Modeling growth of Atlantic cod larvae on the southern flank of Georges Bank in the tidal-front circulation during May 1999

Authored by R G Lough, L J Buckley, E A Broughton, L S Incze, K Pehrson Edwards, R Converse, A Aretxabaleta, F E Werner

Date Published: 2006

DOI: 10.1016/j.dsr2.2006.08.012

Sponsors: United States National Oceanic and Atmospheric Administration (NOAA) United States National Science Foundation (NSF) Global Ocean Ecosystem Dynamics Program (GLOBEC)

Platforms: No platforms listed

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

Cruises were conducted in spring 1999 to describe the interaction between tidal-front processes and the transport, retention, and growth of cod larvae and their prey during the seasonal transition to a stratified water-column along the southern flank of Georges Bank. All the physical and biological observations were integrated in coupled circulation-trophodynamic simulations. The three-dimensional circulation fields were modeled using data assimilation methods described in Aretxabaleta et al. {[}2005. Data assimilative hindcast on the Southern Flank of Georges Bank during May 1999: frontal circulation and implications. Continental Shelf Research 25, 849-874]. The individual-based model (IBM) of Lough et al. {[}2005. A general biophysical model of larval cod growth applied to populations on Georges Bank. Fisheries Oceanography 14, 241-262] was used to consider trophodynamic effects on the growth and survival of larval cod. Prey fields were specified for mixed and stratified water columns from field surveys and allowed to adjust in the circulation model. Encounter and ingestion rates of larvae were functions of prey concentration, larval search patterns, light, swimming speeds of predator and prey, and turbulence. Model outputs provide hourly depth-dependent estimates of growth rates, prey biomass ingested, and larval length and weight. Simulations were conducted along a 2-D transect across the tidal front, from mixed to stratified water columns, before and after a wind event. Pre-storm, observed larval cod growth rates, based on RNA-DNA analysis, were highest in the surface 20 m at the stratified and front stations. Poststorm, larval growth rates decreased 1-2\% d(-1) at the stratified and front stations, corresponding with a < 1 degrees C decrease in temperature. At the mixed station, there was no apparent difference in growth rates with depth, either before or after the storm. Simulations indicate that maximum larval growth rates can occur at the tidal-mixing front due to the accumulation of prey in a region of near optimal temperature, turbulence, and light. However, away from the front, high abundance of prey can compensate for environmental conditions (e.g., light and turbulence levels) that are less than optimal. Published by Elsevier Ltd.

Tags

Vertical-distribution North-sea Gadus-morhua Haddock melanogrammus-aeglefinus Fish larvae Prognostic numerical-model Diapycnal flow-through Buchan area Wind stress Shelf break