Archive for the 'Media coverage' Category

Environmental stresses reshuffle ocean food webs, making them less secure

New experiments show important food web redundancies get left behind

May Law / Pexels

We are often taught about the relationships between organisms as a one-lane, one-way street: the grass is eaten by the rabbit, which is eaten by the snake, which is eaten by the hawk. In reality, this food chain model drastically oversimplifies the complex web of interactions between species. Healthy ecosystems contain numerous species that can fill the same role. Instead of the rabbits only being eaten by a snake, for example, they might be eaten by a snake or a fox or a hawk. This built-in redundancy in ecological roles makes ecosystems more resilient to change.

New research published in Science suggests that marine ecosystems may not have enough redundancy in their food webs to combat the cocktail of changes they could see in the near future.

Researchers set up large-scale ecological experiments called “mesocosms” to test how ecosystems responded to ocean acidification, ocean warming, and a combination of both acidification and warming.

Continue reading ‘Environmental stresses reshuffle ocean food webs, making them less secure’

Disentangling influences on coral health

Numerical modeling isolates the effects of a warming and acidifying ocean on the skeletal density of reef-building coral.

About one-third of the carbon dioxide spewed into our atmosphere since the start of the Industrial Revolution has been absorbed by the oceans. That absorption has made the oceans more acidic and deprived them of some 20% of their carbonate-ion concentration. Calcifying organisms such as coral, which rely on those ions to build their skeletons, are heavily affected. But despite decades of studies, attributing those effects to acidification remains difficult. Century-long records of the animals’ calcification rates do not show a consistent decline as ocean pH dropped in the 20th century. In some regions, the rates have even increased. That’s because ocean warming, among other factors, also affects coral growth. In particular, skeletal density of coral can increase, even in a lower-pH environment, because calcium carbonate precipitates faster at high temperature.

In a new study, Weifu Guo (Woods Hole Oceanographic Institution) and his colleagues have compiled records of existing and new skeletal growth of a stony, long-lived coral genus known as Porites to disentangle the competing effects.

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Ocean acidification causing coral ‘osteoporosis’ on iconic reefs

Scientists have long suspected that ocean acidification is affecting corals’ ability to build their skeletons, but it has been challenging to isolate its effect from that of simultaneous warming ocean temperatures, which also influence coral growth. New research from the Woods Hole Oceanographic Institution (WHOI) reveals the distinct impact that ocean acidification is having on coral growth on some of the world’s iconic reefs.

In a paper published Aug. 27, 2020, in the journal Geophysical Research Letters, researchers show a significant reduction in the density of coral skeleton along much of the Great Barrier Reef — the world’s largest coral reef system — and also on two reefs in the South China Sea, which they attribute largely to the increasing acidity of the waters surrounding these reefs since 1950.

“This is the first unambiguous detection and attribution of ocean acidification’s impact on coral growth,” says lead author and WHOI scientist Weifu Guo. “Our study presents strong evidence that 20th century ocean acidification, exacerbated by reef biogeochemical processes, had measurable effects on the growth of a keystone reef-building coral species across the Great Barrier Reef and in the South China Sea. These effects will likely accelerate as ocean acidification progresses over the next several decades.”

Continue reading ‘Ocean acidification causing coral ‘osteoporosis’ on iconic reefs’

Monitoring the Gulf of Maine

The Gulf of Maine is an incredibly useful body of water to study when it comes to exploring the effects of climate change, says Eugen Cotei ’21. “That’s because the waters of the Gulf have warmed faster than 99 percent of the ocean.”

Cotei has been working as a research fellow this summer helping Associate Professor of Earth and Oceanographic Science Michèle LaVigne analyze the conditions in this rapidly warming corner of the Atlantic Ocean. “My goal over the summer has been to validate data collected by the pier sensor at the Coastal Studies Center,” he explained.

“The sensor measures variables like pH, carbon dioxide levels, and dissolved oxygen concentrations in the seawater, all of which are incredibly important in understanding how the dynamic system operates, especially in the context of our changing climate and coastal acidification.” Based at the Schiller Coastal Studies Center less than thirteen miles from campus, Cotei has been collecting water samples from Harpswell Sound at regular intervals during low and high tide. These samples are analyzed and compared with the sensor data, and in theory should be able to validate those data.

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We’re learning about ocean acidification, and ‘SOCAN’ you! (audio)

Photo: Dr. Emily Hall leads the Ocean Acidification Program and Chemical & Physical Ecology Program at Mote Marine Laboratory.

Photo: Dr. Emily Hall leads the Ocean Acidification Program and Chemical & Physical Ecology Program at Mote Marine Laboratory.

Today we welcome back our favorite “ocean chemistry nut,” Dr. Emily Hall, manager of Mote’s Ocean Acidification Research Program and Chemical & Physical Ecology Program. Dr. Hall and her colleagues have been scoping out the challenges of acidification—water chemistry changes partly driven by humans—across ocean environments of the U.S. southeast. Acidification is a concern for shellfish, crabs, corals and other marine species populations that support livelihoods. Dr. Hall updates hosts Hayley and Joe on the possible—and sometimes bizarre—impacts of acidification, and how we can help deal with them. That’s the topic of a new research synthesis that she and her partners authored on behalf of the Southeast Ocean & Coastal Acidification Network (SOCAN).

Continue reading ‘We’re learning about ocean acidification, and ‘SOCAN’ you! (audio)’

Ocean acidification impacts on biomass and fatty acid composition of a post-bloom marine plankton community

A mesocosm approach was used to investigate the effects of ocean acidification (OA) on a natural plankton community in coastal waters off Norway by manipulating CO2 partial pressure ( pCO2). Eight enclosures were deployed in the Raunefjord near Bergen. Treatment levels were ambient (~320 µatm) and elevated pCO2 (~2000 µatm), each in 4 replicate enclosures. The experiment lasted for 53 d in May-June 2015. To assess impacts of OA on the plankton community, phytoplankton and protozooplankton biomass and total seston fatty acid content were analyzed. In both treatments, the plankton community was dominated by the dinoflagellate Ceratium longipes. In the elevated pCO2 treatment, however, biomass of this species as well as that of other dinoflagellates was strongly negatively affected. At the end of the experiment, total dinoflagellate biomass was 4-fold higher in the control group than under elevated pCO2 conditions. In a size comparison of C. longipes, cell size in the high pCO2 treatment was significantly larger. The ratio of polyunsaturated fatty acids to saturated fatty acids of seston decreased at high pCO2. In particular, the concentration of docosahexaenoic acid (C 22:6n3c), essential for development and reproduction of metazoans, was less than half at high pCO2 compared to ambient pCO2. Thus, elevated pCO2 led to a deterioration in the quality and quantity of food in a natural plankton community, with potential consequences for the transfer of matter and energy to higher trophic levels.

Continue reading ‘Ocean acidification impacts on biomass and fatty acid composition of a post-bloom marine plankton community’

Participatory research on using virtual reality to teach ocean acidification: a study in the marine education community

Ocean Acidification (OA) is an emerging environmental issue that is still largely unknown to the public and in its infancy in terms of educational strategies. OA teaching material should address the specific challenges that educators face while building learners’ understanding of OA. The objective of this study is two-fold. First, we identified the barriers to teaching OA as experienced by formal and informal marine educators. Second, we provided educators an opportunity to experience virtual reality and discuss how it could serve as a tool for face-to-face and distance learning to address the identified challenges. The findings shed light on four overarching themes of challenges to teaching OA: lack of science literacy, unprepared education field, complex and invisible nature of OA and lack of personal connection with the ocean. Marine educators consider empowerment, perspective-taking and visualization as the three principal avenues through which virtual reality may contribute to mitigating the challenges to teaching OA.

Continue reading ‘Participatory research on using virtual reality to teach ocean acidification: a study in the marine education community’

UMaine researchers find rising ocean temperatures, acidification worsen immune response, physiology in lobsters

Rising ocean temperatures and acidification, which results from decreasing pH levels, can increase adolescent lobsters’ vulnerability to disease and impact their physiology, according to University of Maine scientists.

Amalia Harrington studied the individual and combined effects of increased ocean acidification and warmth on adolescent, female American lobsters as a postdoctoral researcher at UMaine. Faculty from the Aquaculture Research Institute (ARI) collaborated with her on the study, including Heather Hamlin, an associate professor of aquaculture and marine sciences; Deborah Bouchard, ARI director; and Robert Harrington, an ARI research associate.

Continue reading ‘UMaine researchers find rising ocean temperatures, acidification worsen immune response, physiology in lobsters’

Shells could save our seas, says USC Dornsife undergraduate

Political science major Isabella O’Brien has been working on ways to counter the impact of climate change on our oceans since she was in middle school. (Photos courtesy: Isabella O'Brien)

Political science major Isabella O’Brien has been working on ways to counter the impact of climate change on our oceans since she was in middle school. (Photos courtesy: Isabella O’Brien)

Inspiration struck USC Dornsife sophomore Isabella O’Brien at age 11, during a family vacation in 2009 to the beaches of Akumal, Mexico. A guided dive took them through Gonzalo’s Reef, alive with small, swift fish darting through a network of vibrant coral. For a girl who hailed from landlocked Ontario, Canada, this shimmering underwater world was sheer magic.

But, something felt amiss. Although much of the coral was brightly colored, large swaths had turned a chalky white. “They seemed to guide you away from the dead areas,” O’Brien remembers of the divers conducting the tour. Later that day, she stumbled upon an educational center where she learned that much of the coral was dying due to ocean acidification.

Since 1985, the Mesoamerican Reef system that winds through Mexico’s Gulf Coast has lost nearly half of its reef-building coral to white band disease. Although exact causes of the plague remain unclear, scientists speculate that it’s exacerbated by warming ocean waters and acidification caused by climate change.

Continue reading ‘Shells could save our seas, says USC Dornsife undergraduate’

More carbon in oceans can lead to smaller fish

silverside tank feeding

Credit: UConn

As humans continue to send large quantities of carbon into the atmosphere, much of that carbon is absorbed by the oceans. Now researchers from the University of Connecticut and other institutions have found that high carbon dioxide concentrations in seawater can lead to smaller fish.

U.S. National Science Foundation-funded researchers Christopher Murray of the University of Washington and Hannes Baumann of UConn published their findings in the journal PLoS One.

“The ocean takes up quite a bit of CO2 ,” says Murray. “Estimates are that it takes up about one-third to one-half of all CO2 emissions to date. It does a fantastic job of buffering the atmosphere, but the consequence is ocean acidification.”

Continue reading ‘More carbon in oceans can lead to smaller fish’

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Ocean acidification in the IPCC AR5 WG II

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