How can fragile marine ecosystems best be conserved?

Biological Conservation 66 (1993) 251-255

SELECTED ABSTRACTS The abstracts reproduced here have been selected from the coverage of Ecological

Abstracts. Further information on Ecological Abstracts, and the associated online database GEOBASE is available from Elsevier/Geo Abstracts, Regency House, 34 Duke Street, Norwich, UK, NR3 3AP. 93Z/00004 The value of managing for biodiversity P. J. Burton, A. C. Balisky, L. P. Coward, S. G. Cumming & D. D. Kneeshaw, Forestry Chronicle, 68(2), 1992, pp 225-237. Biodiversity should be protected in more ecosystem and landscape reserves. It is a reasonable management objective on timber lands. Maintaining biodiversity is important because we cannot always identify which individual species are critical to ecosystem sustainability, nor which species may be useful to mankind in future. Many wild species can provide useful naturalproducts and genetic material, and can serve as ecologiealindieators. Diversity reduces pest and disease problems, and encourages recovery from disturbance. Uncertainty exists with regard to climate change and future socioeconomic values. It is therefore prudent to maximize flexibility by promoting a wide array of species and potential jproducts. Suggestions are offered on how to promote biodiversity in multiple-use forests. -from Authors

NATURE CONSERVATION General 93Z/00001 Ecosystem stress and health: an expansion of the conceptual basis J. Kolasa & S. T. A. Pickett, Journal of Aquatic Ecosystem Health, 1(1), 1992, pp 7-13. Assessment of the ecosystem health and departures from it requires clarity of what the system, its structure, dynamics, and healthy conditions are. Available definitions provide inadequate tools to acquire this clarity and may lead to arbitrary diagnoses of ecosystem health. Nested hierarchy of ecosystem structure compounds the difficulty in the assessment of stress and health because both states may occur simultaneously at different hierarchical levels: with stress at one level being a necessary condition of health at another. An approach based on a formal definition of system change is advanced. A conceptual model identifies a self-maintaining minimum interactive structure (MIS) at each level of ecosystem organization. Components o f / d i s are complementary, coordinated, and exchanging information - they are integrated. Function is defined as a contribution of a component to the maintenance of the whole. In this context health is viewed as persistence of the system at a l~iven temporal and spatial scale. Impairment of the function is stress and is contrasted with change of system structure (loss, addition, or replacement of components of MIS) which is disturbance. Stress can be measured directly by changes of function or indirectly by changes in integration. Even though undesirable from the human point of view, a changed system may again be considered healthy. -Authors

93Z/00005 How can fragile m a r i n e ecosystems best be conserved? J. S. Bunt, in: Use and misuse of the seafloor. Report of Dahlem Workshop, 1991, ed K.J. Hsn & J. Thiede, (Wiley; Environmental Sciences Research Report, ES11), 1992, pp 229-242. Uses mangroves, coral reefs, and polar seas as examples of fragile marine ecosystems. Conservation in the parochial sense is unlikely to be of particular value to any natural system except in the short term. Desirable initiatives at that scale are outlined. At the biosphere level and to be effective in the long term, conservation would have to extend to protective management applied in an integrated fashion at global scales. To achieve such a goal could require not only substantial scientific and technical advances but possibly also fundamental revision in political procedures and in the structuring of economic processes along with basic changes to the infrastructural organization of government. -from Author

93Z/00002 Evaluating ecosystem health D . J . Rapport, Journal @Aquatic Ecosystem Health, 1(1), 1992, pp 15-24. If ecosystem medicine is to come of age, it must cope with three fundamental dilemmas: 1) there axe no strictly objective criteria for judging health; 2) stems from the irregular pulse of nature which either precludes the early recognition of substantive changes or gives rise to false alarms; and 3) the quest for indicators that have the attributes of being holistie, early warning, and diagnostic. Comparisons are drawn from studies of environmental transformation in the Laurentian Great Lakes, the Baltic Sea and Canadian terrestrial ecosystems. -from Author

93Z/00006 Disturbance, diversity, and invasion: implications for conservation R . J . Hobbs & L. F. Huermeke, Conservation Biology, 6(3), 1992, pp 324-337. Reviews the effects of disturbances such as fire, grazing, soil disturbance, and nutrient addition on plant species diversity and invasion, with partieulax emphasis on grassland vegetation. Individual components o f the disturbance regtrne can have marked effects on species diversity, but it is often modifications of the existing regime that have the largest influence. Similarly, disturbance can enhance invasion of natural communities, but frequently it is the interaction between different disturbances that has the largest effect, The natural disturbance regime is now unlikely to persist within conservation areas, since fragmentation and human intervention have usually modified physical and biotic conditions. Active management decisions must now be made on what disturbance regime is required, and this requires decisions on what species are to be encouraged or discouraged. -from Authors

93Z/00003 Paleolimnology: an important tool for effective ecosystem m a n a g e m e n t J. P. Stool, Journal of Aquatic Ecosystem Health, 1(1), 1992, pp 49-58. Major advances have been made in paleolimnology over the last decade, and many of these advances can be applied directly to integrated and cost-effective assessments of aquatic ecosystem health. Paleolinmological data provide information crucial to the decision-making processes of ecosystem managers. -from Author

Biological Conservation 0006-3207/93/$06.00 © 1993 Elsevier Science Publishers Ltd. 251