Freshwater biodiversity is the over-riding conservation priority during the International Decade for Action - 'Water for Life' - 2005 to 2015. Fresh water makes up only 0.01% of the World's water and approximately 0.8% of the Earth's surface, yet this tiny fraction of global water supports at least 100000 species out of approximately 1.8 million - almost 6% of all described species. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. Their conservation and management are critical to the interests of all humans, nations and governments. Yet this precious heritage is in crisis. Fresh waters are experiencing declines in biodiversity far greater than those in the most affected terrestrial ecosystems, and if trends in human demands for water remain unaltered and species losses continue at current rates, the opportunity to conserve much of the remaining biodiversity in fresh water will vanish before the 'Water for Life' decade ends in 2015. Why is this so, and what is being done about it? This article explores the special features of freshwater habitats and the biodiversity they support that makes them especially vulnerable to human activities. We document threats to global freshwater biodiversity under five headings: overexploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species. Their combined and interacting influences have resulted in population declines and range reduction of freshwater biodiversity worldwide. Conservation of biodiversity is complicated by the landscape position of rivers and wetlands as 'receivers' of land-use effluents, and the problems posed by endemism and thus non-substitutability. In addition, in many parts of the world, fresh water is subject to severe competition among multiple human stakeholders. Protection of freshwater biodiversity is perhaps the ultimate conservation challenge because it is influenced by the upstream drainage network, the surrounding land, the riparian zone, and - in the case of migrating aquatic fauna - downstream reaches. Such prerequisites are hardly ever met. Immediate action is needed where opportunities exist to set aside intact lake and river ecosystems within large protected areas. For most of the global land surface, trade-offs between conservation of freshwater biodiversity and human use of ecosystem goods and services are necessary. We advocate continuing attempts to check species loss but, in many situations, urge adoption of a compromise position of management for biodiversity conservation, ecosystem functioning and resilience, and human livelihoods in order to provide a viable long-term basis for freshwater conservation. Recognition of this need will require adoption of a new paradigm for biodiversity protection and freshwater ecosystem management - one that has been appropriately termed 'reconciliation ecology'.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/96AA265E3D88C95FB802E7A73CCB4332/S1464793105006950a.pdf/div-class-title-freshwater-biodiversity-importance-threats-status-and-conservation-challenges-div.pdf

Freshwater biodiversity: importance, threats, status and conservation challenges

▪ Abstract Local habitat and biological diversity of streams and rivers are strongly influenced by landform and land use within the surrounding valley at multiple scales. However, empirical associations between land use and stream response only varyingly succeed in implicating pathways of influence. This is the case for a number of reasons, including (a) covariation of anthropogenic and natural gradients in the landscape; (b) the existence of multiple, scale-dependent mechanisms; (c) nonlinear responses; and (d) the difficulties of separating present-day from historical influences. Further research is needed that examines responses to land use under different management strategies and that employs response variables that have greater diagnostic value than many of the aggregated measures in current use. In every respect, the valley rules the stream.      H.B.N. Hynes (1975)

http://deq.idaho.gov/media/525804-Landscapes_Riverscapes_Influence_landuse_stream_ecosystems_Allan_2004.pdf

Landscapes and Riverscapes: The Influence of Land Use on Stream Ecosystems

I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

Principles of Terrestrial Ecosystem Ecology

The world’s population is concentrated in urban areas. This change in demography has brought landscape transformations that have a number of documented effects on stream ecosystems. The most consistent and pervasive effect is an increase in impervious surface cover within urban catchments, which alters the hydrology and geomorphology of streams. This results in predictable changes in stream habitat. In addition to imperviousness, runoff from urbanized surfaces as well as municipal and industrial discharges result in increased loading of nutrients, metals, pesticides, and other contaminants to streams. These changes result in consistent declines in the richness of algal, invertebrate, and fish communities in urban streams. Although understudied in urban streams, ecosystem processes are also affected by urbanization. Urban streams represent opportunities for ecologists interested in studying disturbance and contributing to more effective landscape management.

/pdf/streams-in-the-urban-landscape-mt89v53ix5.pdf

Streams in the Urban Landscape

Publisher Summary This chapter discusses the chemistry of submerged soils. The chemical changes in the submerged materials influence: (a) the character of the sediment or soil that forms, (b) the suitability of wet soils for crops, (c) the distribution of plant species around lakes and streams and in estuaries, deltas, and marine flood plains, (d) the quality and quantity of aquatic life, and (e) the capacity of lakes and seas to serve as sinks for terrestrial wastes. The single electrochemical property that serves to distinguish a submerged soil from a well-drained soil is its redox potential. The redox potential of a soil or sediment provides a quick, useful, semiquantitative measure of its oxidation–reduction status. Two recent developments have stimulated interest in the chemistry of submerged soils: the breeding of lowland rice varieties, with a high yield potential, and the pollution of streams, lakes, and seas, by domestic, agricultural, and industrial wastes. The chemistry of submerged soils is valuable: (a) in understanding the soil problems, limiting the performance of high-yielding rice varieties, and (b) in assessing the role of lake, estuarine, and ocean sediments as reservoirs of nutrients for aquatic plants and as sinks for terrestrial wastes.

The Chemistry of Submerged Soils

The Ecology of Running Waters

The stream and its valley

The biology of polluted waters

Summary

1
The vertical distribution of the benthic fauna of the Speed River, Ontario, was studied over a 13-month period from October 1970 to October 1971. Various physical and chemical parameters of this interstitial environment were also measured.

2
Several new techniques for sampling the interstitial environment of rivers wert devised. These methods and their relative efficiencies are considered.

3
The validity of the terms ‘hyporheal’ and ‘hyporheic’ are discussed and the term ‘hyporheos’ is offered to replace the former.

4
A brief resume of interstitial sampling methods is given with comments on their limitations for sampling deep heterogeneous substrates.

5
Chemical parameters are thought to be more important in the control and distribution ofthe fauna than physical parameters.

6
It is suggested that many larvae of stream-dwelling chironomids have over-wintering stages when they penetrate deep into the substrate to: (a) actively feed on the trapped organic detritus; (b) follow an optimum temperature for development.

7
It is suggested that the shape of an organism determines its success as a hypo-rheic form and examples are given.

8
The numbers of animals oecurring in the sub-benthic populations are shown to be very large indeed. For the Speed River, estimates of between 184,760 and 797,960 animals/m^ are made for different times of the year. Dry weight biomass is estimated o t vary between 30 9 g and 253-2 g/m^ throughout the year.

9
Sub-benthic or hyporheic populations are shown to exist in at least three other Canadian rivers. Some ofthe animals found are shown to be common to two or more of these rivers.

10
The inefficiencies of many conventional benthic samplers in sampling the total biomass of certain streams with hyporheic populations is discussed.

/pdf/the-occurrence-of-benthos-deep-in-the-substratum-of-a-stream-1ljp71uuqp.pdf

The occurrence of benthos deep in the substratum of a stream

It is possible to calculate the annual production of stream benthic animals from data obtained from a series of good quantitative samples collected at intervals during the year. The method is explained and its limitations and shortcomings are discussed. This seems at present to be the only simple and direct method of estimating production.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1968.13.4.0569

H. B. N. Hynes

Papers

The Ecology of Running Waters

The stream and its valley

The biology of polluted waters

The occurrence of benthos deep in the substratum of a stream

a Simple Method of Assessing the Annual Production of Stream BENTHOS1