These new results are revealing the magnitude of undescribed marine species diversity. That discoveries remain, both in numbers of species within a given community and in kinds of species, is thus without question. Rapidly evolving molecular techniques now permit insights into species diversity that were previously unimaginable---the ``molecular hammer'' has and will reveal the global wealth of marine organisms.
These novelties of diversity and form must, however, be accompanied by an equally important understanding of what diversity means to how an ecosystem ``works''; the need for this understanding drives many critical research questions, including the following. How does the new recognition of species complexes alter understanding of the ecology of the relevant community? How does it affect the ways in which a system functions if there are 10, or 100, or 1000 species? How does the trophic diversity of these species affect ecosystem function? If 1 of 5 herbivores, or 2 of 4 carnivores, are removed from a system---or, indeed, if herbivores or carnivores were added to a system---does the system then function in a fundamentally different way, or is there ``redundancy'' in trophic roles? How many species can be removed from an ecosystem---by pollution, by fishing, or by other means---before the system collapses? How many species can be added---by invasions of exotic species---before the system ``rolls over'' and assumes an entirely novel structure? By altering species diversity within given systems, how is the diversity altered of systems less directly impacted elsewhere? In turn, how does overall biodiversity determine the long-term stability of a system, influence its production, and mediate its ability to resist, or recover, from change? These kinds of questions are the foundation for recent, urgent calls for integrated national and international marine biodiversity research programs [ Grassle et al., 1991; Lubchenco et al., 1991; Butman and Carlton, 1993; NRC, 1995].