Coral reef macroalgae are expected to thrive in the future under conditions that are deleterious to the health of reef-building corals. Here we examined how macroalgae would be affected by exposure to future CO2 emission scenarios (pCO2 and temperature), enriched nutrients and combinations of both. The species tested, Laurencia intricata (Rhodophyta), Turbinaria ornata and Chnoospora implexa (both Phaeophyceae), have active carbon-concentrating mechanisms but responded differently to the treatments. L. intricata showed high mortality under nutrient enriched RCP4.5 (“reduced” CO2 emission) and RCP8.5 (“business-as-usual” CO2 emission) and grew best under pre-industrial (PI) conditions, where it could take up carbon using external carbonic anhydrase combined, potentially, with proton extrusion. T. ornata’s growth rate showed a trend for reduction under RCP8.5 but was unaffected by nutrient enrichment. In C. implexa, highest growth was observed under PI conditions, but highest net photosynthesis occurred under RCP8.5, suggesting that under RCP8.5, carbon is stored and respired at greater rates while it is directed to growth under PI conditions. None of the species showed growth enhancement under future scenarios, nutrient enrichment or combinations of both. This leads to the conclusion that under such conditions these species are unlikely to pose an increasing threat to coral reefs.
Archive for April, 2017
Effects of elevated nutrients and CO2 emission scenarios on three coral reef macroalgae
Published 25 April 2017 Science ClosedTags: algae, biological response, growth, laboratory, mortality, multiple factors, nutrients, photosynthesis, physiology, temperature
The effects of elevated temperature and dissolved ρCO2 on a marine foundation species
Published 25 April 2017 Science ClosedTags: biological response, laboratory, mollusks, morphology, mortality, multiple factors, North Atlantic, physiology, temperature
Understanding how climate change and other environmental stressors will affect species is a fundamental concern of modern ecology. Indeed, numerous studies have documented how climate stressors affect species distributions and population persistence. However, relatively few studies have investigated how multiple climate stressors might affect species. In this study, we investigate the impacts of how two climate change factors affect an important foundation species. Specifically, we tested how ocean acidification from dissolution of CO2 and increased sea surface temperatures affect multiple characteristics of juvenile eastern oysters (Crassostrea virginica). We found strong impacts of each stressor, but no interaction between the two. Simulated warming to mimic heat stressed summers reduced oyster growth, survival, and filtration rates. Additionally, we found that CO2-induced acidification reduced strength of oyster shells, which could potentially facilitate crab predation. As past studies have detected few impacts of these stressors on adult oysters, these results indicate that early life stages of calcareous marine organisms may be more susceptible to effects of ocean acidification and global warming. Overall, these data show that predicted changes in temperature and CO2 can differentially influence direct effects on individual species, which could have important implications for the nature of their trophic interactions.
Impacts of CO2-induced ocean acidification on predator detection ability and developementof temperate fish
Published 25 April 2017 Science ClosedTags: biological response, fish, growth, laboratory, morphology, mortality, North Atlantic, performance
Ocean acidification, caused by elevated levels of atmospheric carbon dioxide (CO2), is recognized as a serious threat to marine ecosystems. Until now, most studies have focused on marine calcifying organisms, due to dependence on calcium carbonate, which is likely to become limited under future acidification scenarios. Less attention has been given to fish, but recent studies on the early life stages suggest that behavior, growth, development and otolith size may be highly affected by increasing CO2 levels. Other studies, on the other hand, fail to detect negative effects, suggesting species-specific vulnerabilities to increasing concentrations of CO2 and point to a need of further research. Here we tested the effects of CO2-induced ocean acidification on the early life stages of a temperate marine fish, the clingfish Lepadogaster lepadogaster, by rearing larvae since hatching in control and high pCO2 conditions. Size-at-age metrics and otolith size were examined in pre-settlement stage larvae. Additionally, behavioral response to a predator odour was tested in L. lepadogaster larvae and in Atherina presbyter larvae, maintained in high pCO2 conditions. Recognition of predator odours is a key behavior for predator avoidance and survival, and is one of the most commonly affected behaviors in fishes exposed to high CO2 levels. Results suggest that early life stages of L. lepadogaster might be resilient to future scenarios of ocean acidification, whereas A. presbyter might be more susceptible, with potential impacts on its future survival. Future studies should address species capacity to adapt to the predicted ocean acidification over the next century.
Collaboration with new scholar and NOAA Ocean Acidification Program Show Potenital
Published 24 April 2017 Press releases ClosedThis past month, NCCOS welcomed a new Hollings Scholar, Madison Uetrecht, who will study the effects of ocean acidification on oyster growth under Dr. Beth Turner over the summer months. They visited Mook Sea Farm, where Uetrecht will conduct out-planting experiments with juvenile oysters to assess whether shell growth and calcification changes during different field ocean acidification (OA) conditions.
Dr. Turner is the NOAA lead on a recently funded mini-grant from the NOAA Ocean Acidification Program for citizen science workshops through the Northeast Coastal Acidification Network. Monitoring guidance for coastal acidification developed by EPA will guide workshop participants in demonstrations and hands-on activities to monitor conditions in local estuaries.
Impacts of climate change on fish and shellfish in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)
Published 24 April 2017 Newsletters and reports ClosedTags: fisheries, North Atlantic, review, socio-economy
The commercially important fish and shellfish of Caribbean SIDS have been considered in four groups based on environment and following the typical division of fishery groups used in this region.
There is a dearth of research and long-term datasets on the impacts of climate change on Caribbean marine environments and the important fishery resources. Most research to date has been outside of the Caribbean and has examined the impacts of one or two stressors in short-term ex situ experiments which are unlikely to accurately reflect the true complexity of long-term in situ impacts of climate change in the region. There is a need to consider the combined effects of climate change stressors (direct and indirect) on both individuals and ecosystems, together with the synergistic effects of other chronic anthropogenic stressors in the region.
We consider the reef-associated shallow shelf group to be the most vulnerable of the four fishery groups given: 1) the already apparent negative climate change impacts on their critical habitats; 2) the overexploited state of most reef-associated fishery stocks; 3) the already degraded state of their nearshore habitats as a result of other anthropogenic activities; and 4) their biphasic life history, requiring the ability to settle in specific benthic nursery habitat from a pelagic early life stage.
We consider the most resilient group, over the short-term, to be the oceanic pelagic species that generally show fewer negative responses to the climate change stressors given that they: 1) are highly mobile with generally good acid-base regulation; 2) have an entirely pelagic lifecycle; 3) have less vulnerable reproductive strategies (i.e. they have extended spawning seasons and over broad areas); and 4) are generally exposed to fewer or less severe anthropogenic stressors.
This summary is provided with the following important caveat: “Any attempt to report on what has already happened to fish and shellfish resources in the Caribbean, based on direct evidence, will be strongly biased by the fact that there is a lack of monitoring and directed research examining fish and shellfish species-level impacts of climate change in this region. As such, any conclusions drawn from direct evidence alone will likely misrepresent the true nature and extent of the climate change impacts on the coastal and marine fish and shellfish resources within the Caribbean to date.”
Impacts of physical environments in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)
Published 24 April 2017 Newsletters and reports ClosedTags: mitigation, North Atlantic, review
Temperature – sea surface temperature has risen by more than 1 °C over the last 100 years. Future temperature rises will have impacts on hurricanes, rainfall, coral reefs and wider marine ecosystems.
Hurricanes – The IPCC (IPCC AR5 WG1) found strong evidence for an increase in the frequency and intensity of the strongest tropical hurricanes since the 1970s in the North Atlantic.
El Niño- Understanding the influence of the El Niño – Southern Oscillation (ENSO) phenomenon on Caribbean’s marine environment and timescales of variability is key to understanding how climate has been changing; projecting these relationships and ENSO itself into the future becomes vital to understand the fingerprint of global warming in the region.
Precipitation – there are a wide range of projections for future precipitation change in the area with some models finding increases in the coming century while most suggest a drier future for the region.
Ocean surface aragonite saturation state (Ωarg) has declined by around 3% in the Caribbean region relative to pre-industrial levels.
Climate variability – the Caribbean region needs a smaller increase in temperature for its conditions to become distinct (climate emergence) from the envelope of climate variability over the last hundred years, compared with the rest of the world.
Impacts of ocean acidification in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)
Published 24 April 2017 Newsletters and reports ClosedTags: mitigation, North Atlantic, policy, review
Oceans have absorbed one third of the carbon dioxide (CO2) released to the atmosphere from human activities causing the seawater pH to decrease by 0.1 units since the Industrial Revolution.
There is certainty that ocean acidification caused by anthropogenic activities is currently in progress and will increase in accord with rising atmospheric CO2 concentrations. There is medium confidence that these changes with significantly impact marine ecosystems.
Throughout the Caribbean small islands, ocean acidification effects could be exacerbated due to local processes within coastal zones. Ocean surface aragonite saturation state (Ωarg) has declined by around 3% in the Caribbean region relative to pre-industrial levels potentially already impacting tropical marine calcifying organisms. In addition to the effect on living organisms, ocean acidification is likely to diminish the structural integrity of coral reefs through reduced skeletal density, loss of calcium carbonate, and dissolution of high-Mg carbonate cements which help to bind the reef. This would make coastal areas of the Caribbean small islands increasingly more vulnerable to the action of waves and storm surge. This is likely to have knock-on effects to the tourism sector, fisheries and coastal infrastructure.
More studies about the present and projected impacts of ocean acidification on Caribbean small islands are necessary in order to evaluate alternative adaptive strategies accounting for the different island’s environmental, socioeconomic, and political settings.
Impacts of climate change on coral in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)
Published 24 April 2017 Newsletters and reports ClosedTags: corals, mitigation, North Atlantic, policy, review, socio-economy
Coral reefs are integral to life in the Caribbean – providing protection from storms, sustaining national economies and livelihoods through tourism and fishing, and supporting culture, recreation and biodiversity conservation. Over a decade ago, their value was estimated at US$3.1 – 4.6 billion each year.
Climate change is already impacting coral reefs in the Caribbean, through coral bleaching, disease outbreaks, ocean acidification and physical damage from stronger hurricanes. Coral beaching is the most visible, wide-spread and iconic manifestation of climate change on reefs, with major events in the Caribbean in 1998, 2010 and 2015/16. The extent of bleaching and associated mortality varies by location and event, but has resulted in some mortality. Coral disease has already significantly altered the community composition of reefs in the Caribbean, and is projected to result in increasing frequency of outbreaks as seas warm. The lack of a centralized database to coordinate reef monitoring information, hampers efforts to measure these effects.
Ocean acidification is a direct chemical result of increased carbon dioxide, but it has a variety of different responses in different reef organisms. Corals are the brick foundations of the reef, with crustose coralline algae as their mortar. Both these critical functional groups are already being affected by the reduced pH of surface water, making it more difficult to calcify and grow.
Future impacts are expected to follow and accelerate on these trends.
By 2040–2043 projections are for the onset of annual severe bleaching, which would likely result in significant coral mortality. Disease outbreaks are predicted to become annual events several years earlier. Projections for future ocean acidification result in ocean carbonate saturation levels potentially dropping below those required to sustain coral reef accretion by 2050. Cutting emissions in CO2 (within RCP6.0) would buy many coral reefs a couple of decades more time before the worst impacts occur, but it delays rather than mitigates the threats posed to coral reefs by acidification and bleaching (Maynard et al, 2016).
National leaders of the Caribbean need to adamantly fight for CO2 emissions reductions, and ensure their reef management agencies take all precautionary measures needed to reduce local stress on their reefs to buy them additional time and resiliency potential for withstanding the stress of climate change.
High resolution microscopy reveals significant impacts of ocean acidification and warming on larval shell development in Laternula elliptica
Published 24 April 2017 Science ClosedTags: Antarctic, biological response, laboratory, methods, mollusks, morphology, multiple factors, temperature
Environmental stressors impact marine larval growth rates, quality and sizes. Larvae of the Antarctic bivalve, Laternula elliptica, were raised to the D-larvae stage under temperature and pH conditions representing ambient and end of century projections (-1.6°C to +0.4°C and pH 7.98 to 7.65). Previous observations using light microscopy suggested pH had no influence on larval abnormalities in this species. Detailed analysis of the shell using SEM showed that reduced pH is in fact a major stressor during development for this species, producing D-larvae with abnormal shapes, deformed shell edges and irregular hinges, cracked shell surfaces and even uncalcified larvae. Additionally, reduced pH increased pitting and cracking on shell surfaces. Thus, apparently normal larvae may be compromised at the ultrastructural level and these larvae would be in poor condition at settlement, reducing juvenile recruitment and overall survival. Elevated temperatures increased prodissoconch II sizes. However, the overall impacts on larval shell quality and integrity with concurrent ocean acidification would likely overshadow any beneficial results from warmer temperatures, limiting populations of this prevalent Antarctic species.
Ice Acidification: A review of the effects of ocean acidification on sea ice microbial communities
Published 24 April 2017 Science ClosedTags: biological response, BRcommunity, prokaryotes, review
Sea ice algae are naturally exposed to a wider range of pH and CO2 concentrations than marine phytoplankton. While climate change and ocean acidification (OA) will impact pelagic communities, their effects on sea ice microbial communities remains unclear.
Sea ice contains several distinct microbial communities, which are exposed to differing environmental conditions depending on their depth within the ice. Bottom communities mostly experience relatively benign bulk ocean properties, while interior brine and surface communities experience much greater extremes.
Most OA studies have examined the impacts on single sea ice algae species in culture. Although some studies examined the effects of OA alone, most also examined the effects of OA and either light, nutrients or temperature. With few exceptions, increased CO2 concentration caused either no change or an increase in growth and/or photosynthesis. In situ studies of brine and surface algae also demonstrated a wide tolerance to increased and decreased pH and showed increased growth at higher CO2 concentrations. The short time period of most experiments (< 10 days) together with limited genetic diversity (i.e. use of only a single strain), however, has been identified as a limitation to the broader interpretation of results.
While there have been few studies on the effects of OA on marine bacterial communities in general, impacts appear to be minimal. In sea ice also, the few reports available suggest no negative impacts on growth or community richness.
Sea ice ecosystems are ephemeral, melting and re-forming each year. Thus, for some part of each year organisms inhabiting the ice must also survive outside of the ice, either as part of the phytoplankton or as resting spores on the bottom. During these times, they will be exposed to the full range of co-stressors that pelagic organisms experience. Their ability to continue to make a major contribution to sea ice productivity will depend not only on their ability to survive in the ice but also on their ability to survive the increasing seawater temperatures, changing distribution of nutrients and declining pH forecast for the water column over the next centuries.
UC Davis study reveals how marine animals are dissolving due to warm, acidic waters
Published 24 April 2017 Media coverage ClosedA study by the University of California – Davis has found that marine animals are dissolving quickly due to warming waters and ocean acidification. These conditions are already occurring off the Northern California coast.
Researchers at the UC Davis Bodega Marine Laboratory published their study in the journal “Proceedings of the Royal Society B: Biological Sciences.” They raised bryozoans, also known as “moss animals,” in seawater tanks and exposed them to varying levels of water temperature, food and acidity.
They discovered that the creatures began to dissolve when they were grown in warmer waters and then exposed to acidity. Big portions of their skeletons disappeared in as little as two months.
The one-two punch of warming waters and ocean acidification is predisposing some marine animals to dissolving quickly under conditions already occurring off the Northern California coast, according to a study from the University of California, Davis.
In the study, published in the journal Proceedings of the Royal Society B: Biological Sciences, researchers at the UC Davis Bodega Marine Laboratory raised bryozoans, also known as “moss animals,” in seawater tanks and exposed them to various levels of water temperature, food and acidity.
The scientists found that when grown in warmer waters and then exposed to acidity, the bryozoans quickly began to dissolve. Large portions of their skeletons disappeared in as little as two months.
“We thought there would be some thinning or reduced mass,” said lead author Dan Swezey, a recent Ph.D. graduate in professor Eric Sanford’s lab at the UC Davis Bodega Marine Laboratory. “But whole features just dissolved practically before our eyes.”
Interactive effects of temperature, food and skeletal mineralogy mediate biological responses to ocean acidification in a widely distributed bryozoan
Published 21 April 2017 Science ClosedTags: biological response, BRcommunity, bryozoa, dissolution, laboratory, morphology, multiple factors, nutrients, physiology, temperature
Marine invertebrates with skeletons made of high-magnesium calcite may be especially susceptible to ocean acidification (OA) due to the elevated solubility of this form of calcium carbonate. However, skeletal composition can vary plastically within some species, and it is largely unknown how concurrent changes in multiple oceanographic parameters will interact to affect skeletal mineralogy, growth and vulnerability to future OA. We explored these interactive effects by culturing genetic clones of the bryozoan Jellyella tuberculata (formerly Membranipora tuberculata) under factorial combinations of dissolved carbon dioxide (CO2), temperature and food concentrations. High CO2 and cold temperature induced degeneration of zooids in colonies. However, colonies still maintained high growth efficiencies under these adverse conditions, indicating a compensatory trade-off whereby colonies degenerate more zooids under stress, redirecting energy to the growth and maintenance of new zooids. Low-food concentration and elevated temperatures also had interactive effects on skeletal mineralogy, resulting in skeletal calcite with higher concentrations of magnesium, which readily dissolved under high CO2. For taxa that weakly regulate skeletal magnesium concentration, skeletal dissolution may be a more widespread phenomenon than is currently documented and is a growing concern as oceans continue to warm and acidify.
Effects of seawater acidification and salinity alterations on metabolic, osmoregulation and oxidative stress markers in Mytilus galloprovincialis
Published 20 April 2017 Science ClosedTags: biological response, laboratory, mollusks, physiology
The impacts of seawater acidification and salinity shifts on metabolism, energy reserves, and oxidative status of mussels have been largely neglected. With the aim to increase the current knowledge for the mussel Mytilus galloprovincialis a 28-day chronic test was conducted during which mussels were exposed to two pH (7.8 and 7.3; both at control salinity 28) and three salinity (14, 28 and 35, at control pH, 7.8) levels. After exposure to different conditions, mussels electron transport system activity, energy reserves (protein and glycogen content) carbonic anhydrase activity, antioxidant defences and cellular damage were measured. Results obtained showed that mussels exposed to seawater acidification presented decreased metabolic capacity that may have induced lower energy expenditure (observed in higher glycogen, protein and lipids content at this condition). Low pH condition induced the increase of carbonic anhydrase activity that was related to acid-base balance, while no significant activation of antioxidant defence mechanisms was observed resulting in higher LPO. Regarding the impacts of salinity, the present study showed that at the highest salinity (35) mussels presented lower metabolic activity (also related to lower energetic expenditure) and an opposite response was observed at salinity 14. Carbonic anhydrase slightly increased at stressful salinity conditions, a mechanism of homeostasis maintenance. Lower metabolic activity at the highest salinity, probably related to valves closure, helped to mitigate the increase of LPO in this condition. At low salinity (14), despite an increase of antioxidant enzymes activity, LPO increased, probably as a result of ROS overproduction from higher electron transport system activity. The present findings demonstrated that Mytilus galloprovincialis oxidative status and metabolic capacity were negatively affected by low pH and salinity changes, with alterations that may lead to physiological impairments namely on mussels reproductive output, growth performance and resistance to disease, with ecological and economic implications.
High pCO2 and elevated temperature reduce survival and alter development in early life stages of the tropical sea hare Stylocheilus striatus
Published 20 April 2017 Science ClosedTags: biological response, laboratory, mollusks, morphology, multiple factors, reproduction, temperature
Elevated temperature (ocean warming) and reduced oceanic pH (ocean acidification) are products of increased atmospheric pCO2, and have been shown in many marine taxa to alter morphology, impede development, and reduce fitness. Here, we investigated the effects of high pCO2 and elevated temperature on developmental rate, hatching success, and veliger morphology of embryos of the tropical sea hare, Stylocheilus striatus. Exposure to high pCO2 resulted in significant developmental delays, postponing hatching by nearly 24 h, whereas exposure to elevated temperature (in isolation or in combination with high pCO2) resulted in accelerated development, with larvae reaching several developmental stages approximately 48 h in advance of controls. Hatching success was reduced by ~20 and 55% under high pCO2 and warming, respectively, while simultaneous exposure to both conditions resulted in a nearly additive 70% reduction in hatching. In addition to these ontological and lethal effects, exposure of embryos to climate change stressors resulted in significant morphological effects. Larval shells were nearly 40% smaller under high pCO2 and warming in isolation and up to 53% smaller under multi-stressor conditions. In general, elevated temperature had the largest impact on development, with temperature-effects nearly 3.5-times the magnitude of high pCO2-effects. These results indicate that oceanic conditions congruent with climate change predictions for the end of the twenty-first century suppress successful development in S. striatus embryos, potentially reducing their viability as pelagic larvae.
Variable response to warming and ocean acidification by bacterial processes in different plankton communities
Published 20 April 2017 Science ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, multiple factors, otherprocess, physiology, prokaryotes, South Pacific, temperature
Extracellular bacterial enzymes play an important role in the degradation of organic matter in the surface ocean but are sensitive to changes in pH and temperature. This study tested the individual and combined effects of lower pH (-0.3) and warming (+3°C) projected for the year 2100 on bacterial abundance, process rates and diversity in plankton communities of differing composition from 4 locations east of New Zealand. Variation was observed in magnitude and temporal response between the different communities during 5 to 6 day incubations. Leucine aminopeptidase activity showed the strongest response, with an increase in potential activity under low pH alone and in combination with elevated temperature in 3 of 4 incubations. Temperature had a greater effect on bacterial cell numbers and protein synthesis, with stronger responses in the elevated temperature and combined treatments. However, the most common interactive effect between temperature and pH was antagonistic, with lower bacterial secondary production in the combined treatment relative to elevated temperature, and lower leucine aminopeptidase activity in the combined treatment relative to low pH. These results highlight the variability of responses to and interactions of environmental drivers, and the importance of considering these in experimental studies and prognostic models of microbial responses to climate change.
Trophic transfer of essential elements in the clownfish Amphiprion ocellaris in the context of ocean acidification
Published 20 April 2017 Science ClosedTags: biological response, fish, laboratory, otherprocess, physiology
Little information exists on the effects of ocean acidification (OA) on the digestive and post-digestive processes in marine fish. Here, we investigated OA impacts (Δ pH = 0.5) on the trophic transfer of select trace elements in the clownfish Amphiprion ocellaris using radiotracer techniques. Assimilation efficiencies of three essential elements (Co, Mn and Zn) as well as their other short-term and long-term kinetic parameters in juvenile clownfish were not affected by this experimental pH change. In complement, their stomach pH during digestion were not affected by the variation in seawater pH. Such observations suggest that OA impacts do not affect element assimilation in these fish. This apparent pCO2 tolerance may imply that clownfish have the ability to self-regulate pH shifts in their digestive tract, or that they can metabolically accommodate such shifts. Such results are important to accurately assess future OA impacts on diverse marine biota, as such impacts are highly species specific, complex, and may be modulated by species-specific metabolic processes.
Smell is like noise, the more scents we breathe in one sniff, the more difficult it is to distinguish them to the point of olfactory saturation. Experimental work with clownfish reveals that the increase in dissolved carbon dioxide in seawater, mimicking ocean acidification, alters olfactory physiology, with potential cascading effects on the demography of species.
Places such as a restaurant, a hospital or a library have a characteristic bouquet, and we can guess the emotional state of other people by their scents. Smell is critical between predators and prey of many species because both have evolved to detect each other without the aid of vision. At sea, the smell of predators dissolves in water during detection, attack, capture, and ingestion of prey, and many fishes use this information to assess the risk of ending up crunched by enemy teeth (1, 2). But predator-prey interactionscan be modified by changes in the chemical composition of seawater and are therefore highly sensitive to ongoing ocean acidification (see global measuring network here).
