Annex I Habitats

Annex II Species

Birds

Background levels of toxic substances

Each of the profiles of toxic substances in the Appendix contains a summary of the potential effects on interest features of European marine sites.

The following sections explain the types of effects of toxic substances for Annex I habitats, Annex II species and birds.

Annex I habitats on SACs in the UK 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 communities. Toxic substances can alter the ability of sub-features to support marine communities (e.g. toxic substances can accumulate in sediments and pose a threat to marine organisms associated with the sediment). Toxic substances can directly affect marine organisms through lethal and sub-lethal (including endocrine disruption) effects via exposure in the water column, the sediment and in the food supply.

The hazard assessment of the identified toxic substances for this guidance manual has indicated the degree of toxicity to the most sensitive groups of organisms, i.e. algae, macrophytes, invertebrate phyla and fish. In many cases, this assessment will have been based on very few species that have been tested in the laboratory and it is unlikely that many of the species associated with sub-features will have been tested. Given this mis-match of information, it is only possible to use the degree of toxicity to the main groups of organisms as an indication of likely toxic effects to species associated with sub-features belonging to these groups. For example, atrazine has been identified as very toxic to algae, macrophytes and crustacea (see table linked below) based on tests on a range of algae including Laminaria, some plants including Zostera marina and some crustacea including the copepod Acartia and mysids (Appendix). In seeking to protect a sub-feature comprising algae, macrophytes and associated crustacea, whatever the component species, from a discharge containing atrazine, it is only possible to use the available information to suggest that this substance is very toxic to these groups of organisms and, therefore, the levels of atrazine in the discharge should be stringently controlled.

Marine SACs have been identified in the UK for the Annex II species: bottle-nose dolphins, otters and for common and grey seals. The exposure routes of these organisms to toxic substances include uptake via the skin (including grooming), ingestion of water and of food. The primary exposure route for toxic substances is likely to be via food. Consequently, the toxic substances posing the greatest hazard to these species are likely to be those that have the potential to bioaccumulate and that are toxic to fish (the primary food source of these species) and possibly also those that have been identified as having potential endocrine disrupting effects.

SPAs are designated for bird species and the exposure routes for these animals include ingestion of water and sediment and via the food. The primary uptake route for toxic substances is likely to be via the food. Consequently, the substances posing the greatest hazard are those that have the potential to bioaccumulate and that are toxic to invertebrates and fish (the main food sources of these animals) and possibly also those identified as having potential endocrine disrupting effects.

For Annex II species and birds, consideration also needs to be given to the indirect effects of toxic substances, e.g. acting via depletion of their food supply.

Background levels for those toxic substances contained in monitoring programmes undertaken by the environment agencies in the UK are summarised in Appendix D.

Next Section                                     References