboratory investigations and point towards the importance of field measurements when calculating secondary production.
Key Words: Pseudocalanus elongatus egg production rate population dynamics North Sea
Corresponding editor: R.P. Harris