Knowledge of the present status and future potential of the world's marine food resources is a key prerequisite to their ecological exploitation. Rationales for the exploitation of these resources are twofold. Most important is the expectation that more time to reduce human population growth—the ultimate goal—could be made available. Secondly, because fish and shellfish are typically high in their content of protein and low in fat, nutritional quality in the human diet can be improved through their increased use.

Fundamental to marine biological production are the phytoplankton populations which comprise the basis of the oceanic food-structure. This production involves the photosynthesis of organic matter by phytoplankton and the subsequent flow of this matter through the food-web. Spatial and temporal discontinuities in marine production are related to the patchy distributional pattern of phytoplankton and to natural fluctuations in oceanic populations due to geographically and temporally varying conditions. A review of past estimates of the potential marine yield suggests that there has been significant variation in the methodology employed to arrive at these estimates.

Much-improved management of the oceanic food resources is urgently needed. Present mismanagement of these resources includes chemical pollution and the overexploitation of several important fish-stocks, which together threaten the viability of marine life. On the positive side, the future potential of the overall marine food-resources appears to be considerably larger than the present yield. The current harvest can be augmented by further development of aquaculture and by the exploitation of unconventional species, both of which could offer a relatively untapped source of valuable protein. Thus, Man must quickly establish and implement a rational, global management plan for the world's oceans and control his own population numbers to ensure conservation of the marine food-resources.

A research project in freshwater ecology is described whose main intentions are: 1) to increase the contact between the University of Oslo and a local community; 2) to solve actual problems for the local community by prosecuting applied research without interfering with the researchers' demand for free choice of research items; and 3) to allow for a larger student population without increasing the supervisory staff (compatible with steadily falling grants).

The Voss Project is a cooperative project between the Zoological Institute of the University of Oslo and the Voss District Council, western Norway. It was initiated to analyse the Voss River system, which is threatened by eutrophication and water-power development.

The research is mainly carried out by Cand.Real. students, who live for 1–2 years in the local community. During the work, an intensive exchange of information about biological and social items, and about municipal politics, naturally takes place.

The changing fortunes of ecological issues in American society suggest the importance of citizen attention and attitudes to environmental problems. Only a few studies since Earth Day, 1970, have focused on a key group of political actors in natural resource politics—environmental activists. The great variety of issues that are of interest to environmentally-concerned individuals suggest that important differences exist among environmentalists regarding the nature of ecological problems.

The present paper examines the attitudes of these people and how they have defined the extent and character of the ecological crisis. By adopting an analytical framework that described levels of environmental understanding, this analysis has attempted to explore belief-structures within the environmental movement and the implications of these beliefs for future change. The evidence revealed that, while environmentalism is not a monolithic social movement, a substantial majority of the respondents to sets of questions about key issues were in the ‘reformist’ mode of environmental activity—that is, environmental problems are reasonably well understood by these activists, the origins of environmental problems are seen by them in terms of consumption and production activities in society, and these attitudes demand political action that is compatible with existing institutions.

There are strong arguments for increasing the price which the consumer pays for the use of non-renewable resources. The fact that there are no exact means of determining appropriate prices should not deter society from moving nearer to this objective, particularly in cases where the price paid is likely to increase very steeply when easily-won resources become depleted.

The evolving conservation views and movements in the United States are characterized by their changing social goals and the resultant alteration of attitudes towards the physical environment. Our examination results in a six-stages classification of conservation views: (1) the naturalist view, which was based on the idea of undisturbed harmony of Nature; (2) the utilitarian view, which was highly influenced by Gifford Pinchot's conservation philosophy of ‘common goods for common men’ in natural resource use; (3) the ethical view, which resulted from an awareness that increasing consumption combined with increasing population would deplete resources and depress living standards; (4) the developmental view, or a technocratic approach to resource development, which rejected a fixed inventory of natural resources and perceived an everincreasing resource base; (5) the aesthetic view, which valued the aesthetic contribution of natural resources more than the economic contribution, i.e. amenity value versus commodity value of natural resources; and (6) the ecological view, which is based on the concept of an ecosystem wherein Man is an integral and inseparable part of the total environment and is responsible for the maintenance of the total environment.

These conservation views of the United States reflect a historical conflict between progressivist and preservationist philosophies of natural resource use. The conflict derives from changing societal concepts of resource scarcity regarding their physical, economic, or qualitative, aspects. The current ‘ecological’ view remains uncertain in terms of its concept of scarcity.

Reservoir storage projects are known to alter significantly the environmental settings in which they are established. Extensive data are required to assess quantitatively the physical effects of human interference with rivers. Methodologies must be developed to permit continual monitoring of such changes, so that environmental effects of storage projects may be considered in more integrated, comprehensive plans than hitherto for future river-development efforts.

This study documents stream-channel changes over a five-years period following reservoir completion at eight cross-sections on the main stream below a dam and on one tributary. Of eight main-stream sections, four are increasing in cross-sectional area, namely numbers one, five, six, and seven. Of these, the crosssectional area of numbers one and seven is increasing laterally and that of five and six is increasing vertically. The average annual degradation of sections five and six is 0.092 m over the study period, compared with an average of 0.031 m in the United States over the first 10–15 years after dam closure. Sections three, eight, and nine, are shitfing laterally without a crosssectional area increase, while of sections 2 and 4 the cross-sectional area remained largely unchanged.

Extraction of most of the sediment load by the new reservoir led to increased erosion of the stream channel below the dam. However, it is not always predictable whether the increased erosive power of released clearwater will induce the ongoing channel to erode its bed, widen its section, or cause the bed to move laterally. Nearly all of the nine Deer Creek study sections experienced one of these changes over the study period of five years.

The experiment described was conducted in water impounded by earth dams, for local water-supply, in Nyanza province, Kenya. Control of snails was attempted by introduction of the malacophagous fish Astatoreochromis alluaudi; other species were also introduced. The schedules of introduction of fish were varied between the reservoirs, and one was left as a control without any introduction of fish. The necessity for the establishment of a fish-rearing pond, prior to large-scale stocking, is emphasized.

Assessment of snail control was made by scooping for snails, catches being expressed per man-hour. This was carried out both before and after introduction of fish, over a total period of 15 years. It is concluded that the data indicate that A. alluaudi did reduce the numbers of some species of snails—particularly Biomphalaria pfeifferi and, to a lesser extent and with less certainty, Bulinus spp.

Two other introduced fish species, Tilapia zillii and T. leucosticta, did not appear to be associated with any fall in snail numbers.

The good intentions of specialists involved in the onchocerciasis control project in the Volta Basin of West Africa have not been questioned. It is, however, questioned whether there was not too great a haste to implement the spraying phase of the programme. There is apprehension that the food-chain with Man as terminal link will be contaminated, and that the project will increase the socio-economic as well as political problems of participating countries and yet fail to control the disease.

In view of these considerations and of continuing ‘blind spots’ in human knowledge and especially of the problems involved, it is considered urgent that the spraying as it is now going on be modified or suspended until such time as the gaps in knowledge are reasonably closed.