Calcified coralline algae are ecologically important in rocky habitats in the marine photic zone worldwide and there is growing concern that ocean acidification will severely impact them. Laboratory studies of these algae in simulated ocean acidification conditions have revealed wide variability in growth, photosynthesis and calcification responses, making it difficult to assess their future biodiversity, abundance and contribution to ecosystem function. Here, we apply molecular systematic tools to assess the impact of natural gradients in seawater carbonate chemistry on the biodiversity of coralline algae in the Mediterranean and the NW Pacific, link this to their evolutionary history and evaluate their potential future biodiversity and abundance. We found a decrease in the taxonomic diversity of coralline algae with increasing acidification with more than half of the species lost in high pCO2 conditions. Sporolithales is the oldest order (Lower Cretaceous) and diversified when ocean chemistry favoured low Mg calcite deposition; it is less diverse today and was the most sensitive to ocean acidification. Corallinales were also reduced in cover and diversity but several species survived at high pCO2; it is the most recent order of coralline algae and originated when ocean chemistry favoured aragonite and high Mg calcite deposition. The sharp decline in cover and thickness of coralline algal carbonate deposits at high pCO2 highlighted their lower fitness in response to ocean acidification. Reductions in CO2 emissions are needed to limit the risk of losing coralline algal diversity.
Pseudo-nitzschia australis (Frenguelli), a toxigenic pennate diatom capable of producing the neurotoxin domoic acid (DA), was examined in unialgal laboratory cultures to quantify its physiological response to ocean acidification (OA) – the decline in pH resulting from increasing partial pressure of CO2 (pCO2) in the oceans. Toxic blooms of P. australis are common in the coastal waters of eastern boundary upwelling systems (EBUS), including those of the California Current System (CCS) off the west coast of the United States where increased pCO2 and decreased seawater pH are well-known. This study determined the production of dissolved (dDA) and particulate DA (pDA), the rates of growth and nutrient (nitrate, silicate and phosphate) utilization, cellular elemental ratios of carbon and nitrogen, and the photosynthetic response to declining pH during the exponential and stationary growth phases of a strain of P. australis isolated during a massive toxic bloom that persisted for months along much of the U.S. west coast during 2015. Our controlled lab studies showed that DA production significantly increased as pCO2 increased, and total DA (pDA + dDA) normalized to cell density was 2.7 fold greater at pH 7.8 compared to pH 8.1 (control) during nutrient-limited stationary growth. However, exponential growth rates did not increase with declining pH, but remained constant until pH of 7.8 was reached, and then specific growth rates declined by ca. 30%. The toxin results demonstrate that despite minimal effects of OA observed during the nutrient-replete exponential growth phase, the enhancement of DA production, notably the 3-fold increase in particulate DA per cell, with declining pH from 8.1 to 7.8 during the nutrient-depleted stationary phase, supports the hypothesis that increasing pCO2 will result in greater toxic risk to coastal ecosystems from elevated ambient concentrations of particulate DA. The ecological consequences of decreasing silicate uptake rates and increasing cellular carbon quotas with declining pH may potentially ameliorate some negative impacts of OA on Pseudo-nitzschia growth in natural systems.
Coralline algae play foundational roles in coastal ecosystems and are globally significant components of benthic habitats down to the limits of the photic zone. Despite their vulnerability to ocean acidification (OA) and importance in low light environments, there is a limited understanding of how the interplay between irradiance and OA influences coralline reproduction and recruitment. To better understand this interaction, a 212-day experiment was run exposing coralline communities to two pH(T) levels (present-day pH(T) 8.07/ OA pH(T) 7.65) and a gradient of daily light dose (0.35, 0.17 and 0.1 mol m-2 d-1), based on in situ measurements. In the highest light dose treatment, lowered seawater pH projected for 2100 (pH(T) 7.65) reduced recruitment by 56%. This OA-driven reduction in recruitment was amplified under reduced light, with recruitment near zero in the lowest light treatment. This study shows, for the first time, the increased vulnerability of coralline community recruitment to OA under low light. Coralline algae are known to be the deepest growing macroalgae and thus, in these low light zones, OA many have the potential to reduce coralline depth distribution.
In this study, the variations of the seawater carbonate system parameters and air-sea CO2 flux (FCO2) of Shen’ao Bay, a typical subtropical aquaculture bay located in China, were investigated in spring 2016 (March to May). Parameters related to the seawater carbonate system and FCO2 were measured monthly in 3 different aquaculture areas (fish, oyster and seaweed) and in a non-culture area near the bay mouth. The results showed that the seawater carbonate system was markedly influenced by the biological processes of the culture species. Total alkalinity was significantly lower in the oyster area compared with the fish and seaweed areas, mainly because of the calcification process of oysters. Dissolved inorganic carbon (DIC) and CO2 partial pressure ( pCO2) were highest in the fish area, followed by the oyster and non-culture areas, and lowest in the seaweed area. Oysters and fish can have indirect influences on DIC and pCO2by releasing nutrients, which facilitate the growth of seaweed and phytoplankton and therefore promote photosynthetic CO2 fixation. For these reasons, Shen’ao Bay acts as a potential CO2 sink in spring, with an average FCO2 ranging from -1.2 to -4.8 mmol m-2 d-1. CO2 fixation in the seaweed area was the largest contributor to CO2 flux, accounting for ca. 58% of the total CO2 sink capacity of the entire bay. These results suggest that the carbonate system and FCO2 of Shen’ao Bay were significantly affected by large-scale mariculture activities. A higher CO2 sink capacity could be acquired by extending the culture area of seaweed.
In light of the chronic stress and mass mortality reef-building corals face under climate change, it is critical to understand the processes essential to reef persistence and replenishment, including coral reproduction and development. Here we quantify gene expression and size sensitivity to ocean acidification across a set of developmental stages in the rice coral, Montipora capitata. Gametes and then embryos and swimming larvae were exposed to three pH treatments ranging from 7.8 (Ambient), 7.6 (Low) and 7.3 (Xlow) from fertilization to 9 days post-fertilization. Embryo development and size, planula volume, and stage-specific gene expression were compared between treatments at each stage to determine the effects of acidified seawater on early development. While there was no measurable size differentiation between fertilized eggs and embryos at the prawn chip stage exposed to ambient, low, and extreme low pH, early gastrula and planula raised in reduced pH treatments were significantly smaller than those raised in ambient seawater, suggesting an energetic cost to developing under low pH. However, no differentially expressed genes emerged between treatments at any time point, except swimming larvae. Larvae from pH 7.6 showed upregulation of genes involved in cell division, regulation of transcription, lipid metabolism, and oxidative stress in comparison to the other two treatments, and smallest sizes in this treatment. While low pH appears to increase energetic demands and trigger oxidative stress, the developmental process is robust to this at a molecular level, with swimming larval stage reached in all pH treatments.
They are the archives of the oceans. Corals are a great indicator of how much human activities affect our oceans. Funded by the Franco-German fellowship program “Make Our Planet Great Again,” researchers in the U Bremen Research Alliance are studying the extent of global warming in tropical waters.
The forearm-thick whitish drill core held by Dr. Henry Wu of the Leibniz Centre for Tropical Marine Research (ZMT) has come a long way. It originates from a stony coral from the coastal region off Rotuma, an island in the Republic of Fiji, more than 15,000 kilometers from Bremen. The oldest corals being examined by the paleo-climatologist are more than 100,000 years old. In the course of their lives, they have accumulated a vast amount of information.
Corals grow on average a few millimeters per year. They thrive best in clean water and live up to 50 meters below the surface of the sea, where sunrays can still reach them. Just like the growth rings of trees, the micro samples from their calcareous skeleton tell of changing environmental conditions: temperature fluctuations, the amount of rainfall, ocean acidification, and salinity – and they do so with month-to-month precision.
Wu is using these archives of the ocean within the context of his five-year research project. “Climate has always been changing naturally. We want to know: How profound were these changes? What impact has industrialization had since the beginning of the 19th century?” says the researcher. “If we know the past, we can better predict the future.”
A 3-Day, In-person Professional Development workshop for Middle and High School Teachers
Date: 23-25 August 2021
Time: 9:00 am – 4:30 pm PDT
Location: Padilla Bay NERR, 10441 Bay View-Edison RD, Mount Vernon, Washington 98273, United States, View Map
Participants in this workshop will:
- Gain knowledge of climate change and ocean acidification in the Pacific Northwest
- Explore sources of local environmental data and work towards incorporating data into inquiry-based science learning experiences
- Receive materials and activities included in the Ocean Sciences Sequence (OSS) curriculum on Climate Change developed by UC Berkeley Lawrence Hall of Science
- Become familiar with and utilize Next Generation Science Standards (NGSS) to foster “three dimensional” learning through Cross Cutting Concepts, Core Disciplinary Ideas, and Science and Engineering Practices.
What you will receive:
21 STEM Clock Hours (free)
Ocean Sciences Sequence curriculum
$100 stipend upon implementation in classroom
Inexpensive housing options available in Padilla Bay’s guesthouse.
Questions? Email: Susan Wood, firstname.lastname@example.org
- High CO2 conditions profoundly affected biofilm community composition
- Species turnover explained differences in community composition
- Biofilm communities were more homogeneous under high CO2 conditions
- Toxin producing and turf-forming algae were enriched under high CO2 conditions
Biofilms harbour a wealth of microbial diversity and fulfil key functions in coastal marine ecosystems. Elevated carbon dioxide (CO2) conditions affect the structure and function of biofilm communities, yet the ecological patterns that underpin these effects remain unknown. We used high-throughput sequencing of the 16S and 18S rRNA genes to investigate the effect of elevated CO2 on the early successional stages of prokaryotic and eukaryotic biofilms at a CO2 seep system off Shikine Island, Japan. Elevated CO2 profoundly affected biofilm community composition throughout the early stages of succession, leading to greater compositional homogeneity between replicates and the proliferation of the potentially harmful algae Prymnesium sp. and Biddulphia biddulphiana. Species turnover was the main driver of differences between communities in reference and high CO2 conditions, rather than differences in richness or evenness. Our study indicates that species turnover is the primary ecological pattern that underpins the effect of elevated CO2 on both prokaryotic and eukaryotic components of biofilm communities, indicating that elevated CO2 conditions represent a distinct niche selecting for a distinct cohort of organisms without the loss of species richness.
Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed “tropicalization”. A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral-dominated systems. We conducted field surveys and in situ transplants at natural analogues for present and future conditions under (i) ocean warming and (ii) both ocean warming and acidification at a transition zone between kelp and coral-dominated ecosystems. We show that increased herbivory by warm-water fishes exacerbates kelp forest loss and that ocean acidification negates any benefits of warming for range extending tropical corals growth and physiology at temperate latitudes. Our data show that, as the combined effects of ocean acidification and warming ratchet up, marine coastal ecosystems lose kelp forests but do not gain scleractinian corals. Ocean acidification plus warming leads to overall habitat loss and a shift to simple turf-dominated ecosystems, rather than the complex coral-dominated tropicalized systems often seen with warming alone. Simplification of marine habitats by increased CO2 levels cascades through the ecosystem and could have severe consequences for the provision of goods and services.
The invasion of anthropogenic carbon into the global ocean poses an existential threat to calcifying marine organisms1–4. Observations indicate that conditions corrosive to aragonite shells, unprecedented in the surface ocean, are already occurring in mesoscale upwelling features of the North Pacific2,5,6 and Southern Ocean7, and modeling experiments indicate that large volumes of the global ocean8 including the polar ocean’s surface might become corrosive to aragonite by 20304,9–13. Such changes are expected to compress important marine habitats, but the pathways by which habitat compression manifests over global scales, and their sensitivity to mitigation, remain unexplored. Using a suite of large ensemble projections from an Earth system model14,15, we assess the effectiveness of climate mitigation for averting habitat loss at the ecologically-critical horizon of the base of the ocean’s euphotic zone. We find that without mitigation, 40-42% of this sensitive horizon experiences conditions corrosive to aragonite by 2100, with moderate mitigation this reduces to 16-19%, and with aggressive mitigation to 6-7%. Mitigation has a stronger effect on the eastern relative to western domains of the northern extratropical ocean with some of the greatest benefits in the ocean’s most productive Large Marine Ecosystems, including the California Current and Gulf of Alaska. This work reveals the significant impact that mitigation efforts compatible with the Paris Agreement target of 1.5°C could have upon preserving marine habitats that are vulnerable to ocean acidification.
Oceanic measurements collected during a scientific cruise on NOAA Ship Ronald H. Brown last week confirmed that a large area of poorly oxygenated water is growing off the coast of Washington and Oregon.
Oxygen-depleted bottom waters occur seasonally along the continental shelf of Washington and Oregon when strong winds blowing along the coast in spring and summer trigger upwellings that bring deep, cold, nutrient-rich water to the surface. These waters fuel blooms of plankton that feed small animals like krill, which are food for many marine creatures. When these blooms die off, they sink to the bottom, where their decomposition consumes oxygen, leaving less for organisms such as crabs and bottom-dwelling fish.
Earliest onset in 35 years
“Low dissolved oxygen levels have become the norm ion the Pacific Northwest coast, but this event started much earlier than we’ve seen in our records,” said Oregon State University Professor Francis Chan, director of the NOAA cooperative institute CIMERS. “This is the earliest start to the upwelling season in 35 years.” Typically, hypoxic conditions don’t appear until late June or early July, he said.
The once common kelp forests and abalone fisheries of the Shikine Island in Japan have now vanished. Scientists from Japan identified that these temperate coastal marine ecosystems are transforming into much “simpler” ones, deprived of their biodiversity aesthetic values and complexity.
Researchers from the University of Tsukuba find that the combined effects of ocean warming and acidification in temperate marine ecosystems are resulting in a loss of kelp habitat and a shift to a simple turf-dominated ecosystem. Such changes will lead to a loss of the ecosystem services provided by productive macroalgal forests or tropicalized coral-dominated reefs. These results highlight the need for reductions in greenhouse gas emissions. Image Credit: University of Tsukuba.
Scientists from the University of Tsukuba along with their international collaborators investigated the combined effects of ocean warming and acidification on the temperate coastal marine ecosystems.
Coral reefs are synonymous with the tropical coastal seas. When the ocean temperatures cool in the direction of the poles, corals yield to kelp as the main habitat-forming species. This shift from coral to kelp can be seen evidently on the 2000 km coastline of Japan, where modifications to these ecosystems are ongoing.
Ocean acidification (OA) has both detrimental as well as beneficial effects on marine life; it negatively affects calcifiers while enhancing the productivity of photosynthetic organisms. To date, many studies have focused on the impacts of OA on calcification in reef-building corals, a process particularly susceptible to acidification. However, little is known about the effects of OA on their photosynthetic algal partners, with some studies suggesting potential benefits for symbiont productivity. Here, we investigated the transcriptomic response of the endosymbiont Symbiodinium microadriaticum (CCMP2467) in the Red Sea coral Stylophora pistillata subjected to different long-term (2 years) OA treatments (pH 8.0, 7.8, 7.4, 7.2). Transcriptomic analyses revealed that symbionts from corals under lower pH treatments responded to acidification by increasing the expression of genes related to photosynthesis and carbon-concentrating mechanisms. These processes were mostly up-regulated and associated metabolic pathways were significantly enriched, suggesting an overall positive effect of OA on the expression of photosynthesis-related genes. To test this conclusion on a physiological level, we analyzed the symbiont’s photochemical performance across treatments. However, in contrast to the beneficial effects suggested by the observed gene expression changes, we found significant impairment of photosynthesis with increasing pCO2. Collectively, our data suggest that over-expression of photosynthesis-related genes is not a beneficial effect of OA but rather an acclimation response of the holobiont to different water chemistries. Our study highlights the complex effects of ocean acidification on these symbiotic organisms and the role of the host in determining symbiont productivity and performance.
Understanding decadal changes in the coastal carbonate system is essential for predicting how the health of these waters responds to anthropogenic drivers, such as changing atmospheric conditions and riverine inputs. However, studies that quantify the relative impacts of these drivers are lacking. In this study, the primary drivers of decadal trends in the surface carbonate system, and the spatiotemporal variability in these trends, are identified for a large coastal plain estuary: the Chesapeake Bay. Experiments using a coupled three-dimensional hydrodynamic-biogeochemical model highlight that, over the past three decades, the changes in the surface carbonate system of Chesapeake Bay have strong seasonal and spatial variability. The greatest surface pH and aragonite saturation state (ΩAR) reductions have occurred in the summer in the middle (mesohaline) Bay: −0.24 and −0.9 per 30 years, respectively, with increases in atmospheric CO2 and reductions in nitrate loading both being primary drivers. Reductions in nitrate loading have a strong seasonal influence on the carbonate system, with the most pronounced decadal decreases in pH and ΩAR occurring during the summer when primary production is strongly dependent on nutrient availability. Increases in riverine total alkalinity and dissolved inorganic carbon have raised surface pH in the upper oligohaline Bay, while other drivers such as atmospheric warming and input of acidified ocean water through the Bay mouth have had comparatively minor impacts on the estuarine carbonate system. This work has significant implications for estuarine ecosystem services, which are typically most sensitive to surface acidification in the spring and summer seasons.
Plain Language Summary
Seawater pH, a measure of how acidic or basic water is, is a crucial water quality parameter influencing the growth and health of marine organisms, such as oysters, fishes and crabs. Decreasing pH, commonly referred to as acidification, is a severe environmental issue that has been exacerbated by human activities since the industrial revolution. In the open ocean, elevated atmospheric carbon dioxide is the key driver of acidification. However, in coastal environments the drivers are particularly complex due to changing human influences on land. In this study the primary drivers of acidification in the Chesapeake Bay over the past three decades are identified via the application of a three-dimensional ecosystem model. Increased atmospheric CO2 concentrations and decreased terrestrial nutrient inputs are two primary drivers causing nearly equal reductions in pH in surface waters of the Bay. The pH reductions resulting from decreased nutrient loads indicate that the system is reverting back to more natural conditions when human-induced nutrient inputs to the Bay were lower. As nutrient reduction efforts to improve coastal water quality continue in the future, controlling the emissions of anthropogenic CO2 globally becomes increasingly important for the shellfish industry and the ecosystem services it provides.
The objective of this study was to assess experimentally the potential impact of anthropogenic pH perturbation (ApHP) on concentrations of dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP), as well as processes governing the microbial cycling of sulfur compounds. A summer planktonic community from surface waters of the Lower St. Lawrence Estuary was monitored in microcosms over 12 days under three pCO2 targets: 1 × pCO2 (775 µatm), 2 × pCO2 (1,850 µatm), and 3 × pCO2 (2,700 µatm). A mixed phytoplankton bloom comprised of diatoms and unidentified flagellates developed over the course of the experiment. The magnitude and timing of biomass buildup, measured by chlorophyll a concentration, changed in the 3 × pCO2 treatment, reaching about half the peak chlorophyll a concentration measured in the 1 × pCO2 treatment, with a 2-day lag. Doubling and tripling the pCO2 resulted in a 15% and 40% decline in average concentrations of DMS compared to the control. Results from 35S-DMSPd uptake assays indicated that neither concentrations nor microbial scavenging efficiency of dissolved DMSP was affected by increased pCO2. However, our results show a reduction of the mean microbial yield of DMS by 34% and 61% in the 2 × pCO2 and 3 × pCO2 treatments, respectively. DMS concentrations correlated positively with microbial yields of DMS (Spearman’s ρ = 0.65; P < 0.001), suggesting that the impact of ApHP on concentrations of DMS in diatom-dominated systems may be strongly linked with alterations of the microbial breakdown of dissolved DMSP. Findings from this study provide further empirical evidence of the sensitivity of the microbial DMSP switch under ApHP. Because even small modifications in microbial regulatory mechanisms of DMSP can elicit changes in atmospheric chemistry via dampened efflux of DMS, results from this study may contribute to a better comprehension of Earth’s future climate.
A team of researchers called SEA MATE, led by Stony Brook University professor Matthew Eisaman, is using electricity to remove acid from the ocean while also taking carbon dioxide from the atmosphere.
Continually increasing carbon dioxide concentrations in the atmosphere have already led to changes in the climate as well as the acidification of the oceans. This increased acidity of the oceans is analogous to a slow motion “spill” of acid, so just as oil spills need to be cleaned up, so do these acid spills.
The approach of SEA MATE (Safe Elevation of Alkalinity for the Mitigation of Acidification Through Electrochemistry) uses carbon-free electricity and electrochemistry to effectively pump this excess acid out of the ocean and then sells the acid for useful purposes. This acid removal restores the ocean chemistry such that the remaining ions in the ocean react with atmospheric carbon dioxide, safely locking it up for 10,000 – 200,000 years as oceanic bicarbonate. The net effect of SEA MATE is the reversal of ocean acidification along with the net removal of carbon dioxide from the atmosphere.
Early deployments will likely partner with existing marine industries such as seawater desalination, aquaculture, maritime transport, and offshore wind. As an example, performing the SEA MATE process on the waste effluent from desalination plants would provide value to these plants by reducing their environmental impact, while also mitigating ocean acidification and decreasing the concentration of atmospheric carbon dioxide.
In 2017, the United Nations General Assembly proclaimed the time frame of 2021-2030 as the UN Decade of Ocean Science for Sustainable Development, also known as the “Ocean Decade,” to address the degradation of the ocean and encourage innovative science initiatives to better understand and ultimately reverse its declining health.
Several collaborative initiatives featuring work by scientists at NOAA’s Atlantic Oceanographic Meteorological Laboratory (AOML) have recently been endorsed in the first Ocean Decade Actions announcement, made by the United Nations Intergovernmental Oceanographic Commission (IOC) of UNESCO in 2021.
Scientists at AOML are collaborating with national and international partners and stakeholders to carry out research that supports the vision of the UN Ocean Decade through initiatives such as the Observing Air-Sea Interactions Strategy (OASIS), the Ocean Biomolecular Observing Network (OBON), the Global Ocean Biogeochemistry Array (GO-BGC), and the Ocean Acidification Research for Sustainability (OARS) program.
Since the Industrial Revolution, the massive amount of anthropogenic carbon dioxide (CO2) generated has elevated the atmospheric CO2 concentration. About one-fourth to one-third of the anthropogenic CO2 has been absorbed by the ocean, which leads to reductions in both oceanic pH and carbonate ion concentrations, a process known as “ocean acidification” (OA). Theoretically, OA will pose a great threat to a variety of marine invertebrates by influencing the skeletal formation and the chemical properties of habitats. Since invertebrates play a significant role in the marine ecosystem and many marine invertebrates are economically important aquaculture species, the effects of OA on marine invertebrates have been a hotspot for research in recent years. In this chapter, the current knowledge of the physiological influences of OA on marine invertebrates, including gametic traits, fertilization success, embryonic development, biomineralization, metabolism, growth, and immune responses, was summarized. In addition, the potential underlying affecting mechanisms were discussed. The authors hope that the contents of this chapter provide some basic information and guidance for readers who are interested in this area and plan to carry out future studies on this topic.
Human activities and global climate change give rise to the increasing concentration of carbon dioxide (CO2) in the atmosphere, which is subsequently absorbed by the ocean surface, leading to ocean acidification (OA). At present, the global OA driven by CO2 is becoming more and more serious, which poses a great threat to marine ecosystems. A lot of investigations have shown that OA has disrupted various trophic levels of the food chain in marine ecosystems, including marine invertebrates and vertebrates. These impacts are harmful to the health and stability of marine ecosystems. As a typical representative of marine vertebrates, marine teleosts are suffering from the environmental stresses caused by OA, but our understanding of the impacts of OA on these species is not profound. This chapter systematically summarizes the effects of OA on marine teleosts, including acid–base and ion regulation, fertilization, embryonic development, growth, metabolism, reproduction, behaviors, and many other aspects. By analyzing the relevant research progress, we expect to deeply understand the responses of marine vertebrates such as teleosts to OA and the related underlying mechanisms, which will be conducive to effectively avoiding the threat of global climate change and providing theoretical references for formulating effective coping strategies against OA.
Behavioral modification is the distinct response exhibited by marine animals to stressors. Exposure to oceanic environmental changes can alter the behaviors of aquatic animals, such as foraging, antipredation, habitat selection, and social hierarchy. Ocean acidification (OA) can alter the animal behaviors of a single species and thereby affect the structure and function of marine populations, communities, and ecosystems. Recently, the effects of OA on the behavioral responses of marine animals have received much attention. Considering the essential ecological functions and fishery value of marine living resources, we need to remain vigilant about the subsequent risk of OA. Here, we provide a systematic review including some classical case studies to highlight the effects of CO2-driven OA on the most common behaviors studied in marine animals and synthesize the current understanding of how OA may impact marine animal behaviors.