Rhodoliths as Ecosystem Engineers: A new perspective from the investigation of biodiversity associated with Rhodolith Beds

• Grant number: 23/11346-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: December 01, 2023
• End date: March 31, 2025
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Guilherme Henrique Pereira Filho
• Grantee: Fernanda Caroline de Oliveira Carlos
• Host Institution: Instituto do Mar (IMar). Universidade Federal de São Paulo (UNIFESP). Campus Baixada Santista. Santos , SP, Brazil

Abstract

Understanding the ecological interaction between organisms allows for the knowledge of the functioning and organization of communities. Some species stand out in these interactions as they are considered ecosystem engineers, modulating and providing resources for other species. It is common to find in the literature the association of rhodoliths as ecosystem engineers, which, due to the complexity of their three-dimensional structure, provide habitats for associated species. However, there is a lack of information on how rhodoliths modulate biotic and abiotic factors, thereby regulating the species that inhabit them. Aspects such as structural variations and the vitality of nodules appear to be relevant for determining the organisms that establish themselves in these habitats, yet more information on this topic is still needed. In this context, we will use the Rhodolith Bed of Queimada Grande Island (São Paulo) as a model to quantify and identify the vagile macrofauna of associated invertebrates, in order to test the influence of the three-dimensional structure of nodules and the living algae cover that forms the rhodolith in this interaction. We hypothesize that (1) the three-dimensional structure of the nodules will influence the quantification and abundance of associated vagile macrofauna. And (2) the presence of the living cover on the nodules, indicated by the presence of the forming alga, will influence the composition of the macrofauna. For this purpose, specimens of three different rhodolith morphotypes known from our study area will be collected. In the laboratory, they will be washed to remove the associated live organisms. They will also be treated to obtain live nodules (with algal cover) and dead nodules (without algal cover). The specimens will be returned to the original location, organized in random blocks composed of specimens from the three morphotypes, both live and dead. After 30 days, they will be collected again to obtain data on the vagile macrofauna of associated invertebrates. Parameters such as richness, diversity, and species composition will be compared among nodules with different morphologies and between live and dead ones.