San Jose Gulf is a small semienclosed bay connected by a narrow mouth to a much larger basin, the San Matias Gulf. Intriguingly, this comparatively small water body, characterized by high biological productivity, has contributed most of the historical shellfish production in the region.

A remote sensing approach allowed us to advance a composite conjecture aimed at explaining that phenomenon. A combination of circulation, strong tidal currents, and coastal topography leads to the formation of a frontal system inside San Jose Gulf and to the development of turbulent fluxes that drive the hydrographic regime. The front divides the San Jose Gulf in two domains (west and east). The origin of water flowing into the west domain was tracked to the Valdes Frontal System, on the continental shelf. The west domain is highly turbulent due to the formation of vortexes and dipoles during the tidal cycle. Detachable dipoles formed at the edge of jets outflowing from San Jose Gulf can reach the central part of San Matias Gulf, constituting a possible larval transport mechanism between the two gulfs. Our results led us to postulate that (1) nutrients from the continental shelf are “trapped in” and larvae are retained in the east domain of San Jose Gulf, resulting in persistently high biomass of secondary producers, and (2) asymmetrical exchange, in the form of vorticial flows, “pumps out” waterborne material from the San Jose Gulf into San Matias Gulf, affecting the connectivity between the two basins.