Month: February 2017

One of wettest winters on record in CA- new warm & wet atmospheric river to affect Oroville Dam watershed

Ellie Cohen

by Daniel Swain on February 16, 2017

Very heavy precipitation expected across Southern California on Friday and Northern California on Monday (including the Feather River watershed). NCEP

California is currently experiencing one of its wettest winters on record. Precipitation has been especially remarkable across the Northern Sierra watersheds, where liquid equivalent (rain+melted snow) is presently above 200% of average. Widespread flooding has already occurred across Northern California in recent weeks, and supersaturated soils are now leading to slope failures (mudslides and landslides) across much of the state. In additional to the “typical” flooding of regional rivers and streams that one might expect with prolonged heavy precipitation, California’s vast water storage and conveyance infrastructure is starting to crack under the strain–in some cases, quite literally….

Disappearing Seagrass Protects Against Pathogens, Even Climate Change, Scientists Find

Ellie Cohen

February 16 2017  Carl Zimmer NY Times Full article here

Every continent save Antarctica is ringed by vast stretches of seagrass, underwater prairies that together cover an area roughly equal to California.

Seagrass meadows, among the most endangered ecosystems on Earth, play an outsize role in the health of the oceans. They shelter important fish species, filter pollutants from seawater, and lock up huge amounts of atmosphere-warming carbon.

The plants also fight disease, it turns out. A team of scientists reported on Thursday that seagrasses can purge pathogens from the ocean that threaten humans and coral reefs alike. (The first hint came when the scientists were struck with dysentery after diving to coral reefs without neighboring seagrass.)

But the meadows are vanishing at a rate of a football field every 30 minutes. Joleah B. Lamb, a postdoctoral researcher at Cornell University and the lead author of the new study, said she hoped it would help draw attention to their plight….

…The plants also draw fertilizer runoff and other pollutants out of the water, locking them safely away in meadow soil. Scientists have estimated that an acre of seagrass provides more than $11,000 worth of filtering every year….

In one survey, they collected seawater and put it in petri dishes to see if colonies of disease-causing bacteria known as Enterococcus grew from the samples. Levels of the bacteria in water from seagrass meadows, they found, were a third of the levels in water from other sites. In a second search, the scientists grabbed fragments of DNA floating in seawater. By examining the sequences, they identified 18 kinds of disease-causing bacteria. Water from the seagrass meadows had only half the level of this DNA, compared with water collected at other sites. The scientists next turned their attention to coral reefs around the islands. Reefs next to seagrass meadows, they found, were half as diseased as those without meadows.

…Seagrass meadows can store enormous amounts of carbon. Their soils don’t decompose because they have very little oxygen in them. As a result, seagrass meadow soil around the world has accumulated an estimated nine billion tons of carbon.

As seagrass meadows disappear, that carbon is being released back into the ocean. Some of it may make its way into the atmosphere as heat-trapping carbon dioxide. As dire as the situation has become, there is cause for hope. In recent years, Dr. Orth and his colleagues have successfully restored seagrass meadows off the coast of Virginia. “Now we have 6,200 acres of seagrass,” he said, “where in 1997 there wasn’t a single blade of grass.

Underwater seagrass beds dial back polluted seawater

Ellie Cohen

February 16 2017 ScienceDaily  full article here

Seagrass meadows — bountiful underwater gardens that nestle close to shore and are the most common coastal ecosystem on Earth — can reduce bacterial exposure for corals, other sea creatures and humans, according to new research.

…While research is beginning to reveal the mechanisms driving bacterial-load reductions in these ecosystems, it is evident that an intact seagrass ecosystem — home to filter-feeders like bivalves, sponges, tunicates (marine invertebrates) — removes more bacteria from water.

As seagrass meadows and coral reefs are usually linked habitats, Lamb’s team examined more than 8,000 reef-building corals for disease. The researchers found lower levels — by twofold — of disease on reefs with adjacent seagrass beds than on reefs without nearby grasses. “Millions of people rely on healthy coral reefs for food, income and cultural value,” said Lamb….

Joleah Lamb et al. Seagrass Ecosystems Reduce Exposure to Bacterial Pathogens of Humans, Fishes and Invertebrates. Science, 2017 DOI: 10.1126/science.aal1956

Monitoring birds by drone

Ellie Cohen

15 Feb 2017 Science Daily  full story here

Forget delivering packages or taking aerial photographs — drones can even count small birds. A new study tests this new approach to wildlife monitoring and concludes that despite some drawbacks, the method has the potential to become an important tool for ecologists and land managers….

Andrew M. Wilson, Janine Barr, and Megan Zagorski. The feasibility of counting songbirds using unmanned aerial vehicles. The Auk: Ornithological Advances, February 2017 DOI: 10.1642/AUK-16-216.1

Long-term eelgrass loss due to joint effects of shade, heat

Ellie Cohen

Analysis puts resulting economic losses at $1-2 billion in Chesapeake Bay alone

February 14 2017  Science Daily see full article here

A new study links a long-term decline in Chesapeake Bay’s eelgrass beds to both deteriorating water quality and rising summertime temperatures. It also shows that loss of the habitat and other benefits that eelgrass provides comes at a staggering ecological and economic cost…….”Declining water clarity has gradually reduced eelgrass cover during the past two decades, primarily in deeper beds where lack of light already limits growth. In shallow beds, it’s more that heat waves are stressing the plants, leading to the sharp drops we’ve seen in recent summers.”

“Not only have we lost a huge ecological resource, there have been real economic and recreational consequences….Blue crab fisheries, for example, have probably lost a year or more of catch based on the amount of eelgrass we’ve already lost. For silver perch, it’s 10-20 years. In all, we estimate the potential economic cost to citizens at $1-2 billion.”…

…mean summertime water temperature in the lower Chesapeake Bay has already increased by more than 2 degrees Fahrenheit since 1984 — from 76.8° to 79.5°F — and that the frequency of extreme warm spells with water temperatures exceeding 82° has doubled in the last decade….As global warming continues to raise the area’s water temperatures — a conservative estimate is a further 3.5° F increase by 2040 — the team predicts a further 38% decline in eelgrass cover. And if water clarity follows its current downward trajectory during the next 30 years, eelgrass would decline an additional 84%. When both declining clarity and warming are considered, say the researchers, the predicted increases in temperature and turbidity would result in a loss of 95% of Bay eelgrass — a near total eradication…

…”Our analysis suggests that eelgrass could still persist in the face of moderate increases in temperature, if the water remains clear enough” adds Lefcheck. “But that will only happen if managers adopt an integrated perspective, and continue with their efforts to curb inputs into the Bay.“

Jonathan S. Lefcheck, David J. Wilcox, Rebecca R. Murphy, Scott R. Marion, Robert J. Orth. Multiple stressors threaten the imperiled coastal foundation species eelgrass (Zostera marina) in Chesapeake Bay, USA. Global Change Biology, 2017; DOI: 10.1111/gcb.13623

Some marine creatures may be more resilient to harsher ocean conditions than expected

Ellie Cohen

Posted: 15 Feb 2017 05:41 AM PST full article here

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: The animal can adapt by rejiggering its shell-making process and other functions…

…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.

The researchers exposed sea snails called periwinkles to the ocean conditions predicted for 2100, when some waters at a pH of 8.10 today are expected to reach a pH of 7.85. Although the animals’ metabolism declined, they were able to speed up their shell-making by producing less-dense inner shells. In addition, they developed less-soluble shells, which are more resistant to future, harsher ocean conditions. The researchers say these changes suggest that the periwinkle, and potentially other calcifying organisms, could have the ability to adapt to the acidifying oceans….

Jonathan Y. S. Leung, Bayden D. Russell, Sean D. Connell. Mineralogical Plasticity Acts as a Compensatory Mechanism to the Impacts of Ocean Acidification. Environmental Science & Technology, 2017; DOI: 10.1021/acs.est.6b04709

Risk of rapid North Atlantic cooling greater than previously estimated

Ellie Cohen

February 15 2017 Science Daily  full article here

The possibility of major climate change in the Atlantic region has long been recognized and has even been the subject of a Hollywood movie: The Day After Tomorrow. To evaluate the risk of such climate change, researchers ….developed a new algorithm to analyze the 40 climate models considered by the latest report from the Intergovernmental Panel on Climate Change (IPCC). Their findings raise the probability of rapid North Atlantic cooling during this century to nearly 50%. Nature Communications publishes their work on February 15, 2017….

Current climate models all foresee a slowing of the meridional overturning circulation (MOC) — the phenomenon behind the familiar Gulf Stream, which carries warmth from Florida to European shores — that could lead to a dramatic, unprecedented disruption of the climate system. In 2013, …the IPCC judged that this slowdown would occur gradually over a long period of time… that fast cooling of the North Atlantic during this century was unlikely.

….The Labrador Sea is host to a convection system ultimately feeding into the ocean-wide MOC. The temperatures of its surface waters plummet in the winter, increasing their density and causing them to sink. This displaces deep waters, which bring their heat with them as they rise to the surface, preventing the formation of ice caps. To investigate this phenomenon in greater detail, the researchers developed an algorithm able to detect quick sea surface temperature variations. Their number crunching revealed that 7 of the 40 climate models they were studying predicted total shutdown of convection, leading to abrupt cooling of the Labrador Sea: by 2-3 °C over less than 10 years. This in turn would drastically lower North Atlantic coastal temperatures……

Giovanni Sgubin, Didier Swingedouw, Sybren Drijfhout, Yannick Mary, Amine Bennabi. Abrupt cooling over the North Atlantic in modern climate models. Nature Communications, 2017; 8 DOI: 10.1038/ncomms14375

Antarctica Just Shed a Manhattan-Sized Chunk of Ice- Pine Island Glacier

Ellie Cohen

By Brian Kahn Published: February 15th, 2017 Climate Central  full article here

The growing crack in the Larsen C ice shelf is the most dramatic example of change in Antarctica right now….Ice around the continent is disappearing as the air and water heat up and the less dramatic breakdowns are just as important to understanding the fate of the ice and the world’s coastal areas. The Pine Island Glacier on the coast of West Antarctica … A massive iceberg roughly 225 square miles in size — or in more familiar terms, 10 times the size of Manhattan — broke off in July 2015. Scientists subsequently spotted cracks in the glacier on a November 2016 flyover. And in January, another iceberg cleaved off the glacier.

… it’s hard to tie these individual events to climate change, but “many studies have shown that Pine Island Glacier is retreating and thinning. That the recent rifting and calving could totally be evidence of an ongoing, rapid disintegration of the ice shelf, mostly due to ocean warming.” The ocean under Pine Island Glacier’s ice shelf has warmed about 1°F since the 1990s. That’s causing the ice shelf to melt and pushing the grounding line — the point where the ice begins to float — back toward land, creating further instability….