Terms of Reference
ESSAS Working Group 2: Bio-Physical Coupling (WGBPC)
Ecosystem Studies of Sub-Arctic Seas (ESSAS)
28 February 2007

Introduction
A major goal of ESSAS is to predict the potential impacts of climate
variability on the sustainable use of the Sub-Arctic seas. ESSAS has elected toemploy a comparative approach, investigating, in each of the sub-arctic seas,
which energy pathways appear particularly vulnerable to decadal and longerterm climate change. The ecosystem response to climate can be non-linear withthresholds, have complex interactions between species, and feature different
species responses to similar climate fluctuations in different ecosystems.
Reducing uncertainty about the future states of ESSAS ecosystems depends on
developing the ability to project future climate states as well as predicting theresponse of the ecosystem to changes in climate. Predicting future climate statesis the primary focus of ESSAS Working Group I on Regional Climate Prediction.
This requires quantitative estimates of the magnitude and uncertainty of futureclimate change for the ESSAS regions, and the frequency distribution of naturalvariability, such as the well-known ecosystem reorganization of the North Pacificin the mid-1970s and historical inter-decadal variability in the marginal seas ofthe North Atlantic. Predicting ecosystem response requires both understandingand modeling the complex linkages between climate variables and species
distributions. This represents the primary focus of two ESSAS Working Groups(ESSAS Working Group 2: Biophysical Coupling Mechanisms and ESSAS
Working Group 3: Modeling Ecosystem Responses).
A Goal of the Working Group on Bio-Physical Coupling (WGBPC) is todetermine how climate-driven variability in physical conditions and processes inthe ocean will affect the organisms that make up marine ecosystems and thus
the transfer of energy and material through sub-arctic marine ecosystems.
Physical aspects of the ocean thought to be crucial to ESSAS ecosystems
include sea ice cover, ocean temperature, circulation, and stratification.
A great deal is already known about the responses of organisms tophysical variability in the ocean, but the literature is scattered and there is needto summarize what is known specifically about the responses of populations andthe ecosystem as a whole in the Sub-Arctic seas and how information gathered
in one basin may be applied to ocean regions elsewhere in the Sub-Arctic. Thusa major task for the WGBPC will be to provide the modelers in the ESSASWGMER with realistic values for parameterizing predictive models of ecosystem
response to climate variability.

Tasks
1. Summarize and evaluate the available information on the responses ofmarine organisms of the Sub-Arctic seas from phytoplankton to marine
mammals and seabirds to variability in physical attributes of the oceansuch as seasonal sea ice cover, ocean temperature, stratification, andcirculation.
2. Working within the larger ESSAS framework, provide the WGMER with arealistic set of values with which to model organism responses to climatedriven variability in the physical attributes of the Sub-Arctic seas.
3. Be a community resource on retrospective and future climate change
issues.
Implementation
1. The Working Group on Bio-Physical Coupling shall exist for an initialperiod of three years, ending six months after the 2009 annual meeting ofESSAS. At this time, the ESSAS SSC will evaluate whether the WG
should continue, be revised slightly or dissolved.
2. Eight to ten members will be chosen from the fields of biological andfisheries oceanography. Input from experts on future climate variability
and the needs of ecosystem modelers will be sought through collaboration
with ESSAS WG 1 and 3, respectively.
3. The development of the proposed products includes conducting
workshops held at the annual ESSAS meetings and will require intersessional work. The purpose of the workshops is to review information on
how changes in various physical attributes of the ocean will affectimportant ecosystem components. Foci of workshops will include theroles of: seasonal sea ice cover, temperature, stratification and circulation.

Expected Results
Workshop products will be one or more review papers based oncomparative studies, to be published in the refereed literature, that summarize
the important mechanisms whereby the changes in the physical attribute underdiscussion affect biological constituents of Sub-Arctic ecosystems and their interrelationships. Where possible, these papers should provide the informationnecessary for parameterizing the biophysical coupling parameters in ecosystemmodels of the sub-arctic seas. Where sufficient data are lacking to accomplish
this task, there should be a clear statement concerning the lack of specific datathat could guide fieldwork during ESSAS.

2Membership
A list of the initial members of ESSAS WG-2:
George L. Hunt, Jr.
Earl Dawe
Elena Dulepova
Erica HeadFranz Mueter
Emma Orlova
Vladimir Ozhigin
Vladimir Radchenko
Marit Reigstad
Sei-ichi Saitoh

USA, Acting Chair
CanadaRussiaCanadaUSA
RussiaRussiaRussiaNorwayJapan

Egil Sakshaug
Yasunori Sakurai
Paul Wassermann
Kai Wieland

NorwayJapan
NorwayDenmark3