7 - Some detailed examples at the population/metapopulation level

Summary

In the following chapters, I discuss some examples of equilibrium and nonequilibrium conditions in populations and communities in greater detail. Some studies deal with both populations and communities. Those with emphasis on populations are discussed in this chapter, those with emphasis on communities in Chapter 8.

Reef fishes: density dependence and equilibrium in populations?

Coral reefs are among the most diverse ecological systems on Earth. Species include not only a great range of fishes but numerous invertebrates and plants. For example, Heron Island, at the southern end of the Great Barrier Reef is a small coral cay (island) 900 × 300 m in size, with a reef about 16 km long by a few km wide around it. Nobody has ever counted the number of invertebrate species, most of which probably have not been described, but more than 900 species of fishes have been recorded there. Knowledge of how such diverse systems function is of paramount importance, and, indeed, a very large number of studies on the behavior and ecology of reef fishes in the Indo-Pacific and Atlantic Oceans have been conducted using a variety of methods. Nevertheless, agreement on some important aspects of reef fish ecology has not been reached, largely due to the great range of habitats and species, and partly due to confusion about concepts and theoretical interpretations of the findings. I will discuss some studies to show the often contradictory findings and interpretations.