Theme 7 Biodiversity of coastal and marine habitats and ecosystems

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This article provides a summary classification for the biodiversity of coastal and marine habitats, including those of transitional waters (e.g. estuaries). It provides an outline of the key areas for developing the Coastal Wiki in relation to coastal and marine biodiversity and their conservation in the light of human management and exploitation. In the face of increasing pressure from human activities, Theme 7 provides a forum for discussion and sharing knowledge on the threats and policy-making requirements aimed at integrated action for conservation and restoration of the coastal and marine habitats and ecosystems.

The State of the Art of theme 7 on Restoration and preservation of coastal biodiversity can be found here


The coastal zone includes three overlapping areas. These are not mutually exclusive but often include transitions between habitats. They are dynamic with special geomorphological characteristics dealt with under Theme 5, which includes a classification of coastlines. The three key areas used to categorise the habitats and ecosystems are:

Fig. Skagen dune & spit. Copyright: J. Pat Doody

1. Terrestrial coastal habitats and ecosystems

Terrestrial coastal habitats and ecosystems are those influenced by coastal processes, but lying above the limit of the tides. They include cliffs, islands, sand dunes, shingle (boulder/pebble) banks and other habitats in close proximity to the sea.

Fig. Blackwater Estuary, Essex, England. Copyright: J. Pat Doody

2. Coastal habitats and ecosystems in transitional waters

Coastal habitats and ecosystems in transitional waters are those where tides and wave action transport sediments, which help to form habitats such as salt marshes. Tidal estuaries and deltas provide a link between the land and the sea where tidal water and freshwater river flows interact.

Fig. Posidonia. Copyright: J.G. Harmelin

3. Marine habitats and ecosystems

Marine habitats and ecosystems are areas covered by the sea all the time and include the seabed and water column. These formed part of the original discussion under the ENCORA Theme 7 introduction to marine biodiversity, which included evaluation of biodiversity in relation to conservation and restoration of marine habitats and species.


Throughout history, humans have exploited the coastal zone. Early occupation had little impact but as populations grew and with it, an ability to modify the environment, coastal areas were amongst the first to be altered. Enclosure for infrastructure, agriculture and other uses affect coastlines around the world Theme 6. The continuing attrition through coastal 'land claim' has resulted in the loss and degradation of coastal habitats around the world. When accompanied by a relative sea level rise the losses can be substantial. The process has become known as 'coastal squeeze' in the UK [1].

The rivers and estuaries became the conduit for disposal of human effluent and the sea a dumping ground resulting in eutrophication. Estuaries in particular also receive many polluting chemicals via river inputs and deposition from the atmospheric, which eventually reach the coastal seas. Some of the more toxic substances directly influence the health of marine/coastal species and through this the coastal and marine food chain and the functioning of entire ecosystems. At the same time increased exploitation of coastal and marine resources, including commercial fishing deplete populations and reduce biodiversity.

Both coastal and marine habitats have seen an increase in the establishment of invasive, alien plant and animal species. This represents a significant threat to the marine environment especially in relation to fishing.

Global climate change affect the coastal zone in a variety of ways, notably as a result of sea level rise and the increased incidence and severity of storms. The effects on the marine environment include changes in primary production, recruitment (of commercial fish species), distribution and community structure. In addition to the impact on the natural environment, it may also affect the ability of the zone to provide the goods and services we rely upon.


Against the background of damage and destruction, unsustainable exploitation and more recently the recognition of the implications of global warming, management and restoration of the zone have become more and more important. The interrelated nature of the coast requires an integrated response to these changes, including the restoration of damage caused by human activities. ENCORA Theme 7 looks at the structure and function of the coastal zone and its natural variability in relation to human activities. It includes descriptions of the physical coast and biological diversity, methods of assessment of change (including the development of marine biological valuation maps), options for management and methods of restoration.

Examples of good practise will include case studies from around the world. Theme 1 deals with “Social and economic aspects of ICZM Multifunctionality and Valuation”; Theme 2 “ICZM Participation and Implementation”; Theme 3 “Coastal and marine spatial planning”; Theme 4 “Pollution, prevention and mitigation”. These collectively deal with the implementation of management and restoration in the coastal and marine environments.


  1. Doody, J.P. (2004) 'Coastal squeeze' - an historical perspective. Journal of Coastal Conservation, 10/1-2, 129-138.
The main author of this article is Doody, Pat
Please note that others may also have edited the contents of this article.

Citation: Doody, Pat (2009): Theme 7 Biodiversity of coastal and marine habitats and ecosystems. Available from [accessed on 17-07-2019]