The importance of periodic droughts for maintaining diversity in the freshwater environment

Whereas some species may rely on periodic drought conditions for part of their life histories, or have life strategies suited to exploiting the habitat or changed environmental conditions that are created by drought, for other organisms it is a time of stress. Periodic drought conditions therefore generate a series of waves of colonization and extinctions. Studies on lowland wet grassland, in winterbournes and in the toiche zone of both ponds and rivers, also demonstrate that different organisms are competitively favoured with changing hydrological conditions, and that this process prevents any one species from overwhelming its competitors. Competitive impacts may be inter- and intraspecific. It is therefore apparent that the death of organisms such as adult fish during severe drought conditions, though traumatic for human onlookers and commercial interests, may be merely a regular occurrence to which the ecosystem is adapted. The variability of climatic conditions thereby provides a direct influence on the maintenance of biological diversity, and it is this very biodiversity that provides the ecosystem with the resilience to respond to environmental changes in both the short and the longer term.

Impact Assesment of ionising Radiation on Wildlife

This is the Impact Assessment of ionising Radiation on Wildlife document produced by the Environment Agency in 2001. This report describes the behaviour and transport of radionuclides in the environment, considers the impact of ionising radiation on wildlife, and makes recommendations on an approach for the Impact assessment of ionising radiation on wildlife for England and Wales. The assessment approach focuses on three ecosystems representative of those considered potentially most at risk from the impact of authorised radioactive discharges, namely a coastal grassland (terrestrial ecosystem); estuarine and freshwater ecosystems. The likely scale of the impact on wildlife is also assessed in light of a preliminary analysis based on this assessment approach. The report demonstrates the behaviour and transfer of radionuclides in a number of different ecosystem types. Particular emphasis is placed on exposure pathways in those ecosystems most likely to be impacted by the authorised discharges of radioactivity within England and Wales. The use of biomarker techniques is reviewed in the report, and their application to the study of exposure to multiple contaminants is discussed.

River Gowy rapid corridor survey July 1995. Ecology South Mersey

This is the River Gowy rapid corridor survey July 1995: Ecology South Mersey report produced by the National Rivers Authority North West Region in 1995. This report looks at the survey carried out by the South Mersey Ecology Team prior to routine deweeding operations on the main River Gowy at the end of July, 1995. The survey covered Flood Defence Stretch References RGOW03 to RGOW16. These stretches were further divided into a series of 43 stretches, each one being approximately 500m in length for ease o f mapping by Ecology. Recommendations for each length have been cross-referenced with the Bill of Quantities where possible, e.g. retention o f margins. In Flood Defence stretch RGOW03, the South West Winter Wetland forms an important habitat for birds. In stretches RGOW04 to RGOW05, the Gowy Meadows and Ditches have been designated a Grade A, Site of Biological Importance, by Cheshire County Council due to the nature of the acidic grassland and diverse ditches. In stretches RGOWIO to RGOW11 the left bank forms Hockenhull Platts, Grade A Site of Biological Importance and County Trust Reserve. In stretches RGOW15 to RGOW16, the area from Mill Farm to the Shropshire Union Canal is a Grade A Site of Biological Importance. These sites are very sensitive and detailed recommendations for working practices can be found in the relevant sections o f the survey.