ABSTRACT
The Central American isthmus is a narrow strip of land that divides the two largest oceans of the world, the Atlantic and the Pacific. The uplift of the isthmus 3-3.5 million years before present created a landbridge connecting South and North America and closed the circumtropical flow of the between the oceans. The landbridge facilitated movement of terrestrial organisms between the two large tectonic plates as it simultaneously blocked movement of marine organisms between the now separated waters to the east (the Atlantic ocean) and to the west (the Pacific Ocean) of the isthmus. With the closure of the pre-Pliocene sea-oceanographic conditions on each side of the isthmus changed slowly, producing the tropical Atlantic and Pacific oceans of today [1, 2]. The Caribbean coast of Central America is characterized by relatively stable water temperatures, extensive coral reefs and seagrass beds, and large areas of carbonate platforms (e.g., Nicaraguan rise) [3]. The Pacific coast of the isthmus is characterized by extensive mangrove systems, isolated coral reefs of limited development, and essentially no seagrasses. Seawater temperatures in the Pacific can be extreme warm during El Niño events (up to 33 °C), or cold (as low as 12 °C) during seasonal upwelling [4-7].
