Natural flood plains are among the most biologically productive and diverse ecosystems on earth. Globally, riverine flood plains cover > 2 × 106 km2, however, they are among the most threatened ecosystems. Floodplain degradation is closely linked to the rapid decline in freshwater biodiversity; the main reasons for the latter being habitat alteration, flow and flood control, species invasion and pollution. In Europe and North America, up to 90% of flood plains are already ‘cultivated’ and therefore functionally extinct. In the developing world, the remaining natural flood plains are disappearing at an accelerating rate, primarily as a result of changing hydrology. Up to the 2025 time horizon, the future increase of human population will lead to further degradation of riparian areas, intensification of the hydrological cycle, increase in the discharge of pollutants, and further proliferation of species invasions. In the near future, the most threatened flood plains will be those in south-east Asia, Sahelian Africa and North America. There is an urgent need to preserve existing, intact flood plain rivers as strategic global resources and to begin to restore hydrologic dynamics, sediment transport and riparian vegetation to those rivers that retain some level of ecological integrity. Otherwise, dramatic extinctions of aquatic and riparian species and of ecosystem services are faced within the next few decades.

Estuaries exhibit a wide array of human impacts that can compromise their ecological integrity, because of rapid population growth and uncontrolled development in many coastal regions worldwide. Long-term environmental problems plaguing estuaries require remedial actions to improve the viability and health of these valuable coastal systems. Detailed examination of the effects of pollution inputs, the loss and alteration of estuarine habitat, and the role of other anthropogenic stress indicates that water quality in estuaries, particularly urbanized systems, is often compromised by the overloading of nutrients and organic matter, the influx of pathogens, and the accumulation of chemical contaminants. In addition, the destruction of fringing wetlands and the loss and alteration of estuarine habitats usually degrade biotic communities. Estuaries are characterized by high population densities of microbes, plankton, benthic flora and fauna, and nekton; however, these organisms tend to be highly vulnerable to human activities in coastal watersheds and adjoining embayments. Trends suggest that by 2025 estuaries will be most significantly impacted by habitat loss and alteration associated with a burgeoning coastal population, which is expected to approach six billion people. Habitat destruction has far reaching ecological consequences, modifying the structure, function, and controls of estuarine ecosystems and contributing to the decline of biodiversity. Other anticipated high priority problems are excessive nutrient and sewage inputs to estuaries, principally from land-based sources. These inputs will lead to the greater incidence of eutrophication as well as hypoxia and anoxia. During the next 25 years, overfishing is expected to become a more pervasive and significant anthropogenic factor, also capable of mediating global-scale change to estuaries. Chemical contaminants, notably synthetic organic compounds, will remain a serious problem, especially in heavily industrialized areas. Freshwater diversions appear to be an emerging global problem as the expanding coastal population places greater demands on limited freshwater supplies for agricultural, domestic, and industrial needs. Altered freshwater flows could significantly affect nutrient loads, biotic community structure, and the trophodynamics of estuarine systems. Ecological impacts that will be less threatening, but still damaging, are those caused by introduced species, sea level rise, coastal subsidence, and debris/litter. Although all of these disturbances can alter habitats and contribute to shifts in the composition of estuarine biotic communities, the overall effect will be partial changes to these ecosystem components. Several strategies may mitigate future impacts.

Globally, humans impact environments and ecosystems faster than they become aware of their effects. The marine pelagic ecosystem includes a tremendously large and diverse environment, which might accordingly be considered to be resilient to externally forced changes, whether from humans or climate. This review considers that general hypothesis by pursuing two objectives. The first is to document the current status of and recent anthropogenic impacts on the marine pelagic ecosystem, with emphasis on the epipelagic zone (0-200 m) where organisms are concentrated and human impacts have been greatest. It shows that humans have proven capable of assuming the role of top carnivore in pelagic ecosystems where living resources are attractive and financially amenable to exploitation, and that overexploitation is the rule under such circumstances. Other anthropogenic activities associated with changes in various marine pelagic ecosystems, such as increased diseases, mortalities, extinctions, habitat invasions, and species replacements, function as sentinels and indicate that portions of the pelagic ecosystem are under considerable stress. It is argued that, without attention, these problems can be expected to worsen up to the year 2025 and beyond. In addition to a comprehensive evaluation of status and trends relating to conservation of the marine pelagic ecosystem, a second major objective is to evaluate whether current paradigms of ecosystem function are sufficient to improve the ability of the scientific community to predict future changes and to recommend relevant management strategies. This review differs from previous ones by proposing that current conceptual models have failed to provide the basis for accurately predicting patterns and features of pelagic communities, notably why specific organisms occur where and when they do. It is argued that predation pressure is shaped by natural selection in the sea as on land, and that it influences organism behaviour, life history strategy and morphology, all of which determine marine pelagic ecosystem structure, and therefore should be used to interpret function. From this perspective, attempting to understand present patterns and predict the future of marine pelagic ecosystems, without understanding the intertwined roles of evolution and predation in forging contemporary pelagic communities, is a hopeless endeavour. It is proposed that both perspectives, resource availability and predation pressure, be incorporated into a revised paradigm of pelagic ecosystem structure and function, a necessity if policies are to predict anthropogenic impacts and environmental conservation is to be effective.

Marine reserves are widely considered to potentially benefit reef fisheries through emigration, yet the empirical basis for predicting the extent of this for small reserves is weak. The effects of fishing pressure and habitat on biomass and catch per unit effort (CPUE) of three species of exploited reef fish were studied at South Caicos, Turks and Caicos Islands. Distribution and abundance of hogfish (Lachnolaimus maximus) and white margate (Haemulon album) were inversely correlated with cover of fleshy macroalgae. Nassau grouper (Epinephelus striatus) were positively associated with vertical relief, but were unaffected by algal cover. Mean size, density, and biomass of hogfish were higher in a small (4 km2) marine reserve than on fished reefs, as was biomass of white margate. CPUE of hogfish was inversely related to distance from the centre of the reserve, suggesting that spillover of this species from the reserve to adjacent reefs may enhance local yields, possibly providing economic incentives for fishers to comply with reserve regulations. Fishing pressure, however, had no apparent effect on Nassau grouper. Larger fishes and those that migrate to spawn, such as economically valuable Nassau grouper, may move over too large a range to be effectively protected by small marine reserves. Small reserves may not protect all fish, but they can increase the biomass of smaller or more sedentary reef fishes and may be a useful tool for the conservation or management of species such as hogfish. Other policy options, such as seasonal spawning closures or total allowable catches, need to be considered for larger, more mobile fishes in the Turks and Caicos Islands.

The impact of human exploitation depends mostly on the size of the catch and the species targeted. The value of a species is an important explanatory variable in understanding human impact. Co-management of resources should take into account these different resource values, when evaluating exploitation strategies. The prey choice and foraging behaviour of women and children searching for crabs and shells on the intertidal area at Inhaca Island, South Mozambique, were investigated using optimal foraging theory. This theoretical framework offers the possibility to understand the reasoning of an exploitation strategy and the preference for certain prey species. The number of people was registered, catches were analysed, and timing and substrate choice were recorded. The value of species was estimated using contingency tables. Women were more efficient than children, as their catch was heavier, and the mean weight/animal was larger. The density of women and their timing were positively correlated to prey availability. During neap tide, they spread their visit over more of the low water period and collected crabs by digging in the mangrove forests. No digging occurred during spring tide when a larger area was exposed, the total abundance of species increased, and more species became available. Women then switched to a second strategy, targeting swimming crabs in the tidal channel. Mean neap and spring tide catches were equal (133 g ash-free dry weight per person), but spring catches comprised significantly fewer animals per catch (42 against 123 per person), and mean animal weight was larger (5.4 against 3.0 g ash-free dry-weight per person). Diet breadth was narrower during spring tide, and decreased significantly with increased catch weight. Species with profitabilities (energy intake/handling time) lower than the mean intake rate of 0.024–0.028 g ash-free dry weight s−1 were generally excluded from the diet. The prey preference was positively related to the relative value ranks of the prey species, as measured by ranking of species by women. Women maximized the cumulative relative value ranks during spring tide, instead of total weight. Using this analysis, differences in prey choice and spatial differences in exploitation can be understood as a strategy aimed at maximizing intake and the relative value of a prey species.

Mangroves, the only woody halophytes living at the confluence of land and sea, have been heavily used traditionally for food, timber, fuel and medicine, and presently occupy about 181 000 km2 of tropical and subtropical coastline. Over the past 50 years, approximately one-third of the world's mangrove forests have been lost, but most data show very variable loss rates and there is considerable margin of error in most estimates. Mangroves are a valuable ecological and economic resource, being important nursery grounds and breeding sites for birds, fish, crustaceans, shellfish, reptiles and mammals; a renewable source of wood; accumulation sites for sediment, contaminants, carbon and nutrients; and offer protection against coastal erosion. The destruction of mangroves is usually positively related to human population density. Major reasons for destruction are urban development, aquaculture, mining and overexploitation for timber, fish, crustaceans and shellfish. Over the next 25 years, unrestricted clear felling, aquaculture, and overexploitation of fisheries will be the greatest threats, with lesser problems being alteration of hydrology, pollution and global warming. Loss of biodiversity is, and will continue to be, a severe problem as even pristine mangroves are species-poor compared with other tropical ecosystems. The future is not entirely bleak. The number of rehabilitation and restoration projects is increasing worldwide with some countries showing increases in mangrove area. The intensity of coastal aquaculture appears to have levelled off in some parts of the world. Some commercial projects and economic models indicate that mangroves can be used as a sustainable resource, especially for wood. The brightest note is that the rate of population growth is projected to slow during the next 50 years, with a gradual decline thereafter to the end of the century. Mangrove forests will continue to be exploited at current rates to 2025, unless they are seen as a valuable resource to be managed on a sustainable basis. After 2025, the future of mangroves will depend on technological and ecological advances in multi-species silviculture, genetics, and forestry modelling, but the greatest hope for their future is for a reduction in human population growth.

The management of fisheries in European Union (EU) waters has generally been regulated through government institutions and agreed quota allocations. This top-down management approach may have contributed to the continued decline of targeted fish stocks by forcing fishers to compete for limited resources without engendering a sense of resource stewardship. In attempting to reverse this decline, scientists and managers should examine management systems that do not solely depend on top-down approaches, and the Inshore Potting Agreement (IPA) is an example. The IPA is a voluntary fishery management system designed and operated by inshore fishers of south Devon, England. The IPA was conceived to reduce conflict between static-gear (pot and net) and towed-gear (trawl and dredge) fishers, and is regarded as a successful fisheries management regime by fishers and managers because it has effectively allowed fishers from both sectors to operate profitably on traditional fishing grounds. Another study determined that the IPA has incidentally protected benthic habitat complexity. Fishers from the static-gear and towed-gear sectors were interviewed to determine the evolution and function of the IPA, and to establish the factors that ensure the high level of regulatory compliance amongst fishers from both sectors. Towed-gear fishers gave significantly different responses to the same questions asked of static-gear fishers, and were generally less satisfied with the existence of the IPA. Multivariate analyses of the interview data suggested that fishers who thought the IPA was a good system also thought the system provided pot protection, but had experienced inter-sector conflict. Fishers who thought the IPA provided no personal benefit also thought that static-gear fishers should be more restricted, and that towed-gear corridors or more seasonal-use areas should be established within the existing IPA area. However, fishers from both sectors agreed that the IPA has maintained traditional practices of the local fishing industry, and that the system has conserved target finfish and scallop species. A number of factors were identified as critical to the success of the IPA. These included the voluntary nature of the agreement, the limited number of organizations representing fishers and very high level of membership of those organizations, and the simplicity of the system. Regulatory compliance is enhanced through the ability of fishers' organizations to respond rapidly to inter-sector conflict issues.

The literature on non-wood forest products (NWFPs) often emphasizes the commercial potential of certain species. However, the utility of the forest to human communities located in or around it often exceeds the cash income residents get from the sale of commercial NWFPs, as indicated by limiting the harvest of the most marketable NWFPs in a forest-edge Philippine village that was formerly highly dependent on rattan (Calamus sp.) collection and processing as a cottage industry. A village survey showed that there was a correlation between specific socio-economic factors such as age, education, size and income of a household, and household food expenditure, and the knowledge and use of non-commercial NWFPs, which were collected for various purposes. The forest was still important and valued by the community for other uses. These other uses, including the extensive, habitual reliance on subsistence non-wood forest products, are described to illustrate the possibility that these products may be the only source of necessities until the greater economic conditions improve.

Posidonia oceanica, the dominant seagrass species in the Mediterranean, appears to be experiencing widespread loss. Efforts to conserve Posidonia oceanica are increasing, as reflected in the increase in the number of marine protected areas in the Mediterranean. However, the effectiveness of these measures to conserve seagrass meadows is unknown. In this study, the present status of the Posidonia oceanica meadows in the Cabrera National Park (Mediterranean), the only marine national park in Spain, was assessed, and the effectiveness of the conservation measures adopted was tested. This was done by reconstruction of past and present growth, quantification of the demographic status of the established meadows, and quantification of patch formation and growth rates in areas where recolonization is occurring. The meadows extended from 1–43 m deep at Santa Maria bay and from 1–33 m at Es Port. Leaf production rate of the stands examined ranged between 6.5 and 7.8 leaves shoot−1 yr−1, with higher rates in Santa Maria than in Es Port. Vertical rhizomes elongated at rates ranging from 5.39–10.12 mm yr−1, annual vertical growth in Santa Maria stands being larger than that in the stands developing at Es Port. Horizontal rhizomes elongated slowly (from 2.6–6.1 cm yr−1), and branching was sparse (<0.25 branches yr−1 axis−1), with maximum elongation and branching rates in areas where patches were actively colonizing. Flowering was a rare event in all the stands (<0.015 flowers shoot−1 yr−1). Patch formation and patch growth rates in active colonizing areas were slow, but they increased after implementation of mooring regulations in the Park. Similarly, the leaf production tended to increase, and vertical rhizome growth to decrease, in both bays following the onset of regulation measures. However, the decrease in vertical growth detected was greater at Santa Maria, where access is prohibited to visitors, than at Es Port, where boats are allowed to moor, attached to permanent weights. Shoot mortality rate was generally low (mean 0.10 ± 0.02 ln units yr−1) but exceeded the recruitment rate (<0.009 and 0.17 ln units yr−1) in 55% of the meadows examined, indicative of negative net population growth rates. Regulation of mooring activities has improved the status of the P. oceanica meadows at Cabrera National Park. The demographic analysis, however, indicated that while P. oceanica meadows at Santa Maria are in good shape, those at Es Port seem to be compromised. The observed differences in meadow status reflect the large differences in circulation inside the bays (water residence time at Santa Maria = 4 days, water residence time at Es Port = 11 days) and the anthropogenic pressure both bays support.

Continental shelf benthic ecosystems play an important role in the economy of many coastal states through the provision of food, non-living resources and through control of climate. Changes in the status of these ecosystems, through either natural or human-induced environmental drivers can be expected to have important economic and social consequences. Agents that could induce change include climate and oceanography, hydrology (river discharge), land-use and waste disposal practices, fishing, aquaculture and extraction of non-living resources. Trends in all of these drivers, particularly those under human influence, suggest that shelf systems will come under increasing pressure. Attempts to predict the future state of any ecological system are fraught with difficulty, particularly over decadal time-frames. This is, perhaps, especially true for continental shelf ecosystems where data on current status are poor and our understanding of many of the drivers of change somewhat rudimentary. What can be said for certain, however, is that change will occur and, in the short term, many of the signs point towards deterioration in the ecological condition of many shelf systems, but particularly those of developing countries. Trends in land-use practices, with consequences for nutrient, sediment and freshwater input to coastal seas appear to be particularly worrying, but the poor state of many demersal fisheries systems must also be acknowledged. In contrast to the developing world, although challenges undoubtedly remain, particularly with respect to atmospheric inputs resulting from energy production, current trends in environmental management suggest that pressures imposed by land use, waste disposal and fishing will probably decline over the coming decades on the shelves of many developed countries. At the global scale, therefore, the key driver for sustainable use of our continental shelf ecosystems would appear to be intimately linked to the social and economic well-being of poorer nations.

New participatory forest management policies are being promoted in South Africa involving devolution from the state to local communities at a time when traditional authority has been eroded and is weak. Here, attitudes of forest stakeholders (forest resource users and managers) to three possible forest management policies, as well as to resource use, were investigated using questionnaires. There was concordance in the attitudes of resource users and managers and a general lack of support for community forest management (CFM), particularly among older resource users. Power shifts, uncertainty about land tenure and the management of what has essentially become an open-access system, all confound attempts to implement community-based forestry programmes. Local communities appeared to be wary of taking on responsibility for forest management at this time and indicated comparatively stronger support for state forest management (SFM). Forest stakeholders were more equivocal in their support for participatory forest management (PFM), although this probably reflects a poor understanding by forest users of the new PFM process. No stakeholders supported a total ban on forest resource use, but all supported controlled use. These latter attitudes were independent of the preferred management system (i.e. CFM, SFM or PFM). This study corroborates the view that CFM has been overemphasized. Rather than narrowing forest management around communities, but recognizing the state's incapacity to ensure the integrity of forest resources into the future without the co-operation of forest users, an all-inclusive approach, such as PFM, provides for greater management input by the state.

Eggs of the olive ridley marine turtle (Lepidochelys olivacea) have been harvested by generations of Pacific coast communities in Central America for both economic and nutritional reasons. There has been little economic analysis that has identified possible points of improvements for management of the resource. Three egg harvesting projects were studied in Costa Rica and Nicaragua. Field research using semi-structured interviews with stakeholders and key informants were undertaken in June and July 2000. Market price data were collected from harvesters, points of sale and government records. Spread price analysis suggested that more flexible seasonal and regional pricing policies might increase egg profits. Contested property rights have weakened incentives to manage the species as an asset rather than an open access resource. Transaction costs have reduced community efficiency in egg marketing. Community egg marketing cartels with authorized urban selling points are recommended to improve resource management, appropriate a higher egg profit margin and clarify the harvesting origin of eggs for consumers.

There is a current trend towards decentralization of forest management, particularly among developing nations. Nepal has taken a lead in initiating innovative policies of community forestry. Although these initiatives have been largely deemed successful in the mountains, within the Terai lowlands, there is considerable debate about their outcomes. This research evaluates forest condition within recently declared community forests, national forests and protected areas in the Nepal Terai, using plot mensuration techniques and interviews with local users. The initial condition of forests that were handed over to local communities for use was significantly poorer than those retained as national forests. Protected areas had the highest levels of plant abundance, biomass and biodiversity, which is not surprising, given the level of funds and manpower input to managing these limited areas. In the context of current controversy about the outcome of community forestry in the Nepal Terai, the poor initial condition of forests handed over to local communities is highly significant, and needs to be factored into evaluations of community forest management. This research underscores the need for benchmark studies for evaluating the future outcomes of forest policies in the Terai, provides a valuable addition to the limited information on forest conditions under different management regimes in Nepal, and indicates some of the difficulties that local communities face while dealing with community forestry in practice.

Species are identified as bioindicators when their presence or abundance within sites of a particular habitat or a conservation area are high. Dufrêne and Legendre (1997), Ecological Monographs 67: 345–366, proposed the use of a flexible asymmetrical approach to detect indicator species and species assemblages characterizing groups of sites, the indicator value for each species being subsequently tested by randomization. Although the advantages of these methods in comparison to other multivariate or two-way indicator species analyses have been demonstrated, relatively few ecological studies have made use of them. The aim of the present study was to demonstrate the advantages of the indicator species test using a data set generated by traditional fisheries activities at four areas in the Bonifacio Strait Marine Reserve, Corsica, France. ANOVA, Kruskal-Wallis and another randomization test were also performed on the same data set. Of the 54 species caught in the fishing nets, the indicator species analyses identified 19 species for which the indicator value was significant for a given area, whereas the a posteriori Tukey test for ANOVA detected only 12 species for which the mass capture per unit effort was significantly greater for a given area. The efficiency of this new approach within the framework of conservation and marine reserve studies is demonstrated by focusing on three species (Sciaena umbra, Palinurus elephas and Maja verrucosa).