A model of copepod population dynamics in the Southern Benguela upwelling region

A simple population dynamics model was constructed to simulate temporal var iability in the biomass of a dominant copepod Calanoides carinatus (Copepod a: Calanoida) along the West Coast region of South Africa. Calanoides carin atus is extensively preyed upon by the commercially important anchovy Engra ulis capensis, thus variability in zooplankton production may serve as a us eful predictor of variability in anchovy recruitment levels. The model deve loped here circumvents the need to include a large number of parameters bec ause it uses satellite-derived estimates of chlorophyll a concentration and sea surface temperature as primary inputs. Abundance estimates necessary t o initialize the model art: readily obtainable from biannual research cruis es. The model successfully simulates observed features of a copepod populat ion's response to pulses of upwelling and is robust with respect to most of its parameters because minor changes in their values result in predictable changes in model output. The model showed greatest sensitivity to paramete rs that are difficult to determine empirically, such as predator-induced mo rtality rates. Gaps in our present understanding of the nature and scale of processes affecting copepod egg abundance, survival and viability in the s outhern Benguela system were identified as the dominant impediment to simul ating copepod population dynamics in the region.