NWA - Chapter 2

REPORT OF THE GEORGES BANK FIELD STUDY WORKSHOP

2.1 GLOBEC Site Selection

2.1.1 Introduction

The purpose of this section is to present the general guidelines for selection of GLOBEC study sites and in particular the Northwest Atlantic study site (Fig. 2-1). It sets forth the central program goals, the key questions, the criteria for site selection, and the process by which field studies will be designed. The scientific community will select sites by participation in a series of workshops which began in mid-1990.

2.1.2 The GLOBEC imperative

Global climate change appears imminent. Its effects on animal populations in the world ocean are neither obvious nor predictable. We do know that population variability is a strong function of physical processes acting through effects on recruitment, larval dispersal, growth and reproduction, but the mechanisms by which physical processes affect biology are poorly understood.

GLOBEC is a process-oriented program designed to elucidate how the dynamics of populations within a community are affected by physical processes. The goal of GLOBEC is to evaluate the potential for community, ecosystem - and ultimately - global ecosystem change.

2.1.3 Key questions

The first order questions posed by the GLOBEC program are:

How do changes in ocean physics affect biological processes and population dynamics?
How do population-level responses to physical dynamics affect the structure and stability of ocean ecosystems?

Answers to these questions will greatly improve our ability to gauge the effect of global climate change on marine animal populations.

2.1.4 The research strategy

The key elements of GLOBEC research should involve modeling and new technology in the context of integrated interdisciplinary field studies.

We suggest a focus on population dynamics processes of individual animal species. How are these species affected by abiotic factors, their own density, and the density of interacting species, both predator and prey? Interdisciplinary field studies are required to answer these questions. New technology should be a significant element of the research at all levels: in sampling, sample analysis, and data interpretation. Modeling should be used interactively, to both plan and verify experimental studies.

There is a dynamic interaction between these key elements of the research strategy (i.e., modeling, new technology, and field studies). The current blueprint for enacting the GLOBEC Science Plan calls for activities to begin on all fronts in 1990. Requests for Proposals (RFPs) have been issued for modeling studies in two areas: (1) conceptual models and (2) site-dependent models. The latter are linked to Field Program planning for a GLOBEC Field Study on Georges Bank; this planning will be accomplished by members of the GLOBEC Steering Committee in concert with a number of scientists in the community. With respect to new technology, instrumentation workshops will be held to specify performance criteria for new instruments; this process will require input from both modeling and field program planning activities, and should result in the issuance of RFPs in 1991. Initial results from modeling studies will help mold final plans for the Field Study, for which RFPs will also be issued in 1991. The Field Study should get underway in 1992 and run for three years; prototype new technology should be available for the field program. Results from the Field Study will be employed to verify models and improve new equipment. This applies generally to all potential GLOBEC field studies; it applies specifically to the Georges Bank Field Study only with respect to anticipated timing. Planning for subsequent field research programs will occur via a series of later site-selection workshops. Research activities at other sites could begin by 1993/94.

This general strategy will result in new approaches, insights and predictive capability from field research, new concepts from modeling, and new instruments from technology development. This is what makes GLOBEC revolutionary. GLOBEC research will arm oceanographers with new tools and new vision for the future.

2.1.5 Key research components of a GLOBEC field study

Marine populations fluctuate in abundance as the cumulative result of three processes: birth, mortality and transport. To understand the local rate of change in any pelagic population one must reliably quantify these processes, expressed conceptually as follows:

A mathematical expression for the population rate of change might be:

where N_i is the abundance of the ith taxon, B and M are the birth and mortality functions which depend on space (x, y, z), physical environmental variables (q), competitive and predator abundances (N_j and P_K), food resources (F) and fishing pressures (F). The population levels are also influenced by movement of the populations by either behavioral attributes of the animal such as swimming V_s(theta,PSI,P_K), and the flow fields in the environment as denoted by the velocity distribution, V(x, y, z). Predator abundances are subject to many of the same influences (e.g., x,y,z,t,theta,N_i).

Birth rate may be influenced by the relative distribution and encounter rates of mature adults, availability of food resources, fecundity, and by the influence of scalars in the physical and chemical environment (e.g., temperature, salinity, oxygen). The rate of active transport, or "swimming," is primarily behavioral, and thus may be affected by anything in the environment which influences behavior, such as the presence of prey, predators, and the desirability of physical and chemical environments. The rate of passive transport will be determined by fluid dynamics at the appropriate scale, ranging from small-scale dynamics which will have the greatest effect on vertical motion, to large-scale dynamics which will have the greatest effect on horizontal motion. The mortality rate may be influenced by the availability of suitable food resources, encounters with predators, as well as by the effect of scalars in the physical and chemical environments.

Any GLOBEC study must quantitatively assess the magnitude of these first-order rates, but at the same time the study must go beyond superficial monitoring. It is the mechanisms which govern those rates - not only at the population level but also at the level of the individual - that must be studied. Although their relative importance may vary according to local climate, physical dynamics, or the population being studied, it is these mechanisms which must be understood.

2.2 Site Selection Criteria

GLOBEC study sites and field programs should fulfill a majority of the following criteria, for both scientific and strategic reasons:

2.2.1 Climate change context

Any GLOBEC research program should have a demonstrable capability to link its results to climate change. Whatever the presumed linkage (e.g., increased seawater temperature, polar icecap melting, increasing ENSO events), the conceptual and data collection infrastructure should allow specific hypotheses to be addressed via direct testing or modeling. Global climate change is the phenomenon on which GLOBEC and all other geosciences funding initiatives are predicated; explicit acknowledgment is critically important.

2.2.2 Target species in benthos, holozooplankton and fish

The selected site should allow for simultaneous studies on at least one species among the benthos, one among the holozooplankton, and one among fish. The scientific rationale is that interactions among the species are probable, and thus studies on target species will complement one another. The strategic rationale is that such a study will allow for broad participation of biological oceanographers.

2.2.3 Definable populations

The research should be designed in such a manner that the target populations are, to the greatest possible extent, demographically and geographically distinct. GLOBEC explicitly seeks to understand how populations fluctuate in abundance in response to physical processes. The scientific rationale is axiomatic: in order to study the fluctuations in a population, one must first be able to define that population.

2.2.4 Population dynamics as the output

Research conducted under the aegis of GLOBEC may focus on a variety of processes which do not expressly operate at the temporal/spatial scale of the population. However, such studies should clearly demonstrate their importance to understanding population dynamics. Ultimately, GLOBEC research must describe the relation of population dynamics to physical processes that may result from climate change.

2.2.5 Focus on process and mechanisms

A key element of GLOBEC research is to understand the processes that give rise to observed fluctuations in populations. Descriptive studies are a necessary, but insufficient, component of GLOBEC research. A greatly improved understanding of mechanisms is critical if we are to model and ultimately predict population dynamics.

2.2.6 Historical database

Ideal study sites will have a considerable historical database on the distribution and abundance of target species, their physiology and ecology, local climate, and fluid dynamics at multiple scales. Such databases do exist, or are presently being created, in certain parts of the ocean. Historical data will aid not only in planning research, but also in model verification.

2.2.7 Modeling input

The improvement of our capability to predict, which is an ultimate aim of GLOBEC, presumes a significant emphasis on modeling. Modeling is considered sufficiently important that some effort will be devoted to modeling which is not directly linked to field programs. However, any field program should be able to demonstrate that modeling will be employed to both plan its execution and test its results. Interaction with independent modeling efforts is encouraged.

2.2.8 New technology

It is anticipated that new technology will be developed under the auspices of the GLOBEC program, for the express purpose of improving our ability to sample, analyze and interpret. Any GLOBEC field program should attempt to apply such new technology.

2.2.9 Relation to other programs

GLOBEC field studies should demonstrate conceptual, informational and logistic linkages to other research programs of similar scale and complementary aims. Such programs include global change research initiatives (e.g., WOCE, JGOFS) and international efforts with similar aims (e.g., France's National Recruitment Program, Canada's OPEN program). Shared resources and information will serve to strengthen all related programs.

2.2.10 Multiple agency support

The greater the inherent interest of multiple funding agencies within the United States, the greater the potential for significant long-term support of GLOBEC research. GLOBEC field research programs can improve their own chances for success by possessing facets which are attractive to as many agencies as possible. Obvious agencies include NSF, ONR, NOAA, DOE and NASA.