Under predicted future ocean conditions, reefs exposed to elevated nutrients will simultaneously experience ocean acidification and elevated temperature. We evaluated if moderate nutrients mitigate, minimize, or exacerbate negative effects of predicted future ocean conditions on coral physiology. For 30 days, Acropora millepora and Turbinaria reniformis were exposed to a fully factorial experiment of eight treatments including two seawater temperatures (26.4 °C and 29.8 °C), pCO2 levels (401 μatm pCO2 and 760 μatm pCO2), and nutrient concentrations (ambient: 0.40 μmol L−1 NO3− and 0.22 μmol L−1 PO43−, and moderate: 3.56 μmol L−1 NO3− and 0.31 μmol L−1 PO43−). Added nitrate was taken up by the algal endosymbionts and transferred to the coral hosts in both species, though to a much higher degree in A. millepora. When exposed to elevated temperature, elevated pCO2, or both, effects observed for chlorophyll a, calcification, biomass, and energy reserves were not compounded by the moderate nutrient concentrations in either species. Moderate nutrients enabled A. millepora to continue to meet daily metabolic demand via photosynthesis under predicted future ocean conditions and T. reniformis to greatly exceed daily metabolic demand via photosynthesis and heterotrophy. Our results suggest that balanced moderate nutrients are not detrimental to corals under predicted future ocean conditions and may even provide some benefits.
Continue reading ‘Moderate nutrient concentrations are not detrimental to corals under future ocean conditions’Archive Page 237
Moderate nutrient concentrations are not detrimental to corals under future ocean conditions
Published 24 June 2021 Science ClosedTags: biological response, calcification, corals, laboratory, mitigation, multiple factors, nutrients, photosynthesis, physiology, protists, respiration, South Pacific, temperature
Alkalinity of diverse water samples can be altered by mercury preservation and borosilicate vial storage
Published 24 June 2021 Science ClosedTags: laboratory, methods, South Pacific
We compared the effects of preservation and storage methods on total alkalinity (AT) of seawater, estuarine water, freshwater, and groundwater samples stored for 0–6 months. Water samples, untreated or treated with HgCl2, 0.45 µm filtration, or filtration plus HgCl2, were stored in polypropylene or borosilicate glass vials for 0, 1, or 6 months. Mean AT of samples treated with HgCl2 was reduced by as much as 49.1 µmol kg−1 (1.3%). Borosilicate glass elevated AT, possibly due to dissolving silicates. There was little change in AT of control and filtered samples stored in polypropylene, except for untreated groundwater (~ 4.1% reduction at 6 months). HgCl2 concentrations of 0.02–0.05% reduced the AT of fresh, estuarine, and ground water samples by as much as 35.5 µmol kg−1 after 1 month, but had little effect on the AT of seawater. Adding glucose as a carbon source for microbial growth resulted in no AT changes in 0.45 µm-filtered samples. We suggest water samples intended for AT analyses can be filtered to 0.45 µm, and stored in polypropylene vials at 4 °C for at least 6 months. Borosilicate glassware and HgCl2 can be avoided to prevent analytical uncertainties and reduce risks related to use of Hg2+.
Continue reading ‘Alkalinity of diverse water samples can be altered by mercury preservation and borosilicate vial storage’Perse community lecture – ‘listening to shells’ (text & video)
Published 24 June 2021 Web sites and blogs Closed
We were pleased to welcome Liz Harper, Professor of Evolutionary Biology at the University of Cambridge’s Department of Earth Sciences, to give the latest online Perse Community Lecture.
Prof Harper provided an insight into evolutionary biology and climate change in her talk entitled Listening to Shells.
She explained the origin of molluscs and the variety of molluscs and brachiopods, as well as how fossils can help us to understand shells and how and why they adapted to suit the organism and environment.
Prof Harper reflected on the materials aspect of shells, using the example of nacre, the ‘wonder material’ of mother of pearl, which has unexpectedly remained unchanged over the past few eras, suggesting that evolutionary development has turned its back on one of the most successful materials.
She outlined that the development of lighter shell materials has enabled species to thrive within their specific habitats. However, ongoing ocean acidification does pose a threat to organisms that make a shell, given the current ocean surface pH of 8.1 is expected to decrease significantly due to climate change, especially those that lay down shells made of calcium carbonate, such as sea butterflies.
Continue reading ‘Perse community lecture – ‘listening to shells’ (text & video)’2021 Northeast spring ecosystem monitoring cruise completed
Published 24 June 2021 Web sites and blogs ClosedThanks to a combination of favorable weather and a well-run vessel, the 2021 Northeast spring ecosystem monitoring survey aboard NOAA Ship Gordon Gunter is complete.
During May, researchers returned to sea for the ecosystem monitoring cruise. This was the first ecosystem monitoring cruise since operations were stopped in 2020 to reduce risks posed by the COVID-19 pandemic. This one-year hiatus is the longest gap in sampling in the nearly 45-year record of oceanographic observations made on this recurring cruise.
Scientists and crew aboard the NOAA Ship Gordon Gunter sampled at 106 stations. They achieved near-complete coverage of the survey area from Delaware through Southern New England.
Fewer days were available for the cruise than originally planned, so the scientific crew dropped all stations south of Delaware Bay to accommodate the time available. Coverage was also reduced on the Scotian Shelf, in the northern Gulf of Maine, and on Georges Bank, when a fast-moving storm front passed through, making sampling impossible. Instead, the team moved into the western Gulf of Maine to keep working, and collected more mackerel eggs and larvae.
Continue reading ‘2021 Northeast spring ecosystem monitoring cruise completed’Elevated pCO2 alters the interaction patterns and functional potentials of rearing seawater microbiota
Published 23 June 2021 Science ClosedTags: biogeochemistry, biological response, community composition, crustaceans, laboratory, molecular biology, mortality, otherprocess, prokaryotes
Highlights
- More simplified and modularized bacterial networks of rearing seawater under elevated pCO2.
- Changed abundances of CNPS cycling genes of seawater microbiome under elevated pCO2.
- Changed C, N, and P chemistry of rearing seawater under elevated pCO2.
- Seawater C, N, and P chemistry may be affected by future elevated pCO2 via seawater microbiome.
Abstract
Mean oceanic CO2 values have already risen and are expected to rise further on a global scale. Elevated pCO2 (eCO2) changes the bacterial community in seawater. However, the ecological association of seawater microbiota and related geochemical functions are largely unknown. We provide the first evidence that eCO2 alters the interaction patterns and functional potentials of microbiota in rearing seawater of the swimming crab, Portunus trituberculatus. Network analysis showed that eCO2 induced a simpler and more modular bacterial network in rearing seawater, with increased negative associations and distinct keystone taxa. Using the quantitative microbial element cycling method, nitrogen (N) and phosphorus (P) cycling genes exhibited the highest increase after one week of eCO2 stress and were significantly associated with keystone taxa. However, the functional potential of seawater bacteria was decoupled from their taxonomic composition and strongly coupled with eCO2 levels. The changed functional potential of seawater bacteria contributed to seawater N and P chemistry, which was highlighted by markedly decreased NH3, NH4+-N, and PO43--P levels and increased NO2−-N and NO3−-N levels. This study suggests that eCO2 alters the interaction patterns and functional potentials of seawater microbiota, which lead to the changes of seawater chemical parameters. Our findings provide new insights into the mechanisms underlying the effects of eCO2 on marine animals from the microbial ecological perspective.
Continue reading ‘Elevated pCO2 alters the interaction patterns and functional potentials of rearing seawater microbiota’Microbiome diversity and host immune functions may define the fate of sponge holobionts under future ocean conditions
Published 23 June 2021 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, molecular biology, morphology, mortality, multiple factors, North Pacific, otherprocess, porifera, prokaryotes, temperature
The sponge-associated microbial community contributes to the overall health and adaptive capacity of the sponge holobiont. This community is regulated by the environment, as well as the immune system of the host. However, little is known about the effect of environmental stress on the regulation of host immune functions and how this may, in turn, affect sponge-microbe interactions. In this study, we compared the microbiomes and immune repertoire of two sponge species, the demosponge, Neopetrosia compacta and the calcareous sponge, Leucetta chagosensis, under varying levels of acidification and warming stress. Neopetrosia compacta harbors a diverse bacterial assemblage and possesses a rich repertoire of scavenger receptors while L. chagosensis has a less diverse microbiome and an expanded range of pattern recognition receptors and proteins with immunological domains. Upon exposure to warming and acidification, the microbiome and host transcriptome of N. compacta remained stable, which correlated with high survival. In contrast, the bacterial community of L. chagosensis exhibited drastic restructuring and widespread downregulation of host immune-related pathways, which accompanied tissue necrosis and mortality. Differences in microbiome diversity and immunological repertoire of diverse sponge groups highlight the central role of host-microbe interactions in predicting the fate of sponges under future ocean conditions.
Continue reading ‘Microbiome diversity and host immune functions may define the fate of sponge holobionts under future ocean conditions’Dialogue strengthens regional coordination for ocean acidification monitoring
Published 23 June 2021 Web sites and blogs ClosedPosting Number: req5768
Department: Geosciences
Department Website Link: www.geo.arizona.edu/Research
Location: Main Campus
Address: Tucson, AZ USA
Target Hire Date: 8/23/2021
Position Highlights:
We seek a postdoctoral researcher to work as part of a collaborative team to better understand the impact of heat stress and ocean acidification on calcification and skeletal geochemistry in corals from the Republic of the Marshall Islands. The postdoctoral researcher will be expected to collect and analyze coral skeletal density and geochemical data, interpret results in the context of simulated ocean evolution over the last millennium using coupled climate models, and synthesize results for presentations at conferences and publications in peer-reviewed journals. This is a year-to-year appointment renewable for up to 4 years contingent upon funding and performance.
Outstanding UA benefits include health, dental, vision, and life insurance; paid vacation, sick leave, and holidays; UA/ASU/NAU tuition reduction for the employee and qualified family members; access to UA recreation and cultural activities; and more!
The University of Arizona has been recognized for our innovative work-life programs. For more information about working at the University of Arizona and relocations services, please click here.
Duties & Responsibilities:
- Collate and analyze coral density and geochemical data
- Help design and participate in field work efforts
- Incorporate data into a modeling framework
- Interpret results and publish findings in peer-reviewed journals
Plastic and toxic chemical induced ocean acidification will cause a plankton crisis that will devastate humanity over the next 25 Years, unless we act now to stop the pollution
Published 22 June 2021 Newsletters and reports , Science ClosedTags: policy, review
Planktonic plants and animals at the base of the marine food chain make all life on Earth possible. Without them the atmosphere would be toxic from carbon dioxide, we would have no oxygen and there would be no whales, birds or fish in the oceans.
Over the last 70 years, more than 50% of all marine life has been lost from the world’s oceans, and it continues to decline at rate of 1% year on year. Atmospheric carbon dioxide causes ocean acidification, and a loss of marine plants and animals accelerates the process.
A small increase in acidity caused by carbon dioxide dissolves magnesium calcite and aragonite, forms of calcium carbonate upon which 50% of all marine life including plankton and coral reefs are composed. Over the next 25 years, the pH will continue to drop from pH8.04 to pH7.95, and an estimated 80% to 90% of all marine life will be lost from the oceans. Even if the world achieves net zero by 2045, atmospheric carbon dioxide will still exceed 500ppm and the oceans will still drop to pH 7.95.
Based on current climate change policy of carbon mitigation, we will not be able to stop the loss of most marine life, which includes fish and the food supply for 3 billion people. In addition, we lose the life support system for the planet. This decline has gone largely unnoticed because most of the plants and animals in the oceans are under 1 mm in size and they are not closely monitored. By way of an example: Prochlorococcus, a cyanobacteria responsible for making 20% of our oxygen, was only discovered in the 1985.
Ocean acidification and climate change cannot adequately describe the loss of marine life. 30% of the ocean have high nutrient (nitrate) concentrations but zero or only low plant growth. If it is not the lack of nutrients or trace nutrients, responsible for the loss of marine life, then this just leaves aquatic environmental pollution as the last plausible explanation. The impact of chemical and micro-plastic pollution on planktonic marine life has been almost completed ignored by the scientific community, and as such industry and governments have not been alerted to the impending threat to the oceans.
This is potentially a good news story, because the solution will be to eliminate pollution from plastic and toxic chemicals or develop green alternatives that do not harm to the environment or humans. We still need to reduce carbon from the burning of fossil fuels, but the priority over the next 25 years should be to protect the oceans, because all life on earth depends upon marine life in the world’s oceans.
Questions and answer on GOES Report.
Continue reading ‘Plastic and toxic chemical induced ocean acidification will cause a plankton crisis that will devastate humanity over the next 25 Years, unless we act now to stop the pollution’Taxing interacting externalities of ocean acidification, global warming, and eutrophication
Published 22 June 2021 Science ClosedTags: globalmodeling, modeling, policy, socio-economy
We model a stylized economy dependent on agriculture and fisheries to study optimal environmental policy in the face of interacting external effects of ocean acidification, global warming, and eutrophication. This allows us to capture some of the latest insights from research on ocean acidification. Using a static two-sector general equilibrium model we derive optimal rules for national taxes on 
emissions and agricultural run-off and show how they depend on both isolated and interacting damage effects. In addition, we derive a second-best rule for a tax on agricultural run-off of fertilizers for the realistic case that effective internalization of 
externalities is lacking. The results contribute to a better understanding of the social costs of ocean acidification in coastal economies when there is interaction with other environmental stressors.
Recommendations for Resource Managers:
- Marginal environmental damages from
emissions should be internalized by a tax on 
emissions that is high enough to not only reflect marginal damages from temperature increases, but also marginal damages from ocean acidification and the interaction of both with regional sources of acidification like nutrient run-off from agriculture. - In the absence of serious national policies that fully internalize externalities, a sufficiently high tax on regional nutrient run-off of fertilizers used in agricultural production can limit not only marginal environmental damages from nutrient run-off but also account for unregulated carbon emissions.
- Putting such regional policies in place that consider multiple important drivers of environmental change will be of particular importance for developing coastal economies that are likely to suffer the most from ocean acidification.
Why are surface ocean pH and CaCO3 saturation state often out of phase in spatial patterns and seasonal cycles?
Published 22 June 2021 Science ClosedTags: chemistry
Abstract
As two most important metrics for ocean acidification (OA), both pH and calcium carbonate mineral saturation states (Ω) respond sensitively to anthropogenic carbon dioxide (CO2). However, contrary to intuition, they are often out of phase in the global surface ocean, both spatially and seasonally. For example, during warm seasons, Ω is lowest at high-latitude seas where there are very high pH values, challenging our understanding that high-latitude seas are a bellwether for global OA. To explain this phenomenon, we separate spatial and seasonal variations of both pH and Ω into thermal components mainly associated with internal acid-base equilibrium of seawater CO2 systems, and nonthermal components mainly associated with external CO2 addition/removal using a global surface ocean climatological dataset. We find that surface pH change is controlled by the balance between its thermal and nonthermal components, which are out of phase but comparable in magnitude. In contrast, surface Ω change is dominated by its nonthermal components, with its thermal components in phase and significantly smaller in magnitude. These findings explain why surface ocean pH and Ω are often out of phase in spatial patterns and seasonal cycles. When pH is primarily controlled by nonthermal components e.g., gas exchange, mixing and biology, pH and Ω will be in phase because their nonthermal components are intrinsically in phase. In comparison, when pH is primarily controlled by thermal components e.g., rapid seasonal cooling or warming, pH and Ω will be out of phase because thermal and nonthermal components of pH are out-of-phase in nature.
Plain Language Summary
Although both pH and calcium carbonate mineral saturation states (Ω) are good metrics for ocean acidification, in the global surface ocean their spatial patterns and seasonal cycles are often out of phase, which appears counter intuitive. To explain this, we separate pH and Ω changes into thermal and nonthermal components. Thermal components are mainly related to the temperature driven internal acid-base equilibrium of seawater CO2 systems. Nonthermal components are the remaining changes, reflecting the effects of other non-temperature processes such as air-sea gas exchange, mixing and biology or a combination of these processes. We find that pH is controlled by the balance between thermal and nonthermal components, which are out of phase but comparable in magnitude, while Ω is almost always dominated by nonthermal components. These findings explain why surface ocean pH and Ω are often out of phase in spatial patterns and seasonal cycles. When pH is more controlled by nonthermal components than thermal components, pH and Ω will be in phase since their nonthermal components are intrinsically in phase. In contrast, when pH is more controlled by thermal components, pH and Ω will be out of phase because of the out-of-phase between thermal and nonthermal components of pH.
Continue reading ‘Why are surface ocean pH and CaCO3 saturation state often out of phase in spatial patterns and seasonal cycles?’
Life on Earth has never been so close to an end as during the environmental catastrophe that marked the Permian-Triassic boundary – 252 million years ago. Scientists have long speculated what could have triggered the sudden disappearance of so many organism groups – more than 95% of marine and 70% of terrestrial species went extinct. Among the favoured hypotheses have been large-scale volcanism, methane release from hydrate mounds on the seafloor, and an asteroid impact similar to that which ended the reign of the dinosaurs 66 million years ago. The latter has been, however, largely rejected in the recent years as no reliable evidence, direct or indirect, of the impact has been found.
…
To illuminate the causes and consequences of the extinction, we used an innovative approach to reconstruct the seawater pH (acidity) from boron isotope measurements in well-preserved fossil brachiopod shells. Seawater pH is a critical parameter; first, because it has direct implications for marine life. Second, because the ocean and the atmosphere are closely coupled and CO2 is readily exchanged between them, we can use data on ocean pH to directly reconstruct the atmospheric CO2 levels. We paired our pH data with the global carbon isotope records, and assimilated it into a model that quantified both the source and volume of CO2 over the extinction period.
Continue reading ‘How life on Earth almost ended once’Robotic boat begins Atlantic crossing (text & video)
Published 22 June 2021 Web sites and blogs ClosedIBM’s Mayflower Autonomous Ship (MAS400) has set sail across the Atlantic ocean without a crew or human control. The autonomous trimaran left Plymouth, England on June 15 and hopes to reach Plymouth, Massachusetts in about three weeks.
The voyage of the robotic Mayflower follows the path of the original Mayflower, which brought the Pilgrim settlers to New England in 1620. The 50-foot long, 20-foot wide craft is made of aluminum and carbon composites, displaces five tonnes, and is propelled by a solar-powered hybrid motor with a diesel backup, giving it a top speed of 10 knots.
Supervised by a command center in Plymouth, UK, the Mayflower navigates using over 50 sensors, including six IBM AI Vision cameras and an IBM deep learning system to identify and avoid obstacles, hostile currents, and bad weather while adhering to international navigation rules. Data processing is by onboard computers backed up by an IBM Power Systems AC922 onshore.
Onboard is a scientific payload of 1,500 pounds that includes acoustic, nutrient, and temperature sensors, as well as water and air samplers. These are gathering scientific data to help with future studies of ocean chemistry, acidification, sea level height and wave patterns; microplastics; and marine mammal conservation, among other topics. In addition, the autonomous technology could find applications in shipping, oil and gas industries, telecommunications, security, defense, fishing, and aquaculture.
Continue reading ‘Robotic boat begins Atlantic crossing (text & video)’Transcriptional changes revealed water acidification leads to the immune response and ovary maturation delay in the Chinese mitten crab Eriocheir sinensis
Published 21 June 2021 Science ClosedTags: biological response, crustaceans, laboratory, molecular biology, physiology, reproduction
Highlights
- Water acidification delays the oocyte maturation of Eriocheir sinensis.
- Water acidification induces significant changes in gills and ovaries at transcriptomic level.
- E. sinensis increased immune response to response in the water acidification.
Abstract
Nowadays, due to increasing carbon dioxide released, water acidification poses a series of serious impacts on aquatic organisms. To evaluate the effects of water acidification on crustaceans, we focused on the Chinese mitten crab Eriocheir sinensis, which is a spawning migration and farmed species in China. Based on histological and oocyte transparent liquid observation, we found that the acidified environment significantly delayed the ovarian maturation of E. sinensis. Moreover, RNA-seq was applied to obtain gene expression profile from the crab’s gills and ovaries in response to acidified environment. Compared with control groups, a total of 5471 differentially expressed genes (DEGs) were identified in acidified gills and 485 DEGs were identified in acidified ovaries. Enrichment analysis indicated that some pathways also responded to the acidified environment, such as PI3K-Akt signaling pathway, Chemokine signaling pathway, apoptosis and toll-like receptor signaling pathway. Subsequently, some DEGs involved in immune response (ALF, Cathepsin A, HSP70, HSP90, and catalase) and ovarian maturation (Cyclin B, Fem-1a, Fem-1b, and Fem-1c) were selected to further validate the influence of water acidification on gene expression by qRT-PCR. The results showed that the expression level of immune-related genes was significantly increased to response to the water acidification, while the ovarian maturation-related genes were significantly decreased. Overall, our data suggested that E. sinensis was sensitive to the reduced pH. This comparative transcriptome also provides valuable molecular information on the mechanisms of the crustaceans responding to acidified environment.
Continue reading ‘Transcriptional changes revealed water acidification leads to the immune response and ovary maturation delay in the Chinese mitten crab Eriocheir sinensis’Guidance in computer-supported collaborative inquiry learning: capturing aspects of affect and teacher support in science classrooms
Published 21 June 2021 Science ClosedTags: education
Technology-enhanced collaborative inquiry learning has gained a firm position in curricula across disciplines and educational settings and has become particularly pervasive in science classrooms. However, understanding of the teacher’s role in this context is limited. This study addresses the real-time shifts in focus and distribution of teachers’ guidance and support of different student groups during in-person computer-supported collaborative inquiry learning in science classrooms. Teachers’ self-perceptions of their guidance and affect were supplemented with students’ self-reported affect. A mixed-methods approach using video analyses and questionnaire data revealed differences between teacher guidance and support associated with teacher perceptions and group outcomes. Groups’ prior science competence was not found to have an effect on teacher guidance and support, rather the teachers guided the groups they perceived as motivated and willing to collaborate. Teacher affect was compounded by student affect, suggesting that consideration of the reciprocal perceptions of teachers and students is necessary in order to understand the teachers’ role in collaborative learning.
Continue reading ‘Guidance in computer-supported collaborative inquiry learning: capturing aspects of affect and teacher support in science classrooms’Rising temperature is a more important driver than increasing carbon dioxide concentrations in the trait responses of Enhalus acoroides seedlings
Published 21 June 2021 Science ClosedTags: biological response, growth, laboratory, multiple factors, phanerogams, photosynthesis, physiology, temperature
Increasing temperature and CO2 concentration are among the most important factors affecting marine ecosystems under climate change. We investigated the morphological, biochemical, and physiological trait responses of seedlings of the tropical seagrass Enhalus acoroides under experimental conditions. Trait responses were greater under temperature effects than increasing CO2 concentration. Seedlings under rising temperatures showed enhanced leaf growth, lower leaf nutrient content, and stimulated down-regulating mechanisms in terms of photo-physiology. Increasing CO2 concentrations did not show any significant effects independently. There was a significant interaction for some of the trait responses considered, such as leaf number and carbon content in the roots, and trends of higher starch concentrations in the leaves and lower rETRmax under combined enriched CO2 and high temperature, even though none of these interactions were synergistic. Understanding the single and interactive trait responses of seagrass seedlings to increasing temperature and CO2 concentration is of importance to determine the relative responses of early life stages of seagrasses, which may differ from adult plants, in order to form a more holistic view of seagrass ecosystem health under climate change.
Continue reading ‘Rising temperature is a more important driver than increasing carbon dioxide concentrations in the trait responses of Enhalus acoroides seedlings’Will Bay fish feel the bite from ocean acidification? ‘Hooked on OA’ series shares latest science
Published 21 June 2021 Web sites and blogs ClosedOcean waters are becoming more acidic — but how does that affect the Chesapeake Bay? And what does it mean for fish and the people fishing for them?
The ‘Hooked on Ocean Acidification’ webinars answered these questions for mid-Atlantic Anglers in March and April. The four webinars walked through recent research about acidification in coastal waters and out in the open ocean. The webinars were hosted by the Mid-Atlantic Coastal Acidification Network, in collaboration with other mid-Atlantic partners.
In the mid-Atlantic, there are many pieces in the puzzle of acidification
Globally, the oceans absorb carbon dioxide from the atmosphere — and since the industrial revolution, human activities are adding carbon dioxide to the atmosphere 10 times faster than the earth has experienced in the last 50 million years. As the ocean absorbs carbon dioxide, the water becomes more acidic. This effect is known as ocean acidification.
But the effects of acidification aren’t uniform across all water, and the mid-Atlantic region gets its ocean water from several sources, explained Grace Saba, an assistant professor at Rutgers University. The mid-Atlantic continental shelf gets currents of cold water, which can be more acidic, and also warmer, less acidic water from the Gulf stream.
Continue reading ‘Will Bay fish feel the bite from ocean acidification? ‘Hooked on OA’ series shares latest science’Combined effects of seawater acidification and benzo(a)pyrene on the physiological performance of the marine bloom-forming diatom Skeletonema costatum
Published 18 June 2021 Science ClosedTags: biological response, growth, laboratory, multiple factors, photosynthesis, physiology, phytoplankton, toxicants
Highlights
- Skeletonema costatum was tolerant to low and moderate benzo(a)pyrene concentrations.
- The high benzo(a)pyrene concentration remarkably inhibited growth and photosynthesis.
- Negative effects of ocean acidification were detected at the high benzo(a)pyrene level.
Abstract
The combined effects of polycyclic aromatic hydrocarbons and seawater acidification are poorly understood. Hence, we exposed the bloom-forming diatom Skeletonema costatum to four concentrations (0, 0.1, 1 and 10 μg L-1) of benzo(a)pyrene and two pCO2 levels (400 and 1000 μatm) to investigate its physiological performance. The growth and photosynthesis of S. costatum were tolerant to low and moderate benzo(a)pyrene concentrations regardless of the pCO2 level. However, the highest benzo(a)pyrene concentration had remarkably adverse effects on most parameters, decreasing the growth rate by 69%. Seawater acidification increased the sensitivity to high light stress, as shown by the lower relative maximum electron transport rate and light saturation point at the highest benzo(a)pyrene concentration. Our results suggested that benzo(a)pyrene could be detrimental to diatoms at a habitat-relevant level, and seawater acidification might further decrease its light tolerance, which would have important ramifications for the community structure and primary production in coastal waters.
Continue reading ‘Combined effects of seawater acidification and benzo(a)pyrene on the physiological performance of the marine bloom-forming diatom Skeletonema costatum’Physiology, niche characteristics and extreme events: current and future habitat suitability of a rhodolith-forming species in the Southwestern Atlantic
Published 18 June 2021 Science ClosedTags: algae, biological response, individualmodeling, laboratory, modeling, mortality, multiple factors, nutrients, performance, photosynthesis, physiology, policy, reproduction, South Atlantic, temperature
Highlights
- Global climate change and local stressors are the main threats to reef-building organisms and habitats they build, such as rhodolith beds.
- Through an experimental essay and ecological niche modelling, we were able to determine the environmental factors that determine the distribution and affect the physiology of an important rhodolith-forming species in the southwestern Atlantic.
- Our results raise the possibility of some rhodolith-forming species being resilient to future environmental change based on our current understanding of their distributions, a perspective that will need to be further explored by future studies.
- This information is helpful in informing policies for the conservation of priority areas, aiding the preservation of marine biodiversity in the South Atlantic.
Abstract
Given the ecological and biogeochemical importance of rhodolith beds, it is necessary to investigate how future environmental conditions will affect these organisms. We investigated the impacts of increased nutrient concentrations, acidification, and marine heatwaves on the performance of the rhodolith-forming species Lithothamnion crispatum in a short-term experiment, including the recovery of individuals after stressor removal. Furthermore, we developed an ecological niche model to establish which environmental conditions determine its current distribution along the Brazilian coast and to project responses to future climate scenarios. Although L. crispatum suffered a reduction in photosynthetic performance when exposed to stressors, they returned to pre-experiment values following the return of individuals to control conditions. The model showed that the most important variables in explaining the current distribution of L. crispatum on the Brazilian coast were maximum nitrate and temperature. In future ocean conditions, the model predicted a range expansion of habitat suitability for this species of approximately 58.5% under RCP 8.5. Physiological responses to experimental future environmental conditions corroborated model predictions of the expansion of this species’ habitat suitability in the future. This study, therefore, demonstrates the benefits of applying combined approaches to examine potential species responses to climate-change drivers from multiple angles.
Continue reading ‘Physiology, niche characteristics and extreme events: current and future habitat suitability of a rhodolith-forming species in the Southwestern Atlantic’Date: 30 Jun 2021
Time: 6:00 pm – 8:00 pm
Location: Level 4, 50 Kitchener Street, Auckland CBD
Registration is essential
Description
As the oceans warm, what’s happening to the marine species beneath the waves?
Join us at an upcoming alumni lecture at the University’s Auckland premises on the evening of Wednesday 30 June.
Hear about some of our latest research from award-winning marine biologist Dr Christopher Cornwall.
Fresh from his Prime Minister’s MacDiarmid Emerging Scientist Prize, he’ll share what we’re learning about how the world’s coral reefs, marine algae and the species that depend on them will respond to ocean acidification.
There’s good news – thanks to the adapabilty of organisims – but still challenges ahead. Whether you have a background in the sciences or just enjoy catching up on the latest research, hear the full story during this deep dive into the big blue sea.
There’ll also be the opportunity to catch up with fellow graduates during the event over light refreshments.
There is no charge for this event, but places are limited.
Please register via the button above at your earliest convenience to ensure you don’t miss out.
For more information contact: Heidi Stedman
Continue reading ‘Alumni lecture in Auckland: Coral reefs and climate change’
