Sediment tolerance of two different morphotypes of the deep-sea coral Lophelia pertusa from the Gulf of Mexico

Abstract

On the upper slope of the northern Gulf of Mexico, topographic features are often asso- ciated with authigenic carbonate, which provides hard substrate for sessile benthic communities. At depths >300 m, large Lophelia pertusa colonies frequently occur on these carbonate outcroppings. Surficial sediments at these depths are dominated by fine-grained particulates, which are readily resuspended during the episodic high current events that have been documented for the Gulf of Mexico. Colonies of L. pertusa found in the deep Gulf of Mexico exhibit 2 distinct growth forms: the very heavily calcified 'brachycephala' and the more fragile 'gracilis'. The objective of this research was to determine the tolerance of these 2 morphotypes to suspended sediment and to complete bur- ial, using sediment collected from the study region. Results demonstrated that, although both mor- photypes of L. pertusa can tolerate fairly heavy sediment conditions, mortality increases rapidly with longer burial or higher sediment loads.