Aquatic Fauna in Peril: The Southeastern Perspective
Edited By George W. Benz And David E. Collins
Although a keynote speaker may have a function in a symposium in setting the tone, raising audience interest level, and other such things, I doubt that the written versions of such presentations have as important a role in the proceedings. I, therefore, intend to be brief, and I have not cited literature sources for a number of examples presented. Much of this information has been obtained through conversations, correspondence, and in other less formal ways.
In this volume, I see my duties as:
Most of us who work in aquatic habitats realize that they are being degraded. In some cases we may have no quantitative data to document our feelings. Nevertheless, we know beyond doubt that things are going wrong. It is this widespread conviction that is the most compelling reason for concern about these places. The fact that those who know aquatic habitats and their constituent species are worried, is strong evidence that degradation is occurring.
Although most experts are convinced that deterioration of aquatic habitats is occurring, few realize how extensive this deterioration is, fewer realize the extent to which aquatic habitats have been destroyed in the past two decades, and fewer still are cognizant of how rapidly the rate of degradation is likely to increase in the future. Most aquatic biologists have never worked in a system that has not been significantly disturbed. Hence, although we may be concerned because of our impressions about habitat degradation, we may not be as concerned as conditions warrant because our experience has never included familiarity with truly pristine habitats. In the fall of 1993, I was fortunate enough to spend a small amount of time in Four Holes Swamp in South Carolina, a relatively large area of aquatic and wetland habitat preserved and cared for by the National Audubon Society. The fact about the site that struck me most was the apparent superabundance of many elements of the aquatic fauna, including aquatic insects, fishes, and brown water snakes, Nerodia taxispilota. I can only attribute this superabundance to the very small amounts of disturbance in the Four Holes Swamp watershed and to the nearly complete lack of anthropogenic disturbance at the sites I visited. I feel that most of my impressions about how abundant aquatic animals "ought to be" have been jaundiced by the fact that almost all of my experiences have been in habitats that were altered, even though I may have thought of some of them as relatively undisturbed. I have had experiences similar to those at Four Holes Swamp at other sites where little unnatural disturbance had occurred.
Even though knowledge of the world’s freshwater fauna has advanced significantly in the past few decades, much of the information that is needed to understand, conserve, and protect it is still absent. In many parts of the world, especially in the tropics and Asia, little reliable information can be obtained except perhaps on some elements of the charismatic megafauna such as porpoises, otters, and crocodilians. For most groups of aquatic invertebrates, the information available amounts to little more than a smattering. In some areas, the fauna is so incompletely known that even characterizing it before it disappears seems hopeless. Thus, the information aggregated here is, at best, an approximation of reality.
It is far beyond the scope of this paper to discuss the status of any significant fraction of the world’s aquatic habitats or fauna. My concept of freshwater habitats in the following discussion is broad, perhaps including sites and habitat types which many would rather refer to as wetlands. Fresh water comprises less than 0.5 percent of the water on Earth. This fact alone makes the habitats we are concerned with very precious.
Throughout much of human history, human population levels have had only localized and ephemeral effects on the world’s biota. Although the Pleistocene overkill, resulting from early man’s development of hafted weapons and from his ability to use fire to drive game, decimated some components of the terrestrial megafauna, the freshwater fauna was little affected as far as we know. Most of the early anthropogenic extinctions of aquatic organisms, such as that of Steller’s sea cow and the great auk, were of marine species rather than freshwater forms. Decimation of the freshwater biota of the planet has, therefore, been a relatively recent phenomenon in human history.
The recent rapid destruction of freshwater habitats and concomitant massive decimation of the fauna is difficult to grasp. Much of the deterioration has been associated with increased human population levels. At the beginning of this century, Earth supported about 1.5 billion people. The bulk of the human population occupied coastal areas, and few drainage systems or aquatic-wetland complexes of continental interiors suffered from perturbation by the presence of large human populations. During this century humans have come to occupy continental interiors in large numbers, partly as a result of population pressure and partly as a result of development and redistribution schemes promulgated by various countries, such as the development of the Brasilia area in Brazil. Penetration of interiors and population growth away from the coast was coincident with the development of technologies which could be used to drastically alter freshwater systems physically (damming, canalization, diversions, etc.), and with the development of a host of artificial chemicals which have potential for interference with the function of aquatic systems in many ways. As a result, lentic habitats away from coasts and the upstream reaches of many drainages are now being degraded. It is likely that this trend will continue and intensify greatly in the near future.
It is not possible to assemble a complete list of causes for the degradation of freshwater systems throughout the world. Nevertheless, a host of general factors are known. In what follows, I merely touch upon factors that serve to exemplify the types of degradation that exist. I have adopted a rather staccato style of presentation in order to mention briefly a wide variety of topics. Most of the factors mentioned are degrading aquatic habitats in many areas, often throughout the world. The subheadings that follow are used for convenience and are meant to be representative, rather than exhaustive.
Aquatic organisms are not normally considered to be prone to damage by ultraviolet radiation. However, many amphibians lay eggs in masses at the water surface and thus may expose an exceptionally vulnerable part of their life history to potential damage. Kerr and McElroy (1993) found a 35 percent increase in ultraviolet radiation in the winter and a seven percent increase in the summer at Toronto, Canada. Because the decrease in the ozone shielding effect occurs first near Earth’s poles, boreal amphibians would be expected to be the first to show the effects of increased UV radiation. Blaustein et al. (1994) found that two anurans, the cascades frog, Rana cascadae, and the boreal toad, Bufo boreas, showed low levels of the egg enzyme (photolyase) that is involved in repair of damage caused by UV radiation. This finding suggested that ultraviolet damage to these eggs could not be effectively corrected. These two northern species have shown precipitous population declines in the last two decades. The extent to which increased levels of ultraviolet radiation are harming or will harm other aquatic species cannot be reliably estimated at this time.
Global warming resulting from increases in the levels of greenhouse gases will affect all life on Earth. World temperatures were up markedly in 1994 (Kerr, 1995; MacCracken, 1995). Although it is difficult to predict the precise nature of the climatic changes, it seems likely that, in aquatic habitats, elements of the fauna that cannot tolerate changes in thermal regimes will be among the first to be affected. Of major concern, but seldom mentioned, is the possible mass invasion of temperate aquatic systems by tropical species. There have been essentially no studies specifically directed toward an understanding of the problems of global warming in aquatic habitats.
Acidification of freshwater ecosystems has been documented for so many areas of the world that it must be considered a global problem (Fleischer et al., 1993). Long distance movement of sulfur oxides and other acidifying air pollutants means that few parts of the planet escape some perturbation from this source, although most of the conspicuous damage has been near the industrialized areas of Europe and North America. In Sweden, up to 1992, about 6,000 lakes had been limed in attempts to reverse the effects of acidification and preserve fish populations. Russia’s Lake Baikal, the oldest, deepest, and faunistically most unique lake in the world is being acidified by pollutants from industry in Irkutsk (Williams and Conroy, 1993). Its 1,800 endemic species have little formal protection of any kind.
Changes in water quality include chemical pollution from a variety of sources and changes in thermal regimes. The examples mentioned below are intended to represent the great variety of problems that are occurring in the world’s freshwater habitats. Although water quality changes are degrading aquatic habitats throughout the world, much of the damage is attributable to western countries where the driving technology was developed, where the perturbing materials are manufactured, and where the distributors are located. "Midnight shipments," via which industries from First World countries illegally dump hazardous wastes in Third World countries are now common.
Molasses seeping from a sugar mill in 1992 caused massive fish kills along a 160 km (about 100 miles) stretch of rivers in northern Thailand. Fish stocks were devastated in three tributaries of the Mekong, the Mool, the Nam Pong, and the Chee rivers. A dam under construction on the Mool will prevent recolonization of the river from downstream areas. The Mekong drainage has 141 species of fishes.
It is important to remember that many chemicals banned in the United States are still used in other parts of the world and that the U.S. exports many banned chemicals to other countries. Fish eagle (Haliaetus vocifer) eggs in Zimbabwe showed a 60 percent increase in DDT and metabolites in nine years from 1980 to 1989 (Douthwaite, 1992).
In many cases we do not know the precise causes of decline in animal populations. According to Sweden’s salmon research institute, the disease M74, apparently caused by a damaging combination of pollutants (perhaps PCBs and related chemicals) could wipe out the Baltic salmon population within a few generations (MacKenzie, 1993). No definite causes have been found for the recent bald eagle deaths in Sauk and Columbia counties, Wisconsin and at DeGray Lake in Arkansas (K. Miller, National Wildlife Health Service, pers. comm.).
Although problems should have been obvious for a quarter of a century (Bitman and Cecil, 1970), concern about risks from exposure to endocrine disrupting chemicals in both animals and humans has only received wide attention recently (Colborn et al., 1993). The potential problems are extensive, including feminization of males (Peterson et al., 1992), masculinization of females (Bortone and Davis, 1994), disruption of reproductive cycles, alteration of sexual behavior, interference with pheromone communications, and others. In the United States, the Environmental Protection Agency has demonstrated that dioxin and related chemicals pose a major threat to both wildlife species and humans. It is becoming clear that many artificial chlorinated compounds have the potential to disrupt the physiology of animals. In the United States, chlorination of sewage alone could wreak drastic havoc in aquatic systems in the near future.
Rapid increases in the rate at which metals are released into the environment accompany economic development and increased use of western technology. Ecological "hot spots," where contamination by trace metals exceeds rural levels by five to ten fold and exceeds the levels in pristine areas by more than 100 fold, are invariably associated with urban sites (Nriagu, 1990). As urbanization sweeps the earth, the likelihood of contamination of aquatic sites will increase greatly. The atmosphere is becoming a major medium through which trace metals are transported to remote aquatic habitats. Atmospheric fallout alone delivers 100,000 metric tons of lead to world aquatic systems per year (Nriagu and Pacyna, 1988).
Controls on pollution invariably fail to keep up with development. As the former Soviet Union frantically tries to revamp its industrial structure, horrifying pollution episodes, common before glasnost, have become more common. Recently, an oil spill in the Komi republic, as revealed by satellite photos, may have released eight times the amount lost during the Exxon Valdez disaster. Russian officials denied this.
Failure to devise methods to control nonpoint-source pollution and the near impossibility of monitoring nonpoint sources necessitate that the flow of pollutants be halted earlier in the chain of events that leads to the degradation of habitats. This means that changes in agricultural and industrial methodologies are needed. Ultimately, we need to change the way in which we view natural habitats and in our understanding of the purpose of nature.
Drainage schemes in Iraq are destroying the vast Mesopotamian marshes. The projects, initiated by the Iraqi government, have resulted in the diversion of virtually the entire Euphrates River into the so-called "Third River." Along with canalization and drainage work on the Tigris River, the projects prevented water from reaching two-thirds of the delta marshes in 1993. A study by the University of Exeter indicated that this is an ecological catastrophe of a scale not seen in recent times. Conditions are worsened by the huge Ataturk Dam upstream on the Euphrates River in Turkey. These factors not only threaten this region’s freshwater and marine systems, they are also destroying the way of life of the Madan people, the so-called "Marsh Arabs." In a deliberate campaign of genocide, Sadaam Hussein has ordered that the marshes be burned. Large fires in the marshes are clearly visible on satellite photos.
The following examples are included to make it clear that in many parts of the world, the era of dams is still in its infancy. Many developing countries see damming as a way out of some of their economic problems. In many cases, diplomatic nudges and technical assistance come from the United States or other western countries.
Japan has completed plans to dam its last wild river, the free-flowing Nagara near Nagoya. The Ministry of Construction claims that the dam is necessary to prevent flooding and that it will have "no serious effect on natural ecology" (see Cross, 1992). Spanish environmental groups are campaigning to prevent the construction of the Vidrieros Dam on the River Carrion in northern Castilla y Leon. Environmental groups in Czeckoslovakia, Austria, and Hungary have asked that an international park be created along the Danube between Vienna and Gyor, Hungary. It is hoped that such a park will prevent the construction of dams planned at Hainburg, Gabcikovo, and Nagymaros. In India, more than 100 opponents to the dams in the Narmada Valley were held in jail without charge, under miserable conditions. A fifteen-year-old tribal youth was killed by police gunfire. In India, as in many other parts of the world, the local citizenry has little say about environmental alterations that may be detrimental. Four protesters were killed by Indonesian security forces when they opened fire on a peaceful demonstration against the Nipah irrigation dam on the island of Madura. The recent execution of eight anti-government rebels in Nigeria was largely a result of their protests about destruction of their land by international oil interests.
Perhaps the most harmful dam project currently going forward is the Three Gorges Dam on the Changjiang (Yangtze) River in China. When finished, it will be the world’s biggest dam, creating a lake nearly 645 km (about 400 miles) long and displacing over 1.5 million people. It threatens many of the unique components of the Changjiang fauna including the baiji or Chinese river dolphin (Lipotes vexillifer) and the Chinese sturgeon (Acipenser sinensis). Two U.S. agencies, the Bureau of Reclamation and the Corps of Engineers, are providing assistance in design and construction of the dam. In a bold critique of Chinese government policy, Dai Qing (Qing, 1994) argued convincingly against the dam from almost every possible angle. She was imprisoned for ten months without trial and her book on the subject was banned in China.
Lest the impression be left that only large dams harm aquatic faunas, Winston et. al. (1991) documented the upstream disappearance of four species of cyprinids after creation of a small dam on the North Fork of the Red River in Oklahoma. This example also emphasizes that dams can cause upstream as well as downstream effects.
Mr. W. Pircher, the president of the International Commission on Large Dams contended recently that free-flowing rivers and associated conditions are not suited for humans and that "engineered infrastructure" must be made the basis for our survival.
The damages wreaked by dams on aquatic systems of the world need not be enumerated in detail here. They are a well-known and well-studied narrative of environmental degradation, including the impending loss of Pacific salmon stocks, the destruction of the Mediterranean sardine fishery, the loss of Grand Canyon habitats, the destruction of coastal barrier islands, the loss of fertile bottomlands throughout the world, and much more.
Many of the problems facing aquatic habitats are caused by changes in terrestrial habitats. Most of these terrestrial alterations cause aquatic perturbations because they alter normal watershed functions, changing sediment and nutrient levels, water chemistry, flow rates, or water temperatures.
Chief among the current reasons for loss of watershed functions are forest practices that bare the soil, remove woody and herbaceous undergrowth, add herbicides to systems, replace native communities with monocultures, and modify land contours.
Per capita paper consumption in the world is growing at an alarming rate. The pulp and paper portion of the wood products industry is not only involved in clearcutting and conversions to tree farm conditions, but pulp mills release a number of extremely harmful chemicals into the rivers along which they are located.
In Papua New Guinea, the major threat to flowing water habitats is the predicted destruction of all accessible rain forests in the next ten years. Tim Neville, forestry minister in the country, has attempted to halt the threat. He has escaped two assassination attempts by person or persons unknown within the last year.
New threats to forest-associated waters include the aquatic habitats in the forests of Siberia, which now face destruction as Russia attempts to increase its timber exports. Japanese, Korean, and U.S. companies are involved in logging huge areas in Siberia. Economic problems associated with the demise of communism will make many countries in Europe and Asia susceptible to new forms of unscrupulous exploitation by western companies.
It is likely that forestry practices combined with other factors have destroyed the majority of small headwater streams in many areas of the world. These tiny streams have been largely ignored by biologists. They are so fragile that a single event that significantly perturbs the drainage can destroy them, essentially forever. In 1958, I witnessed the destruction of approximately 0.5 km (about 0.3 mile) of stream habitat in Lane County, Oregon through the simple act of careless culvert placement under a road associated with a selection logging operation. Most of the aquatic insects, and tailed frogs (Ascaphus truei) had not yet recolonized the site in 1973. Sediment from the road was still present. Corn and Bury (1989) found that logging extirpated amphibian species from a number of sites in western Oregon.
Fuelwood cutting has also sometimes damaged watersheds and the associated aquatic fauna beyond any hope of recovery. In some portions of Africa and Asia, the expanding treeless areas around human settlements can be seen in satellite photos. Reforestation of logged sites with tree species not characteristic of the sites is occurring on all continents. The eventual changes in soil structure, litter fauna, nutrient runoff, and other factors will certainly affect aquatic habitats. Few studies have addressed these problems.
Although many of the problems resulting from the introduction of non-native species into aquatic systems have been highly publicized, comparatively little effort has been made to understand or solve these problems. If governmental agencies in developed countries can be accused of criminal neglect of a major environmental problem, it is in their failure to address problems of exotic species introduction and control. In the United States, no agency has taken a strong lead or shouldered major responsibility for control of exotic species, even though some of the legal framework to do so evidently exists (Stanley et al., 1991).
Many of the introductions of damaging exotics have been associated with the pet trade, with fisheries "improvement," or have occurred accidentally as water containing exotics was transported. However, the recent unauthorized introduction of lake trout (Salvelinus namaycush) into Yellowstone Lake in Yellowstone National Park points out that vandalism can also represent a significant threat. If the lake trout cannot be removed, extinction of the native cutthroat trout (Oncorhynchus clarki) in the lake is almost certain.
The fish fauna of Lake Victoria in east Africa was originally one of the most unique in the world, including an autochthonous species flock of more than 200 species of haplochromine cichlids. Sometime about 1963, the Nile perch, Lates niloticus, a large predaceous cichlid, was introduced into the lake. Currently it comprises 80 percent of all fishes in the lake and has caused the extinction of the majority of the lake’s native endemic fishes. The change in the fish fauna has also detrimentally affected the native peoples around the lake who depended on the haplochromines for food and for sale in east African markets. The small haplochromines could be sun dried, but Nile perch are so large that they must be fire dried. Cutting of woody vegetation around the lake to use in drying fires has resulted in essentially denuding a large area and has totally disrupted proper functioning of the region’s ecosystem. The end product of this process may be the collapse of the local indigenous cultures.
Similar tragedies are occurring throughout the world. The introduction of Cichla ocellata, a highly predaceous fish, to Lake Gatun in Panama has greatly reduced fish diversity in the lake. The associated decimation of populations of small fishes that feed on mosquito larvae has been held responsible for a resurgence of human malaria in the area. The unique cyprinids of Lake Lanao in the Philippines are being wiped out by introduced species including largemouth bass (Micropterus salmoides), walking catfish (Clarias batrachus), and an introduced goby (Glossogobius sp.). In Lake Titicaca in the central Andes, the introductions of rainbow trout (Oncorhynchus mykiss) and the pejerry (Basilichthys bonairiensis) are destroying the native cyprinodonts of the genus Orestias. The Lake Titicaca endemics have also been detrimentally affected by the introduced parasitic ciliophoran, ich, Ichthyophthirius multifiliis (see Wurtsbaugh and Tapia, 1988).
Exotic species do not have to be from different continental faunas in order to be damaging. The introduction of the flathead catfish (Pylodictis olivaris) from its native range in the Gulf drainages of North America to drainages of the Atlantic Slope has decimated the ichthyofauna of some Atlantic drainages.
Ichthyologists and fisheries biologists sometimes downplay the results of fish introductions if the introduced types have not drastically affected local fish faunas. Affects on the amphibians, aquatic insects, crustaceans, mollusks, and other elements of the aquatic fauna are often overlooked. Bradford (1989) found evidence to indicate that fish introductions to high lakes in the Sierras eliminated some native frog species. To contend that some fish introductions have been harmless or beneficial appears to be naive.
In the Philippines, the introduction of the exotic apple snail, Ampullaria canaliculata, has resulted in an ecological nightmare of major proportions (Anderson, 1993). Not only has it nearly driven the native snail, A. luzonica, to extinction, but it also feeds on rice. The snail turned out not to be exportable as food because of health regulations in First World markets. Additionally, molluscides used in control attempts had serious affects on human health, including blindness and death, and undoubtedly decimated the native aquatic biota further. The subsequent introduction of large flocks of ducks in attempts to control the snail will probably have further detrimental ramifications.
In the Rhine River in Europe, the introduced amphipod Corophium curvispinum, a tube building species, now exists in concentrations as great as 100,000 per m2 (109,361 per square yard). Native substrate dwellers and filter feeders are threatened by its presence. Oddly, the amphipod has also decimated populations of the introduced zebra mussel in the Rhine, causing wildlife biologists to become concerned about some waterfowl species that had come to depend on the zebra mussel for food (Van Den Brink et al., 1991).
The North American Great Lakes now contain a fauna that includes at least 4,500 non-indigenous species (Mills et al., 1994). The rate of damaging introductions to the area has seemingly not slowed, zebra mussels (Dreissena polymorpha), quagga mussels (Dreissena bugensis), spiny water fleas (Bythotrephes cederstroemii), Eurasian ruffes (Gymnocephalus cernuus), and gobies of the genera Neogobius and Proterorhinus having become established in the 1980s.
Although our perspective commonly causes us to think that damaging introductions are introductions from elsewhere that wreak havoc on the North American fauna, North American species are causing problems in many other parts of the world. The red-eared slider, Trachemys scripta elegans, seems to be outcompeting the European pond turtle, Emys orbicularis in parts of France. A North American turbellarian, Phagocata woodworthi, is decimating the triclad fauna of Loch Ness in Scotland. It is thought to have been introduced as cysts on the air tanks of divers looking for the Loch Ness Monster.
Introduced aquatic plants can often be as harmful to freshwater systems as introduced animals. Unintentional introduction of plants is difficult to control and monitor because seeds and other propagules are often hard to detect and can survive for long periods during transport. Water hyacinth (Eichornia crassipes), the most troublesome of the world’s aquatic weeds, now causes problems in 60 countries. Recently it spread into Lake Victoria in Africa. Its presence bodes ill for the lake’s already taxed endemic fish population.
In the southeastern United States, Eurasian water milfoil (Myriophyllum spicatum) has rapidly invaded both reservoirs and natural waters in the past two decades. It displaces native plants, reduces the food available to waterfowl, impedes navigation, and alters substrates available for aquatic invertebrates. There is some indication that white amur (Ctenopharyngodon idella), a fish introduced to control the plant, preferentially feed on native aquatic plant species, thus aggravating the problem.
Rather than create a number of additional categories, I use this catchall heading to mention a spectrum of problems not mentioned above. These are presented merely to apprise the reader of the great diversity of troubles that exist.
Perhaps not really an additional problem but rather a problem resulting from the synergy of many degrading factors is decline of populations as a result of hormonal stress. Although the study of this phenomenon is still in its infancy, Larson and Fivizzani (1994) have documented, in Ambystoma tigrinum larvae, elevated corticosterone levels that were positively associated with the amount of agricultural land in the vicinity of the pond used by the larvae. The assumption is that alterations associated with agriculture stress species more than do conditions present in less altered habitats.
Recreational rafting along the Maligne River in Jasper National Park in Canada has caused damage to the population of harlequin ducks (Histrionicus histrionicus) on the river. In the five-year period 1986 to 1991, raft trips increased from six to 1,700 per year.
In early 1992, Croatian fisherman crossed the border into Hungary and shot 2,000 cormorants, Phalacrocorax carbo, in a nature reserve on the Drava River near the Croatian town of Donji Mihojlac. This was two-thirds of the cormorant population in the reserve.
A study by the U.S. Fish and Wildlife Service indicated that lead weights from fishing tackle may be responsible for 30 percent of all loon deaths. In the survey, 60 percent of the loons autopsied had lead weights in their digestive systems (Pokras, 1993).
The giant grebe (Podilymbus gigas) of Lake Atitlan in the Guatemala highlands is threatened by guerrilla warfare, by condominium development, and by reed cutting by natives who use the reeds in a cottage industry making chair seats and mats. Increased native populations spell more damage to reed beds in which the grebe nests.
Fishing by use of explosives is common in many tropical aquatic systems although illegal in most developed countries. In some areas the aquatic fauna has been locally pauperized. The Irrawady River dolphin, Orcaella brevirostris, has been significantly harmed by this practice.
What should our viewpoint be on the introduction of genetically altered animals and plants into freshwater habitats? Genetically altered salmon with abnormally high growth rates have been produced for use in commercial fish farms (Devlin et al., 1994). Although the assurance has been given that transgenic salmon will be sterilized to make sure that they do not breed with wild salmon, it would seem to require omnipotence to control the spread of all genetically altered types. Tiedje et al. (1989) presented some viewpoints on genetically altered types and noted possible problems.
Conservation efforts in most parts of the world have been largely focused on terrestrial habitats (Ryman et al., 1994). This seemingly has resulted simply from the fact that man is a terrestrial species. As a consequence, not only have aquatic sites sometimes received less protection, but they have also received less attention by biologists. In addition, it is often more difficult to protect aquatic habitats because entire watersheds must usually be protected in order to safeguard aquatic species.
Many Third World countries see exploitation of their natural resources as a panacea for their real or perceived economic or environmental problems. In 1992, President Nujoma of Namibia declared that protected animals in Etosha National Park must be utilized to provide food for the populace during the drought.
In many areas of the world, decline in conditions of freshwater habitats has created additional unforeseen problems whose solutions are problematical. For instance, muskrat predation has been implicated in the further decline of endangered freshwater mussel populations on the North Fork of the Holston River in southwestern Virginia (Neves and Coom, 1989). Should the muskrat, a native animal, be controlled, as has been suggested? Do we set a dangerous precedent by controlling one native animal to promote the welfare of another? Perhaps muskrats are anthropogenically overabundant, like white-tailed deer (Odocoileus virginianus) and raccoons (Procyon lotor) are in many areas of the region? Should we introduce predators to control the muskrats? Is concentrating on proximate causes reducing the attention given to and efforts made to address the ultimate reasons for the decline of populations of aquatic species? Answers may exist to these questions, but I am not aware of any carefully reasoned ones.
Polhemus (1993) noted that populations of the threatened aquatic bug, the Ash Meadows naucorid (Ambrysus amargosus), were harmed as a result of modifications of the habitat designed to provide a refugium for the endangered Devils Hole pupfish (Cyprinodon diabolis). Plans to "fatally remove" sea lions (Eumetopias jubatus) which are preying on wild steelhead trout (Oncorhynchus mykiss) at Ballard Locks on the Cedar River in Washington have caused an uproar in the Pacific Northwest. Conflicts related to possibly benefiting one declining species at the expense of another will become more common as conditions in aquatic systems continue to deteriorate.
Small gains have often been made. I will mention only a few examples. Kenya’s president has decreed that the Tana River Delta is to become a protected area. This Ramsar site was proposed for development. Beavers (Castor fiber) have been successfully reintroduced into the Vistula River Basin in Poland. A recent census revealed 130 lodges. An endangered anabantid fish, Sandelia bainsii, is now protected in a reserve on the Blaauwkrantz River in South Africa. It occurs in only four river systems and is threatened by water withdrawal, pollution, sedimentation, and the presence of the introduced aquatic fern, Azolla filliculoides. Duck numbers in the prairie pothole region of North America were up in 1994, largely as a result of programs now considered for cancellation or major emendation. River otters once again inhabit Great Smoky Mountains National Park after an absence of 50 years.
However, with rose tinted glasses laid aside, the future of the planet’s freshwater systems seems rather bleak. It is clear that human population growth alone, even without commensurate increases in technology or affluence, will significantly degrade freshwater systems within the next few decades. By 2050, there will be 10 billion people on Earth. It is unlikely that per capita effects on freshwater habitats at that time will be less than they are presently. To put this in a clearer perspective, if the size of the human population is related to the rate of destruction and degradation of aquatic habitats, there will be three times the damage in the year 2025 as in the year 1965. The results of such an increase are obvious.
The southeastern portion of North America once harbored one of the most diverse temperate aquatic faunas in the world, with species richness in many groups being exceeded only by some areas in southeastern Asia. As examples only, there are about 200 fish species endemic to the Southeast, approximately 250 species of freshwater mussels native to the area, and more than 30 of the world’s 257 turtle species. This rich fauna is still poorly known, especially for invertebrate groups. It is certain that some species disappeared before their discovery.
In 1970, the human population of the southeastern United States (i.e., Alabama, Arkansas, Georgia, Florida, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee) was approximately 35 million. In the year 2000 it will be 62 million, having nearly doubled in thirty years. Per capita pressures on natural systems are unlikely to decrease significantly in the next few decades. If by some near miracle, per capita effects were cut in half by the year 2030, resultant benefits to aquatic systems would be negated by population growth.
In many ways, the southeastern United States has been treated as a Third World country by the rest of the nation, or, perhaps more accurately, by industrial interests throughout the world. Industrial sitings in the region have often been based on the same criteria used to site plants in Latin American countries, i.e., lower salaries can be paid, tax rates on industries are lower, and perhaps most importantly, pollution laws and other measures to preserve environmental integrity are poorly enforced and easily circumvented by using political pressure.
One of the greatest known extinction episodes in the first half of the twentieth century took place in the Southeast — the virtual disappearance of the Coosa River molluscan fauna. Dams on the Coosa River destroyed the shoals on which the snails and mussels depended. Although accurate information will never be available, perhaps 40 snail species and a number of mussel species disappeared (Stansbery, 1976; Stein, 1976; Bogan and Pierson, 1993; Hartfield, 1993). Today, most of the remnants of this once diverse fauna teeter on the brink of extinction.
Proof of the Third World status of the Southeast lies in the fact that the damming era is not yet over in the area, as it essentially is in the rest of the nation. Plans to dam many of the remaining free-flowing rivers or reaches are in various stages of development even though not highly publicized.
Although alarm about the rate of destruction of tropical forests is certainly justified, the rate of forest destruction in the southeastern United States exceeds that of any tropical area of comparable size. Since the late 1960s, the practices of clearcutting and pine monoculture have altered fully one-third of all of the forested areas on the Coastal Plain of the Southeast and have affected virtually every aquatic habitat in the area. We tend to think that the rate of damage must be decreasing, but, as an example, in the period 1980 to 1990 the rate of logging doubled in the areas surrounding Great Smoky Mountain National Park.
Herbicides used to kill hardwoods and control the growth of herbaceous plants will cause further harm to associated watersheds. Not only do these chemicals destroy plants which help to retain nutrients on site, but some have been shown to be toxic to algae (Austin et al., 1991) and thus are bound to interfere with processes in aquatic habitats. There have been no thorough tests of how herbicides applied to forests will affect aquatic systems.
Although surface waters of the Southeast have been thought of as being less susceptible to acidification than those in more northerly areas, atmospheric deposition of sulfur oxides has been cited as at least a partial cause of stream acidification in the Great Smoky Mountains (Cook et al., 1994). Acid mine runoff has already destroyed stream biotas in many areas.
The rate of introduction of damaging exotics is increasing in the Southeast. The fish fauna of southern Florida has been permanently altered by tropical types. The zebra mussel has entered the Tennessee River drainage. Little effort is being made to keep it from invading the unique Gulf and Atlantic drainages. Biofouling, competition with native mussels, and alteration of substrate associated with its encroachment will change southeastern aquatic habitats in unpredictable ways.
River beds in the southeastern United States are lined with an array of toxic chemicals deposited over the last half century. Even if we stop all pollution immediately, these chemicals will cause effects for at least the next century. The stretch of the Mississippi River between Baton Rouge and New Orleans is often given the appellation "cancer alley." Not only do the banks support a large number of industries that release dangerous materials into the water, but the lower Mississippi lies downstream from sites as far away and as widely separated as New Mexico, Alberta, Minnesota, New York, and North Carolina. Thus, the Southeast receives contaminants from most of the continent.
Preservation of wild and scenic segments of flowing water habitats and setting aside tracts containing important lentic sites is necessary and laudable. However, it is clear that isolated preserves are not a long-term answer to the maintenance of aquatic biodiversity. Habitat fragmentation has already affected numerous freshwater species in the region (e.g., the flattened musk turtle; see Dodd, 1990).
There are biologists who profess to believe that a dispassionate and detached view of nature is necessary to perform unbiased scientific work. They are wrong. In most cases those who attempt such a view dehumanize their relationship with what they study to the extent that their talents cannot be effectively used or focused. Second, they often function as parasites on those in the scientific community who are willing to spend portions of their careers attempting to conserve, preserve, and protect the natural systems so vital to their work and absolutely vital to the future well-being of our species. Third, those who claim that resource custodianship is outside the realm of their proper endeavors sometimes fear that their funding, derived from sources committed to environmental destruction, may be lost. All in all there is little justification, ethically, practically, or scientifically for scientists to ignore the fate of the life forms that they study.
Those who are most aware of the declining health of natural systems must be the ones to sound the alarm. They must be willing to take a stand. Some biologists are reluctant to vigorously defend sound practices in the treatment of the earth because they feel that their jobs, funding, and perhaps even their lives may be threatened, as indeed they may. Even so, if those who understand freshwater systems best, and are most aware of their inestimable value to mankind are not to be advocates, then there will be little effective advocacy.
Biologists, as a group, have been rather sluggish and timid in active protection of freshwater resources. Somehow there has been the feeling that compromise, half-hearted defense, and carefully not treading on the toes of the agents of destruction were appropriate postures. Evidence for the continuation of this trend is present in recent works on aquatic systems, some of which have apologist overtones. Many papers considering degradation of habitats include tacit support for the folklore inherent in currently fashionable themes such as "sustainable growth," "managed development," and "economic realities." Such positions, if continued, will soon result in the loss of all of our natural systems and their diverse faunas. Supposed economic realities are created by those in power to insure their continued power and economic gain. Considering these artifices to be reality is not compatible with the health of the planet’s life support systems.
Perhaps the most obvious failure on our part is our failure to educate the public about the significance of nature to our future well-being. Although some surveys show that a majority of the American public supports environmental concerns, few understand natural systems well enough to know when to be concerned. In most cases, the majority of the educated public still believes that jobs are more important than protection of natural systems. When the representative governing body of a nation can consider weakening, destroying, and making a sham of major pieces of legislation designed to make the world a more livable place for all life, it is clear that the educational process has malfunctioned badly.
Zero future alteration and rapid return of natural systems to functioning states is the only realistic goal. When this is mentioned, many carp by contending that man must alter the earth in order to live. This is undoubtedly true. The question is, does the alteration inevitably have to be destructive? Rather than continue to work toward goals which will only slow the degradation for short periods, let us admit that the only way to maintain the earth in a state that will continue to support both a diverse biota and a human population is to quickly reverse many of the trends of the past half century.
What should some of our goals be in the southeastern United States? Perhaps we could set as one goal, the removal of all dams from rivers and large streams by the year 2050. Considerable planning would be necessary. Reservoir waters would have to be released gradually over a period of years. Sediment in reservoirs would have to be removed and partially returned to the land. Downstream developments and cities in floodplains would have to be flood-proofed or moved. A new "science" would have to emerge, combining biology, hydrology, geology, engineering, agriculture, sociology, and many other disciplines. This proposal clearly presents many difficulties. Perhaps, 2050 is unrealistically soon, but putting off goals may make their achievement impossible. If we let these challenges thwart our efforts to repair potentially mortal wounds to natural systems, then we have accepted the demise of nature as inevitable. Coupled with energy conservation, development of solar energy, and use of more efficient means of materials transport than barging, removal of dams should be good for human and non-human biota.
Protection of watersheds and ensuring the quality, quantity, and periodicity of the runoff is absolutely vital. Current common forest practices such as large tract clearcutting, monoculture, and the use of heavy machinery on forest lands are incompatible with both natural systems and the welfare of the citizenry. They must be abandoned immediately.
We came to the symposium in Chattanooga to consider the fate of our region’s freshwater fauna. If all we do is consider, then the gathering will have been meaningless. We must be strong advocates of proper treatment of the world. We must be much less willing to compromise with the forces of ruin. If we do not take the lead and take it immediately, it is absolutely certain that the freshwater biota will be pauperized to a functionless level within the lifetimes of many of us. In some cultures, water and the life associated with it are sacred. In western culture, aquatic habitats have been viewed as enemies, to be controlled, defeated, and destroyed. If we cannot successfully change this viewpoint, we will have little left to study or enjoy.
The author gratefully acknowledges assistance and advice received from George Benz, Dave Collins, Dave Etnier, Debbie Rymal Folkerts, Bud Freeman, Paul Hartfield, and Bill Redmond. Partial support for the generation of this paper was supplied by the Alabama Agricultural Experiment Station.
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