Interannual variability in chitobiase-based production rates of the crustacean zooplankton community in the Strait of Georgia

Abstract

The temporal patterns of biomass development and biomass production rate (BP) of the crustacean zooplankton community in the Strait of Georgia, British Columbia, Canada, were tracked during the spring blooms of 2004 and 2005. BP was estimated directly using a method based on the turnover rate of the crustacean moulting enzyme, chitobiase. The relationship between individual chitobiase activity and body weight was found to be consistent for copepods, decapod larvae and mysids. The native activity of chitobiase in the water column was also found to vary significantly with the biomass derived from traditional plankton net tows. In 2004, chitobiase-based estimates of BP generally varied with temperature. The peak BP estimated in the spring of 2004 was 6.10 mg C m -3 d-1, corresponding to biomass-dominance of the crustacean zooplankton community by the calanoid copepod Neocalanus plumchrus. In 2005, however, BP was unrelated to temperature and relatively low (<2 mg C m-3 d-1) during the peak and early decline of the spring phytoplankton bloom. During the spring of 2005, the developing N. plumchrus population collapsed and has yet to recover. © Inter-Research 2009.