Archive for July, 2019

Ocean acidification

For tens of millions of years, Earth’s oceans have maintained a relatively stable acidity level. It’s within this steady environment that the rich and varied web of life in today’s seas has arisen and flourished. But research shows that this ancient balance is being undone by a recent and rapid drop in surface pH that could have devastating global consequences.

Since the beginning of the industrial revolution in the early 1800s, fossil fuel-powered machines have driven an unprecedented burst of human industry and advancement. The unfortunate consequence, however, has been the emission of billions of tonnes of carbon dioxide (CO2) and other greenhouse gases into Earth’s atmosphere.

Continue reading ‘Ocean acidification’

C-CAN webinar: Understanding acidification risks across habitats through a 10-site intertidal network

Presented by: Dr. Micah Horwith, Washington State Department of Natural Resources, Aquatic Resources

Time: August 7, 10 to 11pm CEST

Description: In 2015, the Washington State Department of Natural Resources established the Acidification Nearshore Monitoring Network. This program – ANeMoNe – collects co-located data on water quality, shellfish, and aquatic vegetation at 10 intertidal sites that span greater Puget Sound and the Washington Coast. ANeMoNe is designed to support hypothesis-driven research through replicated field experiments, and to measure the progress of ocean warming and acidification over tidelands. Here, we offer a survey of work from across the network, which has explored 1) the effects of eelgrass on local water chemistry, 2) the potential of eelgrass as a refuge for shellfish, and 3) regional differences in pH and other parameters of water quality. Through persistent monitoring and limited-term experiments, ANeMoNe fosters collaboration between agency and academic scientists, tribes, and community members invested in understanding and planning for rapid environmental change.

Continue reading ‘C-CAN webinar: Understanding acidification risks across habitats through a 10-site intertidal network’

Biological modification of seawater chemistry by an ecosystem engineer, the California mussel, Mytilus californianus

Marine habitat‐forming species often play critical roles on rocky shores by ameliorating stressful conditions for associated organisms. Such ecosystem engineers provide structure and shelter, for example, by creating refuges from thermal and desiccation stresses at low tide. Less explored is the potential for habitat formers to alter interstitial seawater chemistry during their submergence. Here, we quantify the capacity for dense assemblages of the California mussel, Mytilus californianus, to change seawater chemistry (dissolved O2, pH, and total alkalinity) within the interiors of mussel beds at high tide via respiration and calcification. We established a living mussel bed within a laboratory flow tank and measured vertical pH and oxygen gradients within and above the mussel bed over a range of water velocities. We documented decreases of up to 0.1 pH and 25 μmol O2 kg−1 internal to the bed, along with declines of 100 μmol kg−1 in alkalinity, when external flows were  95% of the time. Reductions in pH and O2 inside mussel beds may negatively impact resident organisms and exacerbate parallel human‐induced perturbations to ocean chemistry while potentially selecting for improved tolerance to altered chemistry conditions.

Continue reading ‘Biological modification of seawater chemistry by an ecosystem engineer, the California mussel, Mytilus californianus’

Provision of carbon skeleton for lipid synthesis from the breakdown of intracellular protein and soluble sugar in Phaeodactylum tricornutum under high CO2

Background
Increasing CO2 emissions have resulted in ocean acidification, affecting marine plant photosynthesis and changing the nutrient composition of marine ecosystems. The physiological and biochemical processes of marine phytoplankton in response to ocean acidification have been reported, but have been mainly focused on growth and photosynthetic physiology. To acquire a thorough knowledge of the molecular regulation mechanisms, model species with clear genetic background should be selected for systematic study. Phaeodactylum tricornutum is a pennate diatom with the characteristics of small genome size, short generation cycle, and easy to transform. Furthermore, the genome of P. tricornutum has been completely sequenced.

Results and discussion
In this study, P. tricornutum was cultured at high and normal CO2 concentrations. Cell composition changes during culture time were investigated. The 13C isotope tracing technique was used to determine fractional labeling enrichments for the main cellular components. The results suggested that when lipid content increased significantly under high CO2 conditions, total protein and soluble sugar contents decreased. The 13C labeling experiment indicated that the C skeleton needed for fatty acid C chain elongation in lipid synthesis under high CO2 conditions is not mainly derived from NaHCO3 (carbon fixed by photosynthesis).

Conclusion
This study indicated that breakdown of intracellular protein and soluble sugar provide C skeleton for lipid synthesis under high CO2 concentration.

Continue reading ‘Provision of carbon skeleton for lipid synthesis from the breakdown of intracellular protein and soluble sugar in Phaeodactylum tricornutum under high CO2’

Combined effects of acute temperature change and elevated pCO2 on the metabolic rates and hypoxia tolerances of clearnose skate (Rostaraja eglanteria), summer flounder (Paralichthys dentatus), and thorny skate (Amblyraja radiata)

Understanding how rising temperatures, ocean acidification, and hypoxia affect the performance of coastal fishes is essential to predicting species-specific responses to climate change. Although a population’s habitat influences physiological performance, little work has explicitly examined the multi-stressor responses of species from habitats differing in natural variability. Here, clearnose skate (Rostaraja eglanteria) and summer flounder (Paralichthys dentatus) from mid-Atlantic estuaries, and thorny skate (Amblyraja radiata) from the Gulf of Maine, were acutely exposed to current and projected temperatures (20, 24, or 28 °C; 22 or 30 °C; and 9, 13, or 15 °C, respectively) and acidification conditions (pH 7.8 or 7.4). We tested metabolic rates and hypoxia tolerance using intermittent-flow respirometry. All three species exhibited increases in standard metabolic rate under an 8 °C temperature increase (Q10 of 1.71, 1.07, and 2.56, respectively), although this was most pronounced in the thorny skate. At the lowest test temperature and under the low pH treatment, all three species exhibited significant increases in standard metabolic rate (44–105%; p < 0.05) and decreases in hypoxia tolerance (60–84% increases in critical oxygen pressure; p < 0.05). This study demonstrates the interactive effects of increasing temperature and changing ocean carbonate chemistry are species-specific, the implications of which should be considered within the context of habitat.

Continue reading ‘Combined effects of acute temperature change and elevated pCO2 on the metabolic rates and hypoxia tolerances of clearnose skate (Rostaraja eglanteria), summer flounder (Paralichthys dentatus), and thorny skate (Amblyraja radiata)’

Simultaneous determination of dissolved inorganic carbon (DIC) concentration and stable isotope (δ13C-DIC) by Cavity Ring-Down Spectroscopy: application to study carbonate dynamics in the Chesapeake Bay

Highlights
• A CRDS-based approach was developed to simultaneously determine DIC and δ13C-DIC.

• High accuracy and precision comparable to the traditional methods of NDIR and IRMS.

• Main biogeochemical controls on DIC and δ13C-DIC in Chesapeake Bay in early May.

Abstract
Dissolved inorganic carbon (DIC) and its stable isotope (δ13C-DIC) are powerful tools for exploring aquatic biogeochemistry and the carbon cycle. Traditionally, they are determined separately with a DIC analyzer and an isotope ratio mass spectrometer. We present an approach that uses a whole-water CO2 extraction device coupled to a Cavity Ring-Down Spectroscopy (CRDS) CO2 and isotopic analyzer to measure DIC and δ13C-DIC simultaneously in a 3–4 mL sample over an ~11 min interval, with an average precision of 1.5 ± 0.6 μmol kg−1 for DIC and 0.09 ± 0.05‰ for δ13C-DIC. The system was tested on samples collected from a Chesapeake Bay cruise in May 2016, achieving a precision of 0.7 ± 0.5 μmol kg−1 for DIC and 0.05 ± 0.02‰ for δ13C-DIC. Using the simultaneously measured DIC and δ13C-DIC data, the biogeochemical controls on DIC and its isotope composition in the bay during spring are discussed. In the northern upper bay, the main controlling processes were CO2 outgassing and carbonate precipitation, whereas primary production (surface) and degradation of organic carbon (subsurface) dominated in the southern upper bay and middle bay. By improving the mode of sample introduction, the system could be automated to measure multiple samples. This would give the system the potential to provide continuous shipboard measurements during field surveys, making this method more powerful for exploring the complicated carbonate system across a wide range of aquatic settings.

Su J., Cai W.-J., Hussain N., Brodeur J., Chen B. & Huang K., in press. Simultaneous determination of dissolved inorganic carbon (DIC) concentration and stable isotope (δ13C-DIC) by Cavity Ring-Down Spectroscopy: Application to study carbonate dynamics in the Chesapeake Bay. Marine Chemistry. Article (subscription required).

Study considers sensory impacts of global climate change

Studies with cormorants reveal that increased turbidity may lower feeding success among these highly visual predators. © D. Malmquist/VIMS

Studies of how global change is impacting marine organisms have long focused on physiological effects–for example an oyster’s decreased ability to build or maintain a strong shell in an ocean that is becoming more acidic due to excess levels of carbon dioxide.

More recently, researchers have begun to investigate how different facets of global change can disrupt animal behavior.

Now, a study led by Dr. Emily Rivest of William & Mary’s Virginia Institute of Marine Science synthesizes the results of these pioneering behavioral studies–revealing both broad patterns and intriguing outliers–and provides a conceptual framework to help guide future research in this emerging field.

Continue reading ‘Study considers sensory impacts of global climate change’

PICES Press: Working together at the 4th GOA-ON International Workshop

The North Pacific Marine Science Organization (PICES) summer 2019 newsletter “PICES Press”, was recently published. This newsletter highlights the 4th GOA-ON International Workshop in Hangzhou, China, and PICES’ participation in this workshop.

Continue reading ‘PICES Press: Working together at the 4th GOA-ON International Workshop’

A model for integrating the effects of multiple simultaneous stressors on marine systems

While much has been learnt about the impacts of specific stressors on individual marine organisms, considerable debate exists over the nature and impact of multiple simultaneous stressors on both individual species and marine ecosystems. We describe a modelling tool (OSIRIS) for integrating the effects of multiple simultaneous stressors. The model is relatively computationally light, and demonstrated using a coarse-grained, non-spatial and simplified representation of a temperate marine ecosystem. This version is capable of reproducing a wide range of dynamic responses.Results indicate the degree to which interactions are synergistic is crucial in determining sensitivity to forcing, particularly for the higher trophic levels, which can respond non-linearly to stronger forcing. Stronger synergistic interactions sensitize the system to variability in forcing, and combinations of stronger forcing, noise and synergies between effects are particularly potent. This work also underlines the significant potential risk incurred in treating stressors on ecosystems as individual and additive.

Continue reading ‘A model for integrating the effects of multiple simultaneous stressors on marine systems’

The question of ocean acidification

Unprecedented floods that swamp cars and damage homes; dangerous storm surges that batter coastal roads and smash seawalls. We can already see the dramatic effects of climate change in the Northeast. But even on the clearest and calmest of days, a change is brewing in our world’s oceans that could have worse and more destructive consequences for local industries and livelihoods.

Oceans are warming and acidifying. Warming seawater has already caused economic damages such as periodic closures of Dungeness crab fishing. Ocean acidification is starting to take a toll. And the long-term effects of this change could be ruinous for marine life worldwide, and the people who depend on it for their food and income. Will ocean acidification hurt stocks in the Gulf of Maine, where the fishing industry nets hundreds of millions of dollars annually? If acidifying waters contribute to the decline of marine life in the region, can we slow the decline? Who is responsible for the damages—and can they be made to pay?

Continue reading ‘The question of ocean acidification’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,400,694 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book

Archives