Annex I Habitats

Annex II Species

Birds

Background levels of non-toxic substances

Each of the profiles of non-toxic substances in Appendix C contains a summary of the potential effects on interest features of European marine sites. The following Sections explain the types of effects of non-toxic substances for Annex I habitats, Annex II species and birds.

Annex I habitats on SACs in the UK (see Table 1) include interest features that are either physiographic (estuaries, shallow inlets and bays, lagoons) or major habitats (subtidal sandbanks, intertidal sand and mudflats, reefs and caves) and each comprises possible sub-features. The sub-features are biotopes comprising physical aspects of the habitat and associated marine organisms.

Non-toxic substances can have profound effects on Annex I habitats because they can be discharged in large quantities. For example, many UK estuaries have been changed fundamentally because of the discharge of sewage effluents containing organic carbon, oxygen depleting substances, nutrients as well as some toxic substances.

The primary effects of the non-toxic substances considered in this guidance manual are to change the physico-chemical nature of the environment. This often leads to secondary effects resulting in changes in the physical aspects of the habitat and associated marine organisms.

The hazard assessment of the identified non-toxic substances has indicated primary and secondary effects on the marine environment.

Marine SACs have been identified in the UK for Annex II species: bottle-nose dolphins, otters and for common and grey seals. These animals are not affected by the primary effects of non-toxic substances but may be by secondary effects. Nutrient and organic enrichment can stimulate fish production and therefore potentially have a positive effect on sea mammal population. However, excess supply can suppress fish production and potentially have a detrimental effect. The scale of any effect depends largely on the extent to which these animals feed in European marine sites and what proportion of their life they spend there.

SPAs are designated for bird species and these are not affected by the primary effects of non-toxic substances. However, the secondary effects of many of the non-toxic substances can have a considerable effect on bird populations by influencing the availability of an appropriate food supply. Nutrient and organic enrichment can have a positive effect on populations by increasing the supply of organic carbon to the sediments, stimulating the production of sediment-dwelling invertebrates and enhancing the food supply. Increased temperature from power station effluents can also stimulate greater production of sediment-dwelling organisms. However, excessive supply of nutrients and organic carbon can result in deoxygenation of the water column and the sediments suppressing the production of food organisms and therefore adversely affect bird populations.

Background levels for non-toxic substances are contained within each of the profiles in the Appendix.

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