Most examples of regional and latitudinal variation in species richness cited in

Most examples of regional and latitudinal variation in species richness cited in chapter 22 have been terrestrial. Consider regional variation in marine biotas. Like birds on land, fish are one of the best-studied groups of marine organisms. Moyle and Cech (1982) cite the following patterns of fish species richness:

Atlantic and Gulf Coasts          Pacific Coast
of North America             of North America__________
Area          Species       Area          Species

Texas          400          Gulf of California    800
South Carolina    350          California       550
Cape Cod       250          Canada       325
Gulf of Maine    225
Labrador       61
Greenland       34___________________________________________

As you can see, fish species richness decreases northward on both coasts. However, the Pacific coast generally supports a larger number of species. This contrast may be another situation requiring historical- and geographic-level explanations. Explore and explain this contrast in species richness using information from the fields of marine biology, oceanography, and ichthyology. Moyle and Cech (1982) and Briggs (1974) are good starting points.