Taxonomic composition of mobile epifaunal invertebrate assemblages on diverse benthic microhabitats from temperate to tropical reefs

Anthropogenic drivers are flattening reef structure from 3-dimensional habitats composed of macroalgae and live branching corals towards low-profile turfing algae. Our current understanding of the consequences of widespread reef degradation currently fails to consider the responses of small mobile invertebrates (‘epifauna’) to patterns of change amongst reef structural elements (‘microhabitats’). Here, the taxonomic composition of 152 epifaunal assemblages was compared among 21 structurally diverse benthic microhabitats across an Australian temperate to tropical climatic gradient, spanning 28.6 degrees in latitude from Tasmania to the northern Great Barrier Reef. Epifauna varied consistently with different microhabitat types, and to a much lesser extent with latitude. Macroalgae, live branching coral and turfing algae represented 3 extremes for epifaunal community structure, with most microhabitats possessing epifaunal assemblages intermediate between these endpoints. Amongst structural characteristics, epifauna related primarily to the degree of branching and hardness of microhabitats. Mobile invertebrate communities are likely to transform in predictable ways with the collapse of large erect macroalgae and live coral towards low-lying turf-associated communities.

ESTRUCTURA DE LA COMUNIDAD EPIFAUNAL ASOCIADA A COLONIAS DE VIDA LIBRE DEL HIDROCORAL MILLEPORA ALCICORNIS LINNAEUS 1758 EN BAHÍA PORTETE, CARIBE COLOMBIANO

The epifaunal community associated with free-living colonies of Millepora alcicornis, the dominant coral species in Portete Bay, was characterized from twenty living colonies randomly collected within a shallow Thalassia testudinum seabed. The three-dimensional growth colonies sheltered 15 families, 15 genera and 18 mobile invertebrate species. The 97% of individuals was represented by decapods crustaceans specially adapted as to live in association with the host. Within them, the porcelanid Petrolisthes armatus, representing 79% of the epifauna (961 individuals), was exclusively found in a juvenile stage suggesting that M. alcicornis is mainly used by this species as a nursery zone. The epifaunal composition is partially related to coral living tissue whereas the principal simbionts size is correlated with the spatial separation of coral branches. In spite of being slightly diverse in comparison with the epifaunal community found in other coral species, the epifauna found in M. alcicornis is of great interest and peculiarity by their association with the free-living form of this coral.