Motile cryptofauna associated with live and dead coral substrates: implications for coral mortality and framework erosion

Coral reef cryptofauna are a diverse group of metazoan taxa that live within intra- and inter-skeletal voids formed by framework structures. Despite a hypothesized high biomass and numerous trophic roles, they remain uncharacterized relative to exposed reef communities. Motile cryptofauna were sampled from live coral colonies and dead frameworks typifying four successive levels of degradation on an eastern Pacific pocilloporid reef. Abundances and biomass were higher on live versus dead corals habitats. The density of cryptofauna per volume substrate was highest on dead coral frameworks of intermediate degradation, where complex eroded substrates provide abundant shelters. These data have important and far-reaching ramifications for how the diverse multispecies assemblages that are reef ecosystems will respond to anthropogenic stressors such as those associated with climate change. Extreme levels of coral mortality, bioerosion, and habitat destruction will lead to impairment and eventually loss of ecosystem functions.