|
Aquatic creepy-crawlies tell us we’re improving their environment! Five year report shows general improvement in rivers 23 January 2007 Overall the Isle of Man’s rivers are of good quality - indeed better on average than those in England, Wales and Northern Ireland. No less than 99% rate as at least fair in terms of both biological quality (i.e. types of insects, snails and crustaceans living in the rivers) and general chemical quality (i.e. oxygen levels and ammonia), meeting the Department of Local Government and the Environment’s Key Performance Indicator for river water quality. These facts are detailed in a new report covering river surveys from Autumn 2000 to Autumn 2005 issued by the Government Laboratory. The majority of rivers have improved over the past five years, though there are localised differences, with some stretches of some rivers having deteriorated slightly. This is illustrated by nutrients such as phosphate, typically arising from artificial fertilisers, farm slurry and sewage effluent. Whilst the level of phosphate in the majority of rivers is moderately low or better, levels have increased in several rivers so that only 95% now meet this rating for phosphate, although another key nutrient, nitrate, is moderately low or better in 99% of rivers. Excessive nutrients can lead to excessive plant growth and lower oxygen levels for fish and invertebrates. Ever-present threats to water quality such as this mean that although our watercourses are in a good condition overall, vigilance is always required to protect them. The latest report on river quality also includes the results of an Island-wide survey of metal levels in rivers, which in some cases show residual levels that correlate with historical mining activities. While the levels of metals found are not a concern for human health, the Island’s geology, disused mine workings and associated deposits, and land use all interact to determine the sorts of insects, crustacea and fish that can live in the rivers. The Department of Local Government and the Environment’s Environmental Protection Unit sets limits for and licenses any discharges of trade or sewage effluents into rivers, and takes action on pollution incidents. This vital work is undertaken to clean up rivers where necessary, and otherwise to maintain their quality as a natural resource for the Island, and also to protect the marine environment into which they flow. The assessment of river water quality informs the work of that Unit, and shows the beneficial outcome of effective pollution control. The science behind this assessment involves the Government Laboratory’s Freshwater Biologist investigating over 80 sites three times a year, covering all major rivers on the Island. His work requires him to venture out in all but the wildest of weathers to collect samples of water and mud, leaves, stone and rock from the river bed. These are taken back to the Laboratory for chemical analysis of the water, and for detailed examination to determine the types of invertebrate life (insects, crustaceans, snails and worms) that are present in the river bed. This is key to the assessment as it is the survival of these natural inhabitants that gives a real indication of the quality of the water on which they depend for their existence, and of any changing conditions. Aquatic creepy-crawlies telling us whether or not we are being kind to their environment, which is part of our environment! More stories >>>
|
