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Journal of Plankton Research Vol.23 no.10 pp.1061-1071, 2001
© Oxford University Press 2001
Reproductive response of the copepods Calanoides carinatus and Calanus agulhensis to varying periods of starvation in the southern Benguela upwelling region
Marine And Coastal Management, Private Bag X2, Roggebaai 8012 And Marine Biology Research Institute, Zoology Department, University Of Cape Town, Rondebosch, 7701 South Africa
Egg production by the calanoid copepods Calanoides carinatus and Calanus agulhensis fed excess Thalassiosira weissflogii was monitored in the laboratory following starvation periods of 1, 3, 5, 7 and 9 days. Following short (1–3 day) periods of starvation, egg production by C.agulhensis returned to the satiated rate (51.1 eggs {female} day–1) more rapidly (after 0.9–2.4 days of excess food) than that of Ca. carinatus (after 2.8–3.1 days). However, following longer (5–9 day) periods of starvation, Ca. carinatus regained satiated levels of egg production (55.8 eggs {female}–1 day–1) more rapidly (after 3.1–4.0 days of excess food) than C. agulhensis (after 3.8–5.2 days of feeding following 5–7 days of starvation). Moreover, many C. agulhensis females did not regain normal rates of egg production after 9 days of starvation. For both species, the time required for egg production to recover was proportional to the starvation period, although only up to 7 days for C. agulhensis, and was the same following 4.25 days of starvation. Previously fed Ca. carinatus terminated egg production more rapidly than C. agulhensis when starved. The ability of Ca. carinatus to tolerate, and recover rapidly from, prolonged periods of starvation, combined with a comparatively fast development time and high rate of egg production, provides this species with a strong competitive advantage over C. agulhensis in the highly pulsed food environment of the southern Benguela upwelling region.