Figure 4

Changes in chlorophyll a concentration with increasing  abundances of the introduced clams Potamocorbula  amurensis and Mya arenaria in San Francisco Bay. 

Source: Alpine and Cloern (1992).

but gone, in terms of species diversity, abundances, and local distributions. In more remote estuaries, little is known regarding the balance between pristine and altered conditions. And, for other estuaries, there appear to be far more species now than ever before (e.g., 200 introduced marine, brackish, and freshwater animal and plant species have been added in 150 years to the San Francisco Bay and delta region [Carlton and Cohen, pers. comm., 1994]), but little is known about the structural or functional consequences of this increased diversity, or of the addition of so many species to a single system at such a rapid rate.

In addition, the naturally lower diversity of most estuaries provides an opportunity to study the relationship between diversity and ecosystem function over a range of systems (see Box 9).

Coral Reefs

"At the rate things are going, there may be very few Caribbean corals to be affected by global climate change (Smith & Buddemeier 1992)."

Jackson (1994, p. 59)

Coral reefs are renowned for their remarkable diversity (Connell, 1978). Reef organisms display extraordinary specializations, intensive predator-prey evolutionary pathways, and competitive interactions within and among species



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