Larval Transport Mechanisms Along the Yucatan Coast of Mexico and into the Gulf of Mexico

In 2004 an international cooperative research program between the U.S., Republic of Mexico, and Belize was developed to study the distribution and potential transport pathways of the larvae of commercially important fisheries species from western Caribbean spawning sites into the northern Gulf of Mexico and the Florida Straits. Our overall goal was to study larval reef fish transport mechanisms on local and regional scales between the Florida Keys and the northern extension of the MesoAmerican Barrier Reef System (MBRS). The eastern coast of the Yucatan Peninsula, south of Cozumel, contains 39 sites where spawning aggregations occur along a strong western boundary current flowing northward into the Gulf of Mexico. The Florida Keys and Dry Tortugas coral reef systems lie downstream of these spawning areas. Ocean currents and gyres in this area play a potentially important but as yet unknown role in the biological production and transport of larval fish throughout the region. During a research cruise in 2007, a cyclonic gyre formed south of Cozumel entraining large numbers of larvae and other zooplankton. The presence or absence of small coastal process such as this may play an important role in regulating downstream transport. Larval abundances of grouper and other reef fish were significantly higher in the gyre than in surrounding waters. We suggest that these processes play a key role in larval transport within this region.