Microbiologist Petya Orozova: Antarctic Marine Ecosystem Easily Susceptible to Negative Changes By Human Activity

The Antarctic marine ecosystem is easily susceptible to negative changes caused by human activity. The growing human presence in Antarctica poses a risk for the introduction of invasive organisms and human pathogenic bacteria, said Assoc. Prof. Petya Orozova, who is head of the national reference laboratory on marine life disease with the National Diagnostic Research Veterinary-Medical Institute under the Bulgarian Agency for Food Safety, and a participant in the 31st Bulgarian Antarctic expedition. Her project aims to study the species diversity of Antarctic fish and bacteria communities in the waters near the coast of the Bulgarian Antarctic base St. Kliment Ohridski on Livingstone Island.

The project is broad in scope and covers several countries, explained Assoc. Prof. Orozova. The aim is to establish the species diversity of the bacteria communities, both in the water and in the internal organs of fish. The health status of Antarctic fish will also be checked, as recent studies have shown that alongside global climate change, Antarctic waters are becoming colonized with pathogens that can cause disease in local fish populations.

"Human presence in the Antarctic leads to the transmission of enteropathogens. They cannot, of course, live for long in Antarctic waters, but in their short stay they can accumulate from aquatic inhabitants such as fish and mussels, and transmit virulence and antibiotic resistance genes to their natural microflora," the microbiologist warned.

The project also aims to test the diversity of psychrophilic bacteria species in the water column, determining which of them are beneficial to humans, as for example members of the genus Alteromonas have unlimited possibilities in their production of bioactive molecules and can be used in both medicine and industry. They produce bioactive molecules in response to the hostile environment in which they exist. This way they can survive in hostile environments, marked by intense UV radiation, low temperatures and high salinity," added Assoc. Prof. Orozova.

The microbiologist explained how the research is being conducted: "Fish are caught, their health status is checked, as well the presence of external, internal parasites and pathological changes of their internal organs. Samples are taken for microbiological analysis of the internal organs. Samples (fins, livers, stomach) are also collected for a dietary study of Antarctic fish and a complete genomic analysis to determine their species affiliation.

So far, all fish examined have been found to be heavily parasitized, with parasites found in both the liver and the intestine. The parasites will be examined and identified, and their role in the Antarctic biocenosis will be assessed," she said. An external parasite has been found for the first time in the Antarctic fish Notothenia rossii - it is a species of leech, which is yet to be identified.

"Seawater samples collected from various points around the South Shetland Islands (the archipelago to which Livingstone Island belongs) are also being tested. Using a vast array of nutrients, marine bacteria are being isolated, classified and identified as the results are yet to be released. Work on the project will continue in Sofia. There, the project leader, Assoc. Prof. Eliza Uzunova, will investigate the nutrition of Antarctic fish as well as the presence of microplastics in the Antarctic Ocean and its inhabitants. Assoc. Prof. Ivan Ivanov of the National Centre of Infectious and Parasitic Diseases (NCIPD) will examine the presence of resistance and virulence genes in bacterial communities of the water column by metagenomic analysis. Dr. Iskra Tomova of NCIPD will check for the presence of Legionella pneumophila in the drinking water sources of the Bulgarian Antarctic base and determine the potential risk of Legionellosis on board the Bulgarian naval research ship Sv. Sv. Kiril i Metodii, from which water samples have been taken periodically throughout the voyage," continued Orozova.

She also pointed out that the study of the species diversity of bacteria in Antarctic fish and waters is still at an early stage and expressed hope that research will continue in the future. Assoc. Prof. Orozova hopes that the results can be applied to industry and health care, as well as to protect Antarctica from invasive anthropogenic impacts.

BTA's Daily News editor Konstantin Karagyozov is the only member of the media who is travelling on board the ship to Livingston Island and back, and covered the Bulgarian expedition on site throughout the stay in Antarctica.

All media outlets can use the Bulgaria-Antarctica BTA's Log for free.