Distribution, habitat associations, and threats to Patagonian seahorses in an Argentine protected area


Effective conservation of rare and threatened marine species is reliant on a robust understanding of their distribution patterns and habitat associations. In this thesis, I carried out the first in situ dive study on spatial distribution, biological traits, ecological correlates, and habitat features for the most significant (and most southerly) population of the Patagonian seahorse in Argentina (Hippocampus patagonicus, Vulnerable on the IUCN Red List). I conducted dive surveys within the 690 km² marine portion of the Bahia San Antonio (BSA) Protected Area of Rio Negro Province, Argentina during the H. patagonicus breeding season in the austral late spring.

I found that seahorses showed patchy distributions with significantly higher densities inside the sheltered waters of the BSA than in the Gulf of San Matias (GSM), with density ranging from 0.1 – 12.0 individuals/100m², and a mean density of 1.5 individuals/100 m² across the entire area sampled. Seahorses were most abundant in subtidal sandy and macroalgae bed habitats that featured denser algae coverage and a greater diversity of holdfast species. Seahorses were negatively associated with subtidal sandy-muddy and subtidal rocky reef habitats. Over half the seahorses (55%, n=136) sampled were found using brown and red algae as holdfasts. Despite its designation, the BSA Protected Area is subject to ongoing anthropogenic pressures including fisheries, pollution from poorly planned urban and industrial development, invasive species, and unsustainable levels of tourism. It is critical that regional management safeguard zones and habitat types that support high seahorse density. Such habitat protections will provide spillover benefits to other marine species that rely on the BSA Protected Area as a nursing and breeding ground.

Templeton, P. (2023). Distribution, habitat associations, and threats to Patagonian seahorses in an Argentine protected area. MSc dissertation, The University of British Columbia. http://hdl.handle.net/2429/87002