The Temperate Shelf and Seas are highly productive regions of
great biological importance, supporting resident as well as
migratory species during various life cycle stages. The relative
shallowness of these regions (the continental shelf extends to
an average maximum depth of 150 meters) leads to warmer
temperatures and seasonal stratification of the water column
based on temperature. Seasonal variability, along with
freshwater influxes from coastal streams and tidal action,
contribute to very heterogeneous habitats and a corresopondingly
high diversity of organisms: fish, invertebrates (productive
benthic communities), marine mammals, and numerous marine bird
species. Some of the most productive marine ecosystems occur in
the Grand Banks and New Zealand plus the Patagonia ecoregions.
The South Australian coastal waters are remarkable for unusually
high levels of endemism in invertebrates, in addition to the
diverse marine mammal assemblage found there. Two of the world's
largest temperate estuaries, the Che