Discussion
Strikingly, nearly 70% of Pocillopora corals bleached and died
between August 2007 and July 2008 at our three study sites in the
Galápagos, which coincided with the 2007-2008 La Niña-related cold-water
anomaly. This represents a major loss of live coral foundational habitat
for associated fishes and mobile macroinvertebrates. Nevertheless, dead
coral colonies were still able to retain the ecosystem function of
hosting high species richness of associated fish and mobile
macroinvertebrates for more than two years after the disturbance.
However, the species composition of these assemblages (and particularly
of invertebrates) significantly varied between mutualistic xanthid crabs
on live corals to opportunistic and predatory pencil urchins, hermit
crabs, and gastropod snails on dead corals, and shifted over time on
live and dead corals. This shift in associated species composition was
likely due to changes in structure and provisioning of food on coral
tissue, and loss or growth of live coral tissue. Furthermore, the
speciose and opportunistic associated assemblage on dead corals
ultimately declined in richness due to erosion and disappearance of
complex coral structure, and likely led to loss of coral-associated
richness after 32-49 months.