Fish larvae assemblages in the Gulf of California

The distributional diversity and assemblages of fish larvae in the Gulf of California indicated two main seasonal stages and two transitional periods: in winter, the tropical water mass is confined to the south-east portion of the mouth of the Gulf and larval fish assemblages are dominated by subtropical and temperate-subarctic species; in summer; tropical water invades the Gulf and assemblages are dominated by tropical species. Both seasonal stages are separated by transitional periods coinciding with strong latitudinal temperature gradients. During the autumn and spring transitional periods, the Gulf of California splits into three regions: a northern region where temperate and subarctic species spawn from autumn to spring, a southern region dominated by tropical and subtropical species year round and a central region where tropical and temperate assemblages merge. Seasonal changes in the location of the regions, as well as the borders between them, show expansion and contraction of the northern and southern faunas related to the general oceanic circulation patterns during the year.