/pdf/economic-and-environmental-threats-of-alien-plant-animal-and-3hccj4yjhj.pdf

Economic and environmental threats of alien plant, animal, and microbe invasions

With recent increases in the numbers of species reintroduction projects and reintroduction-related publications, there is now a recognizable field of reintroduction biology. Nevertheless, research thus far has been fragmented and ad hoc, rather than an organized attempt to gain reliable knowledge to improve reintroduction success. We reviewed 454 recent (1990-2005) peer-reviewed papers dealing with wildlife reintroductions from 101 journals. Most research has been retrospective, either opportunistic evaluations of techniques or general project summaries, and most inference is gained from post hoc interpretation of monitoring results on a species-by-species basis. Documentation of reintroduction outcomes has improved, however, and the derivation of more general principles via meta-analyses is expected to increase. The fragmentation of the reintroduction literature remains an obstacle. There is scope to improve reintroduction biology by greater application of the hypothetico-deductive method, particularly through the use of modeling approaches and well-designed experiments. Examples of fruitful approaches in reintroduction research include experimental studies to improve outcomes from the release of captive-bred animals, use of simulation modeling to identify factors affecting the viability of reintroduced populations, and the application of spatially explicit models to plan for and evaluate reintroductions. We recommend that researchers contemplating future reintroductions carefully determine a priori the specific goals, overall ecological purpose, and inherent technical and biological limitations of a given reintroduction and that evaluation processes incorporate both experimental and modeling approaches. We suggest that the best progress will be made when multidisciplinary teams of resource managers and scientists work in close collaboration and when results from comparative analyses, experiments, and modeling are combined within and among studies.

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Developing the science of reintroduction biology.

Studies were conducted in four distinct geographic areas (biomes/sites) in northern United States to examine changes in key ecosystem parameters: benthic organic matter (BOM), transported organic matter (TOM), community production and respiration, leaf pack decomposition, and functional feeding-group composition along gradients of increasing stream size. Four stations ranging from headwaters (1st or 2nd order) to midsized rivers (5th to 7th order) were examined at each site using comparable methods. The results for each parameter are presented and discussed in light of the River Continuum Concept of Vannote et al. (1980). The postulated gradual change in a stream ecosystem's structure and function is supported by this study. However, regional and local deviations occur as a result of variations in the influence of: (1) watershed climate and geology, (2) riparian conditions, (3) tributaries, and (4) location-specific lithology and geomorphology. In partic- ular, the continuum framework must be visualized as a sliding scale which is shifted upstream or downstream depending on macroenvironmental forces (1 and 2) or reset following the application of more localized "micro"-environmental influences (3 and 4). Analysis of interactions between BOM and TOM permitted evaluation of stream retentiveness for organic matter. Headwaters generally were most retentive and downstream reaches the least. Estimates of organic matter turnover times ranged between 0.2 and 14 yr, and commonly were 1-4 yr. Both turnover times and distances were deter- mined primarily by the interaction between current velocity and stream retention. Biological processes played a secondary role. However, the streams varied considerably in their spiraling of organic matter due to differences in the interplay between retentiveness and biological activity. Differences in the relative importance of retention mechanisms along the continuum suggest that headwater stream ecosystems may be functionally more stable, at least to physical disturbances, than are their inter- mediate river counterparts.

Interbiome comparison of stream ecosystem dynamics

While the impacts of high exploitation on fish populations and aquatic ecosystems are well-documented for commercial fishing, particularly in the marine environment, the potential biological impacts of angling received less attention. This paper discusses angling patterns within a framework of basic ecological and evolutionary literature and examines potential biological impacts of angling by focusing on study results associated with high exploitation rates and pronounced selective exploitation. The impacts range from impacts occurring directly on the exploited species (truncation of the natural age and size structure, depensatory mechanisms, loss of genetic variability, evolutionary changes), to those that occur on the aquatic ecosystem (changes in trophic cascades, trait-mediated effects). As a third category, impacts related to the angling activity per se are distinguished (habitat modifications, wildlife disturbance, nutrient inputs, loss of fishing gear). Although the main threats to fish often are l...

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Documented and Potential Biological Impacts of Recreational Fishing: Insights for Management and Conservation

Freshwater species and habitats are among the most threatened in the world. One way in which this growing conservation concern can be addressed is the creation of freshwater protected areas. Here, we present three strategies for freshwater protected-area design and management: whole-catchment management, natu- ral-flow maintenance, and exclusion of non-native species. These strategies are based on the three primary threats to fresh waters: land-use disturbances, altered hydrologies, and introduction of non-native species. Each strategy draws from research in limnology and river and wetland ecology. Ideally, freshwater protected areas should be located in intact catchments, should have natural hydrological regimes, and should contain no non- native species. Because optimal conservation conditions are often difficult to attain, we also suggest alterna- tive management strategies, including multiple-use modules, use of the river continuum concept, vegetated buffer strips, partial water discharges, and eradication of exotic species. Under some circumstances it may be possible to focus freshwater conservation efforts on two key zones: adjacent terrestrial areas and headwaters.

/pdf/freshwater-protected-areas-strategies-for-conservation-2qsy6978ol.pdf

Freshwater Protected Areas: Strategies for Conservation

Today fish are no longer seen as simply prey to man's obsession with catching things, but have become important indicators to the health of any water body, as well as a fascinating area of our fauna. In this treatise on freshwater fish, the authors analyze the reasons for the paucity of British fish species as well as identifying reasons for a particular species' distribution. They discuss the biology and its effect on the ecology of each species, including methods of investigation, distribution, habitats, conservation, rare and endangered species and identification.

Freshwater fishes of the British Isles

The conservation of freshwater fish: Past and present experience

1. The objective of this paper is to review the status of all freshwater fishes in the British Isles and to identify theatened species, races and communities which are in need of conservation.

2. Using objective criteria to assess the degree of threat, two of the 55 freshwater species known in the British Isles are thought to be extinct here and eight are believed to be under significant threat.

3. The biology of these ten species is reviewed. They are: Sturgeon Acipenser sturio, Allis Shad Alosa alosa, Twaite Shad Alosa fallax, Arctic Charr Salvelinus alpinus, Houting Coregonus oxyrinchus (extinct), Powan Coregonus lavaretus, Pollan Coregonus autumnalis, Vendace Coregonus albula, Smelt Osmerus eperlanus and Burbot Lota lota (extinct).

4. In addition, there are several races of commoner species which are believed to be worthy of special conservation measures. These fish include the purely freshwater race of River Lamprey Lampetra fluviatilis in Loch Lomond, dwarf Brook Lampreys Lampetra planeri in the Inner Hebrides, spineless Three-spined Sticklebacks Gasterosteus aculeatus in the Outer Hebrides and a number of important races of Brown Trout Salmo trutta in various waters in Ireland and Scotland.

5. There is also a range of fish communities in individual rivers and lakes which merit conservation attention. These are important for a variety of reasons, including high (and very low) diversity, unique assemblages, pristine stocks and highly characteristic communities.

6. The major threats to these species and communities include industrial and domestic pollution, acidification, land use changes, river barriers, drainage, fish farming, fishery management and the introduction of new species.

7. The identification of these threatened fishes and important freshwater sites provides a foundation for a review of existing protection in the British Isles and a major fish conservation management programme. These will be described in subsequent papers.

Peter S. Maitland

Papers

Freshwater fishes of the British Isles

The conservation of freshwater fish: Past and present experience

Conservation of freshwater fish in the British Isles: The current status and biology of threatened species

A comparative study of water level regimes and littoral benthic communities in Scottish lochs

A Key to the Freshwater Fishes of the British Isles