Depth distribution of a new invasive coral (Gulf of Mexico) – Tubastraea micranthus, comparisons with T. coccinea, and implications for control

Abstract

The Indo-Pacific coral Tubastraea micranthus recently invaded a region near the Mississippi River mouth, Gulf of Mexico, and its populations have been expanding. Its congener, Tubastraea coccinea, invaded during the 1940s and is now common in the western Atlantic. Accessibility is important in determining whether an invasive species can be controlled/eradicated. In the marine environment, depth limits accessibility. We assessed the depth distribution of T. micranthus and T. coccinea on 15 oil/gas platforms using remotely operated vehicles (ROVs). Pooled data indicated that T. micranthus extends to 138 m and probably deeper, while T. coccinea is generally limited to 138 m. Tubastraea coccinea were limited to shallow waters on all platforms. Detailed depth distribution patterns varied significantly between analyses using density and percent-cover data, with density probably indicating colonization rates, and percent-cover colony growth. Depth limitation by T. coccinea may be associated with food availability rather than light since it is azooxanthellate. The occurrence of T. micranthus in deep water will most likely make any control or eradication efforts difficult, due to cost and a rapid rate of population expansion.