Description: Ocean acidification (OA) could become a serious threat for the Antarctic marine ecosystem over coming years, as the solubility of atmospheric CO2 and CaCO3 minerals increases at lower temperatures. We evaluated the effect of OA on the stress response of the limpet Nacella concinna by measuring gene expression levels. The experiment was performed with the two ecotypes (Littoral and Sublittoral) of the species during 54 days (IPCC, 2019 scenario RCP8.5; control, 375 ppm; low-pH treatment, 923 ppm). Exposure to low-pH treatment during 15 days triggered the down-regulation of two heat-shock protein genes (HSP70A, HSP70B) only in sublittoral individuals. Little variation in the relative expression values of all genes in both ecotypes was observed probably, due to a historical exposure to the substantial daily natural pH fluctuations recorded in the study area during the experiment. This study provides relevant baseline data for future OA experiments on coastal species in Antarctica.

Description: Benthic organisms of the Southern Ocean are particularly vulnerable to ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. OA most strongly affects animals with calcium carbonate skeletons or shells, such as corals and mollusks. We exposed the abundant cold-water coral Malacobelemnon daytoni from an Antarctic fjord to low pH seawater (LpH) (7.68 +/- 0.17) to test its physiological responses to OA, at the level of gene expression (RT-PCR) and enzyme activity. Corals were exposed in short- (3 days) and long-term (54 days) experiments to two pCO2 conditions (ambient and elevated pCO2 equaling RCP 8.5, IPCC 2019, approximately 372.53 and 956.78 μatm, respectively). Of the eleven genes studied through RT-PCR, six were significantly upregulated compared with control in the short-term in the LpH condition, including the antioxidant enzyme superoxide dismutase (SOD), Heat Shock Protein 70 (HSP70), Toll-like receptor (TLR), galaxin and ferritin. After long-term exposure to low pH conditions, RT-PCR analysis showed seven genes were upregulated. These include the mannose-binding C-Lectin and HSP90. Also, the expression of TLR and galaxin, among others, continued to be upregulated after long-term exposure to low pH. Expression of carbonic anhydrase (CA), a key enzyme involved in calcification, was also significantly upregulated after long-term exposure. Our results indicated that, after two months, M. daytoni is not acclimatized to this experimental LpH condition. Gene expression profiles revealed molecular impacts that were not evident at the enzyme activity level. Consequently, understanding the molecular mechanisms behind the physiological processes in the response of a coral to LpH is critical to understanding the ability of polar species to cope with future environmental changes. Approaches integrating molecular tools into Antarctic ecological and/or conservation research make an essential contribution given the current ongoing OA processes.

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Corals were collected from the summit of Condor Seamount (Azores, NE Atlantic) at depths between 185-210 m in August 2014. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. PMS particles were obtained by grinding PMS inactive chimney rocks collected at the hydrothermal vent field Lucky Strike. Both particle types were delivered at a concentration of 25 mg L-1. The putative effects of PMS particles were evaluated through measurements of the coral physiological responses at the levels of the organism (oxygen consumption, ammonium excretion), tissue (bioaccumulation of metals) and cell (enzyme activity and gene expression).

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. The concentration of suspended PMS and quartz particles in each treatment was measured during an exposure period of 4 hours. Suspended particle concentrations were measured one minute after particle addition, and then at intervals of 5, 15, 30 minutes, 1 hour, 2 hours and 4 hours after particle addition in the PMS and quartz particle treatments and in control aquaria with no particle addition.

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Seawater physical-chemical parameters were measured daily in each aquarium. Seawater salinity was measured with a S30 SevenEasy™ conductivity meter, pH and temperature with a glass electrode (Crison pH 25+), and oxygen with a Fibox4 (PreSens) with a Oxygen Dipping Probe DP-PSt3. Seawater samples for inorganic nutrient analyses were collected on times 0 (immediately before the start of the experiment), and once a week on days 6, 13, 20 and 27 of the experiment and determined using a colorimetric autoanalyzer Sanplus with segmented flow.

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Trace elements in the tissues and skeletons of corals at the end of the experiment were quantified by a quadrupole ICPMS (Thermo Elemental, X-Series). The metal concentrations in coral tissues are given in microgram per gram of dry weight tissue (μg g-1; dw).

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Integrated measurements of coral respiration and ammonium release rates were carried out by closed-chamber incubation in cylindrical acrylic chambers on days 0, 13 and 27 of the experiment using an oxygen meter Fibox4 with a PSt3 sensor (PreSens, Germany). Coral respiration and excretion rates were normalized to the coral skeletal surface area.

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Antioxidant stress related biomarkers (glutathione S−transferase, superoxide dismutase, catalase, malondialdehyde) in D. aff. meteor tissues were used to evaluate the degree of cellular stress induced by exposure to PMS and quartz particles at times 0 and 13 days in all treatments and from the control and quartz treatments also at time 27 days of the experiment.

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Gene expression profiles in D. aff. meteor were used to evaluate the physiological pathways involved in the response to exposure to PMS and quartz particles. Coral fragments were collected from each treatment at times 0, 3, and 13 days and for the control and quartz treatments also at time 27 days. The study targeted genes involved in cellular stress and antioxidant reaction system (heat shock protein, superoxide dismutase, ferritin), cell structure/integrity (α-carbonic anhydrase, receptor-type protein tyrosine phosphatase) and immune responses (toll-like receptor, lysozyme, rel homology domain, ferritin).

Description: We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. Trace elements (Co, Cu, Mn) released from the resuspension of PMS particles to the water column in each aquaria were determined using passive sampling (DGT® Research Ltd) coupled with inductively coupled plasma mass spectrometry (ICPMS). DGT-holders were deployed in all aquaria and replaced every week (days 6, 13, 20, 27).