Coastal communities

The intertidal zone is a complex area where the division between land and sea is unclear. Here there is a diverse range of communities including sandy beaches, rocky shores, mudflats, saltmarshes, mangrove forests as well as the complex world of estuaries. In many areas, these lie in close proximity to sources of terrestrial waste, including sediments, solid waste and pollutants such as sewage and toxic waste.

The strand-line is an area where large quantities of solid waste accumulate, and also often receives oil spills. These can have a smothering effect on some coastal communities. Oil in particular can be very damaging to intertidal plants such as mangroves, and to saltmarsh species, whilst oil impacts are also very damaging to more mobile animals, notably birds . Toxins and pathogenic micro-organisms regularly build up in filter feeders and other animals.

Climate change is likely to have effects both through changing temperatures and rising sea levels. Already observations have been made of changing distribution patterns relating to rising temperatures. In the Antarctic, Adélie Penguins, which like to nest on beaches close to sea ice have been moving further south, while the closely related Chinstrap Penguins which prefer ice-free waters are also moving further south to new nesting beaches. Detailed studies of intertidal invertebrates on the coast of California have show a gradual replacement of cool temperate species by those from more northerly climes. Sea level rise threatens coastal communities both through slow inundation and more rapid erosion. As coastlines have always been dynamic places there is little doubt that many communities could adapt to such influences, however problems are likely to occur where coastal habitats back directly onto urban and agricultural land as these habitats may be unable to undergo a process of natural retreat.