by DGR News Service | Mar 20, 2014 | Climate Change
By Renee Lewis / Al Jazeera
Climate change may be stunting fish growth, a new study has said. Fish sizes in the North Sea have shrunk dramatically, and scientists believe warmer ocean temperatures and less oxygenated water could be the causes.
The body sizes of several North Sea species have decreased by as much as 29 percent over a period of four decades, according to the report, published in the April issue of Global Change Biology.
The report presents evidence gathered as researchers followed six commercial fish species in the North Sea over 40 years. Their evidence showed that as water temperatures increased by 1 to 2 degrees Celsius, an accompanying reduction in fish size was observed.
It is generally accepted among scientists that decreased body size is a universal response to increasing temperatures, known as the “temperature size rule,” the report said. But before this report, led by scientists at Scotland’s University of Aberdeen, there was no empirical evidence showing this response in marine fish species.
The scientists warned that fish stunting cannot be unequivocally blamed on temperature changes, but they did observe fish stunting across varying species and backgrounds that coincided with a period of increasing ocean temperature.
Other factors that could have influenced fish size include fisheries-induced evolution and intensive commercial fishing — which favors larger specimens. But, the scientists said, these causes would not be likely to affect growth rates across species, which was observed in the North Sea study.
Scientists at the University of Washington have been working on a similar study, looking at many species of fish from Alaska to California. Tim Essington, an associate professor of aquatic and fishery sciences at UW who is working on the study, said he was looking into whether changes in fish body size could be related to environmental parameters.
“We haven’t seen the same strong response,” Essington told Al Jazeera. “But we have seen variation in the sizes of some stocks, like halibut. Its body size has been shrinking sharply over the past 10 years, and has resulted in reduced catch quotas and higher prices at the supermarket.”
He said various factors explain why UW results were different from those of the Scottish team. University of Aberdeen scientists were looking at a much more localized area and a unique data set, and had many more years of data to make comparisons.
Overall, Essington said the Aberdeen findings represented a plausible hypothesis that should be looked at more closely, and that warmer temperatures could explain the stunting.
“Fish aren’t any different than us. It’s all about the difference between how much we eat and how much energy we expend. And they’re arguing that temperature is changing the fishes’ energy versus expension rates,” which could result in smaller sizes, Essington said.
The Aberdeen findings echoed earlier model-derived predictions that fish would shrink in warmer waters. Those projections for future fish size reduction are already being seen in the North Sea, scientists said.
The first global projection of the potential for fish stunting in warmer, less oxygenated oceans was carried out by the University of British Columbia in 2012, and published in the journal Nature Climate Change.
The projection said changes in ocean and climate systems by 2050 could result in fish that are 14 to 24 percent smaller globally.
“It’s a constant challenge for fish to get enough oxygen from water to grow, and the situation gets worse as fish get bigger,” said Daniel Pauly, principal investigator with the University of British Columbia’s Sea Around Us Project, and the co-author of the UBC study.
The study warned that strategies must be developed to curb greenhouse-gas emissions or risk disrupting food security, fisheries and the very way ocean ecosystems work.
From Al Jazeera America: http://america.aljazeera.com/articles/2014/3/19/report-climate-changestuntingfish.html
by DGR News Service | Mar 7, 2014 | Climate Change
By Agence France-Presse
Time is running out for Australia’s iconic Great Barrier Reef, with climate change set to wreck irreversible damage by 2030 unless immediate action is taken, marine scientists said Thursday.
In a report prepared for this month’s Earth Hour global climate change campaign, University of Queensland reef researcher Ove Hoegh-Guldberg said the world heritage site was at a turning point.
“If we don’t increase our commitment to solve the burgeoning stress from local and global sources, the reef will disappear,” he wrote in the foreword to the report.
“This is not a hunch or alarmist rhetoric by green activists. It is the conclusion of the world’s most qualified coral reef experts.”
Hoegh-Guldberg said scientific consensus was that hikes in carbon dioxide and the average global temperature were “almost certain to destroy the coral communities of the Great Barrier Reef for hundreds if not thousands of years”.
“It is highly unlikely that coral reefs will survive more than a two degree increase in average global temperature relative to pre-industrial levels,” he said.
“But if the current trajectory of carbon pollution levels continues unchecked, the world is on track for at least three degrees of warming. If we don’t act now, the climate change damage caused to our Great Barrier Reef by 2030 will be irreversible.”
The Great Barrier Reef, one of the most biodiverse places on Earth, teems with marine life and will be the focus of Australia’s Earth Hour—a global campaign which encourages individuals and organisations to switch off their lights for one hour on April 29 for climate change.
The report comes as the reef, considered one of the most vulnerable places in the world to the impacts of climate change, is at risk of having its status downgraded by the UN cultural organisation UNESCO to “world heritage in danger”.
Despite threats of a downgrade without action on rampant coastal development and water quality, Australia in December approved a massive coal port expansion in the region and associated dumping of dredged waste within the marine park’s boundaries.
The new report “Lights Out for the Reef“, written by University of Queensland coral reef biologist Selina Ward, noted that reefs were vulnerable to several different effects of climate change; including rising sea temperatures and increased carbon dioxide in the ocean, which causes acidification.
It found the rapid pace of global warming and the slow pace of coral growth meant the reef was unlikely to evolve quickly enough to survive the level of climate change predicted in the next few decades.
From Physorg: http://phys.org/news/2014-03-great-barrier-reef-scientists.html
by Deep Green Resistance News Service | Sep 12, 2013 | Climate Change
By University of South Florida
Acidification of the Arctic Ocean is occurring faster than projected according to new findings published in the journal PLoS One. The increase in rate is being blamed on rapidly melting sea ice, a process that may have important consequences for health of the Arctic ecosystem.
Ocean acidification is the process by which pH levels of seawater decrease due to greater amounts of carbon dioxide being absorbed by the oceans from the atmosphere. Currently oceans absorb about one-fourth of the greenhouse gas. Lower pH levels make water more acidic and lab studies have shown that more acidic water decrease calcification rates in many calcifying organisms, reducing their ability to build shells or skeletons. These changes, in species ranging from corals to shrimp, have the potential to impact species up and down the food web.
The team of federal and university researchers found that the decline of sea ice in the Arctic summer has important consequences for the surface layer of the Arctic Ocean. As sea ice cover recedes to record lows, as it did late in the summer of 2012, the seawater beneath is exposed to carbon dioxide, which is the main driver of ocean acidification.
In addition, the freshwater melted from sea ice dilutes the seawater, lowering pH levels and reducing the concentrations of calcium and carbonate, which are the constituents, or building blocks, of the mineral aragonite. Aragonite and other carbonate minerals make up the hard part of many marine micro-organisms’ skeletons and shells. The lowering of calcium and carbonate concentrations may impact the growth of organisms that many species rely on for food.
The new research shows that acidification in surface waters of the Arctic Ocean is rapidly expanding into areas that were previously isolated from contact with the atmosphere due to the former widespread ice cover.
“A remarkable 20 percent of the Canadian Basin has become more corrosive to carbonate minerals in an unprecedented short period of time. Nowhere on Earth have we documented such large scale, rapid ocean acidification” according to lead researcher and ocean acidification project chief, U.S. Geological Survey oceanographer Lisa Robbins.
Globally, Earth’s ocean surface is becoming acidified due to absorption of man-made carbon dioxide. Ocean acidification models show that with increasing atmospheric carbon dioxide, the Arctic Ocean will have crucially low concentrations of dissolved carbonate minerals, such as aragonite, in the next decade.
In the Arctic, where multi-year sea ice has been receding, we see that the dilution of seawater with melted sea ice adds fuel to the fire of ocean acidification” according to co-author, and co-project chief, Jonathan Wynn, a geologist from the University of the South Florida. “Not only is the ice cover removed leaving the surface water exposed to man-made carbon dioxide, the surface layer of frigid waters is now fresher, and this means less calcium and carbonate ions are available for organisms.
Researchers were able to investigate seawater chemistry at high spatial resolution during three years of research cruises in the Arctic, alongside joint U.S.-Canada research efforts aimed at mapping the seafloor as part of the U.S. Extended Continental Shelf program. In addition to the NOAA supported ECS ship time, the ocean acidification researchers were funded by the USGS, National Science Foundation, and National Oceanic and Atmospheric Administration.
Compared to other oceans, the Arctic Ocean has been rather lightly sampled. “It’s a beautiful but challenging place to work,” said Robert Byrne, a USF marine chemist. Using new automated instruments, the scientists were able to make 34,000 water-chemistry measurements from the U.S. Coast Guard icebreaker. “This unusually large data set, in combination with earlier studies, not only documents remarkable changes in Arctic seawater chemistry but also provides a much-needed baseline against which future measurements can be compared.” Byrne credits scientists and engineers at the USF College of Marine Science with developing much of the new technology.
From University of South Florida News: http://news.usf.edu/article/templates/?a=5681&z=210
by Deep Green Resistance News Service | Sep 1, 2013 | Climate Change
By Jeremy Hance / Mongabay
As if ocean acidification and climate change weren’t troubling enough (both of which are caused by still-rising carbon emissions), new research published in Nature finds that ocean acidification will eventually exacerbate global warming, further raising the Earth’s temperature.
Scientists have long known that tiny marine organisms—phytoplankton—are central to cooling the world by emitting an organic compound known as dimethylsulphide (DMS). DMS, which contains sulfur, enters the atmosphere and helps seed clouds, leading to a global cooling effect. In fact, in the past scientists have believed that climate change may actually increase DMS emissions, and offset some global warming, but they did not take into account the impact of acidification.
Researchers, headed by Katharina Six with the Max Planck Institute for Meteorology, tested how acidification affects phytoplankton in the laboratory by lowering the pH (i.e. acidifying) in plankton-filled water tanks and measuring DMS emissions. When they set the ocean acidification levels for what is expected by 2100 (under a moderate greenhouse gas scenario) they found that cooling DMS emissions fell.
Plugging the results into global modeling system, Six says, “we get an extra warming of 0.23 to 0.48 degree Celsius from the proposed impact [by 2100],” adding that “less sulphur results in a warming of the Earth surface.” This creates a positive feedback loop that will likely have impacts that are anything but positive, according to scientists.
To date, the world has warmed approximately 0.8 degrees Celsius in the last century with a variety of impacts including worsening severe weather, rising sea levels, melting glaciers and sea ice, and imperiled species.
Six also notes that a warmer world does not necessarily mean a more productive world for phytoplankton as has been argued by researchers in the past.
“In former times it was assumed that phytoplankton potentially growth better in a warmer ocean,” she explained to mongabay.com. “However, the basis for plant growth is the supply with nutrients. As the oceans will stabilize in the warmer climate, fewer nutrients will be transported into the sunlight zone. Earth system models, like the MPI-ESM that was used for our study, project a decrease in primary production of 17 percent at the end of this century for a moderate climate scenario. The impact from climate change alone led to a decrease in DMS emission of 7 percent.”
The results are still preliminary as researchers have yet to test how DMS emissions will by impacted in tropical and subtropical waters, focusing to date on polar and temperate waters. In addition, further modeling should be done in order to understand possible uncertainties according to Six.
Still, the evidence is strong enough that the researchers write in the paper that “this potential climate impact mechanism of ocean acidification should be considered in projections of future climate change.” Essentially raising current estimates for a moderate climate scenario by around 10 percent.
Ocean acidification, which has been dubbed “climate change’s equally evil twin” by U.S. National Oceanic and Atmospheric Administration (NOAA)’s Jane Lubchenco, is expected to have largely negative impacts on many marine species, including dissolving the shells of crustaceans and molluscs, hampering coral reefs, and even changing how far fish can hear.
So, how do we stop this from happening?
“There is only one answer,” Katharina Six told mongabay.com, “the abatement of fossil fuel emissions.”
From Mongabay: “Bad feedback: ocean acidification to worsen global warming“
by Deep Green Resistance News Service | Aug 2, 2013 | Climate Change, Toxification
By Fiona Harvey / The Guardian
A major survey of the coral reefs of the Caribbean is expected to reveal the extent to which one of the world’s biggest and most important reserves of coral has been degraded by climate change, pollution, overfishing and degradation.
The Catlin scientific survey will undertake the most comprehensive survey yet of the state of the region’s reefs, starting in Belize and moving on to Mexico, Anguilla, Barbuda, St Lucia, Turks & Caicos, Florida and Bermuda.
The Catlin scientists said the state of the regions’ reefs would act as an early warning of problems besetting all of the world’s coral. As much as 80% of Caribbean coral is reckoned to have been lost in recent years, but the survey should give a more accurate picture of where the losses have had most effect and on the causes.
Loss of reefs is also a serious economic problem in the Caribbean, where large populations depend on fishing and tourism. Coral reefs provide a vital home for marine creatures, acting as a nursery for fish and a food resource for higher food chain predators such as sharks and whales.
Stephen Catlin, chief executive of the Catlin Group, said: “It is not only important that scientists have access to this valuable data, but companies such as ours must understand the impact that significant changes to our environment will have on local economies.”
Globally, coral reefs are under threat. The future of the Great Barrier Reef in Australia is in doubt as mining and energy companies want to forge a shipping lane through it to form a more direct link with their export markets.
Warming seas owing to climate change can lead to coral being “bleached” – a state where the tiny polyps that build the reefs die off. The US government’s National Oceanic and Atmospheric Administration predicts increasing frequency and severity of mass bleaching events as global warming takes effect.
Richard Vevers, director of the project, told the Guardian that one important role of the new survey would be to describe a new “baseline” to establish how far such problems have taken their toll to date, which will enable future scientists to judge how degradation – or conservation – progresses.
He said the team of scientists would also probe the underlying reasons for such degradation, with a view to informing conservation efforts.
The team will use satellite data as well as direct observations to assess the reefs. As part of the survey, they will develop software that marine scientists can apply to other reefs around the world. A new camera has been constructed to assist their efforts.
Vevers said: “The Caribbean was chosen to launch the global mission because it is at the frontline of risk. Over the last 50 years 80% of the corals have been lost due mainly coastal development and pollution. They now are also threatened by invasive species, global warming and the early effects of ocean acidification — it’s the perfect storm.”
From The Guardian: http://www.theguardian.com/environment/2013/aug/01/caribbean-coral-reef-loss
