Viewing the status of Virginia’s environment through the lens of freshwater fishes

We summarize a range of topics related to the status of Virginia’s freshwater fishes, their reflection of environmental quality, and their contribution to human wellbeing. Since 1994 the list of extant Virginia fishes has lengthened from 210 species to 227 species, mostly due to taxonomic reorganizations. Virginia’s list of Species of Greatest Conservation Need currently contains 96 fish species, predominated by darters (32 species) and minnows (28 species). Increasing trends in species rarity and threats to fishes suggest that Virginia’s aquatic environment is becoming less hospitable for fishes. Prevailing anthropogenic threats to fishes include agriculture, urban development, mineral extraction, forestry, and power generation; emerging threats include introduction of nonnative species and climate change. Agency assessments of Virginia’s streams, rivers, and lakes indicate that over 40% of them are impaired and that dozens of these waterbodies have fishes that, if consumed by people, contain harmful levels of mercury and polychlorinated biphenyls. Multiple state agencies are responsible for managing Virginia’s freshwaters and fishes to achieve objectives related to recreation, conservation, and environmental health. We close with a discussion of the challenges and opportunities associated with conserving Virginia’s diverse fish fauna and identify several research, management, and outreach actions that may enhance conservation effectiveness. INTRODUCTION Freshwater fishes represent a substantial component of Virginia’s rich natural heritage and are tightly interwoven into our economic, environmental, and cultural fabrics. With over 200 native species, Virginia’s fish fauna far exceeds the average diversity among other states in the United States. One reason for this remarkable diversity is that the state is uniquely situated at the distributional crossroads of many southern, northern, eastern and western fish species. The importance of fishes to * Corresponding Author: Paul L. Angermeier Virginia Journal of Science, Vol. 66, No. 3, 2015 http://digitalcommons.odu.edu/vjs/vol66/iss3 148 VIRGINIA JOURNAL OF SCIENCE Virginians goes back centuries to connect with Native Americans and European colonists (McPhee 2002) but still holds true today, albeit in different ways. Whereas most early Virginians were connected to fishes primarily as a major source of food, most Virginians today are not. Instead, our main uses of freshwater fishes are related to recreation (e.g., sportfishing) and environmental monitoring. Of course, fishes are also an important source of natural beauty and knowledge for those who take the time to study them. In this paper, we focus on the insights that fishes offer regarding the condition of our precious water resources. Fishes are excellent environmental monitors because they reflect conditions in the water bodies where they live; those conditions are strongly affected by how people use water and land nearby. Water bodies integrate environmental conditions in their watersheds and, in turn, fishes integrate the conditions of the water in which they live (Karr and Chu 1999). Ultimately, fishes’ abilities to persist in a water body reflect the environmental conditions to which they are exposed. For example, human activities are shifting the spatial and temporal dynamics of the water cycle, accelerating the rates at which sediment and nutrients enter freshwaters, preventing some animals from migrating upstream and downstream, and altering river flooding patterns (Helfman 2007). Common practices that alter freshwater availability through time include building impoundments (especially those that regulate the release of water) and altering land cover. The many ways in which people use land and water affect water quality by altering a wide range of its physical, chemical, and biotic properties. Intensive uses of land and water, such as uses by large industries or many people, commonly diminish water quality. The regional and local status of freshwater fishes can teach us a lot about our performance as environmental stewards. Below, we discuss a range of topics connecting Virginia’s fishes to environmental quality and human wellbeing. We begin with a brief summary of ecological factors limiting fish distributions, then describe key recent changes to the state’s fish fauna and its conservation status. We also devote considerable text to the prevailing anthropogenic threats to fishes and how fishes are used to measure stream health. We close with a summary of Virginia’s regulatory framework germane to fish conservation and some thoughts on needs for fish conservation going forward. FACTORS LIMITING FISH DISTRIBUTIONS Well over 200 species of freshwater fish live among Virginia’s water bodies, including streams, swamps, rivers, ponds, lakes and estuaries (Jenkins and Burkhead 1994; Figure 1). However, the particular species living in a water body vary greatly among locations, depending on a suite of factors that includes zoogeography, prevailing physicochemical conditions, dispersal abilities of fishes, interspecific interactions, and anthropogenic impacts. Many physicochemical factors collectively determine if a given water body is suitable for a given fish species, and each species has distinctive sensitivities to these factors. Further, these limiting factors vary naturally through space and time but can also be dramatically influenced by human uses of air, land, and water. Herein, we follow Jenkins and Burkhead (1994) and Jelks et al. (2008) in defining ‘freshwater’ fishes. This definition encompasses all fishes that commonly spend much of their life in fresh waters, including diadromous species. Fishes are especially sensitive to water chemistry and temperature and most species have narrow ranges of chemistry and temperature under which they can thrive. Virginia Journal of Science, Vol. 66, No. 3, 2015 http://digitalcommons.odu.edu/vjs/vol66/iss3 STATUS OF VIRGINIA FRESHWATER FISHES 149 Chemical parameters such as pH, dissolved oxygen, nutrients, salinity, and a vast array of toxicants (e.g., metals, pesticides, chlorine) commonly limit fish distributions (Matthews 1998, Helfman 2007). Different tolerances to salinity distinguish most freshwater fishes from marine fishes but a few freshwater species, such as American Eel (Anguilla rostrata) and Striped Bass (Morone saxatilis), can adapt to very different ranges of salinity during certain life stages. Similarly, seasonally high or low water temperatures preclude coldwater or warmwater fishes, respectively, from occurring in certain water bodies. In addition to being sensitive to properties of the water itself, fishes are also sensitive to the physical structure of water bodies, such as their size, slope, depth, movement, and bottom composition. Thus, species are differentially adapted to live and thrive in streams versus rivers, rivers versus lakes, rocky streams versus sandy streams, and other structural types of water bodies. Collectively, parameters of temperature, water chemistry, and physical structure are used to describe fish habitats; the availability of suitable habitat is a fundamental factor regulating species’ distributions. The types of habitat available to fishes can vary widely, so in turn the fish assemblages present at a locality also vary considerably among regions of Virginia. Each of the five physiographic provinces represented in Virginia (i.e., Appalachian Plateau, Ridge and Valley, Blue Ridge, Piedmont, and Coastal Plain) exhibit distinctive geology, topography, and land use, all of which promote distinctive arrays of habitat types and distinctive fish assemblages. Similarly, each of the ten major river drainages (i.e., Potomac, Rappahannock, York, James, Chowan, Roanoke, Peedee, New, upper Tennessee, and Big Sandy; see Jenkins and Burkhead 1994) is bounded by barriers to fish dispersal (e.g., ridge tops and ocean), which promote evolution of sibling species and differentiation among assemblages. Accounting for the various combinations of elevation (a surrogate for temperature), stream size, physiography, and river drainage, Virginia supports approximately 90 distinctive types of freshwater fish assemblage (Angermeier and Winston 1999). Understanding natural patterns of habitat availability and fish distribution across Virginia is crucial to using fishes as a lens to interpret environmental quality. Readers interested in learning more about natural and anthropogenic factors that limit freshwater fish distributions, including patterns specific to Virginia, are encouraged to see Jenkins and Burkhead (1994), Matthews (1998), and Helfman (2007) for additional details. CHANGES IN VIRGINIA’S FISH LIST SINCE 1994 Over 20 years ago, Robert Jenkins and Noel Burkhead authored the seminal volume on the systematics, morphology, biology, habitat, and distribution of Virginia’s freshwater fishes (Jenkins and Burkhead 1994). In that volume they provided a thorough summary account for each of the 210 species known to occur in Virginia waters, including chronologies of taxonomic reorganizations, introductions, and extirpations. Many changes in Virginia’s freshwater fish fauna have occurred since Jenkins and Burkhead’s book was published, largely due to introductions, discoveries, and taxonomic reorganization. In short, the list of extant Virginia fishes has lengthened from 210 species and 230 taxa (i.e., species, subspecies, and undescribed forms) to 227 species and 235 taxa (Tables 1 and 2). Two species have been introduced: Northern Snakehead (Channa argus) and Blackside Dace (Chrosomus cumberlandensis). One Virginia Journal of Science, Vol. 66, No. 3, 2015 http://digitalcommons.odu.edu/vjs/vol66/iss3 150 VIRGINIA JOURNAL OF SCIENCE TABLE 1. List of freshwater fish families and species known from Virginia. The order is taxonomic. Scientific names are followed by common names. Numbers in parentheses indicate species counts. “*” indicates a spe