Summaries of Biological Status Methods
Phytoplankton utilise sunlight energy and dissolved nutrients converting these into organic materials which are often consumed by higher life forms such as fish. As phytoplankton are short lived and derive their nutrients from the water; they are an ideal indicator of changing nutrient conditions and therefore useful for assessing pollution of coastal waters.
Benthic invertebrate communities are good indicators of acidification which is caused by acidic pollution from precipitation and acids leaching from the surrounding soils. Benthic invertebrates are easily suited to biological monitoring as they are common, widespread and easily sampled. This method is based on the principle that different benthic invertebrates have different tolerances to acidification. The method only applies to acid sensitive rivers or rivers that naturally have a pH lower than 7.
Macroalgae are good indicators of general pressures including, toxic substances and disturbance. They are ideally suited to monitoring as many are large, widespread and relatively easily identified. The method is based on the principle that pollution and disturbances from man made activities can alter the number of species of macroalgae expected on a shore of similar type.
Phytoplankton utilise sunlight energy and dissolved nutrients converting these into organic materials which are often consumed by higher life forms such as fish. As phytoplankton are short lived and derive their nutrients from the water; they are an ideal indicator of changing nutrient conditions and therefore useful for assessing pollution of coastal waters.
Opportunistic Macroalgae are able to utilise excess nitrogen in the environment and outcompete other seaweed species. They are easy to identify and sample so are good for monitoring the effects of nutrient enrichment. The method is based on the principle that high nutrient levels increase the growth of certain macroalgae species smothering the other species that are less tolerant to nutrient enrichment.
Macroalgae (Seaweeds belonging to the group known as ‘wracks’ of the genus ‘Fucus’). This method has been designed primarily to detect the impact of toxic substances on the distribution of certain species of macroalgae. This method monitors the upstream limit of three brown seaweed species; horned wrack, Fucus ceranoides, spiral wrack, Fucus spiralis and bladderwrack, Fucus vesiculosus. It works on the basis that man-made disturbances can limit the upstream colonisation of estuarine habitats by these species of seaweed.
Estuarine fish communities are good indicators of a range of man-made disturbances. They are mobile, relatively long lived, found near to the top of the food chain (so are affected by other parts of the chain and prone to bioaccumulation effects) and are easy to identify and return to the water: all of these characteristics make them ideal for the monitoring of estuaries. This method is based on the principle that the abundance of fish and the number of individual species found can change depending on the pressures on the estuary.
Benthic invertebrate communities are good indicators of organic pollution and are also sensitive to toxic pollutants. They are ideally suited to biological monitoring as they are sedentary and either feed upon sediment dwelling animals or the sediment . They are also relatively long-lived (more than one year) so will react to contaminant effects over time. This method is based on the principle that different benthic invertebrates have different tolerances to pollutants.
Dogwhelks are a good indicator of the contamination of the hazardous substance called tributyltin (TBT) which is used in anti-fouling paints on the hulls of large ships. Dog whelks can be used to assess the levels of TBT as it has been shown that high levels of this pollutant in the water has led to deformities in the reproductive organs of female dogwhelks. These deformities are known as imposex and the larger the concentration of TBT in the surrounding waters then the more significant the deformity of the dog whelk.
Seagrass beds provide habitats for fish, prawns and other invertebrates and provide seafloor stability and are found in the littoral1 and sub-littoral zones along the coast and estuaries. Angiosperms are sensitive to general physical disturbance such as dredging and boat traffic which can destroy the seagrass beds and also increases the suspended sediment in the coastal waters. This method works on the principle that physical disturbance and water quality changes can decrease the extent and density of seagrass beds and may also reduce the number of species found.
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