Ph.D. Hinojosa-Toledo, Ivan

Identifying the diverse assemblage of species inhabiting rocky and coral reef habitats in isolated oceanic environments, and the important sound cues emitted from the reef, are crucial components to understand how species locate suitable habitats for the completion of their life-cycle and, thus, the functioning of these vulnerable ecosystems. Recent field information suggests that the majority of reef biodiversity comprises small cryptic invertebrates; however, knowledge on these small components is extremely scarce. The present study used light attraction methods to explore the diversity of larval, post-larval and macrobenthic cryptic fauna, and hydrophones to characterize the natural soundscape of rocky and coral reef habitats at the Robinson Crusoe island (Juan Fernandez Archipelago; 33°38′S, 78°50′W), and Rapa Nui (Easter Island; 27°7′S, 109°21′W), respectively. Pelagic collections found important site-specific patterns and idetified two main species assemblages: early-life stages (e.g. eggs, larval and juvenile stages of crustaceans, molluscs, and fishes) and emerging macrobenthos (e.g. demersal zooplankton such as peracarid crustaceans, ostracods, copepods, and polychaetes), with the latter contributing between 73 and 98% to the total catches. The soundscape records showed marked differences among sites and seasons at Robinson Crusoe island, with variable differences found between day and night. However, at Rapa Nui, there were no differences between sites, but the ambient sound was higher at night possibly due to higher snapping shrimp activity. This information highlights the importance of considering small-scale (site-to-site) patterns when evaluating overlooked components of diversity (i.e. biological or acoustic) in oceanic habitats, and provides the basis for understanding the importance of natural noise in the settlement of most reef-associated species, crucial features for the conservation of these remote and vulnerable ecosystems.

Reef Life Survey (RLS) provides a new model for ecological monitoring through training experienced recreational divers in underwater visual census methods to the level of skilled scientists. Detail produced is similar to that of programs with professional scientific teams, at low cost to allow global coverage. RLS differs from most other citizen science initiatives in its emphasis on rigorous training and data quality rather than open participation, selectively involving the most skilled and committed members. Volunteers participate primarily because they appreciate the close relationship with scientists, other divers, and managers, and see their efforts directly contributing to improved environmental outcomes. RLS works closely with Australian management agencies, scheduling annual events at core monitoring sites associated with 10 inshore marine protected areas Australia wide. Surveys of 12 offshore Australian Marine Parks (AMPs) are realized through 2–4 week voyages in a sailing catamaran crewed by volunteers. Across the AMP network, RLS surveys have quantified densities of fishes, mobile invertebrates, macroalgae and corals at 350 shallow coral reef sites (180 sites surveyed on two or more occasions), providing an understanding of (i) population changes amongst threatened species including sea snakes, (ii) responses of fish and invertebrate populations following fisheries closures, (iii) ecosystem-wide impacts of marine heat-waves, and (iv) the extent that AMPs spanning the network comprehensively encompass national coral reef biodiversity. This scientist/volunteer/manager collaboration could be greatly expanded globally (presently 3537 sites in 53 countries).