Proteomics in Marine Organisms.

Environmental behavior and toxic effects of micro(nano)plastics and engineered nanoparticles on marine organisms under ocean acidification: A review

Natural analogues of the future ocean allow us to identify the impacts and associated mechanisms of ocean warming, ocean acidification and oxygen loss on marine organisms from effects on species right up to an ecosystem scale. This is improving understanding about how ongoing rapid changes to the structure and functioning of marine systems are and will continue to affect human society. Strong marine gradients in temperature, pH, alkalinity and oxygen provide test beds to show the practical real-world advantages to society of complying with the UN SDGs, the Paris Agreement, and the CBD, demonstrating what ecosystem services are secured as ecosystems are ‘dialed-back’ from business-as-usual emissions and poor ocean management scenarios.The International CO2 Natural Analogue (ICONA) network, an ocean decade action endorsed under the “Ocean Acidification Research for Sustainability' programme, brings together experts, local communities, and stakeholders to use futuristic marine test bed environments, spanning temperate, sub-tropical and tropical regions. Our findings are showing the varieties of responses to future ocean conditions from molecules to ecosystems. They highlight that reducing CO2 emissions and limiting ocean warming, acidification, and oxygen loss brings tangible benefits to society by restoring ecosystem services that have been degraded. Moreover, resistant species and populations of marine organisms found in these futuristic environments have been selected through chronic exposure to end of the century levels of heatwaves, CO2 and reduced oxygen. These can be a source of genes of resilience for the development of adaptation strategies such as assisted evolution and assisted gene flows. Finally, the microbial diversity found at this global network of study sites has proven its potential for the development of carbon sequestration techniques which can help achieve a carbon neutral society. The ICONA network aims to expand to engage more partners, scientists and diverse stakeholders to unlock the ways in which these systems can benefit humanity, through novel hidden biodiversity and as demonstration sites for how our societies can best adapt to near-future CO2 levels, and to co-design conservation strategies around these ecosystems.

Ocean acidification is changing the fate of marine organisms. It is essential to predict the biological responses and evolutionary processes driven by ocean acidification, to maintain the equilibrium of the marine ecosystem and to facilitate aquaculture. However, how marine organisms, particularly the marine fish species, respond to ocean acidification, is still poorly understood. Consequences of ocean acidification on finfish aquaculture are largely not well known. We studied the effects of ocean acidification for 7days on growth, behaviour and gene expression profiles in the brain, gill and kidney of Asian seabass juveniles. Results showed that growth and behaviour were not affected by short-term ocean acidification. We found tissue-specific differentially expressed genes (DEGs) involving many molecular processes, such as organ development, growth, muscle development, ion homeostasis and neurogenesis and development, as well as behaviours. Most of the DEGs, which were functionally enriched in ion homeostasis, were related to calcium transport, followed by sodium/potassium channels. We found that genes associated with neurogenesis and development were significantly enriched, implying that ocean acidification has also adversely affected the neural regulatory mechanism. Our results indicate that although the short-term ocean acidification does not cause obvious phenotypic and behavioural changes, it causes substantial changes of gene expressions in all three analysed tissues. All these changes of gene expressions may eventually affect physiological fitness. The DEGs identified here should be further investigated to discover DNA markers associated with adaptability to ocean acidification to improve fish's capability to adapt to ocean acidification.

Ocean acidification threatens many marine organisms, especially marine calcifiers. The only global-scale solution to ocean acidification remains rapid reduction in CO2 emissions. Nevertheless, interest in localized mitigation strategies has grown rapidly because of the recognized threat ocean acidification imposes on natural communities, including ones important to humans. Protection of seagrass meadows has been considered as a possible approach for localized mitigation of ocean acidification due to their large standing stocks of organic carbon and high productivity. Yet much work remains to constrain the magnitudes and timescales of potential buffering effects from seagrasses. We developed a biogeochemical box model to better understand the potential for a temperate seagrass meadow to locally mitigate the effects of ocean acidification. Then we parameterized the model using data from Tomales Bay, an inlet on the coast of California, USA which supports a major oyster farming industry. We conducted a series of month-long model simulations to characterize processes that occur during summer and winter. We found that average pH in the seagrass meadows was typically within 0.04units of the pH of the primary source waters into the meadow, although we did find occasional periods (hours) when seagrass metabolism may modify the pH by up to ±0.2units. Tidal phasing relative to the diel cycle modulates localized pH buffering within the seagrass meadow such that maximum buffering occurs during periods of the year with midday low tides. Our model results suggest that seagrass metabolism in Tomales Bay would not provide long-term ocean acidification mitigation. However, we emphasize that our model results may not hold in meadows where assumptions about depth-averaged net production and seawater residence time within the seagrass meadow differ from our model assumptions. Our modeling approach provides a framework that is easily adaptable to other seagrass meadows in order to evaluate the extent of their individual buffering capacities. Regardless of their ability to buffer ocean acidification, seagrass meadows maintain many critically important ecosystem goods and services that will be increasingly important as humans increasingly affect coastal ecosystems.

Ocean acidification drives gut microbiome changes linked to species-specific immune defence

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non-calcifying organisms across numerous response variables, with the exception of crustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.

Ocean carbon sequestration by direct carbon dioxide injection to the deep-sea or by the fertilization of the upper ocean with iron to accelerate the biological pump are methods under consideration to mitigate rapidly rising atmospheric carbon dioxide levels and avoid, in part, excessive greenhouse gas warming. Both sequestration efforts will elevate carbon dioxide levels in the deep ocean, which after reaction with the seawater carbonate system, will decrease the pH of the ocean. In addition, ocean acidification is occurring through the passive influx of carbon dioxide through the ocean surface. Efforts to understand the effects of accelerating ocean acidification from carbon sequestration efforts or passive CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> absorbance will require study of marine ecosystems from the surface to the deep-sea. In many deep-sea environments, hypoxia can also be stressful for marine organisms. Therefore, studies to assess the impacts of ocean acidification in deep-sea habitats should also include examination of the effects of hypoxia, due to the potentially synergistic interaction between these stressors. In this report, we describe the development of a gas-controlled aquarium (GCA) system used for laboratory studies of the effects of hypoxia or ocean acidification or both on marine animals. The GCA system is capable of regulating the temperature, oxygen, and carbon dioxide content of waters in three aquarium tanks for use in assays of growth and metabolic rate studies or various marine animals. The GCA design uses a main reservoir and 3 aquarium tanks in which different set-points for oxygen and carbon dioxide levels are possible. Membrane contactors connected to recirculation pumps and gas sources are used to control gas concentrations in each tank. A LabVIEW software system integrated with mass flow controllers for oxygen, carbon dioxide, and nitrogen sources allows real-time, automated regulation of gas concentrations in each tank.

Meta-analyses reveal climate change impacts on an ecologically and economically significant oyster in Australia

Biocalcification crisis in the continental shelf under ocean acidification

The ubiquitous and pleiotropic dual specificity protein kinase CK2 has been studied and characterized in many organisms, from yeast to mammals. Generally, the enzyme is composed of two catalytic (alpha and/or alpha') and two regulatory (beta) subunits, forming a differently assembled tetramer. Although prone to controversial interpretation, the function of CK2 has been associated with fundamental biological processes such as signal transduction, cell cycle progression, cell growth, apoptosis, and transcription. Less known is the role of CK2 during meiosis and the early phase of embryogenesis. In this work, we studied CK2 activity during oocyte activation, a process occurring at the end of oocyte maturation and triggered by fertilization. In ascidian Ciona intestinalis, an organism whose complete genome has been published recently, CK2 was constitutively active in unfertilized and fertilized oocytes. The enzymatic activity oscillated through meiosis showing three major peaks: soon after fertilization (metaphase I exit), before metaphase II, and at the exit from metaphase II. Biochemical analysis of CK2 subunit composition in activated oocytes indicated that CK2-alpha was catalytically active as a monomer, independently from its regulatory subunit beta; however, CK2-beta was only detectable in unfertilized oocytes where it was associated with a bona fide identified ascidian mitogen-activated protein kinase. After fertilization, CK2-beta was undetectable, suggesting its rapid degradation. Protein sequence analysis of CK2-alpha and -beta cDNA indicated a high identity compared with vertebrate homologs. In addition, the absence of putative phosphorylation sites for Cdc2 kinase on both alpha and beta subunits suggested an important role for CK2 in regulating meiotic cell cycle in C. intestinalis oocytes.

This paper investigates the mechanisms of ocean acidification and its effects on marine biota. Ocean acidification is where seawater absorbs too much carbon dioxide from the atmosphere, increasing acidity, measured by pH value. Its causes include human activities (fossil fuel burning, deforestation), climate activities (ocean warming, sea ice melting), and natural phenomena (volcanic eruptions, etc.). Historical PETM events and the end Permian mass extinction event indicate ocean acidification significantly impacts biodiversity. Ocean acidification may induce behavioral and physiological alterations in non-calcifying marine organisms, including modifications to the swimming patterns of clownfish and the foraging behaviors of planktonic fauna. For calcified microorganisms, it can hinder coral bone formation and shellfish shell formation, reducing juvenile survival rates. Overall, ocean acidification disrupts the marine food web, reduces biodiversity, damages ecosystem stability and adaptability, and requires in-depth exploration of its mechanisms and the development of response strategies.

The impacts of pharmaceutical drugs under ocean acidification: New data on single and combined long-term effects of carbamazepine on Scrobicularia plana

Internal controls for quantitative RT-PCR analysis of gene expression in response to ocean acidification in edible oysters

The "contact reaction" is an extremely rapid allogeneic cytotoxic reaction (ACR) mediated by hemocytes in the solitary ascidian Halocynthia roretzi. It has been proposed that regulation of the alloreactivity of hemocytes may be involved in preference for fertilization or self-sterility in this species. To identify the receptors and target ligands involved both in self-recognition by somatic cells and self-discrimination by gametes, we produced monoclonal antibodies (mAbs) that inhibit the ACR mediated by hemocytes and tested their effects on fertilization. Six different mAbs that inhibit the ACR were prepared and categorized into three groups. Although all three mAbs seemed to have the same ability to inhibit the ACR, almost constant and statistically significant inhibition (CRB1.1) and infrequent but significant inhibition (CRB2.1, and CRB3.1) of the ACR were observed in the same pairs of animals. Pretreatment of the unfertilized eggs with CRB1.1, CRB2.1, and CRB3.1, resulted in the constant and statistically significant inhibition, infrequent but significant inhibition, and no inhibition, respectively, of fertilization. Antigens recognized by CRB1.1 (CRB1.1 antigens) were detected on the cell surface of all types of hemocytes and on the vitelline coat and follicle cells of unfertilized eggs. CRB2.1 and CRB3.1 antigens were detected on the surface of certain types of hemocytes and follicle cells, but not on the vitelline coat. CRB mAbs were directed against different epitopes in the N-linked glycan on glycoproteins. These common carbohydrate antigens on somatic cells and gametes may function in some recognition processes in ACR and fertilization in H. roretzi.

Effects of seawater acidification and cadmium on the antioxidant defense of flounder Paralichthys olivaceus larvae