Response of bacterioplankton activity in an Arctic fjord system to elevated pCO2: results from a mesocosm perturbation study

The effect of elevated seawater carbon dioxide (CO₂) on the activity of a natural bacterioplankton community in an Arctic fjord system was investigated by a mesocosm perturbation study in the frame of the European Project on Ocean Acidification (EPOCA). A pCO₂ range of 175–1085 μatm was set up in nine mesocosms deployed in the Kongsfjorden (Svalbard). The bacterioplankton communities responded to rising chlorophyll a concentrations after a lag phase of only a few days with increasing protein production and extracellular enzyme activity and revealed a close coupling of heterotrophic bacterial activity to phytoplankton productivity in this experiment. The natural extracellular enzyme assemblages showed increased activity in response to moderate acidification. A decrease in seawater pH of 0.5 units roughly doubled rates of β-glucosidase and leucine-aminopeptidase. Activities of extracellular enzymes in the mesocosms were directly related to both seawater pH and primary production. Also primary production and bacterial protein production in the mesocosms at different pCO₂ were positively correlated. Therefore, it can be suggested that the efficient heterotrophic carbon utilization in this Arctic microbial food web had the potential to counteract increased phytoplankton production that was achieved under elevated pCO₂ in this study. However, our results also show that the transfer of beneficial pCO₂-related effects on the cellular bacterial metabolism to the scale of community activity and organic matter degradation can be mitigated by the top-down control of bacterial abundances in natural microbial communities.

Oyster industry struggles to adapt to climate change

Ocean acidification has reduced some oyster yields by 80% or more.

Oysters on the half shell may be a delicacy, but oysters need their shells to grow and thrive in the first place. Unfortunately, increasing levels of ocean acidification caused by carbon-dioxide emissions and climate change threaten the integrity of oyster shells — and therefore the tasty mollusks themselves — and the oyster industry around the world is struggling to adapt.

Oyster hatcheries and nurseries in the Pacific Northwest started seeing the effect of ocean acidification in the middle of the last decade when oyster larvae started dying after their shells were corroded, NPR station WRVO recently reported. The region’s oyster farms saw a 60 percent drop in production in 2008 and another 80 percent drop the following year. The cause, as determined by National Oceanic and Atmospheric Administration research scientist Richard Feely, was increased anthropogenic CO2 in the ocean water.

WHOI hosts ocean science forum

WHOI scientists highlighted the issue of ocean acidification.

The Woods Hole Oceanographic Institution hosted a public forum at Redfield Auditorium Wednesday evening, highlighting the serious but little-discussed issue of ocean acidification. The event shed light on the causes and consequences of acidification through an outdoor expo featuring exhibits and demonstrations, and presentations by WHOI scientists.

President and Director Susan Avery began the program by summarizing acidification, calling it “one of the greatest problems facing our ocean and our planet.”

Acidification is a byproduct of carbon dioxide emissions, largely the result of the mass burning of fossil fuels. When carbon dioxide is released into the atmosphere, some it remains there—to contribute to global warming—some is absorbed by the land, and some—about a quarter of the total—comes to rest in the earth’s oceans.

Op-ed: how we can fight ocean acidification, protect marine life

We must embrace ocean conservation and management strategies to fight ocean acidification.

THOSE of us who care about the health of our coastal and marine resources recently received yet another wake-up call. A longtime oyster grower in Willapa Bay has moved a portion of its operation to Hawaii because of concerns over ocean acidification impacts on hatchery production.

Is the failure of tiny oyster larvae in Northwest coastal waters akin to the death of canaries in coal mines, warning us of imminent threats to our health and livelihoods? Perhaps. As a scientist, I look for the best evidence to support a statement of impending risk.

BIOS study: climate change, ocean bacteria

When it comes to climate change, few people think about potential impacts on bacteria, but that’s just what a team of researchers from the Bermuda Institute of Ocean Sciences [BIOS] and Princeton University did in a recent study chosen as the feature article in the current issue of Aquatic Microbial Ecology.

Led by Dr. Michael Lomas, PI of the Phytoplankton Ecology Lab at BIOS, the team investigated the short-term responses of photosynthetic bacteria populations to a series of treatments that mimic ocean acidification trends from the last glacial minimum [120,000 years ago] to projected year 2100.

Effect of ocean acidification on cyanobacteria in the subtropical North Atlantic

Cyanobacteria make significant contributions to global carbon and nitrogen cycling, particularly in the oligotrophic subtropical and tropical gyres. The present study examined short-term (days) physiological and acclimation responses of natural cyanobacterial populations to changes in pH/pCO2 spanning the last glacial minimum, ~8.4/~150 ppm, to projected year 2100 values of ~7.8/~800 ppm. Fe- and P-replete colonies of Trichodesmium increased N2-fixation rates (nmol N colony−1 h−1) at pH 7.8 by 54% (range 6 to 156%) over ambient pH/pCO2 conditions, while N2-fixation at pH/pCO2 8.4 was 21% (range 6 to 65%) lower than at ambient pH/pCO2; a similar pattern was observed when the rates were normalized to colony C. C-fixation rates were on average 13% (range −72 to 112%) greater at low pH than at ambient pH and 37% (−53 to 23%) greater than at high pH. Whole community assemblages dominated by Prochlorococcus and Synechococcus (47 to 95% of autotrophic biomass), whether nutrient-replete or P-limited, did not show a clear response of C-fixation rates to changes in pH/pCO2. Comparison of initial and final C-fixation responses across pH/pCO2 treatments suggests rapid acclimation of cellular physiology to new pH/pCO2 conditions. Changes in cell size and pigment content for Prochlorococcus and Synechococcus were minor and did not vary in a consistent manner with changes in pH/pCO2. These results for natural populations of all 3 cyanobacteria concur with previous research and suggest that one important response to changes in ocean pH and pCO2 might be an increase in N2 and C fixation by Trichodesmium under nutrient-replete conditions. The response of single-cell cyanobacteria to changes in pH/pCO2 will likely be indirect and controlled by the response to other variables, such as nutrients.

Ocean’s rising acid levels threaten sea life

Skeletons, shells becoming thinner

A thinning of the protective cases of mussels, oysters, lobsters and crabs is likely to disrupt marine food chains by making the creatures more vulnerable to predators. This could reduce human sources of seafood.

“The results suggest that increased acidity is affecting the size and weight of shells and skeletons, and the trend is widespread across marine species,” the British Antarctic Sur-vey (BAS) said in a statement of the findings.

Gonsalves: hard sell for hard shells

Just in time for football season, the big news in science over the weekend was the Martian touch-down scored by the robotic explorer Curiosity.

For the next two years, Curiosity will search for microscopic life on the red planet, which is why NASA chose a landing site near the Gale Crater — thought to be rich in minerals, remnants of ancient seas.

As scientists have long known, water is an ideal biosolvent uniquely suited to support life. So this new Mars mission is exciting stuff.

Meanwhile, closer to home, the big (though not quite as sexy) news this week in Earth ocean science is the Woods Hole Oceanographic Institution’s science expo on Wednesday. Called Ocean’s Acid Test, it’s designed as a public crash course in the very real global problem of ocean acidification.

Big deal, you say? I’ll let WHOI marine chemist Sarah Cooley tell you why it’s a big deal, especially for those whose livelihood or quality of life is tied to shellfish.

Ocean acidification (audio)

Iosefa Percival recently joined Conservation Internationals Pacific Islands Program (CI – PIP) as an intern to research the likely impacts of ocean acidification in the Pacific Islands.

Born and raised in Tiapapata, Iosefa Percival recently returned to Samoa from Brandeis University in Boston, USA for an internship with Conservation International. In this interview Iosefa discusses Ocean Acidification, his research plans in Samoa and why this information is so important for our region.