• Various marine systems present different opportunities to address fundamental questions because the systems vary in their evolutionary history, resulting in different biotas; in their connectivity (among sites within a system and among systems); and in the knowledge and description of their biodiversity.
  • Establishing the appropriate regional-scale is simpler for systems whose boundaries are more easily defined, and for which there is greater knowledge of specific anthropogenic stresses and their effects, as well as greater understanding of the role of dispersal mechanisms.
  • There are fundamentally different levels of environmental impact in different marine systems: some are now highly impacted (such as most coastal and coral-reef systems), whereas for others there is a grave possibility of future impact (such as open-ocean and deep-sea systems through, for example, human alterations to the global climate) suggesting the advisability of "anticipatory" research.

At larger—possibly the largest—scales, it is clear that distinct regional systems thousands of kilometers apart may have reciprocal influences on each other. Currents carry larvae of some species transoceanic distances, far from their parents (Scheltema, 1986). For example, the larvae of the Caribbean spiny lobster spend 9 or more months traversing the open-ocean pelagic ecosystems of the North Atlantic gyre (Farmer et al., 1989). Thus, an important factor influencing the abundance of adult lobster populations may be very distant oceanographic and biological processes—in an ecosystem not likely to be directly studied by Caribbean lobster ecologists. Likewise, larvae of the American eel undergo planktonic development in the Sargasso Sea, thousands of kilometers from the adult habitat in coastal rivers (Avise et al., 1986; McCleave, 1993). Also, currents associated with periodic El Niño-Southern Oscillations are known to transport warm water and propagules across the Pacific, causing population and community changes (Glynn, 1988).

Although this marine biodiversity initiative focuses on the larger within-regional-scale oceanographic and ecological processes that directly bear on the expression of local, site-specific biodiversity, awareness of the ocean-wide influences between regions remains important to an overall understanding of regional biodiversity. Furthermore, addressing a well-defined set of research questions in regional-scale studies of several different types of marine ecosystems will permit meaningful comparisons of the causes and consequences of changes in biodiversity due to human activities. Such comparisons will greatly enhance predictive capability relative to future human impacts on the marine environment.

Objectives of this Initiative

This marine biodiversity initiative sets a research agenda that represents a fundamental change in the approach to measuring and studying biodiversity in



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