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Benthic recovery from climate-related disturbances does not always warrant
a commensurate functional recovery for reef-associated fish communities.
Here, we examine the distribution of benthic groupers (family Serranidae)
in coral reef communities from the Lakshadweep archipelago (Arabian Sea)
in response to structural complexity and long-term habitat stability.
These coral reefs that have been subject to two major El Niño Southern
Oscillation-related coral bleaching events in the last decades (1998 and
2010). First, we employ a long-term (12-yr) benthic-monitoring dataset to
track habitat structural stability at twelve reef sites in the
archipelago. Structural stability of reefs was strongly driven by exposure
to monsoon storms and depth, which made deeper and more sheltered reefs on
the eastern aspect more stable than the more exposed (western) and
shallower reefs. We surveyed groupers (species richness, abundance,
biomass) in 60 sites across the entire archipelago, representing both
exposures and depths. Sites were selected along a gradient of structural
complexity from very low to high. Grouper biomass appeared to vary with
habitat stability with significant differences between depth and exposure;
sheltered deep reefs had a higher grouper biomass than either sheltered
shallow or exposed (deep and shallow) reefs. Species richness and
abundance showed similar (though not significant) trends. More
interestingly, average grouper biomass increased exponentially with
structural complexity, but only at the sheltered deep (high stability)
sites, despite the availability of recovered structure at exposed deep and
shallow sites (lower-stability sites). This trend was especially
pronounced for long-lived groupers (life span >10 yrs). These
results suggest that long-lived groupers may prefer temporally stable
reefs, independent of the local availability of habitat structure. In
reefs subject to repeated disturbances, the presence of structurally
stable reefs may be critical as refuges for functionally important,
long-lived species like groupers.
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