Diversity and Connectivity of polychaetes in different habitats of the Santos Basin deep waters

Author(s)

Gilberto Bérgamo Neto

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2024-09-06

Examining board members

Paulo Yukio Gomes Sumida; Rafael Eiji Iwama; Wagner Ferreira Magalhães; Miguel Mies

• Advisor: Paulo Yukio Gomes Sumida

Abstract

Recent advancements in deep-sea exploration are noteworthy, revealing a diversity of organisms inhabiting unique habitats. These advances are also notable in the Brazilian Continental margin, especially at the Santos Basin, the most prolific in oil and gas exploration. Deep-sea habitats found at the Santos Basin included carbonate mounds, pockmarks, exhumed salt diapirs and organic falls, the latter represented by whale bones and wood. Polychaete species dominate the fauna of these habitats in both diversity and abundance, with different species described in the last years. Still, few studies advanced in the connectivity and evolutionary history of annelids using molecular data, which is the main focus of the present dissertation. Different case studies from distinct species were analyzed, including an eyeless group of the genus Nereis (Nereididae) with three new species, which formed a monophyletic group. This clade includes a formerly known species from Brazilian deep waters, one species formerly described from China, and the tree new species, which distribution can be explained by water masses delimitation (Chapter 1). Two Siboglinum (Siboglinidae) species previously described from the Brazilian Continental margin, from which the type specimens were lost, have been redescribed based on newly collected material. Molecular data from Siboglinum besnardi was successfully extracted and results are reported in Chapter 2. Seven distinct Gymnonereidinae (Nereididae) species are reported from different habitats of the Santos Basin and organized as two cryptic complexes based on species delimitation and phylogenetic analyses. The Micronereides capensis cryptic complex includes three species and the Ceratocephale sp. 4 cryptic complex includes other four species. These reports, together with discussions on cryptic speciation are discussed in Chapter 3. The population genetics and connectivity of a widely distributed Aphelochaeta species (Cirratulidae), inhabiting various deep-sea habitats, were investigated using different molecular markers. The gene flow seems to be continuous without habitat delimitation (Chapter 4). A comprehensive dataset produced during this dissertation is made accessible through the ABYSSAL database, which structure and operation of the latter is explained in Chapter 5. Lastly, in the final remarks section, the findings are synthesized, including a general phylogeny and species, to serve as the basis for discussion. (AU)

• FAPESP's process: 19/18136-2 - Diversity and connectivity of polychaetes in different habitats of the Santos Basin deep waters
• Grantee: Gilberto Bergamo Neto
• Support Opportunities: Scholarships in Brazil - Doctorate