Distribution patterns and benthic assemblages associated with Pyropia columbina, a harvested alga from the Atlantic Patagonian coast

Abstract

The benthic communities on rocky shores are shaped by a combination of biological, physical, and anthropogenic stressors. On Atlantic Patagonia's intertidal rocky shores, the seaweed Pyropia columbina plays an important ecological role and contributes economically to local communities. Despite its dominance in the benthic assemblage and the longstanding harvesting tradition, no previous studies have described changes in algae cover or the environmental factors shaping these patterns. Moreover, basic characteristics associated with the species have not been described in detail yet. The main objective of this study was to describe the populations of P. columbina along the Patagonian coast. Specific goals included evaluating the spatial and temporal distribution, abundance patterns of P. columbina and its associated benthic assemblages, and identifying the influence of environmental factors on these patterns. Additionally, we detailed the settlement substrates and attachment strength across different sites. Sampling was conducted at five locations on Patagonian coast, during two seasons (autumn and spring) over two years at the mid-intertidal level. Our results showed a greater cover of P. columbina in spring, related to its annual life cycle. Multivariate analyses of primary cover revealed similar assemblage structures across most sites. The main factors influencing the structure of benthic assemblages were wave exposure, rugosity, slope, maximum wave height, and suspended matter. Perumytilus purpuratus was the dominant species at most sites and the primary settlement substrate for P. columbina. The attachment strength of the algae was higher in spring and at sites with greater wave exposure, varying across different substrates. This study offers the first comprehensive description of the distribution patterns of P. columbina and its associated benthic communities on the rocky shores of Patagonia, providing valuable insights for the ecosystem-based management of these coastal areas.