Abstracts

03/18/09: Modeling Climate - to Fish - to Fishers: Yes We Can!

There are many challenges to developing Earth System, or end-to-end, models. Some of the challenges are technical: How to represent the widest possible range of relevant physical and biological scales and processes given limited computational resources. Some are conceptual: How many nutrients, phyto- and zoo-plankton functional groups are needed for a given application, how to account for species migration and adaptability and how to explore the relative roles of climate and fishing pressure on fish populations. In this talk we focus on two aspects of an emerging endto- end model: 1. Downscaling of the climate system to regional scales and 2. The development of a fully integrated ecosystem model that includes fish and fishers. The climate downscaling is based on a two-way coupled climate (NCAR-CCSM) and regional (ROMS) models. We will describe the strategies adopted for the coupling and the usefulness of the system for downscaled climate projections. The ecosystem model we present is based on the NEMURO family of ecosystem models. It includes a lower trophic level NPZD model tightly coupled to an individual based model, currently implemented for sardine and anchovy. The ecosystem model is being developed as a tightly coupled module of the regional physical model ROMS. We discuss the challenges that arise from this integration, and present some early results from the ongoing work.

03/26/09: Coupled biophysical modeling in the Northern California Current: GLOBEC results and future directions

More than a decade of US GLOBEC funding of model and field investigations has improved knowledge on atmospherically-forced patterns of circulation and hydrography in the Northern California Current, and how physical processes interact with ecology to structure continental shelf pelagic ecosystem dynamics and function. Results of coupled biophysical models are highly dependent on having realistic simulations of the ocean physics. This talk will summarize some of the results of GLOBEC's modeling investigations in the Northeast Pacific. How the physical and ecosystem models may be used to answer climate- and conservation-related societal needs will be addressed. Directions for future coupled biophysical models of the Oregon shelf region, including real-time forecasts of the production and fate of shelf primary production and its effects on dissolved oxygen concentration and incipient hypoxic conditions will be outlined.

03/31/09: Global Climate Variability and its Impacts on North Pacific Ecosystem

One on the important legacies of the US GLOBEC program is that it has advanced our view of climate-ecosystem linkages from a simplistic correlative relationship to one that recognizes and understands the mechanisms by which global climate variability drives changes in regional ecosystem productivity and structure. This talk will describe the multiple approaches to and results of recent work by GLOBEC scientists and colleagues to decipher the patterns in time and space that characterize environmental variability and climate change. Spatial variability from global down to sub-ecosystem scales is important in driving ecosystem processes. Temporal variability includes not only natural interannual to centennial cycles and an apparent anthropogenic global climate change trend, but shifts in seasonal cycles that are critical for the life histories of many managed and protected populations. These analyses have helped us to understand the relationships between past climate and ecosystem variability, and allowed scientists to develop indicators that summarize and assess ecosystem state. Many of these indicators are now being implemented.

04/01/09: Climate change, marine food webs and survival of juvenile salmon during the first summer at sea in the northern California Current

Long-term sampling of hydrography and zooplankton at biweekly intervals in the coastal upwelling zone off Oregon for the past 13 years has shown that variations in copepod biodiversity, species richness and community structure are highly-correlated with the PDO. When the PDO is in negative phase (as in 1999-2002), waters from the Gulf of Alaska feed the northern California Current (NCC) and transport large, lipid-rich copepods to the shelf waters of the NCC; when the PDO is positive (as in 2003-2006), waters from offshore and south feed the NCC and transport small, oceanic lipid-poor copepods to the coast. Thus the forces that drive the PDO, basin scale variations in wind, result in local food chains with vastly different bio-energetic content. These signals may be transmitted up the food chain to salmon since interannual variations in salmon returns are highly-correlated with biomass of "northern" lipid-rich zooplankton species. Thus, knowledge of source waters which feed the NCC is critical for understanding ecosystem dynamics in the shelf waters of the NCC. A comparison of hydrographic and zooplankton data from the 1960s and 1970s with recent data, shows that the Northern California Current ecosystem is becoming more subtropical in nature, likely due to climate change.