Archive for January, 2020

Upcoming webinar: Community of Ocean Action on Ocean Acidification

Time: 11 February at 3pm US East Coast Time, 11 February 9pm Central Europe Time, 12 February at 9am New Zealand time

Description: The webinar will include presentations from Alexis Valauri-Orton / Mark Spalding on The Ocean Foundation on their Ocean Acidification Initiative, including an overview of their capacity building activities, lessons learned, and future plans (Voluntary Commitment #15877), and from Dr. Kim Currie on New Zealand efforts to address ocean acidification through building partnerships and advancing research efforts (Voluntary Commitments #18232 and #18286). The webinar will also include discussions on upcoming plans for the 2020 UN Ocean conference, and several other updates.

Full Agenda here.

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Climate change and aquaculture: considering adaptation potential

Increases in global population and seafood demand are occurring simultaneously with fisheries decline in an era of rapid climate change. Aquaculture is well positioned to help meet the world’s future seafood needs, but heavy reliance of most global aquaculture on the ambient environment and ecosystem services suggests inherent vulnerability to climate change effects. There are, however, opportunities for adaptation. Engineering and management solutions can reduce exposure to stressors or mitigate stressors through environmental control. Epigenetic adaptation may have the potential to improve stressor tolerance through parental or early life stage exposure. Stressor-resistant traits can be genetically selected for, and maintaining adequate population variability can improve resilience and overall fitness. Information at appropriate time scales is crucial for adaptive response, such as real-time data on stressor levels and/or species’ responses, early warning of deleterious events, or prediction of longer-term change. Diet quality and quantity have the potential to meet increasing energetic and nutritional demands associated with mitigating the effects of abiotic and biotic climate change stressors. Research advancements in understanding how climate change affects aquaculture will benefit most from a combination of empirical studies, modelling approaches, and observations at the farm level. Research to support aquaculture adaptation requires an increasing amount of environmental data to guide biological response studies for regional applications. Increased experimental complexity, resources, and duration will be necessary to better understand the effects of multiple stressors. Ultimately, in order for aquaculture sectors to move beyond short-term coping responses, governance initiatives incorporating the changing needs of stakeholders, users, and culture ecosystems as a whole are required to facilitate planned climate change adaptation and mitigation.

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Measurement of feeding rates, respiration, and pH regulatory processes in the light of ocean acidification research

The physiology of marine larvae has received considerable attention in the context of anthropogenic ocean acidification (OA). Many marine larvae including those of echinoderms, hemichordates, and mollusks are characterized by a developmental delay when exposed to reductions in seawater pH with the underlying mechanisms being largely unexplored.

A key task in the frame of OA research lies in the identification of unifying physiological principles that may explain reductions in growth and development. The sea urchin larva has been identified as a good model organism, and energy allocations toward compensatory processes were found to be key factors affecting development. However, physiological approaches to assess the animal’s energy budget, as well as methods to characterize energy consuming processes (e.g., gut pH homeostasis and biomineralization) were scarce. During the last decade, a suite of physiological techniques was developed, to accurately determine the larval energy budget including feeding and metabolic rate measurements. To identify and characterize energy consuming processes, gastroscopic pH measurements in the larval gut and intracellular pH measurements of primary mesenchyme cells were developed.

These techniques helped to understand fundamental processes of gut homeostasis and biomineralization in the developing sea urchin larva and their interaction with the environment. Using the sea urchin larva as a model these methods were successfully transferred to other echinoderm and hemichordate early developmental stages. This chapter explains and provides the methodological basis for the determination of feeding and metabolic rates as well as intracellular and extracellular pH measurements using the sea urchin larva as an example.

Continue reading ‘Measurement of feeding rates, respiration, and pH regulatory processes in the light of ocean acidification research’

Climate change enhances disease processes in crustaceans: case studies in lobsters, crabs, and shrimps

Climate change has resulted in increasing temperature and acidification in marine systems. Rising temperature and acidification act as stressors that negatively affect host barriers to infection, thus enhancing disease processes and influencing the emergence of pathogens in ecologically and commercially important species. Given that crustaceans are ectotherms, changes in temperature dominate their physiological and immunological responses to microbial pathogens and parasites. Because of this, the thermal ranges of several crustacean hosts and their pathogens can be used to project the outcomes of infections. Host factors such as molting, maturation, respiration, and immune function are strongly influenced by temperature, which in turn alter the host’s susceptibility to pathogens, further amplifying morbidity and mortality. Microbial pathogens are also strongly influenced by temperature, arguably more so than their crustacean hosts. Microbial pathogens, with higher thermal optima than their hosts, grow rapidly and overcome host immune defenses, which have been weakened by increased temperatures. Pathogen factors such as metabolic rates, growth rates, virulence factors, and developmental rates are often enhanced by rising temperature, which translates into increased transmission, dispersal, and proliferation at the population level, and ultimately emergence of outbreaks in host populations. Less well known are the effects of acidification and salinity intrusion on host-pathogen processes, but they operate alongside temperature, as multiple stressors, that impose significant metabolic and physiological demands on host homeostasis.

Continue reading ‘Climate change enhances disease processes in crustaceans: case studies in lobsters, crabs, and shrimps’

Impacts of temperature, CO2, and salinity on phytoplankton community composition in the western Arctic Ocean

The Arctic Ocean has been experiencing rapid warming, which accelerates sea ice melt. Further, the increasing area and duration of sea ice-free conditions enhance ocean uptake of CO2. We conducted two shipboard experiments in September 2015 and 2016 to examine the effects of temperature, CO2, and salinity on phytoplankton dynamics to better understand the impacts of rapid environmental changes on the Arctic ecosystem. Two temperature conditions (control: <3 and 5°C above the control), two CO2 levels (control: ∼300 and 300/450 μatm above the control; i.e., 600/750 μatm), and two salinity conditions (control: 29 in 2015 and 27 in 2016, and 1.4 below the control) conditions were fully factorially manipulated in eight treatments. Higher temperatures enhanced almost all phytoplankton traits in both experiments in terms of chl-a, accessory pigments and diatom biomass. The diatom diversity index decreased due to the replacement of chain-forming Thalassiosira spp. by solitary Cylindrotheca closterium or Pseudo-nitzschia spp. under higher temperature and lower salinity in combination. Higher CO2 levels significantly increased the growth of small-sized phytoplankton (<10 μm) in both years. Decreased salinity had marginal effects but significantly increased the growth of small-sized phytoplankton under higher CO2 levels in terms of chl-a in 2015. Our results suggest that the smaller phytoplankton tend to dominate in the shelf edge region of the Chukchi Sea in the western Arctic Ocean under multiple environmental perturbations.

Continue reading ‘Impacts of temperature, CO2, and salinity on phytoplankton community composition in the western Arctic Ocean’

Upcoming webinar: studying coastal acidification effects upon the Atlantic Surfclam through an experimental and modeling approach

Time: Wed, Feb 12, 2020 5:00 PM – 6:00 PM CET

Description: Emilien Pousse, a Postdoctoral Research Associate at NOAA’s Northeast Fishery Science Center will share results from a series of experiments and modeling efforts to understand how various carbon dioxide levels affect the physiology and energy budget of the Atlantic Surfclam.

Continue reading ‘Upcoming webinar: studying coastal acidification effects upon the Atlantic Surfclam through an experimental and modeling approach’

Oysters as catch of the day? Perhaps not, if ocean acidity keeps rising

Oysters on ice

Commercially important oysters are vulnerable to ocean acidification. Creative Commons

When it comes to carbon emissions, people tend to focus more on what happens in the atmosphere and on land. But about a quarter of carbon emissions dissolve into oceans, lowering the water’s pH and causing ocean acidification.

That could affect what kind of seafood is on the menu in coming years. Species such as oysters and clams appear to be vulnerable to the change while others, including lobsters and crabs, are more resilient.

Robert Eagle, a UCLA expert on climate change and oceans, has explored the complex ways acidification affects marine life. Perhaps the biggest concern is that acidification interferes with the ability of organisms such as corals to form shells and skeletons — but it doesn’t affect all shell-forming organisms in the same way. Some are unaffected or actually grow faster in more acidic waters, previous research showed. But why?

Continue reading ‘Oysters as catch of the day? Perhaps not, if ocean acidity keeps rising’

Regulation of calcification site pH is a polyphyletic but not always governing response to ocean acidification

The response of marine-calcifying organisms to ocean acidification (OA) is highly variable, although the mechanisms behind this variability are not well understood. Here, we use the boron isotopic composition (δ11B) of biogenic calcium carbonate to investigate the extent to which organisms’ ability to regulate pH at their site of calcification (pHCF) determines their calcification responses to OA. We report comparative δ11B analyses of 10 species with divergent calcification responses (positive, parabolic, threshold, and negative) to OA. Although the pHCF is closely coupled to calcification responses only in 3 of the 10 species, all 10 species elevate pHCF above pHsw under elevated pCO2. This result suggests that these species may expend additional energy regulating pHCF under future OA. This strategy of elevating pHCF above pHsw appears to be a polyphyletic, if not universal, response to OA among marine calcifiers—although not always the principal factor governing a species’ response to OA.

Continue reading ‘Regulation of calcification site pH is a polyphyletic but not always governing response to ocean acidification’

Anomalies in the carbonate system of Red Sea coastal habitats (update)

We use observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) to assess the impact of ecosystem metabolic processes on coastal waters of the eastern Red Sea. A simple, single-end-member mixing model is used to account for the influence of mixing with offshore waters and evaporation–precipitation and to model ecosystem-driven perturbations on the carbonate system chemistry of coral reefs, seagrass meadows and mangrove forests. We find that (1) along-shelf changes in TA and DIC exhibit strong linear relationships that are consistent with basin-scale net calcium carbonate precipitation; (2) ecosystem-driven changes in TA and DIC are larger than offshore variations in >70 % of sampled seagrass meadows and mangrove forests, changes which are influenced by a combination of longer water residence times and community metabolic rates; and (3) the sampled mangrove forests show strong and consistent contributions from both organic respiration and other sedimentary processes (carbonate dissolution and secondary redox processes), while seagrass meadows display more variability in the relative contributions of photosynthesis and other sedimentary processes (carbonate precipitation and oxidative processes). The results of this study highlight the importance of resolving the influences of water residence times, mixing and upstream habitats on mediating the carbonate system and coastal air–sea carbon dioxide fluxes over coastal habitats in the Red Sea.

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Baywatchers data highlights path to protecting shellfish from acidification

a woman holding a Secchi disc by the water in Dartmouth

Volunteer Baywatchers take water samples every summer that help the Coalition track Buzzards Bay’s health over time.

Using water quality data collected by the Coalition, scientists at the Woods Hole Oceanographic Institution (WHOI) have uncovered another reason to reduce nitrogen pollution in Buzzards Bay­: nitrogen makes coastal waters more acidic, posing a threat to the region’s shellfish industry as well as important Bay habitats.

What’s more, it’s a problem that is getting worse due to climate change.

“Shellfish are a critical part of the Bay’s ecosystem that help to filter our water,” said Dr. Rachel Jakuba, Coalition science director and a co-author on the research. “In this study, we looked at how nitrogen pollution in Buzzards Bay could make it harder for our oysters, quahogs, scallops, and mussels to grow their protective shells.”

The results underscore the importance of reducing major nitrogen pollution sources in the Bay’s watershed, especially septic systems.

Continue reading ‘Baywatchers data highlights path to protecting shellfish from acidification’

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Ocean acidification in the IPCC AR5 WG II

OUP book