ALBERT

Description: Areas of the Arctic Ocean are already experiencing seasonal variation in low pH/elevated pCO2and are predicted to be the most affected by future ocean acidification (OA). Krill play a fundamental ecological role within Arctic ecosystems, serving as a vital link in the transfer of energy from phytoplankton to higher trophic levels. However, little is known of the chemical habitat occupied by Arctic invertebrate species, and of their responses to changes in seawater pH. Therefore, understanding krill's responses to low pH conditions has important implications for the prediction of how Arctic marine communities may respond to future ocean change. Here, we present natural seawater carbonate chemistry conditions found in the late polar winter (April) in Kongsfjord, Svalbard (79°North) as well as the response of the Arctic krill, Thysanoessa inermis, exposed to a range of low pH conditions. Standard metabolic rate (measured as oxygen consumption) and energy metabolism markers (incl. adenosine triphosphate (ATP) and l-lactate) of T. inermis were examined. We show that after a 7 days experiment with T. inermis, no significant effects of low pH on MO2, ATP and l-lactate were observed. Additionally, we report carbonate chemistry from within Kongsfjord, which showed that the more stratified inner fjord had lower total alkalinity, higher dissolved inorganic carbon, pCO2 and lower pH than the well-mixed outer fjord. Consequently, our results suggest that overwintering individuals of T. inermis may possess sufficient ability to tolerate short-term low pH conditions due to their migratory behaviour, which exposes T. inermis to the naturally varying carbonate chemistry observed within Kongsfjord, potentially allowing T. inermis to tolerate future OA scenarios.

Description: Physiological responses to temperature are known to be a major determinant of species distributions and can dictate the sensitivity of populations to global warming. In contrast, little is known about how other major global change drivers, such as ocean acidification (OA), will shape species distributions in the future. Here, by integrating population genetics with experimental data for growth and mineralization, physiology and metabolomics, we demonstrate that the sensitivity of populations of the gastropod Littorina littorea to future OA is shaped by regional adaptation. Individuals from populations towards the edges of the natural latitudinal range in the Northeast Atlantic exhibit greater shell dissolution and the inability to upregulate their metabolism when exposed to low pH, thus appearing most sensitive to low seawater pH. Our results suggest that future levels of OA could mediate temperature-driven shifts in species distributions, thereby influencing future biogeography and the functioning of marine ecosystems.

Description: We are starting to understand the relationship between metabolic rate responses and species' ability to respond to exposure to high pCO2. However, most of our knowledge has come from investigations of single species. The examination of metabolic responses of closely related species with differing distributions around natural elevated CO2 areas may be useful to inform our understanding of their adaptive significance. Furthermore, little is known about the physiological responses of marine invertebrate juveniles to high pCO2, despite the fact they are known to be sensitive to other stressors, often acting as bottlenecks for future species success. We conducted an in situ transplant experiment using juveniles of isopods found living inside and around a high pCO2 vent (Ischia, Italy): the CO2 'tolerant' Dynamene bifida and 'sensitive' Cymodoce truncata and Dynamene torelliae. This allowed us to test for any generality of the hypothesis that pCO2 sensitive marine invertebrates may be those that experience trade-offs between energy metabolism and cellular homoeostasis under high pCO2 conditions. Both sensitive species were able to maintain their energy metabolism under high pCO2 conditions, but in C. truncata this may occur at the expense of [carbonic anhydrase], confirming our hypothesis. By comparison, the tolerant D. bifida appeared metabolically well adapted to high pCO2, being able to upregulate ATP production without recourse to anaerobiosis. These isopods are important keystone species; however, given they differ in their metabolic responses to future pCO2, shifts in the structure of the marine ecosystems they inhabit may be expected under future ocean acidification conditions.

Description: Platynereis spp. were collected via snorkelling or scuba from either inside (40°43′53″N, 13°57′47″E) or outside (40°43'33.33N, 13°57'36.38E and 40°44′48″N, 13°56′39″E) the carbon dioxide (CO2) vent on the island of Ischia (Italy) and used in a reciprocal transplant experiment. The effect of exposure to high or low partial pressures of CO2 (pCO2) conditions on the metabolome (metabolome, and lipidome) of worms from different pCO2 regimes was investigated to understand the effect of exposure to different pCO2 conditions on the cellular physiological response. This experiment was conducted between 04/09/2013 and 16/09/2013. The experiment was staggered during this time so all worms could be processed. After five days exposure to either low or high CO2 conditions worms were snap frozen in liquid nitrogen and shipped to the University of Birmingham for metabolomic analysis which was finalised on 21/01/2016. Metabolomic profiles of worms were characterised using a mass spectrometry approach. A standard mass spectrometry based metabolomics workflow was used to analyse both the polar and lipid extracts from the samples (Kirwan et al. 2014). Raw mass spectral data were processed using the SIM-stitching algorithm, using an in-house Matlab script. The data matrices were normalized using the PQN algorithm. Missing values were imputed using the KNN algorithm. The resulting data matrix was analysed using univariate statistics, described below. The same matrix was transformed using the generalised logarithm to stabilise the technical variance across the measured peaks prior to analysis using multivariate statistics. Signals were putatively annotated with empirical formulae calculated by the MIPack software (Weber et al. 2010), searching the KEGG (Kanehisa et al. 2012) and LipidMaps (Fahy et al. 2007) databases, and confirmed by performing calculations based on the original spectra in Xcalibur 2.0.7 (Thermo Fisher Scientific).

Description: Platynereis spp. were collected via snorkelling or scuba from either inside (40°43′53″N, 13°57′47″E) (stations A1-A3) or outside (40°43'33.33"N, 13°57'36.38"E and 40°44′48″N, 13°56′39″E) (stations C1-C3) the carbon dioxide (CO2) vent on the island of Ischia (Italy) and used in a reciprocal transplant experiment between 04/09/2013 and 16/09/2013. The effect of exposure to high or low partial pressures of CO2 (pCO2) conditions on the proteome and metabolome (metabolome, and lipidome) of worms from different pCO2 regimes was investigated to understand the effect of exposure to different pCO2 conditions on the cellular physiological response. Before and during the transplant experiment water samples were taken to characterise the physio-chemical parameters of sea water used when exposing the worms to: (i) low pCO2 conditions (‘control’ stations C1, C2 and C3) and (ii) high pCO2 conditions (‘acidified’ stations A1, A2, A3). Salinity, temperature, pH NBS (Mettler-Toledo pH meter, Beaumont Leys, UK), total alkalinity (TA) (AS-ALK2, Apollo SciTech, Bogart, USA), dissolved inorganic carbon (DIC), carbon dioxide partial pressure (pCO2), bicarbonate and carbonate ion concentration ([HCO3–] and [CO32–), calcite and aragonite saturation state (Ωcal and Ωara) are provided.

Description: Platynereis spp. were collected via snorkelling or scuba from either inside (40°43′53″N, 13°57′47″E) (stations A1-A3) or outside (40°43'33.33"N, 13°57'36.38"E and 40°44′48″N, 13°56′39″E) (stations C1-C3) the carbon dioxide (CO2) vent on the island of Ischia (Italy) and used in a reciprocal transplant experiment. The effect of exposure to high or low partial pressures of CO2 (pCO2) conditions on the proteome of worms from different pCO2 regimes was investigated to understand the effect of exposure to different pCO2 conditions on the cellular physiological response. This experiment was conducted between 04/09/2013 and 16/09/2013. The experiment was staggered during this time so all worms could be processed. After five days exposure to either low or high CO2 conditions worms were snap frozen in liquid nitrogen and shipped to the University of Hong Kong for proteomic analysis which was finalised on 02/08/2015. Proteomic profiles of worms were characterised using a liquid chromatography-mass spectrometry/mass spectrometry triple time of flight (LC-MS/ MS Triple TOF) approach.