Composition of Floating Debris in Harbours of the United States

As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources.     

Tropical forests: The policy challenge

Summary Tropical forests are being destroyed faster than ever, the rate having almost doubled during the 1980s. The main agent of deforestation now turns out to be the displaced peasant or landless farmer, sometimes known as the shifted cultivator; that group accounts for more forest loss than the combined impacts of the commercial logger, the cattle rancher and all other better known sources of deforestation. Yet, the over-riding target of conservation efforts remains the minor players in the forest's decline. All too little attention is directed towards the shifted cultivator, and next to nothing is done to address the problem which this group represents. Policy purviews need to be expanded to include the key factor of the shifted cultivator. In turn, it must determined what impels these people to abandon established farming areas in the countries concerned and to migrate into the forests. It appears that these people are driven by an array of forces: population growth, maldistribution of arable lands, inadequate rural infrastructure and lack of government attention to subsistence agriculture. In other words, the source problem is an amalgam of non-forestry factors, and conservationists will not achieve success in safeguarding the remaining forests unless they direct much more emphasis towards these root causes of deforestation.Dr Norman Myers is a consultant in environment and development, a member of this journal's Advisory Board and a regular contributor to the journal (seeThe Environmentalist,8(3), 187–208 and10(4), 243–256).     

The biodiversity crisis and the future of evolution

A large proportion of existing species — possibly half, conceivably even more — may be lost within the foreseeable future. But this may not prove to be the most consequential outcome of the current biodiversity crisis. More significant could be the disruption and degradation of several basic processes of evolution. It appears likely that for mass extinction episodes (MEEs) in the geological past, the recovery period usually lasted at least five million years. Because of certain unique features of the present MEE — notably the near elimination of biomes such as tropical forests, wetlands and coral reefs, which have served as powerhouses of evolution in the past — the bounce-back phase could extend several times longer than five million years. Among distinctive features of future evolution could be; in the short term, homogenization of biotas, a proliferation of opportunistic species, an outburst of speciation among particular taxa, and a pest-and-weed ecology; and, in the long term, a decline of biodisparity, the elimination of megavertebrates, an end to speciation among large vertebrates, and multiple constraints on origination, innovation and adaptive radiation. These disruptive phenomena would rank among the most prominent departures in the entire course of evolution. Full knowledge and understanding of what may characterize future evolution remains largely a black hole of research. As a consequence, conservation policies fail to reflect a further problem of the biodiversity prospect, perhaps exceeding the better recognized problem of the mass extinction of species.Professor Norman Myers is an Editorial Board member and regular contributor toThe Environmentalist. He is an Honorary Visiting Fellow at Green College, Oxford. This paper is a greatly expanded version of a preliminary probing in a popular magazine a decade ago (Myers, 1985). It has been prompted by a major international conference organized by the US National Academy of Sciences, scheduled for late 1996.     

Our forestry prospect: the past recycled or a surprise-rich future?

NORMAN MYERS: An honorary visiting fellow at Green College. He is an independent scientist and consultant working in environment and development.Like most other environmental and economic sectors, forestry worldwide looks set to encounter a growing number of surprises in the sense of major divergencies from established trends. These surprises will be largely environmental or economic or both at once. Unless we do a better job of identifying them ahead of time, these surprises will often be of a scale to overwhelm our anticipatory and preventive capacities. Indeed and as this paper demonstrates, the most likely as well as the most taxing forestry problems of the future will often be the ones we have scarcely thought of. Fortunately, the same applies to forestry opportunities. In these circumstances, there is a premium on not only supplying answers to recognized questions but on raising entirely new questions.     

CUMULATIVE IMPACTS OF LANDUSE ON WATER QUALITY IN A SOUTHERN APPALACHIAN WATERSHED1

ABSTRACT: Water quality variables were sampled over 109 weeks along Coweeta Creek, a fifth-order stream located in the Appalachian mountains of western North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with concomitant downstream changes in the mix of landuses. Variables sampled include pH, HCO₃^2?, conductivity, NO₃^?_?-N, NH₄⁺-N, PO₄^3?-P, C1^?-, Na, K, Ca²⁺, Mg²⁺, SO₄^2?, 5iO₂, turbidity, temperature, dissolved oxygen, total and fecal coliform, and focal streptococcus. Landcover/landuse was interpreted from 1:20,000 aerial photographs and entered in a GIS, along with information on total and paved road length, building location and density, catchment boundaries, hydrography, and slope. Linear regressions were performed to relate basin and near-stream landscape variables to water quality. Consistent, cumulative, downstream changes in water quality variables were observed along Coweeta Creek, concomitant with downstream, human-caused changes in landuse. Furthermore, larger downstream changes in water quality variables were observed during stormflow when compared to baseflow, suggesting cumulative impacts due to landscape alteration under study conditions were much greater during storm events. Although most water quality regulations, legislation, and sampling are promulgated for baseflow conditions, this work indicates they should also consider the cumulative impacts of physical, chemical, and biological water quality during stormflow.     

Ecosystem management to achieve ecological sustainability: The case of South Florida

The ecosystems of South Florida are unique in the world. The defining features of the natural Everglades (large spatial scale, temporal patterns of water storage and sheetflow, and low nutrient levels) historically allowed a mosaic of habitats with characteristic animals. Massive hydrological alterations have halved the Everglades, and ecological sustainability requires fundamental changes in management.The US Man and the Biosphere Human-Dominated Systems Directorate is conducting a case study of South Florida using ecosystem management as a framework for exploring options for mutually dependent sustainability of society and the environment. A new methodology was developed to specify sustainability goals, characterize human factors affecting the ecosystem, and conduct scenario/consequence analyses to examine ecological and societal implications. South Florida has sufficient water for urban, agricultural, and ecological needs, but most water drains to the sea through the system of canals; thus, the issue is not competition for resources but storage and management of water. The goal is to reestablish the natural system for water quantity, timing, and distribution over a sufficient area to restore the essence of the Everglades.The societal sustainability in the Everglades Agricultural Area (EAA) is at risk because of soil degradation, vulnerability of sugar price supports, policies affecting Cuban sugar imports, and political/economic forces aligned against sugar production. One scenario suggested using the EAA for water storage while under private sugar production, thereby linking sustainability of the ecological system with societal sustainability. Further analyses are needed, but the US MAB project suggests achieving ecological sustainability consistent with societal sustainability may be feasible.     

Angler survey contributes to socially acceptable modification of harvest regulations to preserve cutthroat trout fishery in Snake River,Wyoming, USA

This is a case study that describes a survey of anglers that was used to assist in modifying fishing regulations for indigenous trout in the Snake River, Wyoming. A mail survey of anglers who purchased 1991 Wyoming fishing licenses in the two counties adjacent to the Snake River was conducted during fall 1992. Differences in angler preferences were noted between anglers who purchased licenses in two adjacent counties with different socioeconomic structures, as well as between residents and nonresidents in each county. Anglers who purchased licenses in Teton County, where there is extensive tourism and immigration by relatively wealthy residents, tended to be more specialized and less harvest oriented. Anglers in Lincoln County, which is largely agricultural and has substantially less tourism and immigration of residents, tended to fish in many different ways and indicated more desire to harvest fish. Anglers from the two counties segregated themselves; those from Teton County primarily used the upstream portion of the study reach, and those from Lincoln County primarily used a short downstream portion of the reach. Modification of fishing regulations to reduce harvest of spawning-size cutthroat trout in the Snake River probably was acceptable to most anglers due to spatial segregation and their attitudes toward harvest.The unit is jointly supported by the University of Wyoming, the Wyoming Game and Fish Department, and the National Biological Survey.     

TEMPORAL AND GEOMORPHIC VARIATIONS OF STREAM STABILITY AND MORPHOLOGY: MAHOGANY CREEK,NEVADA1

ABSTRACT: Detailed studies of long-term management impacts on rangeland streams are few because of the cost of obtaining detailed data replicated in time. This study uses government agency aquatic habitat, stream morphologic, and ocular stability data to assess land management impacts over four years on three stream reaches of an important rangeland watershed in northwestern Nevada. Aquatic habitat improved as riparian vegetation reestablished itself with decreased and better controlled livestock grazing. However, sediment from livestock disturbances and road crossings and very low stream flows limited the rate of change. Stream type limited the change of pool variables and width/depth ratio, which are linked to gradient and entrenchment. Coarse woody debris removal due to previous management limited pool recovery. Various critical-element ocular stability estimates represented changes with time and differences among reaches very well. Ocular stability variables tracked the quantitative habitat and morphologic variables well enough to recommend that ocular surveys be used to monitor changes with time between more intensive aquatic surveys.