Archive for June, 2015

Effects of CO2-driven ocean acidification on early life stages of marine medaka (Oryzias melastigma) (update)

The potential effects of high CO2 and associated ocean acidification (OA) in marine fishes and other non-calcified organisms are less well understood. In this study, we investigated the responses of early life stages (ELS) of marine medaka (Oryzias melastigma) exposed to a series of experimental manipulation of CO2 levels. Results showed that CO2-driven seawater acidification (pH 7.6 and pH 7.2) had no detectable effect on hatching time, hatching rate, or heart rate of embryos. However, the deformity rate of larvae in the pH 7.2 treatment was significantly higher than that in the control treatment. There is no significant difference between the left and right otolith areas in each treatment. However, the average otolith area of larvae in the pH 7.6 treatment was significantly smaller than that in the control. Such alterations in the developmental abnormalities and otolith size of marine medaka larvae due to elevated-CO2 levels suggests that this species will be increasingly challenged by future OA. Further studies of the impacts of OA on marine fish to assess whether or not the environmental influence in one generation can affect the later life history and the phenotype of subsequent generations are needed.

Continue reading ‘Effects of CO2-driven ocean acidification on early life stages of marine medaka (Oryzias melastigma) (update)’

Metabolic responses to temperature stress under elevated pCO2 in Crepidula fornicata

In the current context of environmental change, ocean acidification is predicted to affect the cellular processes, physiology and behaviour of all marine organisms, impacting survival, growth and reproduction. In relation to thermal tolerance limits, the effects of elevated pCO2 could be expected to be more pronounced at the upper limits of the thermal tolerance window. Our study focused on Crepidula fornicata, an invasive gastropod which colonized shallow waters around European coasts during the 20th century. We investigated the effects of 10 weeks’ exposure to current (380 µatm) and elevated (550, 750, 1,000 µatm) pCO2 on this engineer species using an acute temperature increase (1 °C 12 h−1) as the test. Respiration rates were measured on both males (small individuals) and females (large individuals). Mortality increased suddenly from 34 °C, particularly in females. Respiration rate in C. fornicata increased linearly with temperature between 18 and 34 °C, but no differences were detected between the different pCO2 conditions either in the regressions between respiration rate and temperature or in Q10 values. In the same way, condition indices were similar in all the pCO2 treatments at the end of the experiment, but decreased from the beginning of the experiment. This species was highly resistant to acute exposure to high temperature regardless of pCO2 levels, even though food was limited during the experiment. Crepidula fornicata appears to have either developed resistance mechanisms or a strong phenotypic plasticity to deal with fluctuations of physicochemical parameters in its habitat. This suggests that invasive species may be more resistant to future environmental changes than its native competitors.

Continue reading ‘Metabolic responses to temperature stress under elevated pCO2 in Crepidula fornicata’

Acidification reduced growth rate but not swimming speed of larval sea urchins

Swimming behaviors of planktonic larvae impact dispersal and population dynamics of many benthic marine invertebrates. This key ecological function is modulated by larval development dynamics, biomechanics of the resulting morphology, and behavioral choices. Studies on ocean acidification effects on larval stages have yet to address this important interaction between development and swimming under environmentally-relevant flow conditions. Our video motion analysis revealed that pH covering present and future natural variability (pH 8.0, 7.6 and 7.2) did not affect age-specific swimming of larval green urchin Strongylocentrotus droebachiensis in still water nor in shear, despite acidified individuals being significantly smaller in size (reduced growth rate). This maintenance of speed and stability in shear was accompanied by an overall change in size-corrected shape, implying changes in swimming biomechanics. Our observations highlight strong evolutionary pressure to maintain swimming in a varying environment and the plasticity in larval responses to environmental change.

Continue reading ‘Acidification reduced growth rate but not swimming speed of larval sea urchins’

Effects of ocean acidification on the photosynthetic performance, carbonic anhydrase activity and growth of the giant kelp Macrocystis pyrifera

Under ocean acidification (OA), the 200 % increase in CO2(aq) and the reduction of pH by 0.3–0.4 units are predicted to affect the carbon physiology and growth of macroalgae. Here we examined how the physiology of the giant kelp Macrocystis pyrifera is affected by elevated pCO2/low pH. Growth and photosynthetic rates, external and internal carbonic anhydrase (CA) activity, HCO3 versus CO2 use were determined over a 7-day incubation at ambient pCO2 400 µatm/pH 8.00 and a future OA treatment of pCO2 1200 µatm/pH 7.59. Neither the photosynthetic nor growth rates were changed by elevated CO2 supply in the OA treatment. These results were explained by the greater use of HCO3 compared to CO2 as an inorganic carbon (Ci) source to support photosynthesis. Macrocystis is a mixed HCO3 and CO2 user that exhibits two effective mechanisms for HCO3 utilization; as predicted for species that possess carbon-concentrating mechanisms (CCMs), photosynthesis was not substantially affected by elevated pCO2. The internal CA activity was also unaffected by OA, and it remained high and active throughout the experiment; this suggests that HCO3 uptake via an anion exchange protein was not affected by OA. Our results suggest that photosynthetic Ci uptake and growth of Macrocystis will not be affected by elevated pCO2/low pH predicted for the future, but the combined effects with other environmental factors like temperature and nutrient availability could change the physiological response of Macrocystis to OA. Therefore, further studies will be important to elucidate how this species might respond to the global environmental change predicted for the ocean.

Continue reading ‘Effects of ocean acidification on the photosynthetic performance, carbonic anhydrase activity and growth of the giant kelp Macrocystis pyrifera’

Opinion: Ocean acidification is an indisputable problem

Oceans are like giant vacuum cleaners. They absorb carbon dioxide emitted from burning fossil fuels and help clean the air. This has a beneficial effect on the Earth’s atmosphere and climate.

But the effects on the oceans and on the species that inhabit them are far less positive because, in the process, oceans are becoming more acidic. As a result, many of the micro-organisms at the bottom of the marine food chain are endangered and may become extinct, with far-reaching consequences for all.

Moreover, because the speed at which the ocean absorbs CO2 varies with the depth of water, it is difficult to envisage what the long-term effects of our current output will be on the oceans. (The creation of a balance between the percentage of CO2 in the air and in the top 1,000 metres of water in the ocean occurs within the space of a year. But, below this level, the same process will take 1,000 years, as the gas-containing water slowly sinks).

Continue reading ‘Opinion: Ocean acidification is an indisputable problem’

Probing human vulnerability to ocean acidification uncovers mitigation and adaptation opportunities

Ocean acidification has recently elbowed its way onto the list of wicked problems that coastal communities need to plan for. Coastal communities depend on a variety of oceanic goods and services, often led by marine harvests [1]. However, ocean acidification is poised to disrupt this dependence: for example, it jeopardized the Pacific Northwest United States’ shellfish industry for multiple years when upwelling waters soured by ocean acidification killed millions of oyster larvae [2]–[4]. Carbon dioxide released into the atmosphere by burning fossil fuels dissolves in seawater, adding even more carbon dioxide to what’s naturally in the water. This extra carbon dioxide changes seawater’s acidity and carbonate ion balance [5].

Pacific oysters are not the only organism harmed by ocean acidification, though. Many types of mollusks, corals, crustaceans, and coralline algae grow more slowly or die [6]–[10] due to ocean acidification, and squid [11]–[13], crustaceans [14]–[16] , and finfish and sharks [17]–[21]  experience changes in metabolism, immunity, olfaction, or behavior that are likely to affect the animals’ chances of survival.

Continue reading ‘Probing human vulnerability to ocean acidification uncovers mitigation and adaptation opportunities’

Altered waters: ocean acidification leads shellfish growers to adapt for survival

Image credit: NOAA

Image credit: NOAA

Pulling off the scenic highway that winds up the west coast and through the Puget Sound region, our tires crunch gravel as we enter the parking lot at Taylor Shellfish Farms in Shelton, Washington. It is difficult to imagine that this modest array of buildings is part of the largest shellfish growing operation in North America. The fifth generation family farm, established in 1889, is based here in Shelton, Washington, and over the years they have added facilities in Canada, California, and Hawaii.

Inside the processing plant, the smell of the ocean is vivid, fresh but not fishy.

The sound of machines – conveyor belts, forklifts, and refrigeration equipment – drowns out the voices of the workers packaging oysters, mussels, clams, and geoducks to be shipped to restaurants and stores around the globe.

Water runs over fresh oyster meat to remove sand and bits of shell. It washes across the cement floor between processing stations, and cascades in sheets off the edge of a stainless steel conveyor belt that ferries oysters to a line of men and women in yellow aprons who stand on milk crates as they sort and shuck the oysters.

Continue reading ‘Altered waters: ocean acidification leads shellfish growers to adapt for survival’

Pacific Walrus and Coastal Alaska native subsistence hunting: considering vulnerabilities from ocean acidification

An Ocean Way of Life

Life in Alaska Native coastal communities revolves around the ocean and all that it provides. For thousands of years, Iñupiaq, Central Yup’ik, Cup’ik, St. Lawrence Island Yupik, and Aleut communities along Alaska’s Bering and Chukchi seas have depended on marine resources to meet their physical, nutritional, spiritual, and cultural needs. This dependence is the foundation of a reciprocal relationship between the people and the ocean that has been maintained since time immemorial.

Now, however, Alaska Native hunting and fishing communities face cumulative pressures from ocean changes. Sea ice is diminishing and becoming increasingly unpredictable, fisheries are declining, and culturally important species such as the Pacific walrus are under threat. These changes upset travel routes and subsistence strategies of hunters, make the seas less safe, impact animal migrations, and undermine food security.

From Barrow to Bristol Bay, Alaska Native communities depend on the Pacific walrus as an important source of food, as well as materials for skin boats and ivory to support practical and artistic traditions of carving that also provide small amounts of money in an otherwise cash-limited environment. Pacific walrus are integral to the way of life, cultural identity, and community health of the indigenous people of the Bering and Chukchi seas.

Continue reading ‘Pacific Walrus and Coastal Alaska native subsistence hunting: considering vulnerabilities from ocean acidification’

The ocean under climate change – a message for COP21

The world’s oceans are in a state of decline. Climate change is already having a profound impact on ocean ecosystems. Increased ocean temperatures, sea level rise, altered weather patterns, changes in ocean currents, melting sea ice, and the effects of ocean acidification are upon us. These impacts are being exacerbated by man-made stresses such as overfishing, habitat loss and land-based sources of pollution.
The Our Common Future under Climate Change conference brings together some of the world’s leading marine scientists for an up-to-the minute assessment of the state of the global ocean under climate change, and discussion of two key questions: will the new climate treaty that emerges from the United Nations climate negotiations in Paris in December contain adequate commitments to protect the ocean – and specifically, will a 2 degree limit to global warming be sufficient to prevent the worst damage to the global ocean foreseen in risk scenarios.

Continue reading ‘The ocean under climate change – a message for COP21’

PhD Candidate in Marine geology/Ocean Acidification at the Centre of Excellence CAGE, University of Tromsø, Norway

Application deadline: 31 August 2015!

Ref. 2015/2037 – 3121

The Centre of Excellence CAGE at the Department of Geology, has a PhD position vacant for applicants who wish to obtain the degree of Philosophiae Doctor (PhD). The appointment is for a period of four years.

The PhD position is for a fixed term, with the objective of completion of research training to the level of a doctoral degree. Admission to a PhD programme is a prerequisite for employment, and the programme period starts on commencement of the position. The PhD Candidate shall participate in the faculty’s organized research training, and the PhD project shall be completed during the period of employment. Information about the application process for admission to the PhD programme, application form and regulations for the degree of Philosophiae Doctor (PhD) are available at the following address: NT-Faculty.

Continue reading ‘PhD Candidate in Marine geology/Ocean Acidification at the Centre of Excellence CAGE, University of Tromsø, Norway’


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