Recurrent partial mortality events in winter shape the dynamics of the zooxanthellate coral Oculina patagonica at a high latitude in the Mediterranean
Serrano, E.; Ribes, M.; Coma, R.
2017
Coral Reefs
36
27-38
Global warming has many biological effects on
corals and plays a central role in the regression of tropical
coral reefs; therefore, there is an urgent need to understand
how some coral species have adapted to environmental
conditions at higher latitudes. We examined the effects of
temperature and light on the growth of the zooxanthellate
coral Oculina patagonica (Scleractinia, Oculinidae) at the
northern limit of its distribution in the eastern Iberian
Peninsula (western Mediterranean) by transplanting colonies
onto plates and excluding them from space competition
over a *4-yr period. Each year, most of the colonies
(*70%) exhibited denuded skeletons with isolated polyps
persisting on approximately half of the coral surface area.
These recurrent episodes of partial coral mortality occurred
in winter, and their severity appeared to be related to colony
exposure to cold but not to light. Although O. patagonica
exhibited high resistance to stress, coral linear
extension did not resume until the coenosarc regenerated.
The resumption of linear extension was related to the dissociation
of the polyps from the coenosarc and the outstanding
regenerative capacity of this species
(10.3 mm2 d-1). These biological characteristics allow the
species to survive at high latitudes. However, the recurrent
and severe pattern of denuded skeletons greatly affects the
dynamics of the species and may constrain population
growth at high latitudes in the Mediterranean.