Model-based estimates of Calanus finmarchicus abundance in the Gulf of Maine

Abstract

Ocean observing systems and satellites routinely collect a wealth of information on physical conditions in the ocean. With few exceptions, such as chlorophyll concentrations, information on biological properties is harder to measure autonomously. Here, we present a system to produce estimates of the distribution and abundance of the copepod Calanus finmarchicus in the Gulf of Maine. Our system uses satellite-based measurements of sea surface temperature and chlorophyll concentration to determine the developmental and reproductive rates of C. finmarchicus. The rate information then drives a population dynamics model of C. finmarchicus that is embedded in a 2-dimensional circulation field. The first generation of this system produces realistic information on interannual variability in C. finmarchicus distribution and abundance during the winter and spring. The model can also be used to identify key drivers of interannual variability in C. finmarchicus. Experiments with the model suggest that changes in initial conditions are overwhelmed by variability in growth rates after approximately 50 d. Temperature has the largest effect on growth rate. Elevated chlorophyll during the late winter can lead to increased C. finmarchicus abundance during the spring, but the effect of variations in chlorophyll concentrations is secondary to the other inputs. Our system could be used to provide real-time estimates or even forecasts of C. finmarchicus distribution. These estimates could then be used to support management of copepod predators such as herring and right whales.

Model-based estimates of right whale habitat use in the Gulf of Maine

“…3b) and the CPR data ( Fig. 4c in Pershing et al 2009). The right whale arrival date showed a consistent negative relationship with the C. finmarchicus model over much of the Gulf of Maine (Fig.…”

“…A detailed evaluation of our model as a representation of interannual variability in Calanus finmarchicus is provided in Pershing et al (2009). To evaluate the potential of this model to provide information on right whales in the Gulf of Maine, a brief discussion of C. finmarchicus patterns in the Gulf and our model's ability to simulate those patterns is necessary.…”

Weekly predictions of North Atlantic right whale Eubalaena glacialis habitat reveal influence of prey abundance and seasonality of habitat preferences

“…Daily satellite imagery was processed into 8 d means using a simple arithmetic mean, and was then interpolated to eliminate pixels with missing data, which were a consequence of cloud cover. We used the interpolation procedure described by Pershing et al (2009a). All chlorophyll data were log 10 (x + 1) transformed.…”

“…The modeled Calanus abundance estimates used in our study were described in detail by Pershing et al (2009a). Briefly, the model couples a Calanus lifehistory model to output from an ocean circulation model.…”

“…This suggests that (1) the environmental preferences of right whales are dynamic and change on seasonal time scales, and (2) the distribution and availability of prey are important factors in determining the distribution of right whales. Pershing et al (2009a) went on to build and ground-truth a model of Calanus abundance throughout the Gulf of Maine, and Pershing et al (2009b) found a statistically significant relationship between modeled concentration of Calanus and the arrival date of right whales in the Great South Channel region. Thus, modeled concentration of Calanus was found to be a good predictor of right whale abundance at regional spatial scales.…”