Gorgonian distribution patterns in coral reef environments of the Gulf of Mexico:: evidence of sporadic ecological connectivity?

Gorgonian species richness and abundance were documented in a survey of 14 reefs across the Gulf of Mexico. The results show two main patterns: (1) a westward decreasing gradient in gorgonian diversity and abundance at both supraspecific and specific levels, from the Yucatan straits to the southwestern Gulf of Mexico reefs; and (2) a northward decreasing gradient in gorgonian diversity and abundance, only apparent at the reef group scale, in the southwestern Gulf of Mexico. Even though the Campeche reef system consists of widely dispersed reefs, their gorgonian faunas are relatively rich, indicating that no isolation exists in this extensive area. In contrast, gorgonians in the continentally influenced reefs of the southwestern Gulf of Mexico are rare, even though scleractinians are diverse and abundant. The author suggests that the observed patterns in gorgonian species richness and abundance cannot be explained solely by factors such as geographical setting, reef morphology, habitat suitability, storm effects, or anthropogenic impacts. Instead the observed patterns may primarily reflect limitations in ecological connectivity at the mesoscale, variably affected by ocean and shore current dynamics, as well as by continental and local effects.