Terry Parr notes "the importance of the thousands of protected sites, not as individual sites, but as a single inter-linked network. ..... to create a network of sites that enables species to disperse to new sites and gives the greatest resilience to climate change?"

I have never believed that an interconnected 'network' of marine protected areas is a possibility - and argued that point with folks who worked hard to get "network" into the wording from the World Summit on Sustainable Development to "develop a representative network of marine protected areas (MPAs) by 2012".

The marine environment is highly connected - species that have planktonic larvae or that are free-swimming/drifting spread readily especially via water currents. It is most likely that man-made structures (artificial reefs, wrecks, coastal defences) provide stepping-stones that are aiding spread of species as a result of seawater and air temperature warming.

Exceptions to connectedness occur - especially where larvae are short-lived or where asexual reproduction is the norm or where larvae are trapped by geography.

Recent work undertaken at Queens University Belfast (Mark Jessop, Louise Allcock, Mark Johnson, Catriona McInerney) University College Dublin (Olwyen Mulholland, Tasman Crowe) and University College Cork (Rob McAllen) and presented at the European Marine Biology Symposium last week suggests, through genetic mapping, that in some reserves such as Lough Hyne, species are genetically isolated from the adjacent coast. In others, such as Strangford Lough, connections can be found but do not generally extend more than about 35 km (my interpretation). My interpretation of their findings is that reserves are important as 'high value refuges' which might supply larvae and juveniles to exploited areas immediately adjacent to them but not because they are connected and they will not re-colonise each other in case of disaster. Recolonisation would come from the adjacent (un-designated) sea area.

There are also naive calculations being undertaken to identify critical distances between SACs established under the Habitats Directive. Only if the biotopes in those SACs are the same should critical distances for those biotopes and their component species be suggested.

All-in-all, my view is - do not go looking for connectedness between protected areas in the sea; such connections are only part of a generality. Marine protected areas should work to maintain the richness and 'specialness' of the particular area and, especially if strictly protected, should have the bonus of supplying larvae and individuals to adjacent exploited/damaged areas. Protected areas work to mitigate the effects of climate change by taking-off other pressures which, with climate change, might otherwise have adverse effects.

Keith Hiscock
Marine Biological Association