An introduction to directions in freshwater mollusk conservation: molecules to ecosystems

The goal of conservation biology is to protect Earth’s biological diversity. Biodiversity includes genetic diversity (the number and frequency of genes within species), species diversity (i.e., plants, animals, and microorganisms on Earth), and assemblage/ecosystem diversity (McNeely et al. 1990). Thus, biodiversity can be studied from a multitude of disciplinary perspectives, ranging from molecular genetics to evolutionary biology, and from autecology (e.g., life history) through population, community, and ecosystem ecology. Moreover, studies of biodiversity often address biotic and abiotic factors that influence biodiversity at spatial scales that range from microhabitat to global. The more that is known about biodiversity, the more likely it is that scientists and conservationists will be able to protect biodiversity. Thus, scientific knowledge about organisms drives conservation efforts. However, we know far more about some groups of organisms than we do about others. For example, Strayer (2006) reported that the best-studied freshwater invertebrate groups have roughly the same number of described species as do freshwater fishes, but the number of published papers about those freshwater invertebrates is 1/10 the number of published papers about freshwater fishes. Freshwater mollusks belong to one of the more intensively studied invertebrate groups. Freshwater mollusks are among the most imperiled taxonomic groups in the world, and they constitute 708 of the ;7000 species included in the 2002 International Union for the Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species (Lydeard et al. 2004). Furthermore, 42% of the 693 recorded animal species extinctions are mollusks, and 99% of the mollusks that have become extinct were nonmarine taxa. Freshwater bivalves of the superfamily Unionoidea are distributed worldwide, but they are most diverse in North America. Between 850 and 900 freshwater bivalve species are recognized, 200 of these species are on the IUCN Red List, and 189 of the listed species are located in the USA (Lydeard et al. 2004). Thirty-seven of the 297 known North American taxa are presumed extinct, and another 165 are considered possibly extinct, critically imperiled, imperiled, or vulnerable (Master et al. 2000). The scorecard is even more dismal for freshwater gastropods in the USA. Approximately 60 freshwater gastropod species in the USA are presumed extinct, 20 are on the US federal endangered or threatened species list, and another 290 species are of conservation concern (Johnson 2003). In other words, 9% of all freshwater gastropod species in the USA are extinct, and 48% are conservation targets. This rate of imperilment exceeds that of every other major animal group in North America (Perez and Minton 2008). Because of the growing concern about the conservation of freshwater mussels in North America, stakeholders met in 1995 to discuss freshwater mussel declines and to gather information on trends, research needs, and recovery activities, and they drafted a National Strategy for the Conservation of Native Freshwater Mussels. The 2007 Symposium of the Freshwater Mollusk Conservation Society (FMCS; http://ellipse.inhs.uiuc.edu/FMCS/) was held in Little Rock, Arkansas, from 13 to 15 March 2007. The theme of the symposium was Directions in Freshwater Mollusk Conservation: Molecules to Ecosystems. The plenary session of the symposium was structured to provide information to support revision of the 1 E-mail addresses: achristian@astate.edu 2 john.harris@arkansashighways.com