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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

Illegal hunting of resident and migratory herbivores is widespread in the Serengeti National Park, Tanzania. To devise effective strategies to reduce levels of hunting, information is required on why people are involved in illegal hunting and the role of bushmeat in the local economy. Participation in hunting may be influenced by measures of relative wealth, including livestock ownership, means of generating cash income and access to alternative sources of meat. Data came from 300 individuals responding to a questionnaire in 10 villages, from responses by 359 people in 24 group discussions in another 12 villages, and from 552 people arrested and interviewed in the National Park. A smaller proportion of individual respondents (32%) than group respondents (57%) volunteered that they participated in illegal hunting. Most individual and group respondents were subsistence farmers who considered bushmeat to be a source of protein and a means of generating cash income. Three-quarters of those arrested participated in hunting primarily to generate cash income and a quarter claimed that they only hunted to obtain food. Participation in illegal hunting decreased as wealth in terms of the number of sheep and goats owned increased. People with access to alternative means of generating income or acquiring protein were also less likely to be involved in illegal hunting. Arrested respondents were typically young adult males with low incomes and few or no livestock. Illegal hunting was not reduced by participation in community-based conservation pro-grammes. Results suggested that between 52 000 and 60 000 people participated in illegal hunting within protected areas, and that many young men (approximately 5200) derived their primary source of income from hunting.