ACTIQUIM Ecología química en organismos antárticos y la búsqueda de sustancias bioactivas con potencial farmacológico

El Instituto Español de Oceanografía (IEO) participa, con la Universidad de Barcelona (UB) y otros centros de investigación, en el proyecto ACTIQUIM, cuya finalidad principal es determinar la actividad ecológica de productos naturales marinos obtenidos de organismos antárticos mediante experimentos de ecología química realizados in situ.Instituto Español de OceanografíaVersión del edito

Effects of ocean acidification on acid-base physiology, skeleton properties, andmetal contamination in two echinoderms fromvent sites in Deception Island, Antarctica

Antarctic surface waters are expected to be the first to experience severe ocean acidification (OA) with carbonate undersaturation and large decreases in pH forecasted before the end of this century. Due to the long stability in environmental conditions and the relatively low daily and seasonal variations to which they are exposed, Antarctic marine organisms, especially those with a supposedly poor machinery to eliminate CO2 and protons and with a heavily calcified skeleton like echinoderms, are hypothesized as highly vulnerable to these environmental shifts. The opportunities offered by the natural pH gradient generated by vent activities in Deception Island caldera, Western Antarctic Peninsula, were used to investigate for the first time the acid-base physiologies, the impact of OA on the skeleton and the impact of pH on metal accumulation in the Antarctic sea star Odontaster validus and sea urchin Sterechinus neumayeri. The two species were sampled in four stations within the caldera, two at pH (total scale) 8.0-8.1 and two at reduced pH 7.8. Measured variables were pH, alkalinity, and dissolved inorganic carbon of the coelomic fluid; characteristic fracture force, stress and Young's modulus using Weibull statistics and Cd, Cu, Fe, Pb and Zn concentrations in the integument, gonads and digestive system. Recorded acid-base characteristics of both studied species fit in the general picture deduced from temperate and tropical sea stars and sea urchins but conditions and possibly confounding factors, principally food availability and quality, in the studied stations prevented definitive conclusions. Reduced seawater pH 7.8 and metals had almost no impact on the skeleton mechanical properties of the two investigated species despite very high Cd concentrations in O. validus integument. Reduced pH was correlated to increased contamination by most metals but this relation was weak. Translocation and caging experiments taking into account food parameters are proposed to better understand future processes linked to ocean acidification and metal contamination in Antarctic echinoderms

Biodiversity and chemical diversity in Antarctica: new species and new natural products

Antarctica is a still unexplored area in many senses, among which biological diversity and even more, chemical diversity. Over the last years our research group has been studying marine benthic ecosystems in different Antarctic areas in the frame of the projects ECOQUIM and ACTIQUIM. These studies have produced many interesting discoveries regarding both new species to science, as well as new natural products. We have been trying to unravel the complex interactions network existing between marine benthic organisms in these cold and hardly accessible ecosystems. We present here a review of our recent results, considering the biology and ecology of these organisms and the chemistry laying behind their interactions. As a summary, we may say that these ecosystems are as complex as any other similar environment in the planet, although many questions remain to be answered yet.Instituto Español de Oceanografí

Gersemiols A–C and Eunicellol A, Diterpenoids from the Arctic Soft Coral Gersemia fruticosa,

International audienceThree new diterpenes named gersemiols A–C (1–3) and a new eunicellane diterpene, eunicellol A (4), have been isolated together with the known sesquiterpene (+)-α-muurolene (5) from the Arctic soft coral Gersemia fruticosa. The name gersemiane was assigned to the rare and unnamed diterpene skeleton of compounds 1–3 corresponding to 4-isopropyl-1,5,8a-trimethyltetradecahydrophenanthrene. The chemical structures were elucidated on the basis of extensive spectroscopic analysis (HR-ESIMS, 1D and 2D NMR) as well as coupling constant calculations for the determination of the relative configurations. All compounds were tested for their antimicrobial activity against several bacteria and fungi and eunicellol A was found to exhibit moderate and selective antibacterial activity

A submerged volcanic cone in Deception Island (Antarctica) ¿Benthic communities and proximal volcanism in a rapidly changing sedimentological environment

Scientific Committee on Antarctic Research (SCAR) Online Conference, August 5, 2020Deception Island (DI) is amongst the most active volcanoes, with >20 explosive eruptions in the last two centuries. DI¿s caldera-forming eruption, a volcano-climatic event with hemispheric impact occurred 3980 ± 125c.y. before present, is the largest eruption documented in Antarctica during Holocene. Mortality of benthic organisms occurredby eruptions in 1967, 1969, 1970, with very low abundances from 1967-1973. Volcanic activity post-caldera-forming comprises many scattered eruptive vents across the island. A submarine volcanic axis with several volcanic cones is observed within the caldera, and volcanic edifices, morphologically well-preserved in the southern part of the bay raise from the seafloor up to >50 m. A multidisciplinary team sampled one of the submerged volcanoes, Stanley Patch (SP), in Port Foster (PF). Geophysical data allocated the volcano and characterized its morphology and inner structure. Direct sampling by SCUBA provided sediment and rocks, and photographs/video images of benthic organisms and landscape. Morphology of SP cone and textural characteristics of pyroclastic rocks (vesiculation, bubble shape) indicate an explosive volcanism origin, and fits with the post-caldera magmatic trend. A sediment core from the crater (4 cm Ø, 8 cm length) was collected for sedimentological, geochemical and geochronological analysis. Antarctic climate and seasonal sea ice, together with organic degradation due to high sedimentation rates, explain low TOC data. SP, and the whole PF, provide a unique, great natural laboratory for benchmarking the reestablishment of benthic communities on avolcanological-influenced shallow marine environment, offering relevant data for future studies evaluating global change effects on Antarctic seabed.Thanks are duet o the crew of B.A.E.Gabrielde Castilla for their logistic support during the Antarctic expedition.This is a contribution to the Ant Eco(State of the Antarctic Ecosystem) SCAR Programme.This research was partially supported by the research projects:BLUEBIO(CTM2016-78901-ANT),POSVOLDEC(CTM2016-79617-P)(AEI/FEDER-UE),and CRONOANTAR (CTM2016-77878-P