The polar front, an oceanographic barrier between the Austral Ocean and its surrounding water masses, is not the impermeable biogeograpgical barrier it was thought to be, according to an article published in the journal Marine Environmental Research with Blanca Figuerola, from the Faculty of Biology of the University of Barcelona and the Biodiversity Research Institute of the UB (IRBio) as main author of the study.
Other authors of the study are the experts David K.A Barnes, from the British Antarctic Survey (BAS) in the United Kingdom; Paul Brickle, from the South Atlantic Environmental Research Institute (SAERI) in the Falkland Islands, and Paul E. Brewin, from the Directorate of Natural Resources -- Fisheries in South Georgia and South Sandwich Islands.
In the transition area between South America and the Antarctica, between 45 and 60º S. latitude, we can find these archipelagos, which have a marine fauna that could bring essential information on biodiversity distribution patterns and biogeography of the most extreme ocean ecosystems. The new study shows the most complete inventory so far on the distribution of bryozoans -marine invertebrates living in colonies and forming mineralized skeletons- in the shallow waters of the Falkland Islands (Atlantic Ocean) and South Georgia Islands (Austral Ocean), located in the north and south of the polar front, respectively.
Unknown marine ecosystems between South America and the Antarctica
The scientific team identified 85 different species, among which are 18 types and 23 species that could be unknown to this date. From all the identified species, a 65% were named for the first time in the Falkland Islands (41% in South Georgia Islands).
According to the researcher Blanca Figuerola, from the Department of Evolutionary Biology, Ecology and Environmental Sciences, "the new inventory for bryozoans will enable creating a database of regional bryozoan diversity and will allow us to detect possible invasive species."
"The research study, which spreads the bathymetric study range into 30 marine species, analyzes the fauna similarities among the communities of bryozoans in neighboring areas, and will serve to design biogeographical distribution patterns. Bryozoans represent a taxon which is widely shown in biodiversity studies to detect future changes in marine ecosystems caused by global change" says Figuerola.
According to the conclusions, the polar front is not such an impermeable biogeographical barrier as originally thought in the case of bryozoans -efficient surface colonizers- due the existence of possible spreading paths between the Patagonian region and the Antarctica. This phenomenon that crosses oceanographic barriers could benefit from the Antarctic Circumpolar Current -able to bring bryozoan colonies fixed to marine remains- or through some mechanisms of human dispersal (ballast water from ships, etc.), according to the authors.
Protecting marine biodiversity in the most extreme ecosystems
Comparative studies on biodiversity between the Antarctica and the last fragments that separated from Gondawana -in particular, the Patagonian region- are essential to understand the evolution of regional communities and their relations with the fauna outside the polar front. One of the priorities of the Biodiversity Strategy of the Falkland Islands is the cartography of the oceanic habitat and the identification of marine invertebrate species.
"This new study will also help to improve marine management initiatives of the government of the Falkland and South Georgia Islands, as well as sub-Antarctic islands and neighbouring regions, which are still quite unknown in the field of science," says Figuerola, who got a Shackleton grant to work on this research. Figuerola is one of the members of the project Distantcom, the continuation of the projects Ecoquim and Actiquim, led by Professor Conxita Àvila, from the Faculty of Biology and IRBio, to study chemical ecology on communities of marine invertebrates in the Antarctica.
In this study, the team of experts collected samples of cold water bryozoans -during diving surveys- in several areas of the Falkland Islands. The collected samples were later identified, as it is done with the samples in the collections of different groups and institutions such as the Shallow Marine Surveys Group (SMSG); the South Atlantic Environmental Research Institute (SAERI) and the Fisheries Department of the Falkland Islands -institutions that funded the research activity. According to the experts, it would be important to widen this study line on the marine fauna of deeper areas in South America and the Antarctic continent.
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