Reproductive biology of the two main reef-building cold-water coral species (Desmophyllum pertusum and Madrepora oculata) in the Mediterranean Sea.

Although cold-water coral (CWC) biology, physiology, and connectivity, have been extensively studied, few studies have so far focused on their reproductive biology. The reproductive biology of colonies of the reef-building Lophelia pertusa (Linnaeus 1758), now synonymised as Desmophyllum pertusum , and Madrepora oculata (Linnaeus 1758) from the Mediterranean Sea, an area particularly exposed to the effects of anthropogenic pressures, was investigated for the first time using histological techniques. Samples were collected from the Lacaze-Duthiers canyon in the Gulf of Lion, northwestern Mediterranean Sea, where the corals are living at 13 °C, close to their upper limit of thermal tolerance. The gametogenic cycle suggests a seasonal spawning of D. pertusum in autumn to early winter, similarly to population from the Gulf of Mexico. This period corresponds to the formation of storm-induced deep-sea water plumes, likely acting as a time giver for coral spawning and facilitates larval dispersal. Madrepora oculata shows continuous reproduction as already identified in eastern and western North Atlantic, with reproductive features of a species less opportunistic than D. pertusum , consistent with its other biological characteristics. This difference between the two species is of paramount importance to define strategies of conservation. • First data on the reproduction of two cold-water corals in the Mediterranean Sea. • Potential spawning date in autumn and/or early winter for Desmophyllum pertusum. • Role of deep-sea currents in timing of spawning for this species. • Madrepora oculata harbor different strategy, with a continuous reproduction. [ABSTRACT FROM AUTHOR]