Increasing public support for carbon emissions mitigation is crucial for solving global issues like climate change and ocean acidification (OA). Yet carbon emissions mitigation policies are typically discussed in the context of climate change and hardly ever in the context of OA. In this paper, we present carbon emissions in five different contexts (climate change, global warming, carbon pollution, air pollution, and ocean acidification) and use an online survey tool—with a politically diverse sample of the US population—to measure support for mitigation policies. Though air pollution mitigation receives the highest amount of policy support overall, OA mitigation receives higher levels of support than carbon pollution, climate change, and global warming from conservatives who have heard of ocean acidification. This finding, coupled with other trends in OA perceptions has interesting potential for future risk communication and carbon emissions mitigation policies; OA may offer a new way to engage conservatives in carbon mitigation policy.
Archive for September, 2016
Building support for carbon emissions mitigation: can we use an ocean acidification frame to promote support?
Published 30 September 2016 Science ClosedTags: methods, mitigation, policy
Metabolic responses to high pCO2 conditions at a CO2 vent site in juveniles of a marine isopod species assemblage
Published 30 September 2016 Science ClosedTags: biological response, chemistry, crustaceans, field, Mediterranean, mortality, physiology, vents
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.
Intraspecific variability in the response to ocean warming and acidification in the scleractinian coral Acropora pulchra
Published 30 September 2016 Science ClosedTags: biological response, BRcommunity, calcification, corals, laboratory, multiple factors, temperature
Studies of coral colonies show that ocean acidification and temperature can affect calcification; however, less is known about the consequences for their populations. Understanding intraspecific variation in the response of corals to these conditions will be important for evaluating population-level consequences of environmental change. We examined intraspecific variability in the effects of elevated temperature and carbon dioxide levels on net calcification (Gn) in the coral Acropora pulchra in Moorea, French Polynesia. A common garden experiment showed that Gn in four colonies was affected negatively by high partial pressure of CO2 (pCO2) (~1000 μatm cf. ~400 μatm ambient conditions), whereas elevated temperature (30 °C cf. 27 °C) had a negative effect on one colony. Together, these results reveal intraspecific variation in the response of Gn to temperature but not to pCO2. The fastest growing colonies under ambient temperature and ambient pCO2 showed the greatest decline in Gn at high temperature and elevated pCO2. For reef corals, effects of temperature and pCO2 on calcification that depend on the intrinsic growth rate have potentially important consequences, because they imply that coral colonies contributing the most to population-level calcification will be disproportionately affected by changing environmental conditions.
Sea sponges likely to weather climate change: New Zealand study
Published 30 September 2016 Media coverage ClosedWELLINGTON, Sept. 29 (Xinhua) — Some species of sea sponge could be “winners” in global climate change and ocean acidification, New Zealand scientists said Thursday.
Researchers from Victoria University of Wellington examined the physiological responses of four Great Barrier Reef sponge species in response to rising acidification and seawater temperature.
They found that while all four species were sensitive to predicted ocean warming, their sensitivity reduced under ocean acidification for sponges that received their nutrition from symbiotic organisms which get their energy from the sun.
“Our results show that some sponges may be able to deal with future predicted ocean conditions, making them future ‘winners’ under global climate change,” researcher Holly Bennett said in a statement.
The study also found that early-life stages of sponges exhibited greater tolerance to ocean warming than their adult counterparts, which was likely to be crucial to the survival and adaptive capacity of some sponges.
Continue reading ‘Sea sponges likely to weather climate change: New Zealand study’
Disparate acidification and calcium carbonate desaturation of deep and shallow waters of the Arctic Ocean
Published 30 September 2016 Science ClosedTags: Arctic, biogeochemistry, chemistry, modeling, regionalmodeling
The Arctic Ocean is acidifying from absorption of man-made CO2. Current predictive models of that acidification focus on surface waters, and their results argue that deep waters will acidify by downward penetration from the surface. Here we show, with an alternative model, the rapid, near simultaneous, acidification of both surface and deep waters, a prediction supported by current, but limited, saturation data. Whereas Arctic surface water responds directly by atmospheric CO2 uptake, deeper waters will be influenced strongly by intrusion of mid-depth, pre-acidified, Atlantic Ocean water. With unabated CO2 emissions, surface waters will become undersaturated with respect to aragonite by 2105 AD and could remain so for ∼600 years. In deep waters, the aragonite saturation horizon will rise, reaching the base of the surface mixed layer by 2140 AD and likely remaining there for over a millennium. The survival of aragonite-secreting organisms is consequently threatened on long timescales.
Combined effects of elevated pCO2 and temperature on biomass and carbon fixation of phytoplankton assemblages in the northern South China Sea
Published 30 September 2016 Science ClosedTags: abundance, biological response, laboratory, multiple factors, North Pacific, otherprocess, photosynthesis, phytoplankton, primary production, respiration, temperature
The individual influences of ocean warming and acidification on marine organisms have been investigated intensively, but studies regarding the combined effects of both global change variables on natural marine phytoplankton assemblages are still scarce. Even fewer studies have addressed possible differences in the responses of phytoplankton communities in pelagic and coastal zones to ocean warming and acidification. We conducted shipboard microcosm experiments at both off-shore (SEATS) and near-shore (D001) stations in the northern South China Sea (NSCS) under three treatments, low temperature (30.5 °C at SEATS and 28.5 °C at D001) and low pCO2 (390.0 µatm at SEATS and 420.0 µatm at D001) (LTLC), high temperature (33.5 °C at SEATS and 31.5 °C at D001) and low pCO2 (390 µatm at SEATS and 420 µatm at D001) (HTLC), and high temperature (33.5 °C at SEATS and 31.5 °C at D001) and high pCO2 (1000 µatm at SEATS and 1030 µatm at D001) (HTHC). Biomass of phytoplankton at both stations were enhanced by HT. HTHC did not affect phytoplankton biomass at station D001 but decreased it at station SEATS. At this offshore station HT alone increased daily primary productivity (DPP, µgC (µg chl a)−1 d−1) by ~ 64 %, and by ~ 117 % when higher pCO2 was added. In contrast, HT alone did not affect DPP and HTHC reduced it by ~ 15 % at station D001. HT enhanced the dark respiration rate (µg C (µg chl a)-1 d−1) by 64 % at station SEATS, but had no significant effect at station D001, and did not change the ratio of respiration to photosynthesis at either station. HTHC did not affect dark respiration rate (µg C (µg chl a)−1 d−1) at either station compared to LTLC. HTHC reduced the respiration to photosynthesis ratio by ~ 41 % at station SEATS but increased it ~ 42 % at station D001. Overall, our findings indicate that responses of coastal and offshore phytoplankton assemblages in NSCS to ocean warming and acidification are contrasting, with the pelagic phytoplankton communities being more sensitive to these two global change factors.
Effects of elevated carbon dioxide and temperature on survival and morphology of Japanese whiting Sillago japonica
Published 30 September 2016 Science ClosedTags: biological response, fish, laboratory, morphology, mortality, multiple factors, North Pacific, performance, reproduction, temperature
The objective of the present study was to examine the effect of elevated CO2 and temperature on survival and morphology of Sillago japonica yolk sac larvae under the Institute for East China Sea Research(ECSER) Nagasaki, Japan. In this study, we examined hatching success, survival and morphology of the larvae of Sillago japonica under four conditions: control (C), seawater pCO2 382µatm, temperature 27 °C; high CO2 (HC), 915µatm, 27 °C; high temperature (HT), 385 µatm, 31 oC; and high CO2+high temperature (HCT), 932µatm, 31 oC. Fertilized eggs were obtained from broodstock reared in natural seawater, and transferred to experimental containers in each treatment. Hatched larvae were observed until the completion of yolk sac absorptions on 3 days post hatching (dph). The experiment was repeated four times with 4 replicates for each treatment in each experiment. Also, the temperature appeared to have exerted a stronger influence on hatching success (Hs) and larval survival (Sv): Hs and Sv at 3 dph were both significantly (p>0.05) depressed in HT (Hs 52.5±1.25%, Sv 23.8±4.38%) and HCT (Hs 51.3±3.13%, Sv 20.0±0.63%) treatments than in C (Hs 98.1±0.94%, Sv 74.4±2.03%) and HC (Hs 95.0±2.5%, Sv 49.7±3.44%) treatments. In contrast, CO2 was the predominant factor responsible for morphological abnormality: percentage morphological abnormality was significantly (p>0.05) higher in HC (15.8±2.72%) and HCT (41.0±10.86%) treatments than in C (0.4±0.65%) and HT (2.4±2.40%) treatments. Most individuals in HC and HCT treatments had body axis either curved or bent, with aberrant swimming behavior. These results indicate that projected future ocean environments will have significant negative impacts on hatching success, and larval survival and morphology of S. japonica, which might have serious ramifications for recruitment of the species. Comparative studies on other teleost and elasmobranch species are critically needed.
Missions CARIOCA – Papouasie-Nouvelle-Guinée – Acclimatation des coraux à l’acidification des océans (in French)
Published 29 September 2016 Media coverage , Projects ClosedUne équipe internationale pilotée par l’IRD embarque à bord de l’Alis pour étudier en Papouasie-Nouvelle-Guinée des espèces de coraux capables de se développer dans des sites naturellement plus acides. Objectif : en savoir plus sur leur capacité d’acclimatation et d’adaptation aux conditions prévues d’ici la fin du siècle dans le cadre du changement climatique.
En péril… Plus de la moitié des récifs coralliens dans le monde sont menacés de disparition par le changement climatique. Outre l’élévation de la température, l’augmentation dans l’atmosphère du dioxyde de carbone CO2, engendre une plus grande absorption de ce gaz par l’océan. Environ 800 kg de CO2 sont ainsi dissous dans les mers et océans de la planète par seconde. Sans ce puits de carbone, l’effet de serre sur la Terre serait encore plus important. Mais l’augmentation de ce phénomène provoque une acidification de l’océan et perturbe la biologie des organismes marins. Pour les coraux bâtisseurs de récifs, ceci se traduit par une plus grande difficulté à construire leur squelette calcaire et par une augmentation de sa dissolution. Or les récifs coralliens hébergent un tiers de la biodiversité marine et fournissent des biens et des services écosystémiques à plus de 500 millions de personnes dans le monde.
A direct CO2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum
Published 29 September 2016 Science ClosedTags: algae, biological response, laboratory, mesocosms, methods, multiple factors, photosynthesis, respiration, temperature
Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO2. However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and pCO2. Here we describe a system in which the target pCO2 is controlled via direct analysis of pCO2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA) that measures pCO2 and conveys this value to a Proportional-Integral-Derivative (PID) controller. The controller commands a solenoid valve that opens and closes the CO2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of pCO2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum. We found that after 11 months of high CO2 exposure, photosynthesis increased with CO2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO2, such as temperature, irradiance and nutrients.
Ocean Acidification “State of the Science” Workshop, 30 November – 1 December 2016, Anchorage, Alaska
Published 29 September 2016 Courses and training , Events ClosedDate and time: November 30, 2016 9:00 AM – December 1, 2016 6:00 PM (AKST)
Location: Anchorage Downtown Marriott
Registration: This workshop is free and open to the public. Please register by November 7.
The Alaska Ocean Acidification Network is hosting a TWO-day workshop in Anchorage, inviting a broad audience across the state interested in ocean acidification issues.
There will be opportunities for remote participation at satellite viewing sites and via personal computer.
Workshop goals include educating the broader Alaska community on the processes and consequences of OA, creating connections between researchers and stakeholders, and developing new ideas and partnerships to enhance monitoring and community engagement. A report on the state of the science in Alaska will be produced after the workshop, as well as a set of recommendations to help guide the Alaska OA Network.
Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean) (update)
Published 28 September 2016 Science ClosedTags: biogeochemistry, chemistry, field, Mediterranean, sediment
The Rhône River is the largest source of terrestrial organic and inorganic carbon for the Mediterranean Sea. A large fraction of this terrestrial carbon is either buried or mineralized in the sediments close to the river mouth. This mineralization follows aerobic and anaerobic pathways, with a range of impacts on calcium carbonate precipitation and dissolution in the sediment near the sediment–water interface. This study focuses on the production of dissolved inorganic carbon (DIC) and total alkalinity (TA) by early diagenesis, consequential pH variations and the effect on calcium carbonate precipitation or dissolution. The sediment porewater chemistry was investigated along a transect from the Rhône River outlet to the continental shelf. TA and concentrations of DIC, SO42− and Ca2+ were analyzed on bottom waters and extracted sediment porewaters, whereas pH and oxygen concentrations were measured in situ using microelectrodes. The average oxygen penetration depth into the sediment was 1.7 ± 0.4 mm close to the river mouth and 8.2 ± 2.6 mm in the continental shelf sediments, indicating intense respiration rates. Diffusive oxygen fluxes through the sediment–water interface ranged between 3 and 13 mmol O2 m−2 d−1. In the first 30 cm of the sediment, TA and DIC porewater concentrations increased with depth up to 48 mmol L−1 near the river outlet and up to 7 mmol L−1 on the shelf as a result of aerobic and anaerobic mineralization processes. Due to aerobic processes, at all stations pH decreased by 0.6 pH units in the oxic layer of the sediment accompanied by a decrease of the saturation state regarding calcium carbonate. In the anoxic layer of the sediments, sulfate reduction was the dominant mineralization process and was associated with an increase of porewater saturation state regarding calcium carbonate. Ultimately anoxic mineralization of organic matter caused calcium carbonate precipitation demonstrated by a large decrease in Ca2+ concentration with depth in the sediment. Carbonate precipitation decreased in the offshore direction, together with the carbon turnover and sulfate consumption in the sediments. The large production of porewater alkalinity characterizes these sediments as an alkalinity source to the water column, which may increase the CO2 buffering capacity of these coastal waters. Estuarine sediments should therefore receive more attention in future estimations of global carbon fluxes.
Benthic foraminiferal shell weight: Deglacial species-specific responses from the Santa Barbara Basin
Published 28 September 2016 Science ClosedTags: abundance, biological response, morphology, North Pacific, otherprocess, paleo, protists
Here we present a record of size-normalized shell weight for four species of benthic foraminifera through a period of rapid environmental change during the most recent deglaciation (Santa Barbara Basin, CA). A strong Oxygen Minimum Zone (OMZ), the product of high surface productivity and poor ventilation, characterizes the eastern Pacific; this subsurface zone is mechanistically coupled with high concentrations of dissolved inorganic carbon. The OMZ migrated vertically during warming of the last deglaciation, leading to rapid shifts in the oxygenation and inorganic carbon system of the benthos. The size-normalized weight (SNW) of benthic foraminifers Uvigerina peregrina, Bolivina interjuncta, and Bolivina tumida reflects only the broad trends of the vertical migration of the OMZ, and inorganic carbon system, overshadowed by clear species-specific trends. The relative importance of OMZ migrations versus other environmental variables and optimal growth conditions differs across species of benthic foraminifera. In U. peregrina, SNW primarily peaks with foraminiferal density and increased abundance of that species, while B. interjuncta and B. tumida increase in SNW with a shrinking of the OMZ (and carbon maximum) in the late Holocene. Bolivina argentea shows no long-term trends in SNW potentially due to its ability to migrate through the sediment. Our results suggest that, while inorganic carbon and dissolved oxygen may play a role in determining shell weight across species of benthic foraminifera, neither parameter alone is responsible for changes in benthic foraminiferal shell weight in the fossil record.
Sea food industry faces threat from ocean acidification, rising temperatures: Study
Published 28 September 2016 Media coverage ClosedResearchers observed that ocean acidification could threaten lobsters and also affect the behavior and size of the larva.
Rise in the water temperatures of Gulf of Maine within a century can be threatening for lobsters and the sea food industry, according to the latest research conducted by the University of Maine Darling Marine Center and Bigelow Laboratory for Ocean Sciences. The study got published in the ICES Journal of Marine Science on September 21, 2016.
This study focuses on the impact of ocean acidification and rise of temperature on the larvae of the American lobster.
Ocean acidification is an outcome of climate change, which leads to the entry of more carbon dioxide in our environment while turning the oceans more acidic.
This study revealed that the survival of young lobsters was not affected by ocean acidification, but the lobster larvae reared by the researchers in water with 3 degree higher temperature, which will be similar to that of the temperature in the Gulf of Maine by the year 2100, were found to struggle.
Biogeographic variability in the physiological response of the cold-water coral Lophelia pertusa to ocean acidification
Published 27 September 2016 Science ClosedTags: biological response, calcification, corals, laboratory, North Atlantic, performance, respiration
While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold-water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short-term physiological response of the cold-water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.
EPA needs to get serious about ocean acidification
Published 27 September 2016 Media coverage ClosedOcean acidification is underway, and it’s hurting oysters in Washington, plankton in California and corals around the world.
This serious, escalating problem, caused by increasing carbon dioxide emissions and local pollution and runoff, is acknowledged by the U.S. Environmental Protection Agency but strangely, the federal agency has chosen to ignore the developing crisis in its regulations.
Gov. Jerry Brown just signed Assembly Bill 2139, calling for California to start addressing acidification that is already affecting our coastal waters, but the EPA shouldn’t wait until 2018 when the first recommendations from that new law are due.
The EPA sets baseline water-quality standards for each state under the Clean Water Act, but it hasn’t updated its criteria on water acidity in 40 years. The Center for Biological Diversity, where I work, petitioned the EPA in 2013 to update those standards, but more than three years later, it has taken no formal action. So we sued the agency this month to force it to finally meet its legal obligations.
Continue reading ‘EPA needs to get serious about ocean acidification’
OCSEF Ask-A-Scienctist/Engineer Night – Ocean Acidification Station, 12 October 2016, Tustin, California
Published 27 September 2016 Courses and training ClosedWhen: Wednesday, 12 October 2016, from 4:30 PM to 5:45 PM PDT
Where: A. G. Currie Middle School, 1402 Sycamore Ave, Tustin, CA 92780
In this experiment, participants will learn about the process of ocean acidification by adding CO2 to water and measuring its pH.
Estimating the ecological, economic and social impacts of ocean acidification and warming on UK fisheries
Published 27 September 2016 Science ClosedTags: abundance, biogeochemistry, biological response, chemistry, fish, fisheries, growth, modeling, mollusks, morphology, multiple factors, North Atlantic, otherprocess, performance, policy, regionalmodeling, reproduction, review, socio-economy, temperature
Assessments of the combined ecological impacts of ocean acidification and warming (OAW) and their social and economic consequences can help develop adaptive and responsive management strategies in the most sensitive regions. Here, available observational and experimental data, theoretical, and modelling approaches are combined to project and quantify potential effects of OAW on the future fisheries catches and resulting revenues and employment in the UK under different CO2 emission scenarios. Across all scenarios, based on the limited available experimental results considered, the bivalve species investigated were more affected by OAW than the fish species considered, compared with ocean warming alone. Projected standing stock biomasses decrease between 10 and 60%. These impacts translate into an overall fish and shellfish catch decrease of between 10 and 30% by 2020 across all areas except for the Scotland >10 m fleet. This latter fleet shows average positive impacts until 2050, declining afterwards. The main driver of the projected decreases is temperature rise (0.5–3.3 °C), which exacerbate the impact of decreases in primary production (10–30%) in UK fishing waters. The inclusion of the effect of ocean acidification on the carbon uptake of primary producers had very little impact on the projections of potential fish and shellfish catches (<1%). The <10 m fleet is likely to be the most impacted by-catch decreases in the short term (2020–50), whereas the effects will be experienced more strongly by the >10 m fleet by the end of the century in all countries. Overall, losses in revenue are estimated to range between 1 and 21% in the short term (2020–50) with England and Scotland being the most negatively impacted in absolute terms, and Wales and North Ireland in relative terms. Losses in total employment (fisheries and associated industries) may reach approximately 3–20% during 2020–50 with the >10 m fleet and associated industries bearing the majority of the losses.
Effects of light, temperature, and ocean acidification on the physiology and ecology of tropical crustose coralline algae
Published 27 September 2016 Science ClosedTags: algae, biological response, calcification, laboratory, light, multiple factors, North Pacific, photosynthesis, physiology, respiration, South Pacific, temperature
In the oceans, changes in seawater carbonate chemistry associated with increasing atmospheric concentrations of carbon dioxide (a process referred to as ocean acidification, or OA) is predicted to have significant effects on many marine species, particularly ones that calcify and/or photosynthesize. The effects of OA on these groups likely will be modulated by other environmental factors such as temperature and light. Understanding how these factors (which vary across different spatial scales within marine ecosystems), will interact with OA to influence calcifying autotrophs is important to inform predictions of how species distributions and community structure will shift under future OA and climate change. Thus, to explore the effects of temperature and light on the response of calcifying autotrophs to OA, this thesis investigated how temperature, light, and their interactions with OA affect the physiology and ecology of crustose coralline algae (CCA) found in Pacific coral reefs. In Chapter 2, surveys conducted in the backreef of Moorea, French Polynesia demonstrated that under contemporary conditions, microhabitats that differed strongly in their level of light exposure had significant heterogeneity in the relative abundances of different CCA species. Additionally, the competitive abilities of individual CCA species generally shifted across the light exposure gradient, sometimes leading to switches in competitive dominance within an interacting species pair. These shifts in competitive abilities could partially explain differences in the abundances of the CCA species across the microhabitat types. Thus, light appears to be important for species interactions and community structure of these calcifying autotrophs in a contemporary coral reef. Using this ecological context, in Chapter 3 experiments were conducted in Moorea using the most common species of CCA found in its backreef, Porolithon onkodes. These experiments demonstrated that OA has an inhibitory effect on some aspects of photophysiology (e.g., Fv/Fm), and neutral (Pmax) or positive (the responsiveness of photosynthesis to sub-saturating light, α) effects on other aspects. However, when there was an effect, its magnitude generally depended upon light. Additionally, light did not influence how net calcification or respiration of light-adapted samples responded to OA. However, dark-adapted respiration rates doubled under OA conditions. These different responses potentially imply that in the short-term, photosynthesis can mitigate the stimulatory effect of OA on respiration, but has no effect on calcification rates under OA. Overall, the responses of Fv/Fm and dark-adapted respiration indicate that there may be a contraction in the light range tolerated by P. onkodes under OA. Consequently, due to the decreased competitive ability of this dominant species in lower light habitats (Chapter 2), this change in distribution under OA could magnify the decline of this species at the whole reef scale. Results from Chapter 4 demonstrate that contrary to studies conducted on P. onkodes from other parts of the Pacific, increases in temperature from 25 to 28 C significantly reduced the negative effect of OA on calcification in individuals from Okinawa, Japan. Gross photosynthesis, respiration, and tissue necrosis also significantly increased in the 28 C treatment, but were not influenced by pCO2. These results imply that some populations of this species may benefit from temperature increases associated with climate change, which will occur concurrently with OA (although tissue necrosis may limit the extent of this benefit). Combined with the results from Chapters 2 and 3, these findings indicate that the effects of OA on coral reef calcifiers like CCA will vary at multiple spatial scales both within and across coral reef ecosystems due to light and temperature differences at these locations. Consequently, it is probable that there will be shifts in the microhabitats, depth zones, and potentially geographic regions where various species of these calcifying autotrophs will persist in the future under OA.
Acidification and γ-aminobutyric acid independently alter kairomone-induced behaviour
Published 27 September 2016 Science ClosedTags: biological response, chemistry, crustaceans, field, laboratory, North Atlantic, performance, physiology
Exposure to high pCO2 or low pH alters sensation and behaviour in many marine animals. We show that crab larvae lose their ability to detect and/or process predator kairomones after exposure to low pH over a time scale relevant to diel pH cycles in coastal environments. Previous work suggests that acidification affects sensation and behaviour through altered neural function, specifically the action of γ-aminobutyric acid (GABA), because a GABA antagonist, gabazine, restores the original behaviour. Here, however, gabazine resulted in a loss of kairomone detection/processing, regardless of pH. Our results also suggest that GABAergic signalling is necessary for kairomone identification in these larvae. Hence, the mechanism for the observed pH effect varies from the original GABA hypothesis. Furthermore, we suggest that this pH effect is adaptive under diel-cycling pH.
Metabolic responses of the North Pacific krill, Euphausia pacifica, to short- and long-term pCO2 exposure
Published 27 September 2016 Science ClosedTags: biological response, crustaceans, laboratory, North Pacific, performance, physiology, respiration, zooplankton
While ocean acidification is likely to have major effects on many marine organisms, those species that regularly experience variable pCO2 environments may be more tolerant of future predicted changes in ocean chemistry. Euphausia pacifica is an abundant krill species along the Pacific coast of North America and one that regularly experiences varying pCO2 levels during seasonal upwelling, as well as during daily vertical migrations to depth where pCO2 is higher. Krill were collected from Monterey Bay, California (36.8°N, 121.9°W), and experiments were performed from June to August 2014 and maintained at two pCO2 levels (400 and 1200 µatm). Three metabolic responses (oxygen consumption, ingestion rate, and nutrient excretion rates) of E. pacifica were measured. Oxygen consumption declined by 31 % in the first 24 h following exposure to high pCO2 and remained low after 21 days. Oxygen consumption at low pCO2 was low for the first 12 h, increased by 34 % at 24 h, but returned to initial values by 21 days. After 3 weeks of continuous exposure, oxygen consumption rates were 32 % lower in the high pCO2 group. Ingestion and ammonium excretion rates were both significantly lower in the high pCO2 group after 24-h exposure, but not after 7 or 21 days. There was no effect of pCO2 on phosphate excretion. Taken together, these results indicate that E. pacifica has a lower metabolic rate during both short-term (24 h) and longer-term (21 days) exposure to high pCO2. Such metabolic depression may explain previously reported declines in growth of E. pacifica exposed to high pCO2.
