Archive for December, 2015

Ocean acidification as one of multiple stressors: growth response of Thalassiosira weissflogii (diatom) under temperature and light stress

Shifts in phytoplankton composition and productivity are anticipated in the future, because phytoplankton are frequently bottom-up controlled, and environmental conditions, like temperature, partial pressure of CO2 (pCO2), and light climate continue to change. Culture experiments revealed that whereas future (elevated) pCO2 had no effect on T. weissflogii in the absence of environmental stressors, growth rate was drastically decreased under future pCO2 if cells grew under light and temperature stress. The reduction in growth rates and a smaller decline in cellular photosynthesis under high pCO2 were associated with 2- to 3-fold increases in the production of transparent exopolymer particles (TEP), in the cell quotas of organic carbon, and the chl a:C ratios. Results suggest that under light- and temperature-stressed growth, elevated pCO2 led to increased energy requirements, which were fulfilled by increased light harvesting capabilities that permitted photosynthesis of acclimatized cells to remain relatively high. This was combined with the inability of these cells to acclimatize their growth rate to sub-optimal temperatures. As a consequence, growth rate was low and decoupled from photosynthesis. This decoupling led to large cell sizes and high excretion rates in future pCO2 treatments compared to ambient treatments if growth temperature and light were sub-optimal. Under optimal growth conditions the increased energy demands required to re-equilibrate the disturbed acid-base balance in future pCO2 treatments were likely mediated by a variety of physiological acclimatization mechanisms, individually too small to show a statistically detectable response in terms of growth rate, photosynthesis, pigment concentration, or excretion.

Continue reading ‘Ocean acidification as one of multiple stressors: growth response of Thalassiosira weissflogii (diatom) under temperature and light stress’

Impacts of ocean acidification in a warming Mediterranean Sea: An overview

Mediterranean Sea fisheries supply significant local and international markets, based largely on small pelagic fish, artisanal fisheries and aquaculture of finfish (mainly seabass and seabream) and shellfish (mussels and oysters). Fisheries and aquaculture contribute to the economy of countries bordering this sea and provide food and employment to coastal communities employing ca 600,000 people. Increasing temperatures and heat wave frequency are causing stress and mortality in marine organisms and ocean acidification is expected to worsen these effects, especially for bivalves and coralligenous systems. Recruitment and seed production present possible bottlenecks for shellfish aquaculture in the future since early life stages are vulnerable to acidification and warming. Although adult finfish seem able to withstand the projected increases in seawater CO2, degradation of seabed habitats and increases in harmful blooms of algae and jellyfish might adversely affect fish stocks. Ocean acidification should therefore be factored into fisheries and aquaculture management plans. Rising CO2 levels are expected to reduce coastal biodiversity, altering ecosystem functioning and possibly impacting tourism being the Mediterranean the world’s most visited region. We recommend that ocean acidification is monitored in key areas of the Mediterranean Sea, with regular assessments of the likely socio-economic impacts to build adaptive strategies for the Mediterranean countries concerned.

Continue reading ‘Impacts of ocean acidification in a warming Mediterranean Sea: An overview’

Season’s greetings and all the best in the new year!

2015 season greetings oaicc version 3

NOAA Awards Grants to Study Climate Change Impacts on Fisheries

NOAA Fisheries Office of Science and Technology is teaming up with the NOAA Research Climate Program Office to provide $5 million in grant money for seven new projects over the next three years.

The projects will aim to study the impacts the changing climate is having on the fish and fisheries of the Northeast Shelf Large Marine Ecosystem.

Warming Oceans, rising seas, ocean acidification and hypoxia are impacting marine life and the people, businesses, communities and economies that depend on the fisheries.

Continue reading ‘NOAA Awards Grants to Study Climate Change Impacts on Fisheries’

Direct and indirect impact of near-future pCO2 levels on zooplankton dynamics

Ocean acidification has direct physiological effects on organisms by, for example, dissolving the calcium carbonate structures of calcifying species. However, non-calcifiers may also be affected by changes in seawater chemistry. To disentangle the direct and indirect effects of ocean acidification on zooplankton growth, we carried out a study with two model organisms. We investigated the individual effect of short term exposure to (1) high and low seawater pCO2 and (2) different phytoplankton qualities as a result of different CO2 incubations on the growth of a heterotrophic dinoflagellate and a copepod species. It has been previously observed that higher CO2 concentrations can decrease phytoplankton food quality in terms of carbon:nutrient ratios. We therefore expected both seawater pCO2 (pH) and phytoplankton quality to result in a decrease of zooplankton growth. Although we expected lowest growth rates for all zooplankters under high seawater pCO2 and low algal quality, we found that direct pH effects on consumers seem to be of lesser importance than the associated decrease in algal quality. The decrease of primary producers’ quality under high pCO2 conditions negatively affected zooplankton growth, which may lead to lower availability of food for the next trophic level and thus potentially affect the recruitment of higher trophic levels.

Continue reading ‘Direct and indirect impact of near-future pCO2 levels on zooplankton dynamics’

Animal behaviour shapes the ecological effects of ocean acidification and warming: moving from individual to community-level responses

Biological communities are shaped by complex interactions between organisms and their environment as well as interactions with other species. Humans are rapidly changing the marine environment through increasing greenhouse gas emissions, resulting in ocean warming and acidification. The first response by animals to environmental change is predominantly through modification of their behaviour, which in turn affects species interactions and ecological processes. Yet, many climate change studies ignore animal behaviour. Furthermore, our current knowledge of how global change alters animal behaviour is mostly restricted to single species, life phases and stressors, leading to an incomplete view of how coinciding climate stressors can affect the ecological interactions that structure biological communities. Here, we first review studies on the effects of warming and acidification on the behaviour of marine animals. We demonstrate how pervasive the effects of global change are on a wide range of critical behaviours that determine the persistence of species and their success in ecological communities. We then evaluate several approaches to studying the ecological effects of warming and acidification, and identify knowledge gaps that need to be filled, to better understand how global change will affect marine populations and communities through altered animal behaviours. Our review provides a synthesis of the far-reaching consequences that behavioural changes could have for marine ecosystems in a rapidly changing environment. Without considering the pervasive effects of climate change on animal behaviour we will limit our ability to forecast the impacts of ocean change and provide insights that can aid management strategies.

Continue reading ‘Animal behaviour shapes the ecological effects of ocean acidification and warming: moving from individual to community-level responses’

Job vacancy: Postdoctoral research opportunity – Impact of ocean acidification on coral biomineralization, Northeastern University Marine Science Center, Boston, Massachusetts.

The Ries Lab (http://nuweb2.neu.edu/rieslab/) in the Department of Marine and Environmental Sciences at Northeastern University’s Marine Science Center (MSC) seeks a postdoctoral researcher interested in conducting federally funded research on the impact of ocean acidification on coral biomineralization to begin summer/fall 2016.

Research will include employing a multi-disciplinary approach to quantifying the impact of ocean acidification on the carbonate chemistry of corals’ calcifying fluids.

This opportunity affords access to newly acquired state-of-the-art analytical equipment at the MSC, including a laser ablation inductively-coupled plasma mass spectrometer for trace element analysis, a powder x-ray diffractometer for mineralogical characterization, and a scanning electron microscope with energy dispersive spectrometry and electron backscatter diffraction for micro-imaging and elemental/mineralogical mapping of skeletal ultrastructure, and a 72-tank array for conducting ocean acidification experiments.

The selected postdoc will receive interdisciplinary training in ocean acidification research, carbonate geochemistry, coral biomineralization, boron isotope analysis (via multi-collector ICPMS), and deployment of pH microelectrodes and pH-sensitive dyes for quantifying calcifying fluid chemistry. The postdoc will be based at Northeastern University’s MSC (http://www.northeastern.edu/marinescience/), located on the shores of Massachusetts Bay on the Nahant tombolo (13 miles north of downtown Boston).

The renovated MSC features a state-of-the-art flow through seawater facility, direct access to classic New England rocky shore intertidal study sites, an in-house SCUBA program, and small-craft research vessels.

Applicants should be highly motivated and creative, possess strong writing and analytical skills, and have a solid foundation in both theoretical and applied isotope geochemistry (preferably focused on boron isotope systematics in carbonates), pH microelectrodes, and pH-sensitive dyes. Funding for a postdoctoral fellow is available for one year with the option of renewal, pending funding availability.

Interested individuals should contact Prof. Justin Ries (j.ries@neu.edu).

Continue reading ‘Job vacancy: Postdoctoral research opportunity – Impact of ocean acidification on coral biomineralization, Northeastern University Marine Science Center, Boston, Massachusetts.’

Talk: “The end of seashells? Ocean Acidification”, Salem Public Library Loucks Auditorium, 18 February 2016

Speaker : George Waldbusser

Salem Public Library Loucks Auditorium, 585 Liberty St. SE, Salem, 18 February 2016, 7 p.m.

Continue reading ‘Talk: “The end of seashells? Ocean Acidification”, Salem Public Library Loucks Auditorium, 18 February 2016’

Impact of high pCO2 and warmer temperatures on the process of silica biomineralization in the sponge Mycale grandis

Siliceous sponges have survived pre-historical mass extinction events caused by ocean acidification and recent studies suggest that siliceous sponges will continue to resist predicted increases in ocean acidity. In this study, we monitored silica biomineralization in the Hawaiian sponge Mycale grandis under predicted pCO2 and sea surface temperature scenarios for 2100. Our goal was to determine if spicule biomineralization was enhanced or repressed by ocean acidification and thermal stress by monitoring silica uptake rates during short-term (48 h) experiments and comparing biomineralized tissue ratios before and after a long-term (26 d) experiment. In the short-term experiment, we found that silica uptake rates were not impacted by high pCO2 (1050 µatm), warmer temperatures (27°C), or combined high pCO2 with warmer temperature (1119 µatm; 27°C) treatments. The long-term exposure experiments revealed no effect on survival or growth rates of M. grandis to high pCO2 (1198 µatm), warmer temperatures (25.6°C), or combined high pCO2 with warmer temperature (1225 µatm, 25.7°C) treatments, indicating that M. grandis will continue to prosper under predicted increases in pCO2 and sea surface temperature. However, ash-free dry weight to dry weight ratios, subtylostyle lengths, and silicified weight to dry weight ratios decreased under conditions of high pCO2 and combined pCO2 warmer temperature treatments. Our results show that rising ocean acidity and temperature have marginal negative effects on spicule biomineralization and will not affect sponge survival rates of M. grandis.

Continue reading ‘Impact of high pCO2 and warmer temperatures on the process of silica biomineralization in the sponge Mycale grandis’

Testing Antarctic resilience: the effects of elevated seawater temperature and decreased pH on two gastropod species

Continue reading ‘Testing Antarctic resilience: the effects of elevated seawater temperature and decreased pH on two gastropod species’


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Ocean acidification in the IPCC AR5 WG II

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