Published 23 February 2017
The deep ocean floor, earth’s largest habitat, will be starved of food by the end of this century, scientists have warned.
New research published on open-access journal Elementa today shows that food supply to some areas of the Earth’s deep oceans will decline by up to half by 2100.
Dr Andrew Sweetman, based at the Lyell Centre for Earth and Marine Science and Technology at Heriot-Watt University in Edinburgh, and colleagues from 20 of the world’s leading oceanographic research centres have used earth system models and projected climate change scenarios, developed for the Intergovernmental Panel on Climate Change (IPCC), to quantify impending changes to deep oceans.
The team looked at a number of sea and ocean beds, from the Arctic to Antarctic Oceans, focusing on bathyal (200-3000m) and abyssal (3000-6000m) depths. As well as measuring how the deep oceans’ food sources will decline, the team examined the impact that increased seabed temperatures, declining oxygen levels and increasingly acidic seawater will have, under the sea and across the planet.
Sweetman, associate professor at Heriot-Watt’s Lyell Centre for Earth and Marine Science and Technology, said: “The rate of change underway in our oceans is faster than at any point we know of in geological history.
Continue reading ‘Deep oceans face starvation by end of century’
Published 16 February 2017
As the world continually emits carbon dioxide into the atmosphere, the oceans are taking a hit, absorbing some of it and growing more acidic. Among other effects, scientists have found that coral reefs and oyster hatcheries are deteriorating as a result. However, scientists studying a type of sea snail report a bit of bright news in the ACS journal Environmental Science & Technology: The animal can adapt by rejiggering its shell-making process and other functions.
A lower pH in ocean waters means fewer carbonate ions are available to calcifying organisms, such as coral reefs and oysters, which need the ions to produce shells and skeletons. While ocean acidification appears to cause damage to many calcifying organisms, recent studies have suggested that some of those organisms may be more resistant to acidification than previously thought. Sean D. Connell and colleagues wanted to find out how this might be possible.
Continue reading ‘Some marine creatures may be more resilient to harsher ocean conditions than expected’
Published 3 February 2017
Climate-driven disturbances are having profound impacts on coastal ecosystems, with many crucial habitat-forming species in sharp decline. However, among these degraded biomes, examples of resilience are emerging. Writing in BioScience, Jennifer O’Leary, a California Sea Grant Marine Biologist based at Polytechnic State University, and her colleagues describe these recoveries and highlight the possible implications for ecosystem-sparing management.
To gain insight into disturbed coastal habitats, the authors surveyed 97 marine experts about their observations of climate-induced perturbations, including extreme storms, temperature changes, and ocean acidification. Eighty percent of those who had witnessed climate extremes also identified evidence of habitat resistance or rapid recovery. According to O’Leary and her colleagues, the survey results indicated that “bright spots of ecosystem resilience are surprisingly common across six major coastal marine ecosystems.” In some cases, resilience was marked by striking recoveries. In one bleaching event in Western Australia, up to 90% of live coral was lost as a result of severe bleaching. Despite reaching a low of 9% unbleached area, the healthy reef surface recovered to 44% within 12 years.
Continue reading ‘Marine ecosystems show resilience to climate disturbance’
Published 30 January 2017
Fact: More carbon dioxide (CO2) in the air also acidifies the oceans. It seemed to be the logical conclusion that shellfish and corals will suffer, because chalk formation becomes more difficult in more acidic seawater. But now a group of Dutch and Japanese scientists discovered to their own surprise that some tiny unicellular shellfish make better shells in an acidic environment. This is a completely new insight.
Researchers from the NIOZ (Royal Dutch Institute for Sea Research) and JAMSTEC (Japanese Agency for Marine-Earth Science and Technology) found in their experiments that so-called foraminifera might even make their shells better in more acidic water. These single-celled foraminifera shellfish occur in huge numbers in the oceans. The results of the study are published in the leading scientific journal Nature Communications.
Since 1750 the acidity of the ocean has increased by 30%. According to the prevailing theory and related experiments with calcareous algae and shellfish, limestone (calcium carbonate) dissolves more easily in acidic water. The formation of lime by shellfish and corals is more difficult because less carbonate is available under acidic conditions. The carbonate-ion relates directly to dissolved carbon dioxide via two chemical equilibrium reactions.
Continue reading ‘Unexpected result: Ocean acidification can also promote shell formation’
Published 27 January 2017
For Bill Mook, coastal acidification is one thing his oyster hatchery cannot afford to ignore.
Mook Sea Farm depends on seawater from the Gulf of Maine pumped into a Quonset hut-style building where tiny oysters are grown in tanks. Mook sells these tiny oysters to other oyster farmers or transfers them to his oyster farm on the Damariscotta River where they grow large enough to sell to restaurants and markets on the East Coast.
The global ocean has soaked up one third of human-caused carbon dioxide (CO2) emissions since the start of the Industrial Era, increasing the CO2 and acidity of seawater. Increased seawater acidity reduces available carbonate, the building blocks used by shellfish to grow their shells. Rain washing fertilizer and other nutrients into nearshore waters can also increase ocean acidity.
Back in 2013, Mook teamed up with fisherman-turned-oceanographer Joe Salisbury of the University of New Hampshire to understand how changing seawater chemistry may hamper the growth and survival of oysters in his hatchery and oyster farm.
Continue reading ‘New tool helps oyster growers prepare for changing ocean chemistry’
Published 27 January 2017
A NOAA-supported study projects that Dungeness crab and some commercial finfish species living on the sea floor may decline in future years due to increased ocean acidification in the California Current. These estimates were based on computer models forecasting changes in the California Current ocean ecosystem, which includes an expected rise in summer ocean acidification of 50 percent. Other marine organisms, including zooplankton, seabirds, marine mammals, and fish that live in the water column, are expected to be less affected.
Ocean acidification occurs when oceans partially absorb the increasing carbon dioxide in the atmosphere, resulting in a series of chemical reactions that decrease the pH of the seawater, making it more acidic. This process is exacerbated in the California Current during summer, when coastal upwelling brings cold, deep, nutrient-rich waters up onto the continental shelf that already have higher acidity and low oxygen concentrations.
Continue reading ‘Winners and losers in the California Current under future ocean acidification’
Published 13 January 2017
he acidification of the ocean expected as seawater absorbs increasing amounts of carbon dioxide from the atmosphere will reverberate through the West Coast’s marine food web, but not necessarily in the ways you might expect, new research shows.
Dungeness crabs, for example, will likely suffer as their food sources decline. Dungeness crab fisheries valued at about $220 million annually may face a strong downturn over the next 50 years, according to the research published Jan. 12 in the journal Global Change Biology. But pteropods and copepods, tiny marine organisms with shells that are vulnerable to acidification, will likely experience only a slight overall decline because they are prolific enough to offset much of the impact, the study found.
Marine mammals and seabirds are less likely to be affected by ocean acidification, the study found.
“What stands out is that some groups you’d expect to do poorly don’t necessarily do so badly – that’s probably the most important takeaway here,” said Kristin Marshall, lead author of the study who pursued the research as a postdoctoral researcher at the University of Washington and NOAA Fisheries’ Northwest Fisheries Science Center. “This is a testament in part to the system’s resilience to these projected impacts. That’s sort of the silver lining of what we found.”
Continue reading ‘Ocean acidification to hit West Coast Dungeness crab fishery, new assessment shows’