Coral reef fishes The most species-rich vertebrate communities known

Seven important families of coral reef fish Gobiidae Serranidae Labridae Chaetodontidae Zanclidae Acanthuridae Tetraodontidae

species worldwide, comprising 25% of the known species of marine fish

Latitudinal gradient in species richness holds for all marine fishes Possibly a result of the high number of coral reef fishes, which are found only in the tropics

However, do coral reef fishes show such a gradient within the tropical and subtropical regions? Not clearly, and their species richness is not clearly linked with reef area, which does show a gradient within the tropical and subtropical regions (more reef area at the equator)

Longitudinal patterns of coral reef fish species richness Most species-rich areas are in the western Pacific, which also has the highest richness of coral species Investigators have assumed that this is the center of origin of the group

Also, a general pattern of less species richness in the Atlantic as compared to the Pacific exists

The relationship between reef area and fish diversity longitudinally is clearly demonstrated

The high species richness in the western Pacific could be because of Sea-level changes during the period 5-2 mya, resulting in basins of water being isolated, where allopatric speciation of fishes could then take place High endemism levels in western Pacific support this idea, although high endemism is also found in Arabian Sea, Hawaii, and the Red Sea

Low species richness of eastern Pacific may be because of Westward-flowing currents Lack of stepping stones across the Pacific

Lower species richness of Atlantic compared to Pacific may be because of Lack of suitable refuges during times of environmental stress leading to Generalist species and Lack of specialists Ex. Parrotfish

Take-home message Reef area and current patterns explain some, but not all, patterns in coral reef fish species richness

Expedition to coral triangle identifies many new species