Assessment of macroalgae coverage in a scarcely studied deep rocky reef in the tropical eastern Mexican Pacific

Abstract

The biodiversity of epibenthic communities in rocky reefs in the Mexican tropical Pacific has been studied minimally during the past three decades. This study describes the abundance and distribution of algae and invertebrates in a deep rocky reef from this region. Samples were taken at 20 m depth in 2012 by randomly placing 50×50 cm quadrats. Also, photographs were taken of each quadrat to quantify the coverage of organisms. Throughout the study, the algae were the most abundant group (17748.5 cm m-2), of which encrusting calcified (6350.9 cm m-2), turf (3040.3 cm m-2), and larger-sized articulated corallines (2700.9 cm m-2) had the highest coverage. Regarding invertebrates, zoanthids (1153.3 cm m-2) and corals (746.7 cm m-2) had high coverage. All of the algal groups were found on vertical and horizontal substrates. The detrended correspondence analysis showed that larger-sized articulated corallines and encrusting not calcified groups were prevalent on the horizontal substrate and corals on the vertical substrate. These abundance and distribution patterns represent the first quantitative study of rocky reefs from the region. Considering the rapid influence of human activities in this coastal zone and the fact that rocky reefs have been minimally studied, there is a clear need for long-term monitoring programs to establish reef communities' patterns and processes, which are useful in conservation programs.