Small-scale vertical distribution of macrofauna on a shallow tropical coral reef

Abstract

Around 15% of small vagile macrofauna could be radically disturbed and even become locally extinct in a scenario of coral reef drowning in the coming decades. Benthic organisms distribute themselves in zones of their preference, regulated by physical and biological factors, at a broad or small scale. Studies on small-scale vertical distribution are expected to grow in terms of relevance due to the likely consequences of potential rises in sea level for ecosystem biodiversity. Due to the scarcity of knowledge on this topic, this study aims to characterize the small-scale vertical distribution and zonation of the macrobenthic community in the midlittoral and shallow infralittoral zones of a coral reef environment. For the first time, we tested the hypothesis that there are important differences in the vertical distribution patterns of macrofauna in the reef environment using Artificial Substrate Units (ASU). Community structure showed significant differences even within a few centimeters. The midlittoral showed greater heterogeneity than the infralittoral, which may be threatened by the rise in mean sea level. In the horizontal plane, differences in community structure were observed, probably due to physical factors such as current flow and wave energy. The paucity of this type of research suggests the need for experimental work aimed at investigating the risks of sea level rise regarding habitat loss, biodiversity, and the modification of macrobenthic communities of coastal reefs.