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Wetland Systems: Science, Management, Control and Controllers Ted Hollis University College London INTRODUCTION Experience has shown that the science base for wetland management is extensive although usually imperfect for a particular situation or site. Wetland management is, however, much more complex than simply the application of scientific principles to management planning or environmental impact assessment. There is a complex web of factors that need to be negotiated by a successful wetland manager. Ecology and hydrology do not control the dynamics of wetlands and determine the outcome of efforts at wetland management. It is the interplay between the many individuals and organizations, both national and foreign, that determine the success of wetland management. Social organization, economic philosophy, politi- cal structures and the relationship between people and their environment are the critical factors that control wetland systems worldwide. This overview paper asks "What has been learned about the management of river systems and their associated wetlands that can be applied elsewhere?". In answering the question, the paper draws heavily on experience and research, management and conservation work in Britain; the European Economic Community (EEC); the Mediter- ranean Basin especially Tunisia, Greece, Algeria and Spain; and the West African countries of Ghana and Nigeria. This paper is structured around its subtitle "Science, Management, Control and Controllers". SCIENCE In general, the knowledge base exists for the scientific management of wetlands (Etherington, 1983). The essentials of hydrology and ecology are well established and major texts exist covering all of the major botanical, zoological, hydro- logical and ecological principles of wetlands (Mitsch and Gosselink 1986). ornithology Ornithologists are almost always in the vanguard of wetland science and wetland studies. The initial references for almost any wetland in the world are by ornithologists (Valverde 1958, on the Donana Wetlands of Spain) and the initial resident researchers are also usually ornithol- ogists (Skinner et al. 1986). The contribution of ornithology to wetland conservation has been enormous. An international research organization, IWRB (International Waterfowl Research Bureau; "and Wetlands" was added in 1986), was established in 1954 and this organization was in large part responsible for a series of conferences which culminated in the signing of the Ramsar Convention in 1971. The Convention on the Conservation of Wetlands of International Importance especially as Waterfowl Habitat (Ramsar) was the first global conservation convention and it is still the only one devoted to a single habitat type. Ornithologists, as a group, often identify hunting and/or poaching as a major threat to wetlands (Tamisier 1987) and usually concentrate their studies within the limits of the wetland. In this respect they can be rather myopic because, whilst they study and understand inter-continental flyways for migratory waterfowl (Everett et al. 1987), they do not always appreciate the place of wetlands with a catchment-estuarine-coastal system. In addition, the possibility of promoting wetland conservation in the developing world on the basis of birds is limited (Hollis and Adams 1989). Ministers faced with rising populations, a perceived need for additional irrigated agriculture and international assistance for dam construction are usually rather un-interested in waterfowl. Whilst such ministers are wrong to take such a view (Dugan 1990), the migratory waterfowl are often seen as "belonging" to rich and developed northern countries. Ecology Ecology is central to an understanding of wetland ecosystems but many ecological studies focus upon individual species and specific narrow ecological interrelationships. Forecasting is very difficult in ecology and as a result few ecologists are prepared to venture prognosti- cations about the effects of, for instance, human activities on wetlands. Ecologists tend to view the wetland as either an isolated island or one of a series of related wetlands linked by species migrations between them. Rarely are wetlands viewed by ecologists as a part of a wider water system and rarely are wetlands seen as playing a part in more general environmental systems. Probably the greatest difficulty inhibiting ecological scientists contributing to wetland management is their rather narrow view of humans. In general Homo sapiens is seen as a force disturbing the natural equilibrium of wetlands. Rarely are humans seen as integral to the sustainable development of wetlands. Hydrology Since water is the forcing factor in all wetlands, it is obvious that hydrology is central to any scientific and management activity in wetlands (Kusler and Brooks 1987). Changes to the water regime through dams, drainage, dredging, 20