What could happen to the features?
Many features for which marine protected areas have been designated are potentially vulnerable to climate change, meaning the on-going utility of marine protected areas as a conservation tool could be affected.
Where a marine protected area has been identified for its physiographic (e.g. large shallow inlet and bay) or seabed (e.g. mudflats or rocky reef) features, climate change could result in changes to the constituent flora and fauna, rather than the distribution or extent of the feature itself. Such changes are unlikely to compromise the achievement of conservation objectives. Protecting the healthy condition and functionality of these physiographic and seabed habitats might, in such circumstances, be more important than retaining specific species assemblages.
In contrast, where the main feature of a marine protected area is a biogenic habitat (e.g. seagrass beds) or a species, the consequences of climate change could compromise the achievement of conservation objectives. In a worst-case scenario, species or habitats could be lost entirely from the marine protected area.
As marine protected areas have boundaries based on a present-day snapshot of the distribution and condition of marine habitats and species, the consequences of climate change on marine protected areas could be that:
The quality of the feature changes
For example, in the northernmost Atlantic marine ecosystem, increased carbon dioxide (CO2) is likely to stimulate the growth of seagrasses such as Zostera marina, but the increase in acidity of the seawater will be corrosive to maerl.
Maerl bed © Ross Bullimore
A feature is gained to a particular marine protected area
A marine protected area may become more suitable for the establishment of a designated feature. For example, Laminaria ochroleuca, a southern species of kelp is increasing its distribution and abundance in the UK with increasing temperatures and competing with the current dominant species Laminaria hyperborea. This may influence the make-up of kelp beds as a designated feature and could require new approaches to management as L. ochroleuca is more vulnerable to storm damage and exhibits different biodiversity patterns and ecological processes to L. hyperborea.
Laminaria ochroleuca © Keith Hiscock
The composition of the feature changes
This could include a change in biodiversity and increased opportunities for non-native species establishment (e.g. Sargassum muticum) that may continue to spread, altering community composition. Changes in biodiversity may be facilitated by increasing levels of carbon dioxide and warming seas which are expected to impact on feature composition. An example is provided below for predicted changes in boreal northeast Atlantic benthic marine flora.
Reproduced with permission of Brodie et al. (2014) The future of the northeast Atlantic benthic flora in a high CO2 world. Ecology and Evolution. doi:10.1002/ece3.1105
A feature is lost from the UK marine protected area network
Horse mussel beds (Modiolus modiolus) currently appear as a designated feature in ten marine protected areas. Based on the projections below, there is a risk that this feature will no longer be represented in the UK marine protected area network by 2100 due to rising sea temperatures.
Modified under CC-BY license from Gormley et al. (2013) Predictive habitat modelling as a tool to assess the change in distribution and extent of an OSPAR Priority Habitat under an increased ocean temperature scenario: Consequences for Marine Protected Area networks and management. PLoS ONE. 8(7): e68263. doi:10.1371/journal.pone.0068263
A feature expands within the UK marine protected area network
Features limited to a single or small number of marine protected areas may expand into other marine protected areas as a result of more suitable conditions. The little egret, protected under the Tamar Estuaries Complex Special Protection Area, has expanded rapidly in the UK. Its first breeding record was in Poole Harbour, Dorset, in 1996; but by 2012, there were over 900 breeding pairs all around the UK.
Number of breeding pairs of little egret in the UK by year, based on information from the Rare Breeding Birds Panel.
Reproduced with permission from the British Trust for Ornithology.
A feature is lost from a particular marine protected area
There is increasing evidence that the over wintering distributions of some coastal waders has changed in response to warming. In the last decade there has been a general decline in the use of the UK’s east coast sites in favour of the Netherlands by some species, such as dunlins (below), as conditions there have become more favourable.
Photo: Dunlin - iStock.com/PaulReevesPhotography