This review examines the status of temperate-zone freshwater wetlands and makes projections of how changes over the 2025 time horizon might affect their biodiversity. The six geographic regions addressed are temperate areas of North America, South America, northern Europe, northern Mediterranean, temperate Russia, Mongolia, north-east China, Korea and Japan, and southern Australia and New Zealand. Information from the recent technical literature, general accounts in books, and some first-hand experience provided the basis for describing major wetland types, their status and major threats. Loss of biodiversity is a consequence both of a reduction in area and deterioration in condition. The information base for either change is highly variable geographically. Many countries lack accurate inventories, and for those with inventories, classifications differ, thus making comparisons difficult. Factors responsible for losses and degradation include diversions and damming of river flows, disconnecting floodplain wetlands from flood flows, eutrophication, contamination, grazing, harvests of plants and animals, global warming, invasions of exotics, and the practices of filling, dyking and draining. In humid regions, drainage of depressions and flats has eliminated large areas of wetlands. In arid regions, irrigated agriculture directly competes with wetlands for water. Eutrophication is widespread, which, together with effects of invasive species, reduces biotic complexity. In northern Europe and the northern Mediterranean, losses have been ongoing for hundreds of years, while losses in North America accelerated during the 1950s through to the 1970s. In contrast, areas such as China appear to be on the cusp of expanding drainage projects and building impoundments that will eliminate and degrade freshwater wetlands. Generalizations and trends gleaned from this paper should be considered only as a starting point for developing world-scale data sets. One trend is that the more industrialized countries are likely to conserve their already impacted, remaining wetlands, while nations with less industrialization are now experiencing accelerated losses, and may continue to do so for the next several decades. Another observation is that countries with both protection and restoration programmes do not necessarily enjoy a net increase in area and improvement in condition. Consequently, both reductions in the rates of wetland loss and increases in the rates of restoration are needed in tandem to achieve overall improvements in wetland area and condition.

The most recent meeting discussing the Kyoto Protocol focused on market-based mechanisms to reduce greenhouse gases. This could pave the way for initiatives that allow polluters to offset their emissions if they buy carbon sequestered through reforestation (Sandalow & Bowles 2001). But rather than lose credit when the trees are harvested, investors must continue to track the sequestered carbon once trees become timber. I examined trade statistics for the best-tracked timber species, namely mahogany, Swietenia macrophylla King (Meliaceae). Although mahogany is regulated by one of the most restrictive trade agreements, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), I found discrepancies in USA trade statistics of c. 30%, representing c. US$ 100 million over the last 4 years. For comparison, I also calculated differences in trade data for all sawnwood, according to the United Nations Food and Agricultural Organization (FAO); discrepancies between USA and exporter reports were c. 38%. Large accounting problems must be solved before sequestered carbon should become a globally traded commodity.

One of the founders of modern ecology, environmental science, ecological engineering and economics, H.T. Odum, passed away on 11 September 2002 in Gainesville, Florida, from cancer at the age of 78. He died less than a month after the death of his older brother and long-time collaborator, Eugene P. Odum. The two brothers published the classic ecological textbook of the early 1950s (Odum 1953; H.T. Odum's role was not credited until an acknowledgement page in the 3rd edition, published in 1971), one of the first modern holistic views of ecology, ecosystems and human impacts. Among numerous other prizes and awards, they jointly won the Crafoord Prize in 1987, equivalent to a Nobel Prize in ecology, and the Prize of the Institut de la Vie in Paris in 1976. Howard Odum produced 15 books, nearly 300 articles and was chairman for nearly 100 doctoral dissertations of which 75 were during his tenure at the University of Florida from 1970. His students are leaders in many fields of environmental science. His ashes were scattered in the Howard T. Odum Memorial Cypress Swamp, a cypress dome near the University of Florida campus that he donated to the University for research purposes.

The level of recognition of human impacts on climate, contained in the third assessment of the Intergovernmental Panel on Climate Change (IPCC 2001), surely represents a turning point in human history. Some impacts can now be factored into predictions of future states of the world's ecosystems, and, though some powerful countries may for the moment indicate otherwise, it is certainly more difficult now to ignore the concept of global human impacts on the environment and doubt their seriousness. But there are potential pit-falls in this progression; it worries me that attention to incremental albeit significant rises in sea level, for example, may divert serious concern away from the consequences of the ongoing intensive and extensive growth of human population, the sizeable global impact of which on the environment and human society can scarcely either be debated. Environmental science is challenging; it aspires to holism, but the resources and scientific tools are such that it can only very rarely be holistic at anything other than very small scale. And different disciplines can be disappointingly inarticulate in truly interdisciplinary work. Environmental science tilts at comprehensive global understanding, but the problems of extrapolating to that scale are for the most part insuperable. The scientists, typically reticent about erring beyond the disciplinary or geographical boundaries of their work, yet those most trained to deliver objective information, risk becoming an undervalued resource. The danger is that awkward strategic decisions will be made with much less certainty or at least consensus than they should.

A number of recent publications have pointed out the accelerating speed at which ecosystems and biodiversity are being lost (United Nations Development Programme/United Nations Environment Programme/The World Bank/The World Resources Institute 2000). The general view is that conservation can only be achieved in a global network of protected areas (see Pimm et al. 2001). To safeguard the most important ecosystems, Myers et al. (2000) have suggested that we primarily conserve 25 biodiversity hotspots, in particular forests, comprising 1.4% of the land surface of the Earth. The costs for the conservation of these hotspots have been estimated at US$ 500 million per year (Myers et al. 2000), while the costs of a global network of protected areas may even reach US$ 27.5 billion per year (James et al. 1999). Even though these costs may seem minor compared to, for example, the costs of global armament, governments in developing countries and environmental organizations are clearly not in the position to finance conservation. It is thus urgent to raise additional funds to safeguard biodiversity. In the following, I suggest a twofold strategy, based on tourism.

The temperate peatlands are extensive, covering around 3.5 million km2 of land. They contain about 455 Gt of carbon, almost equivalent to the carbon stored in all of the living things on the surface of the planet, and representing around 25% of all the soil carbon on earth. These bogs are a sink for atmospheric carbon and their carbon uptake accounts for about 12% of current human emissions. They vary considerably in their form and structure and are an important resource for scientific research, including the study of past environments and climate change, and they are also valuable in environmental education. They are low in biodiversity, but their fauna and flora are distinctive and many groups are confined to this habitat. For all these reasons, the future conservation of peatlands is a matter for concern. Threats to peatlands come from direct human exploitation in the form of peat harvesting for energy and horticulture, and drainage for forestry. Rising environmental awareness should control both of these processes in the western world, but continued northern peatland losses are likely locally, especially in Asia. Peatland drainage for forestry or agriculture will result in losses of carbon to the atmosphere, adding to the greenhouse effect. Human population pressures, industrialization and urbanization are unlikely to have an important direct and immediate influence in the boreal zone. Fragmentation of the habitat is not an important consideration because bogs are by their very nature ‘island’ habitats. Acidification by aerial pollution may be a local problem close to sources, but the habitat is naturally acid and should not be severely affected. The input of aerial nutrients, however, particularly nitrogen, could have widespread impact on bogs, enhancing their productivity and altering their vegetation composition. The physical rehabilitation of bogs damaged by human activities presents many problems, particularly relating to the re-establishment of peat structure and vegetation, but the process can result in the re-formation of a carbon sink so it is worth the effort. Climate change is the most important consideration in its impact on bogs. Higher temperature (especially if accompanied by raised atmospheric carbon dioxide levels and increased nitrate deposition) will enhance productivity, but will also result in faster decomposition rates. The outcome of these opposing factors for peat formation will ultimately depend on the future pattern of precipitation. If, as seems most likely, summer conditions become warmer and drier in continental regions and winters become milder and wetter, the summer drought could cause peat loss and bog contraction. An excess of decomposition will lead to bogs becoming a carbon source and thus a positive feedback in global warming. Emissions of methane and nitrous oxide would add to the greenhouse gas problem, but likely oxidation of methane and low N2O production may well mean that this impact will not prove to be significant. Tree invasion of bogs as a consequence of summer drought could locally lead to increased water loss through transpiration, and higher heat absorption through albedo change. This will enhance the drying effect on the bog surface. Oceanic mires will be less severely affected if the expected increase in precipitation takes place in these regions. The most important overall factor in determining the future of the northern bogs is likely to be the quantity and pattern (both spatially and temporally) of future precipitation in the zone.

Introduction

In most countries, protected area managers are primarily interested in biology (McNeely & Miller 1984; Nelson & Serafin 1997). This perspective is not suitable for effective nature conservation because there is no real separation between geological and biological processes. Geology is important in all kinds of planning projects because geology is part of all natural systems. Understanding of climate, landforms and biodiversity depends on geological studies. Even human habitation and cultural heritage depend on geology. During the last 30 years, numerous studies have shown that biological conservation is essential to the welfare of all human beings. Nevertheless, the concept of geoconservation and preservation of the geological heritage has appeared only recently (Wilson 1994; Sharples 1998; Barettino et al. 1999, 2000; Osborne 2000).

I argue that real nature conservation can only be attained if geology is integrated into protected area management at the same level of importance as biology and all natural processes are considered together.

Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.

Tropical wetlands assume important functions in the landscape and contribute considerably to the welfare of large parts of the human population, but they are seriously threatened because they are considered free resources of land and water. This review summarizes long-term environmental trends for tropical wetlands and predicts their future to the time horizon 2025. Many tropical countries do not have the economic strength, scientific and technological capacity, and/or administrative infrastructure to adequately react to the challenges of increasing population pressure and globalization of the economy with respect to the sustainable use of the resources. Furthermore, political instability and armed conflicts affect large areas in several tropical countries, hindering wetland research and management. Detailed wetland inventories are missing in most countries, as are plans for a sustainable management of wetlands in the context of a long-term integrated watershed management. Despite large regional variability, a continental ranking shows, in decreasing order of wetland integrity, South America, Africa, Australia and Asia, while efforts to mitigate human impacts on wetlands are largest and most advanced in Australia. Analysis of demographic, political, economic and ecological trends indicates fairly stable conditions for wetlands in tropical Australia, slight deterioration of the large wetland areas in tropical South America excepting the Magdalena and Cauca River flood plains where human population is larger, rapidly increasing pressure and destruction on many African and Central American wetlands and serious threats for the remaining wetlands in tropical Asia, by the year of 2025. Policy deficiencies, deficient planning concepts, limited information and awareness and institutional weakness are the main administrative reasons for wetland degradation and must be overcome to improve wetland management and protection in future. Intensification of international cooperation and assistance is considered of fundamental importance for most tropical countries to solve problems related to wetland research, protection and sustainable management.

Many species of plants and animals are used in traditional Chinese medicine (TCM) to treat impotence (typically erectile dysfunction [ED]; Bensky & Gamble 1993). Some of these taxa are overharvested for their medicinal uses and are now threatened. Efforts to conserve many of these taxa have failed because the market forces driving their commercial collection or poaching remain in place. Shortly after Viagra appeared on the market in 1998, we suggested that Viagra has the potential to eliminate demand for animal sexual potency products (von Hippel & von Hippel 1998). We suggested that the East Asian market in animal potency products could soon fall victim to Viagra's success because Viagra is less expensive than many of these animal products (Viagra costs US$ 8–10 per pill in the countries in which it is legalized) and Viagra's effectiveness is demonstrated (Giuliano et al. 1997; Morales et al. 1998; Sadovsky et al. 2001) rather than hoped for.

Salt lakes are geographically widespread, numerous and a significant part of the world's inland aquatic ecosystems. They are important natural assets with considerable aesthetic, cultural, economic, recreational, scientific, conservation and ecological values. Some features, notably the composition of the biota, uniquely distinguish them from other aquatic ecosystems. The paper reviews the nature of environmental impacts and their effects upon salt lakes. Its aims are two-fold: to draw attention to the extensive damage that salt lakes have now undergone, and to indicate the likely status of salt lakes in 2025. Salt lakes develop as the termini of inland drainage basins where hydrological inputs and outputs are balanced. These conditions occur in arid and semi-arid regions (approximately one-third of total world land area). Many human activities threaten or have already impacted salt lakes, especially surface inflow diversions, salinization and other catchment activities, mining, pollution, biological disturbances (e.g. introduction of exotic species), and anthropogenically-induced climatic and atmospheric changes. The effects of such activities are always adverse and include changes to the natural character of salt lakes, loss of biodiversity and fundamental limnological changes. The effects are geographically widespread, mostly irreversible, and degrade the values of salt lakes. Four salt lakes are discussed, namely the Aral Sea in central Asia, Mono Lake in California, USA, and Lake Eyre and Lake Cantara South, in Australia. By 2025, most natural salt lakes will have undergone some adverse change. Many permanent ones will have decreased in size and increased in salinity, and many unnatural saline water-bodies will have appeared. In certain regions, many seasonally-filled salt lakes are likely to be drier for longer periods. The extent to which episodically-filled salt lakes will change by 2025 will largely depend upon the nature of climate change in arid regions. Objective cost/benefit analyses of adversely affecting salt lakes are rare, and international bodies have not properly recognized salt lakes as important inland aquatic ecosystems. To redress this situation, there is a need to raise awareness of: (1) the values of salt lakes, (2) the nature of threats and impacts from human activities, and (3) their special management requirements. More effective management and conservation measures need to be implemented. Mono Lake provides an example of what can be achieved in the conservation of salt lakes. Its conservation was largely brought about by (1) the commitment of a non-governmental organization which recognized its non-economic values, (2) the freedom to express views, (3) a legal system which took account of non-economic values, and (4) a legislature which implemented judicial findings. The conservation of Mono Lake was difficult; the conservation of other salt lakes is likely to be even more difficult. Only international pressure from appropriate organizations will be effective for the conservation of many.

The large freshwater lakes of the world are an extremely valuable resource, not only because 68% of the global liquid surface fresh water is contained in them, but because of their importance to the economies, social structure, and viability of the riparian countries. This review provides decision makers with the knowledge of large lakes (≥ 500 km2) essential to establishing policies and implementing strategies compatible with sustainable development. This is achieved by considering the present state of the lakes, the extent of changes and factors causing them, long-term consequences of these changes, major threats and possible states of the lakes into the year 2025. Case studies of lakes are presented, namely the St Lawrence Great Lakes of North America as representatives of glacial scour lakes of North America, northern Europe and Asia, and the African Great Lakes as representatives of tropical tectonic lakes. Lake Baikal is also included because it is unique for its species, great age, and largest single volume of liquid surface fresh water. The Aral Sea is further included because of the ecological disaster following diversion of water away from its basin. The major impacts on large lakes are diversions, eutrophication, invasive species, land-use change, overexploitation of resources, and pollution. These impacts can or do affect all the representative lakes, but to varying degree. The St Lawrence Great Lakes have been severely impacted by eutrophication, land-use change, overfishing, invasive species and pollution. Eutrophication has been reversed for these lakes and constraints are now in place on land use change, such as shoreline alteration and destruction of wetlands. With the demise of most commercial fishing, overfishing is no longer as important. Invasive species have become a major problem as increasingly non-indigenous species gain access to the lakes. Pollution continues as a major impact. These problems are likely to continue and seriously impact use of the resources as well as bring about changes in the biota. Among the African Great Lakes, invasive species are a major problem in Lake Victoria, and eutrophication associated with land-use change and overexploitation of resources is a growing problem. Many endemic species have been lost and many are threatened, so that species associations will have changed by 2025. The Aral Sea continues to disappear and in the future, the remaining largest part of it will continue to become increasingly saline and eventually disappear. A small body of water will remain as a freshwater lake with a productive, although small, fishery. Lake Baikal shows evidence of pollution in the southern basin and is likely to be impacted by land-use changes, primarily logging. Some non-indigenous species are present, but so far, they are not a major problem. Overexploitation of resources in the watershed could lead to adverse impacts on inshore waters. Overfishing has been recognized and appears under control. The major threat to Baikal is continued and growing pollution. Climate change and pollution are global problems that will affect all lakes, large and small. At present, while some warming has occurred, climate change appears not to have impacted large lakes. Present studies on the Laurentian Great Lakes predict possible major impacts. Pollution, especially from persistent toxic substances such as PCBs, is a global problem. Diversion of water out or away from large lakes will become more of a threat as global human population growth continues and water supplies from rivers and ground water become depleted.

Rocky shores occur at the interface of the land and sea. Typically they are open ecosystems, with steep environmental gradients. Their accessibility to man has rendered them susceptible to a variety of impacts since prehistoric times. Access can be regulated, however, and they are more amenable to management than open ocean habitats. This review uses examples from throughout the world to demonstrate the extent to which rocky shores have been, and are currently, affected by pollution (examples used are endocrine disrupters, oil, eutrophication), over-collection of living resources, introduced alien species, modification of coastal processes (coastal defences, siltation) and global change (climate, sea level). These impacts are put into the context of natural fluctuations in time and variability in space of both the environment and the organisms. The relative magnitudes of some anthropogenic disturbances differ between the industrialized, developed world and the developing world. For example, in developed, industrialized countries pollution based impacts should diminish over the next 25 years due to improved regulation and a reduction in older ‘dirtier’ heavy industry. Conversely, in many developing countries pollution will increase as a consequence of growth in the human population and industrialization. Except for large-scale disasters such as oil spills, pollution tends mainly to influence embayed coastlines. Chronic effects such as eutrophication can have broader-scale impacts over whole coastlines and elevated nutrient levels have also been implicated in a trend of increasing frequency of catastrophic kills due to harmful algal. Direct removal of living resources has had major effects on coastlines at both local and regional scales and is likely to increase over the next 25 years, especially in developing countries where rapidly expanding human populations will put further pressure on resources. Impacts from recreational activities are likely to increase with greater leisure time in wealthier regions of the world, and cheaper travel will spread these impacts to poorer regions. Invasions by alien species have increased in frequency during the last 20 years leading to some dramatic effects on native assemblages. Problems associated with alien species, especially pathogens, will continue to increase over the next few decades. The proportion of the coastline modified by artificial structures (breakwaters, seawalls, groynes) will increase because of coastal development and defences against sea-level rise and the greater frequency of storms. This will increase connectivity between areas of rocky habitat. Siltation will continue to increase due to urbanization of catchments and estuaries, and changes in agricultural practice. This may have considerable impacts at local and regional scales, favouring sediment tolerant organisms such as turf algae and anemones. In the future, greater frequency of environmental extremes is likely, including large-scale events such as the El Niño Southern Oscillation (ENSO). Global change in temperature, sea-level rise and increases in the frequency of storms will affect rocky shores throughout the world, but this will occur over long time scales; over the next 25 years most of the responses by rocky shore communities will mostly be quite subtle. Thus rocky shores will be subject to increasing degradation over the next 25 years. They are, however, less vulnerable than many other aquatic habitats due to their hard substratum (rock), their relative lack of large biogenic structures and to their generally open nature. They are also remarkably resilient, and recovery can occur rapidly due to recruitment from unaffected areas. Their susceptibility to both terrestrial and marine disturbances does make them more vulnerable than sublittoral and offshore habitats. There are considerable gaps in knowledge, particularly of certain microhabitats such as crevices, boulders, sand-scoured areas and rock pools. These have been much less studied than more accessible assemblages on open, freely draining rock. More research is needed to establish the effects of increasing sediment loads, ultraviolet radiation and introduced species on rocky shore communities. Strategic and applied research programmes should integrate field experiments and carefully selected monitoring programmes to verify management regimes. Hindcasting from the palaeo-record would be valuable, to compare rates of predicted change with periods when change was rapid in the past. This information could, in principle, be used to help conserve rocky shores through networks of marine protected areas and a general reduction of environmental pollution.

Saltmarshes are a major, widely distributed, intertidal habitat. They are dynamic systems, responding to changing environmental conditions. For centuries, saltmarshes have been subject to modification or destruction because of human activity. In this review, the range of factors influencing the survival of saltmarshes is discussed. Of critical importance are changes in relative sea level and in tidal range. Relative sea level is affected by changes in absolute sea level, changes in land level and the capacity of saltmarshes to accumulate and retain sediment. Many saltmarshes are starved of sediment because of catchment modification and coastal engineering, or exposed to erosive forces, which may be of natural origin or reflect human interference. The geographical distribution of individual saltmarsh species reflects climate, so that global climatic change will be reflected by changes in distribution and abundance of species, although the rate of change in communities dominated by perennial plants is difficult to predict. Humans have the ability to create impacts on saltmarshes at a range of scales from individual sites to globally. Pressures on the environment created by the continued increase in the human population, particularly in developing tropical countries, and the likely consequences of the enhanced greenhouse effect on both temperature and sea level give rise to particular concerns. Given the concentration of population growth and development in the coastal zone, and the potential sensitivity of saltmarsh to change in sea level, it is timely to review the present state of saltmarshes and to assess the likelihood of changes in the near (25 years) future. By 2025, global sea level rise and warming will have impacts on saltmarshes. However, the most extensive changes are likely to be the direct result of human actions at local or regional scales. Despite increasing recognition of the ecological value of saltmarsh, major projects involving loss of saltmarshes but deemed to be in the public interest will be approved. Pressures are likely to be particularly severe in the tropics, where very little is known about saltmarshes. At the local scale the cumulative impacts of activities, which individually have minor effects, may be considerable. Managers of saltmarshes will be faced with difficult choices including questions as to whether traditional uses should be retained, whether invasive alien species or native species increasing in abundance should be controlled, whether planned retreat is an appropriate response to rising relative sea level or whether measures can be taken to reduce erosion. Decisions will need to take into account social and economic as well as ecological concerns.

Ecotourism can be a vehicle for community-based conservation if it is conducted with an emphasis on the well-being of local ecosystems and human communities. Birdwatchers form the largest group of ecotourists, and are, on average, well-educated, wealthy and committed. This makes them ideal ecotourists for community-based conservation. Therefore, there is a need for a comprehensive review of birdwatching from a conservation biology perspective. Specific objectives here are: (1) to review the economic potential of non-residential birdwatching for community-based conservation; (2) to outline the potential benefits and problems associated with this activity; and (3) to provide suggestions for improving the conservation value of birdwatching. Birdwatching tourism has a high potential to improve the financial and environmental well-being of local communities, educate locals about the value of biodiversity and create local and national incentives for successful protection and preservation of natural areas. However, there needs to be more research on the economical and environmental impacts of this hobby, birdwatching-related disturbance needs to be reduced, and much has to be done to increase the financial contribution of birdwatching to local communities.

Kelp forests are phyletically diverse, structurally complex and highly productive components of coldwater rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

Pollution, mining, disruption of sand transport and tourism development widely affect sandy shores, and these systems may be subject to increased erosion in future, yet there have been few attempts to review them. The present review focuses largely on ocean sandy beaches, providing an introduction to much of the relevant literature, and predicting possible states of the system by 2025. Sandy shores are dynamic harsh environments, the action of waves and tides largely determining species diversity, biomass and community structure. There is an interchange of sand, biological matter and other materials between dunes, intertidal beaches and surf zones. Storms and associated erosion present the most substantial universal hazard to the fauna. Human-related perturbations vary from beach to beach; however, structures or activities that impede natural sand transport or alter the sand budget commonly lead to severe erosion, often of a permanent nature. Many beaches also suffer intermittent or chronic pollution, and direct human interference includes off-road vehicles, mining, trampling, bait collecting, beach cleaning and ecotourism. These interferences typically have a negative impact on the system. Identified long-term trends include chronic beach erosion, often largely due to natural causes, as well as increased ultraviolet (UV) radiation and changes related to global warming. It is not expected that predicted temperature changes will have dramatic effects on the world's beaches by 2025, but the expected rise in sea level, if coupled with an increase in the frequency and/or intensity of storms, as predicted for some regions, is likely to lead to escalating erosion and consequent loss of habitat. It is suggested that increased UV radiation is unlikely to have significant effects. Increases in coastal human populations and tourism, thus increasing pressure on the shore, while serious, may be largely offset in developed and developing countries by better management resulting from greater understanding of the factors governing sandy-shore systems and better communication with beach managers and developers. Beach nourishment is likely to become more widely practised. However, the continuing hardening of surfaces in and above the dunes is bound to be damaging. Human pressures in many underdeveloped countries show no signs of being mitigated by conservation measures; it is likely that their sandy shores will continue to deteriorate during the first quarter of this century. A long-term trend that cannot be ignored is the excessive amount of nitrogen entering the sea, particularly affecting beaches in estuaries and sheltered lagoons. The data presently available and the uncertainty of a number of predictions do not permit of quantitative assessment or modelling of the state of the world's sandy shores by the year 2025, but some tentative, qualitative predictions are offered.

Lakes and ponds are habitats of great human importance as they provide water for domestic, industrial and agricultural use as well as providing food. In spite of their fundamental importance to humans, freshwater systems have been severely affected by a multitude of anthropogenic disturbances, which have led to serious negative effects on the structure and function of these ecosystems. The aim of the present study is to review the current state of lake and pond ecosystems and to present a likely scenario for threats against these ecosystems for the time horizon of the year 2025. Predictions are based on a review of the current state, projections of long-term trends, for example in population and global climate, and an analysis of the trends in publications in the scientific literature during the past 25 years (1975–2000). The biodiversity of lake and pond ecosystems is currently threatened by a number of human disturbances, of which the most important include increased nutrient load, contamination, acid rain and invasion of exotic species. Analysis of trends suggests that older, well known threats to biodiversity such as eutrophication, acidification and contamination by heavy metals and organochlorines may become less of a problem in developed countries in the future. New threats such as global warming, ultraviolet radiation, endocrine disruptors and, especially, invasion by exotic species including transgenic organisms will most likely increase in importance. However, in developing countries where priorities other than environmental conservation exist, the threat of eutrophication, acidification and contamination by toxic substances is predicted to continue to increase. Although the future of biodiversity in lakes and ponds is seriously threatened, growing concern for environmental problems, implementation of new environmental strategies and administrations, and international agreements, are positive signs of changes that should improve the ability to manage old as well as new, yet undiscovered, threats.

In this paper the current status of coral reefs, predictions concerning the ecological state of coral reefs to the 2025 time horizon and the research needs that can help understanding and management activities that might alleviate detrimental ecological changes are evaluated and discussed. The present rate of CO2 emissions will produce an atmospheric concentration in 100 years not experienced during the past 20 million years and water temperatures above those of the past interglacial 130 000 years before present. Human influences on water temperatures, seawater chemistry (toxic substances, nutrients and aragonite saturation), the spread of diseases, removal of species and food web alterations are presently changing reef ecology. A significant ecological reorganization is underway and changes include a reduction in calcifying and zooxanthellae-hosting organisms, their obligate symbionts, and species at higher trophic levels, with an increase in generalist species of low trophic level that are adapted to variable environments. Late-successional fleshy brown algae of low net productivity or non-commercial invertebrates such as sea urchins, starfish and coral-eating snails will dominate many reefs. These changes will be associated with a loss of both net benthic and fisheries production and inorganic carbonate deposition; this will reduce reef complexity, species richness, reef growth and increase shoreline erosion. To avert these changes management is needed at both global and local levels. Both levels need to reduce greenhouse gases and other waste emissions and renew efforts to improve resource management including restrictions on the use of resources and globalization of resource trade, run-off and waste production, and balancing potential reef production and resource consumption.

Seagrasses cover about 0.1–0.2% of the global ocean, and develop highly productive ecosystems which fulfil a key role in the coastal ecosystem. Widespread seagrass loss results from direct human impacts, including mechanical damage (by dredging, fishing, and anchoring), eutrophication, aquaculture, siltation, effects of coastal constructions, and food web alterations; and indirect human impacts, including negative effects of climate change (erosion by rising sea level, increased storms, increased ultraviolet irradiance), as well as from natural causes, such as cyclones and floods. The present review summarizes such threats and trends and considers likely changes to the 2025 time horizon. Present losses are expected to accelerate, particularly in South-east Asia and the Caribbean, as human pressure on the coastal zone grows. Positive human effects include increased legislation to protect seagrass, increased protection of coastal ecosystems, and enhanced efforts to monitor and restore the marine ecosystem. However, these positive effects are unlikely to balance the negative impacts, which are expected to be particularly prominent in developing tropical regions, where the capacity to implement conservation policies is limited. Uncertainties as to the present loss rate, derived from the paucity of coherent monitoring programmes, and the present inability to formulate reliable predictions as to the future rate of loss, represent a major barrier to the formulation of global conservation policies. Three key actions are needed to ensure the effective conservation of seagrass ecosystems: (1) the development of a coherent worldwide monitoring network, (2) the development of quantitative models predicting the responses of seagrasses to disturbance, and (3) the education of the public on the functions of seagrass meadows and the impacts of human activity.