Archive Page 159

Increased genetic diversity loss and genetic differentiation in a model marine diatom adapted to ocean warming compared to high CO2

Published 25 August 2022 Science Closed
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Although high CO2 and warming could act interactively on marine phytoplankton, little is known about the molecular basis for this interaction on an evolutionary scale. Here we explored the adaptation to high CO2 in combination with warming in a model marine diatom Phaeodactylum tricornutum. Whole-genome re-sequencing identifies, in comparison to populations grown under control conditions, a larger genetic diversity loss and a higher genetic differentiation in the populations adapted for 2 years to warming than in those adapted to high CO2. However, this diversity loss was less under high CO2 combined with warming, suggesting that the evolution driven by warming was constrained by high CO2. By integrating genomics, transcriptomics, and physiological data, we found that the underlying molecular basis for this constraint is associated with the expression of genes involved in some key metabolic pathways or biological processes, such as the glyoxylate pathway, amino acid and fatty acid metabolism, and diel variability. Our results shed new light on the evolutionary responses of marine phytoplankton to multiple environmental changes in the context of global change and provide new insights into the molecular basis underpinning interactions among those multiple drivers.

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Differential effects of warming and acidification on chemosensory transmission and detection may strengthen non-consumptive effects of blue crab predators (Callinectes sapidus) on mud crab prey (Panopeus herbstii)

Published 25 August 2022 Science Closed
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Predators control prey abundance and behavior, both of which strongly influence community dynamics. However, the relative importance of these predator effects may shift with climate change stressors, suggesting understanding the potential effects on these different processes is critical to predicting effects of climate change on community function. We investigated the effects of global warming and ocean acidification on the transmission and detection of chemical cues from blue crab predators (Callinectes sapidus) by mud crab prey (Panopeus herbstii). We measured mud crab feeding rates in the presence of blue crab predator cues, using either predator cues stressed in acidified conditions or mud crabs stressed in warmed and acidified conditions. Mud crabs consumed less food in the presence of predator cues, but acidifying the cues or subjecting mud crabs receiving the cues to acidified environment did not affect this antipredator response. Mud crabs in warmed conditions consumed significantly less food regardless of predator cue, but this effect was reversed in ambient conditions. Therefore, climate change may produce shifts in community regulation as warming potentially compromises consumptive effects of predators by reducing motor function, whereas non-consumptive effects mediated by sensory transmission and detection remain unaffected by acidification. Overall, warming may have stronger effects than acidification on community dynamics in oyster reefs as global temperatures continue to rise.

Continue reading ‘Differential effects of warming and acidification on chemosensory transmission and detection may strengthen non-consumptive effects of blue crab predators (Callinectes sapidus) on mud crab prey (Panopeus herbstii)’

How to reverse the ocean-climate crisis

Published 25 August 2022 Web sites and blogs Closed
Rita Erven/OceanNETs/GEOMAR

For generations, the ocean has appeared to most humans as vast and impenetrable. Mysterious, dangerous, unfathomably large, but certainly not susceptible to being significantly altered by something humans might do.

But over the past century, that understanding has changed—first slowly and then more dramatically—and now, the ocean appears smaller and more fragile than we once thought. We have unimpeachable evidence that humans can have a devastating footprint on the ocean: 20th century whalers decimated global populations of blue, fin, and sperm whales over just a few decades; factory trawlers are depleting today’s fisheries; agricultural runoff has created enormous dead zones in the ocean; and plastic waste litters most of the ocean.

And there is a far more dangerous human-caused stressor that has largely gotten a pass from scrutiny, even though it is creating existential threats to the ocean. That stressor is the carbon dioxide pollution we have released into the atmosphere over the past 200 years, with a significant portion finding its way into the ocean’s upper layer.

Although we may not normally think of CO₂ as pollution, human enterprise since the dawn of the industrial revolution has emitted about 2 trillion tons of this invisible gas into Earth’s atmosphere that otherwise would not have been there. Over this time, we have increased CO₂ levels by 50% in the atmosphere and by 30% in the upper layer of the ocean.

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Ocean acidification will impede swimming in sea urchin sperm

Published 24 August 2022 Science Closed
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A kina sea urchin. Photo credit: Mary Sewell.

The grim impact of ocean acidification on many marine creatures is becoming brutally evident. Pretty much any animal that depends on a calcium carbonate shell or skeleton – including molluscs and coral reefs – is at risk as the oceans soak up human CO2 emissions. But other aspects of their lifestyle may also be affected by the oceans’ plummeting pH. Sea urchin sperm are triggered into action when released into seawater with a pH higher than 8, raising their internal pH and activating the motor proteins that drive their powerful beating tails as they search for an egg. However, some researchers are concerned that the lower pH of seawater as acidification takes hold may mean it will no longer activate sea urchin sperm when released. Without the essential internal pH rise, the sperm may be too sluggish to locate and fertilise eggs. But no one had directly checked how the ocean pH reductions that are predicted to occur by 2100 and 2150 could impact the New Zealand sea urchin (Evechinus chloroticus – known in Māori as the kina). Michael Hudson and Mary Sewell from the University of Auckland, New Zealand, decided to check out what the future may hold for the self-propelled gametes.

‘We prepared the experimental seawaters by bubbling precise mixes of gases through special injectors at a set temperature’, says Hudson, who then diluted fresh kina sperm into two versions of future seawater – simulating the sea in the year 2100 (pH 7.77) and in 2150 (pH 7.51) – to monitor how the gametes would propel themselves. Unfortunately, only 74% of the sperm were able to swim in the turn-of-the-century predicted water conditions, falling to 64% by 2150, compared with 83% in present day seawater. And when Hudson checked their swimming style, he found the 2150 sperm were no more sluggish than the 2100 sperm; however, the gametes took more indirect curving paths, slowing their forward movement, with implications for future fertility. ‘Fertilisation requires sperm to collide with eggs and it is known that the end result of fewer sperm swimming and lower swimming speeds is reduced levels of sperm–egg collisions and lower fertilisation rates’, says Hudson.

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A related article has been published: Ocean acidification impacts sperm swimming performance and pHi in the New Zealand sea urchin Evechinus chloroticus

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Response of planktic foraminiferal shells to ocean acidification and global warming assessed using micro-x-ray computed tomography

Published 24 August 2022 Science Closed
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Ocean acidification is now progressing, primarily due to the fact that the oceans have absorbed about 50% of the anthropogenic CO2 emitted since the industrial revolution. Many marine calcifying organisms, such as foraminifers and coccoliths, are known to build their shells using carbonate ions present in the seawaters surrounding them. Carbonate saturation state has a crucial influence on foraminiferal calcification, and foraminiferal shell production is known to be sensitive to increase in ocean pCO2. Moreover, ocean warming is also progressing along with acidification. Therefore, both environmental changes could affect foraminiferal shell formation. However, the relationship between foraminiferal shell parameters (i.e., size, weight, volume, and density) and ocean pCO2 or sea surface temperature (SST), or both, remains unclear. In this study, we used fossil planktic foraminifer Globigerinoides ruber (white) in a late Quaternary sediment core (MD98-2196) from the East China Sea to investigate a relationship between the shell parameters and oceanographic properties estimated based on the proxies from the same core. The foraminiferal shells were scanned using high-resolution micro-X-ray computed tomography (MXCT) to determine shell volume and density. The results showed that the size-normalized weight and the size-normalized volume of the shell had a negative correlation with the SST and atmospheric pCO2. The negative correlation between weight/volume and atmospheric pCO2 agrees with the previous laboratory experiments and geological record during the Pliocene. However, the correlation between weight/volume and SST should be interpreted with caution because it might be an artifact due to the correlation between SST and atmospheric pCO2. On the other hand, shell density is only weakly or insignificantly correlated with SST and pCO2, suggesting that these environmental parameters do not exert any impact on shell density. Thus, future ocean acidification will negatively affect the carbonate productivity of planktic foraminifers, even if it will not affect shell density. The temperature effect on the shell formation of the planktic foraminifers might be much less than ocean acidification considering controversial results of the temperature sensitivity in previous studies.

Continue reading ‘Response of planktic foraminiferal shells to ocean acidification and global warming assessed using micro-x-ray computed tomography’

Calcification response of reef corals to seasonal upwelling in the northern Arabian Sea (Masirah Island, Oman) (update)

Published 24 August 2022 Science Closed
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Tropical shallow-water reefs are the most diverse ecosystems in the ocean. Their persistence rests upon adequate calcification rates of the reef building biota, such as reef corals. Coral calcification is favoured in oligotrophic environments with high seawater saturation states of aragonite (Ωsw), which leads to an increased vulnerability to anthropogenic ocean acidification and eutrophication. Here we present Porites calcification records from the northern Arabian Sea upwelling zone and investigate the coral calcification response to low Ωsw and high nutrient concentrations due to seasonal upwelling. The calcification rate was determined from the product of skeletal extension rate and bulk density. Skeletal  Ba/Ca and  Li/Mg proxy data were used to identify skeletal portions that calcified during upwelling and non-upwelling seasons, respectively, and to reconstruct growth temperatures. With regard to sub-annual calcification patterns, our results demonstrate compromised calcification rates during the upwelling season. This is due to declining extension rates, which we attribute to light dimming caused by high primary production. Interestingly, seasonal variations in skeletal density show no relationship with temporally low Ωsw during upwelling. This suggests relatively constant, year-round saturation states of aragonite at the site of calcification (Ωcf) independent of external variability in Ωsw. Although upwelling does not affect seasonal density variability, exceptionally low mean annual density implies permanent Ωcf adjustment to the lowest sub-annual Ωsw (e.g. upwelling). In the Arabian Sea upwelling zone, the mean annual calcification rate is similar to Porites from non-upwelling regions because low skeletal density is compensated by high extension growth. Variable responses of reef coral extension to nutrients, which either exacerbate or compensate negative effects of diminished skeletal density associated with ocean acidification, may therefore be critical to the maintenance of adequate carbonate accumulation rates in coral reefs under global change.

Continue reading ‘Calcification response of reef corals to seasonal upwelling in the northern Arabian Sea (Masirah Island, Oman) (update)’

Francois Morel: the effect of ocean acidification on marine phytoplankton (text & video)

Published 24 August 2022 Presentations , Resources Closed
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Francois Morel, Princeton University, presents “The Effect of Ocean Acidification on Marine Phytoplankton” at the Dreyfus Symposium on Environmental Chemistry. This symposium was held at the national meeting of the American Chemical Society on March 22, 2022.

For more information, visit: www.dreyfus.org.

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Basic training course on multiple stressors and ocean acidification

Published 23 August 2022 Courses and training , Events Closed

Date: 24 October – 4 November 2022

Location: The event will be held at the IAEA Marine Environment Laboratories in Monaco.

Deadline for applications: 12 September 2022

Introduction: The basic training course on multiple stressors will be based on previous courses on ocean acidification held as part of the activities of the IAEA Peaceful Uses Initiative project “Ocean Acidification International Coordination Centre” (OA-ICC) and partners.

Objectives: Human health and well-being are closely linked to the ocean and the many goods and services it provides. However, the ocean is under cumulative stress from a range of human-driven pressures. The impact of multiple ocean stressors together and their interplay on marine life and ecosystem function is not well understood, yet it is central to mitigate the negative effects they cause and/or to support adaptation strategies that might counteract stressors. To date, studies often focus on single species or groups of organisms and the influence of a single stressor, while information about ecosystem responses to multiple stressors is limited. Innovative science is needed to resolve the complexity of the interplay of stressors and the resulting impacts. The aim of this course is to train early-career scientists and researchers entering the multiple stressor field with the goal to better understand key concepts (e.g. What is a stressor? What is a mode of action? What is an interaction?), assist them to be able to measure and manipulate seawater physico-chemistry, develop relevant experimental strategies, set up pertinent experiments in the laboratory and in the field, avoid typical pitfalls and ensure comparability with other studies, in a sustainable way.

Target audience: The course is open to 12 trainees. Priority will be given to early-career scientists with experience in marine environmental changes. At least one publication in the field of marine environmental changes is required.

Working language(s): English

Expected outputs: Increased capacity to measure and study multiple stressors and increased networking among scientists working on ocean acidification. Initiate/deepen connections with international networks such as the Global Ocean Acidification Observing Network (GOA-ON; http://www.goa-on.org). Participants will also work on personal projects, developing strategies for their own research and a data-based project using data resources from the OA-ICC.

Structure: The training will include lectures in plenary, guest lectures and hands-on experiments in smaller groups (the level will depend on the basic knowledge of the selected participants). Subjects to be covered include theoretical aspects of multiple stressor research, how to identify relevant scientific questions, best practices for seawater physico-chemistry characterization, experimental strategies and design, lab and field-based methods for measuring organism responses to multiple stressors, including nuclear and isotopic techniques, and data analysis, processing, and modeling.

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Using biomimicry and bibliometric mapping to guide design and production of artificial coral reefs

Published 23 August 2022 Science Closed
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Highlights

  • We created an artificial coral reef based on biomimicry using a bibliometric method.
  • We designed stage-gates to lead the innovation process.
  • Local community and government agencies were included in the conceptualization.
  • We demonstrate the recovery in natural marine ecosystems using 3D printed coral reefs.

Abstract

Worldwide, artificial reefs are being installed to simultaneously attract recreational divers and protect deteriorating natural reefs. This study uses a bibliometric review of artificial coral reefs to identify five clusters as gate criteria for artificial reef design. These clusters enable the conceptualization and testing of artificial reefs for optimum integration of sociotechnical requirements, biological integrity, and ecological marine health. The five clusters are: (1) applications, solutions, and performance; (2) management, technology, and science; (3) calcification, biomineralization, chemistry, and ocean acidification; (4) coral species survival, mortality, and photosynthesis; and (5) artificial reef development, and coral and fish recruitment. The six biomimicry design stages are: define, biologize, discover, abstract, emulate, and evaluate. The 3D printing and hard corals design attracted a large number of planula larvae and different inhabitant corals, and a high species diversity in the surrounding waters. Practical implications include biomimicry-based means for coral reef restoration and recreational ecosystem services.

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Metagenomic shifts in mucus, tissue and skeleton of the coral Balanophyllia europaea living along a natural CO2 gradient

Published 22 August 2022 Science Closed
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Using the Mediterranean coral Balanophyllia europaea naturally growing along a pH gradient close to Panarea island (Italy) as a model, we explored the role of host-associated microbiomes in coral acclimatization to ocean acidification (OA). Coral samples were collected at three sites along the gradient, mimicking seawater conditions projected for 2100 under different IPCC (The Intergovernmental Panel on Climate Change) scenarios, and mucus, soft tissue and skeleton associated microbiomes were characterized by shotgun metagenomics. According to our findings, OA induced functional changes in the microbiomes genetic potential that could mitigate the sub-optimal environmental conditions at three levels: i. selection of bacteria genetically equipped with functions related to stress resistance; ii. shifts in microbial carbohydrate metabolism from energy production to maintenance of cell membranes and walls integrity; iii. gain of functions able to respond to variations in nitrogen needs at the holobiont level, such as genes devoted to organic nitrogen mobilization. We hence provided hypotheses about the functional role of the coral associated microbiome in favoring host acclimatation to OA, remarking on the importance of considering the crosstalk among all the components of the holobiont to unveil how and to what extent corals will maintain their functionality under forthcoming ocean conditions.

Continue reading ‘Metagenomic shifts in mucus, tissue and skeleton of the coral Balanophyllia europaea living along a natural CO2 gradient’

Dissimilar sensitivities of ocean acidification metrics to anthropogenic carbon accumulation in the central north Pacific Ocean and California current large marine ecosystem

Published 22 August 2022 Science Closed
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We analyze and compare changes to ocean acidification metrics caused by anthropogenic carbon (Canth) accumulation in the North Pacific Ocean and California Current Large Marine Ecosystem (CCLME). The greatest declines in pH and carbonate mineral saturation state occur near the surface, coincident with the highest Canth concentrations. However, maximal increases in the partial pressure of carbon dioxide (pCO2) and hydrogen ion concentration occur subsurface where Canth values are lower. We attribute dissimilar sensitivities of these metrics to background ocean chemistry, which has naturally high pCO2 and low buffering capacity in subsurface waters due to accumulated byproducts of organic matter respiration, which interacts with Canth. In the CCLME, rising subsurface pCO2 has increased the frequency, duration, and intensity of hypercapnia (pCO2≥1000 µatm) on the continental shelf. Our findings suggest that hypercapnia induced by Canth accumulation can co-occur with hypoxia in the CCLME and is an additional modern stressor for marine organisms.

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Pelagic calcifiers face increased mortality and habitat loss with warming and ocean acidification

Published 19 August 2022 Science Closed
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Global change is impacting the oceans in an unprecedented way, and multiple lines of evidence suggest that species distributions are changing in space and time. There is increasing evidence that multiple environmental stressors act together to constrain species habitat more than expected from warming alone. Here, we conducted a comprehensive study of how temperature and aragonite saturation state act together to limit Limacina helicina, globally distributed pteropods that are ecologically important pelagic calcifiers and an indicator species for ocean change. We co-validated three different approaches to evaluate the impact of ocean warming and acidification (OWA) on the survival and distribution of this species in the California Current Ecosystem. First, we used colocated physical, chemical, and biological data from three large-scale west coast cruises and regional time series; second, we conducted multifactorial experimental incubations to evaluate how OWA impacts pteropod survival; and third, we validated the relationships we found against global distributions of pteropods and carbonate chemistry. OWA experimental work revealed mortality increases under OWA, while regional habitat suitability indices and global distributions of L. helicina suggest that a multi-stressor framework is essential for understanding pteropod distributions. In California Current Ecosystem habitats, where pteropods are living close to their thermal maximum already, additional warming and acidification through unabated fossil fuel emissions (RCP 8.5) are expected to dramatically reduce habitat suitability.

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Exoskeletal predator defenses of juvenile California spiny lobsters (Panulirus interruptus) are affected by fluctuating ocean acidification-like conditions

Published 19 August 2022 Science Closed
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Spiny lobsters rely on multiple biomineralized exoskeletal predator defenses that may be sensitive to ocean acidification (OA). Compromised mechanical integrity of these defensive structures may tilt predator-prey outcomes, leading to increased mortality in the lobsters’ environment. Here, we tested the effects of OA-like conditions on the mechanical integrity of selected exoskeletal defenses of juvenile California spiny lobster, Panulirus interruptus. Young spiny lobsters reside in kelp forests with dynamic carbonate chemistry due to local metabolism and photosynthesis as well as seasonal upwelling, yielding daily and seasonal fluctuations in pH. Lobsters were exposed to a series of stable and diurnally fluctuating reduced pH conditions for three months (ambient pH/stable, 7.97; reduced pH/stable 7.67; reduced pH with low fluctuations, 7.67 ± 0.05; reduced pH with high fluctuations, 7.67 ± 0.10), after which we examined the intermolt composition (Ca and Mg content), ultrastructure (cuticle and layer thickness), and mechanical properties (hardness and stiffness) of selected exoskeletal predator defenses. Cuticle ultrastructure was consistently robust to pH conditions, while mineralization and mechanical properties were variable. Notably, the carapace was less mineralized under both reduced pH treatments with fluctuations, but with no effect on material properties, and the rostral horn had lower hardness in reduced/high fluctuating conditions without a corresponding difference in mineralization. Antennal flexural stiffness was lower in reduced, stable pH conditions compared to the reduced pH treatment with high fluctuations and not correlated with changes in cuticle structure or mineralization. These results demonstrate a complex relationship between mineralization and mechanical properties of the exoskeleton under changing ocean chemistry, and that fluctuating reduced pH conditions can induce responses not observed under the stable reduced pH conditions often used in OA research. Furthermore, this study shows that some juvenile California spiny lobster exoskeletal defenses are responsive to changes in ocean carbonate chemistry, even during the intermolt period, in ways that can potentially increase susceptibility to predation among this critical life stage.

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Toward a decade of ocean science for sustainable development through acoustic animal tracking

Published 19 August 2022 Science Closed
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The ocean is a key component of the Earth’s dynamics, providing a great variety of ecosystem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human-made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries management, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans-boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United Nations.

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Job opportunity: assistant professor, biology, global change ecology (517800)

Published 19 August 2022 Jobs Closed

Deadline for application: 15 October 2022

Job Description:

San Francisco State University, Department of Biology invites applications for a tenure-track Assistant Professor position in Global Change Ecology to begin August 2023. We seek applicants conducting research in Global Change Ecology, broadly defined (e.g., climate change, biodiversity loss, land use change, invasive species). We welcome scientists developing an externally funded research program towards a comprehensive and holistic understanding of the effects and consequences of global change on ecological systems, biosphere-atmosphere interactions, and coupled natural-human systems across temporal and spatial scales. Research foci may include nature-based adaptation solutions to reduce the causes and impacts of global change (e.g., sea level rise, carbon emissions, fire, ocean acidification, nutrient pollution, hypoxia, etc.). We are open to all research approaches, including experimental field-based research, computational or mathematical modeling, and/or machine learning within the context of natural communities or at the urban/natural ecosystem interface. The successful candidate may also address how social justice and incorporating traditional ecological knowledge fits into understanding and addressing global change through research or outreach. We are especially interested in qualified candidates who can contribute to the excellence and diversity of the SFSU academic community by working on important and relevant research areas, whose teaching and research engages our diverse student body and improves their academic success, and whose service is meaningful to our institution as well as the broader community.

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Responsibilities

The position requires both graduate and undergraduate teaching in biology. Curricular contributions could include Introductory Biology, Climate change, Evolution, Ecology, Research Design and Data Analysis, and specialty courses in the candidate’s area of research focus at the undergraduate and graduate level. In addition, the successful candidate will be required to engage, mentor, and advise undergraduate and master’s students in directed research. The successful candidate is also expected to continue an active, externally-funded research program in their area of expertise, and to participate in committee and service assignments at the department and university level, and to their professional community.

Qualifications

Required

  • Ph.D. or equivalent doctoral degree and post-doctoral experience in a biology or biology-related field are required.
  • Record of scientific and mentorship accomplishments in biology and global change ecology.
  • Evidence of working and communicating effectively with colleagues and students.

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Arctic marine researcher measures the ocean’s contribution to combating climate change

Published 19 August 2022 Web sites and blogs Closed

Brent Else receives federal funding for ground — and ice — breaking research

Brent Else on the CCGS Amundsen during a 2021 expedition to Baffin Bay. Gina Nickoloff

It’s been just over a year since the Canadian Net-Zero Emissions Accountability Act became law, legislating Canada’s commitment to achieve net-zero emissions by 2050. To get to net-zero, the Canadian economy will have to either produce no greenhouse gas emissions or offset the emissions that it does produce.

Earth has built-in ways of naturally offsetting emissions, and Canada’s geography lends itself to one in particular. It’s called the “ocean carbon sink,” and Dr. Brent Else, PhD, is researching how much carbon is being offset by Canada’s 3.57 million square kilometres of Arctic Ocean.

“The ocean carbon sink describes how a large amount of CO2 that humans produce eventually ends up in the ocean,” Else explains. “The common estimate is that the ocean carbon sink offsets about 30 per cent of all CO2 emissions. If we didn’t have the ocean absorbing a significant amount of CO2, then our climate change problems would be a lot worse than they currently are.”

Canada will need to quantify all of its natural carbon sinks to meet its net-zero targets.

Else, associate professor in the Department of Geography in the Faculty of Arts, has been awarded Discovery Grant and Ship Time funding by the Natural Sciences and Engineering Research Council (NSERC) to study and measure just how much carbon is being absorbed by the ocean.

Else’s project is one of 96 UCalgary research projects to receive funding through the NSERC Discovery Grant program in spring 2022.

How the ocean locks away carbon

Carbon uptake by the ocean is most effective when CO2 is absorbed by the surface water of the ocean, and then sinks as it cools into the deep sea, where the absorbed CO2 stays locked until it eventually, over hundreds of years, cycles back up to the surface.

“High latitude oceans take up quite a lot of CO2 for their surface area. Cold water is better at absorbing CO2 than warmer water, so the cold areas of the earth’s surface tend to be areas that are stronger CO2 sinks,” Else says.

Else’s research is focused on Foxe Basin, Nunavut, a large area of the Arctic Ocean north of Hudson’s Bay, and Cambridge Bay, Nunavut.

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Downeast discussions: using meta-analysis research processes in bivalve ocean acidification studies (text & video)

Published 19 August 2022 Presentations Closed

This is the sixth and final presentation of Downeast Institute’s six-part 2022 Downeast Discussion Climate Change Seminar Series. In this seminar, learn about how DEI Fellow Ray Czaja conducted a meta-analysis to compare ocean acidification-focused bivalve experiments, how experimental design choices affect outcomes in individual experiments, and what he learned about the importance of upwelling with regards to ocean acidification resiliency.

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Selection on offspring size and contemporary evolution under ocean acidification

Published 18 August 2022 Science Closed
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Ocean acidification may have deleterious effects on many species, but anticipating long-term changes in the abundance of populations will require an understanding of ocean acidification as an evolutionary force. Here, I show that ocean acidification alters natural selection on offspring size and is likely to drive contemporary evolution. In a detailed study of a coastal fish species (California grunion), I demonstrate that larval mortality is highly sensitive to ocean acidification and that mortality rates are lower for larger larvae. However, these effects are countered by tradeoffs between offspring size and number, suggesting that measurements of maternal fitness are critical for quantifying selection through ocean acidification. Measurements of selection and genetic variation were used to project the evolution of larval size as seawater conditions changed incrementally over many decades. Results for California grunion suggest that contemporary evolution may offset the projected decline in reproductive success by about 50%.

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Ocean warming amplifies the effects of ocean acidification on skeletal mineralogy and microstructure in the Asterinid starfish Aquilonastra yairi

Published 18 August 2022 Science Closed
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Ocean acidification and ocean warming compromise the capacity of calcifying marine organisms to generate and maintain their skeletons. While many marine calcifying organisms precipitate low-Mg calcite or aragonite, the skeleton of echinoderms consists of more soluble Mg-calcite. To assess the impact of exposure to elevated temperature and increased pCO2 on the skeleton of echinoderms, in particular the mineralogy and microstructure, the starfish Aquilonastra yairi (Echinodermata: Asteroidea) was exposed for 90 days to simulated ocean warming (27 °C and 32 °C) and ocean acidification (455 µatm, 1052 µatm, 2066 µatm) conditions. The results indicate that temperature is the major factor controlling the skeletal Mg (Mg/Ca ratio and Mgnorm ratio), but not for skeletal Sr (Sr/Ca ratio and Srnorm ratio) and skeletal Ca (Canorm ratio) in A. yairi. Nevertheless, inter-individual variability in skeletal Sr and Ca ratios increased with higher temperature. Elevated pCO2 did not induce any statistically significant element alterations of the skeleton in all treatments over the incubation time, but increased pCO2 concentrations might possess an indirect effect on skeletal mineral ratio alteration. The influence of increased pCO2 was more relevant than that of increased temperature on skeletal microstructures. pCO2 as a sole stressor caused alterations on stereom structure and degradation on the skeletal structure of A. yairi, whereas temperature did not; however, skeletons exposed to elevated pCO2 and high temperature show a strongly altered skeleton structure compared to ambient temperature. These results indicate that ocean warming might exacerbate the skeletal maintaining mechanisms of the starfish in a high pCO2 environment and could potentially modify the morphology and functions of the starfish skeleton.

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Offshore extinctions: ocean acidification impacting interstitial fauna

Published 18 August 2022 Science Closed
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As problematic as global warming, ocean acidification is a widespread problem, but the consequences of the interstitial fauna are still underrated. The biodiversity within sandy beaches is out of measurement, and its loss will be significantly felt. Estimations of the number of species are still vague. Acting as a key role in the trophic net, the interstitial organisms are threatened by pH value changes. Changing the pH values is already linked with less species richness and weakness of the sea community. The sediments may not be a sufficient buffer. Beyond this, there is another environmental problem aggravating the scenario. The decreasing complexity in the sand structure generated by the destruction of biological-generated sediments will impact the local biodiversity. Other environmental situations such as lack of sufficient O2 levels may be an aggravating combination. Here, I propose a protocol to observe if occur offshore extinctions, the veiled extinctions of interstitial fauna.

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