The Convention on Wetlands, signed in Ramsar, Iran, in 1971, is an intergovernmental treaty which provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources. The Ramsar website, http://www.ramsar.org/, defines wetlands to include marine and estuarine as well as lacustrine (associated with lakes), riverine, and man made wetlands.
There is a recognition that wetlands may need to adapt to changing conditions, in particular, climate change. There is even a special register (the Montreux Record) for sites at which changes in ecological character have occurred or are likely to occur. So the organising bodies of the Ramsar Convention do not expect that any particular wetland will stay the same for ever.
In fact, if seawater were to be allowed into the Lakes, wetlands of a different, but equally valuable nature would develop. The species composition would change, and it is conceivable that areas could contain large seagrass meadows which would support valuable nurseries for marine and coastal species, as well as a haven for all kinds of wildlife and migratory birds.
There are plenty of other nearly enclosed coastal lakes containing seawater (eg. the Gippsland Lakes) which are living examples of what Lakes Alexandrina and Albert could become, given attention to some important aspects described below. Some species which can only live in freshwater environments would gradually move elsewhere, such as refuges which could be set up behind the weirs. Species like samphire which already exist around the lakes are well adapted to saline conditions would expand, and other new species will migrate in to maintain the biodiversity.
by Elizabeth Gordon-Mills, Phd
Update:
Read what went on at the Wetland and Rivers Conference session in Goolwa 9th of September 2009 where a RAMSAR representative discussed that wetlands can change their character and still remain RAMSAR listed.