Data from: Fine-scale environmental specialization of reef- building corals might be limiting reef recovery in the Florida Keys

Despite decades of monitoring global reef decline, we are still largely
unable to explain patterns of reef deterioration at local scales, which
precludes the development of effective management strategies. Offshore
reefs of the Florida Keys, USA, experience milder temperatures and lower
nutrient loads in comparison to inshore reefs yet remain considerably more
degraded than nearshore patch reefs. A year-long reciprocal transplant
experiment of the mustard hill coral (Porites astreoides) involving four
source and eight transplant locations reveals that corals adapt and/or
acclimatize to their local habitat on a <10-km scale. Surprisingly,
transplantation to putatively similar environmental types (e.g., offshore
corals moved to a novel offshore site, or along-shore transplantation)
resulted in greater reductions in fitness proxies, such as coral growth,
than cross-channel transplantation between inshore and offshore reefs. The
only abiotic factor showing significantly greater differences between
along-shore sites was daily temperature range extremes (rather than the
absolute high or low temperatures reached), providing a possible
explanation for this pattern. Offshore-origin corals exhibited significant
growth reductions at sites with greater daily temperature ranges, which
explained up to 39% of the variation in their mass gain. In contrast,
daily temperature range explained at most 9% of growth variation in
inshore-origin corals, suggesting that inshore corals are more tolerant of
high-frequency temperature fluctuations. Finally, corals incur trade-offs
when specializing to their native reef. Across reef locations the
coefficient of selection against coral transplants was 0.07 ± 0.02 (mean ±
SE). This selection against immigrants could hinder the ability of corals
to recolonize devastated reefs, whether through assisted migration efforts
or natural recruitment events, providing a unifying explanation for
observed patterns of coral decline in this reef system.