The Critical Role of Taxonomy
Changes in the sea caused by anthropogenic effects are most commonly measured by changes in the distribution and abundance of species. The loss of individual populations of species may affect the genetic diversity of a species, and thus impact the survival of the species itself. The loss of ecosystem diversity restricts the habitat available for a species, and so, too, may affect the species' survival. At the center of these cascading effects is the species. The ability to identify individual species is thus the key that permits the opening of the first door to an understanding of community structure and function. And yet for all marine systems, the ability to "simply" identify the species present is now threatened by a continuing loss of scientists with the knowledge and ability to understand and describe biodiversity. Moreover, in many systems, species diversity is so poorly known—that is, so many species and entire groups of higher taxa remain undescribed (see Table 1)—that the impact of human activities on diversity is difficult to assess at all.
Even documenting the most obvious patterns of change is proving to be surprisingly difficult. In many cases, there are no or an inadequate number of trained taxonomists in a geographic region to allow the documentation of the distribution and abundance of even well-known species. Furthermore, the description and understanding of new species, genera, families, or even phyla are hindered by declining numbers of taxonomists (Stuessy and Thomson, 1981; SA2000, 1994) and the poor dissemination of taxonomic information to other field and laboratory biologists.
Most taxonomists describe species and undertake major taxonomic revisions according to their own professional interests with little or no communication with
Box 8: Training in taxonomy has declined dramatically over: Training in taxonomy has declined dramatically over: Training in taxonomy has declined dramatically over the last several decades, so that the appropriate scientists may not be available to describe the next round of unique species in a newly discovered marine habitat.
WHO DESCRIBED THE HYDROTHERMAL VENT FAUNA?
All but a few of the taxonomists who described the hydrothermal vent fauna, beginning in 1979, were over 40 years old at the time they published. In the mid-1990s, the same taxonomists—those who have not retired—continue to describe organisms from hydrothermal vents. These individuals were specifically chosen to describe the vent fauna because of their exceptional taxonomic expertise. Those who are still working continue to contribute substantially to the taxonomy and systematics of the group of animals in which they specialize, and some are the only remaining experts on their particular group of organisms. In fact, for most taxonomic groups, there has been little or no training of younger workers in the identification and description of species.
When the next major novel ocean ecosystem is discovered, who will describe the animals, plants and microbes associated with it?
ecologists. At the same time, it is becoming increasingly apparent that a ''graying" of taxonomists is occurring (e.g., Box 8). Taxonomists specializing in taxa of ecological importance have retired or died and there has been little or no training of younger scientists in the field; consequently, ecologists are being left on their own to deal with the seemingly bewildering array of species occupying most ecosystems. Unfortunately, most ecologists do not have the training to deal adequately with this task. Few ecologists today have had any formal training in taxonomic methods and principles, or in the detailed morphology of the group(s) that they study, and even fewer are aware of the ecological importance of such basic knowledge.
There are many examples of ecological studies that have been compromised by taxonomic mistakes (some examples are described in Lee et al., 1978; Knowlton, 1993; Knowlton and Jackson, 1994). Yet in contrast to a strong movement toward requiring, for example, rigorous statistical designs and analyses in ecological studies (with some number of submitted manuscripts being rejected by editors on the basis of inadequate statistical treatment), there are currently no rewards or penalties for good or bad taxonomic work on the part of ecologists and biological oceanographers, nor clear mechanisms by which to assess the quality of such work. Nevertheless, taxonomic competence is just as important for ecology as are rigorous statistics.
Fundamentally, however, the taxonomic bottleneck will only be passed when taxonomists and ecologists begin speaking the same language. This means that taxonomists will need to receive more training in the methods of ecologists, and ecologists will need to learn more taxonomy. Taxonomists, on their own or working with ecologists, can and should use ecological and genetic methods to sort out cryptic sibling species. A recent example of such work is the recognition of cryptic sibling species in mussels of the genus Mytilus, where molecular genetic studies were combined with classic taxonomic approaches to resolve the species complex (see "Significant Opportunities for Forging New Horizons" in Chapter 1).
Likewise, ecologists, working on their own or with taxonomists, can and should describe or revise descriptions of species discovered as a result of their ecological research. Examples of the latter are the joint description by a taxonomist and an ecologist of a new species of isopod crustacean living cryptically on a tropical bryozoa (Buss and Iverson, 1981), and a new species of galatheid crab from hydrothermal vents (Williams and Van Dover, 1983). New methods in taxonomy and systematics, including molecular and cladistic techniques, have made these tasks easier, and have revealed a host of important ecological differences between closely related species.
Do we have to know the name of every species in a given region to address human impacts on biodiversity? It is clearly impractical to locate, identify, and describe every living organism in every community. The level of investigation of biodiversity should be dictated by the basic scientific questions being asked, and the urgency of the perceived environmental threats that demand the development of more informed policies.