U.S. GLOBEC: Modeling biological/physical processes controlling copepod abundance in the Georges Bank / Gulf of Maine region

C. S. Davis (WHOI), D. R. Lynch (Dartmouth), G. R. Flierl (MIT), D.J. McGillicuddy (WHOI)

A modeling project is proposed that will tie together the various components of the GLOBEC Georges Bank Program in addressing its main goal, i.e., to understand how physical processes interact with population dynamics to control the distributions of dominant species in a temperate shelf area, the Georges Bank/Gulf of Maine region. The wealth of data from the GLOBEC field program (broadscale surveys and process studies) and historical sources together with newly developed modeling tools, including a realistic 3-D circulation model of the region and a simplification method which allows for more biological realism, provide a tremendous opportunity for developing a realistic model of the distribution and abundance patterns of marine plankton populations. The proposed modeling will focus on the dynamics of the dominant species of copepods: Calanus finmarchicus, Pseudocalanus newmani and moultoni., Centropages typicus, and Centropages hamatus.

The modeling will proceed in two phases. First, the annual cycle in the large-scale distributional patterns characteristic of each species will be modeled based on the seasonally-varying climatological-mean circulation, mean food and predator distributions, and characteristic life-histories of each copepod species. In the second phase, short-term bank-scale physical and biological processes affecting distributional patterns will be examined in more detail, including water column stratification events, physical exchange due to mean flow and storms (i.e. source, retention, and loss), and vertical migration and aggregation behaviors.

By focusing on the population dynamics of dominant species, the modeling study will provide: 1) new insights into the functioning of the mesozooplankton component of pelagic ecosystems, 2) needed information on the dynamics of the prey field of larval fish , and 3) information on the potential effects of climate change on species distributions in temperate shelf areas.