Abstract Understand the origin, transport, and character of organic matter entering Antarctic fjords is essential as they are major components of the global carbon cycle and budget. Macromolecular pools of particulate organic matter, bulk organic geochemistry, major and trace elements in surface sediments from Collins Bay were analysed as source indicators. Oceanographic conditions, bathymetry (multibeam) and grain size were considered as environmental controlling factors. Sediment samples were taken with a van Veen grab, during the ANTAR XXV Peruvian expedition (February 2018), onboard the R/V “BAP Carrasco” from the Peruvian Navy. Biopolymeric composition revealed the predominance of fresh marine protein-rich organic matter in the seafloor of Collins Bay, denoting high quality food resource for marine benthic heterotrophs. Based on Igeo values (between 0 and 1) Collins Bay can be considered unpolluted with natural levels of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Distribution of most of these elements with a gradient of decrease from the shallow inner fjord towards the outer deepest fjord, suggest their association with the deposition of detrital material and lithogenic particles supplied by Collins Glacier frontal ablation and runoff. This first comprehensive baseline information would assist in interpreting downcore sedimentary reconstructions and future climate-induce changes.

ResumoO conhecimento dos danos no DNA em organismos aquáticos de áreas poluídas é uma questão importante, já que a contaminação pode vir a alterar os organismos em níveis subletais. Apesar dos moluscos terem sido amplamente utilizados para monitorar a poluição da água, não há registros de estudos in vivo de genotoxicidade. Heleobia cf. australis é um pequeno gastrópode amplamente distribuído em quase todos os ecossistemas costeiros uruguaios, inclusive em locais altamente poluídos. O ensaio do cometa é um biomarcador genético do dano baseado na migração de fragmentos de DNA com carga negativa produzidas por agentes mutagênicos. Foram coletados indivíduos vivos na Baía de Montevidéu (área impactada) e Laguna Garzón (área controle) para analisar a presença de agentes mutagênicos que ocasionassem dano genético. Células de organismos da área impactada apresentaram níveis significativamente mais elevados de danos genéticos do que os obtidos na área controle. Esse nível de dano foi medido pela porcentagem de DNA na cauda. Embora preliminar, esta abordagem apoia a noção de que H. cf. australispoderia ser usado como sentinela para avaliar a presença de agentes mutagênicos em ambientes estuarinos, alertando sobre o impacto da poluição em estágios iniciais.

AbstractThe knowledge of the extent of DNA damage in aquatic organisms in polluted areas is an important issue because contamination may alter their health at sublethal levels. Although molluscs have been widely used to monitor water pollution, there are no records of in vivo genotoxicity studies. Heleobia cf. australis, is distributed in almost all Uruguayan coastal ecosystems, including highly polluted sites. The comet assay is a damage genetic biomarker based on the migration of negatively charged DNA fragments produced by mutagenic agents in individual cells. Live individuals were collected in the Montevideo Bay (impacted area) and Laguna Garzón (control) to analyze the presence of mutagenic agents in the former site through comet assay. Cells from organisms of the impacted area showed significantly higher levels of genetic damage than those obtained in the control population, measured by percentage of DNA in the tail. Although preliminary, this approach supports the idea that H. cf. australis could be used as a sentinel to evaluate the presence of mutagenic agents in estuarine environments, alerting to the impact of contamination in its early stages.