For Chesapeake oysters, the way forward leads back—through the fossil record

NOVEMBER 21, 2019 

by Joseph McClain, The College of William & Mary

Big oyster/old oyster: Rowan Lockwood displays one of the 900 oyster fossils studied in a palaeobiological analysis of the oysters of the Chesapeake Bay. She and co-author Roger Mann believe fossil beds paint a picture of the oyster population of a healthy Chesapeake ecosystem. Credit: Stephen Salpukas 

Oysters once dominated the ecosystem of the Chesapeake Bay, and it would be difficult, if not impossible, for the Bay to return to full ecological health without restoring Crassostrea virginica to its glory days of the Chesapeake's apex filterer. 

Rowan Lockwood and Roger Mann believe that you have to go back to the fossil record to get your head around the idea of a fully oystered Chesapeake. Their paper, "A conservation paleobiological perspective on Chesapeake Bay oysters," appears in a special issue of Philosophical Transactions B, titled ""The past is a foreign country: how much can the fossil record actually inform conservation?". 

Lockwood is a professor in William & Mary's Department of Geology, which she chairs. Mann is a professor in the Department of Fisheries Science at the university's Virginia Institute of Marine Science. Their collaboration melds Lockwood's examination of long-dead oysters in the Chesapeake with Mann's expertise in the state of oysters today. 

Their paper looks at 900 fossil oysters from three Pleistocene reefs and compares them to oysters today. Lockwood and Mann employ conservation paleontology methods to create a model of how the Chesapeake Bay looked and functioned long before humans. 

Basically, the prehistoric oysters were bigger and more numerous—and therefore filtered more water. 

"This is clearly a case of bigger is better," Lockwood said. "Larger oysters filter significantly more water, remove more algae, produce more offspring, buffer more acidic bay water, recycle more nitrogen and possibly even bury more carbon than smaller ones." 

Read on

Only eat oysters in months with an 'r'? Rule of thumb is at least 4,000 years old

NOVEMBER 20, 2019 

by Halle Marchese, Florida Museum of Natural History

Foodie tradition dictates only eating wild oysters in months with the letter "r"—from September to April—to avoid watery shellfish, or worse, a nasty bout of food poisoning. Now, a new study suggests people have been following this practice for at least 4,000 years. 

An analysis of a large shell ring off Georgia's coast revealed that the ancient inhabitants of St. Catherines Island limited their oyster harvest to the non-summer months. 

How can scientists know when islanders were collecting oysters? By measuring parasitic snails. 

Snails known as impressed odostomes, Boonea impressa, are common parasites of oysters, latching onto a shell and inserting a stylus to slurp the soft insides. Because the snail has a predictable 12-month life cycle, its length at death offers a reliable estimate of when the oyster host died, allowing Florida Museum of Natural History researchers Nicole Cannarozzi and Michal Kowalewski to use it as a tiny seasonal clock for when people collected and ate oysters in the past. 

Stowaways on discarded oyster shells, the snails offer new insights into an old question about the shell rings that dot the coasts of Florida, Georgia, South Carolina and Mississippi. 

"People have been debating the purpose of these shell rings for a very long time," said Cannarozzi, the study's lead author and Florida Museum environmental archaeology collection manager. "Were they everyday food waste heaps? Temporary communal feasting sites? Or perhaps a combination? Understanding the seasonality of the rings sheds new light on their function." 

The seasonality of oyster deposits in the St. Catherines shell ring may be one of the earliest records of sustainable harvesting, said Nicole Cannarozzi, the study's lead author and Florida Museum environmental archaeology collection manager. Credit: Kristen Grace/Florida Museum 

Cannarozzi and Kowalewski, Thompson Chair of Invertebrate Paleontology, analyzed oysters and snails from a 230-foot-wide, 4,300-year-old shell ring on St. Catherines Island and compared them with live oysters and snails. They found that island inhabitants were primarily harvesting oysters during late fall, winter and spring, which also suggested the presence of people on the island tapered off during the summer. 

The seasonality of the shell ring may be one of the earliest records of sustainable harvesting, Cannarozzi said. Oysters in the Southeast spawn from May to October, and avoiding oyster collection in the summer may help replenish their numbers. 

Continued

Playing 'tag': Tracking movement of young oysters

JUNE 25, 2019

by Dauphin Island Sea Lab

A new publication in the journal Estuaries and Coasts investigates the use of a fluorescent dye to track movements of young oysters. The publication, "Field mark-recapture of calcein-stained larval oysters (Crassostrea virginica) in a freshwater-dominated estuary", provides new knowledge on methods for tracking oysters in low salinity environments common to coastal waters, particularly in the northern Gulf of Mexico. This information is important to understand where oysters settle and grow compared to locations of parent stocks and to guide management practices of oysters or any marine species with larval stages that live in the water column.

Free-living aquatic animals have the potential to be transported long distances during early life development. These movements can influence adult distributions and subsequently how populations are connected. By understanding larval transport pathways, we can better inform restoration efforts of remaining marine invertebrate populations globally. This information is particularly important for commercial species such as oysters, which are a valuable resource for Alabama and other coastal waters.

Continued

Oysters at risk from changing climate

October 9, 2018, Institute of Physics

Climate change's effect on coastal ecosystems is very likely to increase mortality risks of adult oyster populations in the next 20 years.

That is the finding of a new study led by the University of Nantes, the LEMAR (the Marine Environmental Science Laboratory) in Plouzané and the Cerfacs (European center for research and advanced training in scientific computing) in Toulouse (France).

Published today in the journal Environmental Research Letters, the research highlights a novel and comprehensive relationship between climate variability and historical mortality of adult oysters on the French Atlantic coast from 1993 to 2015.

The team's results show oyster mortality usually increases after warm and wet winters over Northern Europe, affected by recurrent storms embedded in large weather circulation patterns covering the whole North Atlantic basin – known as the positive phase of the North Atlantic Oscillation (NAO).

The study's lead author is Dr. Yoann Thomas, from the French National Research Institute for Sustainable Development (IRD) at LEMAR. He said: "Benthic species like oysters are keystone species in coastal ecosystems. For example, they build reef habitats, which sustain a high biodiversity, and provide tremendous food source worldwide though fishing or aquaculture activities.

"But they are very sensitive to changes in climate and water quality, because they cannot move if a location becomes inhospitable. In this sense, oyster populations are sentinels of long-term climate fluctuations and climate trends, and more broadly of the 'health' of coastal ecosystems.

Read more at: 

Marine scientists urge protection for endangered shellfish reefs

Shellfish reefs, formed by oysters or mussels in or near estuaries, have declined by up 99% since British colonisation

Calla Wahlquist

Wed 14 Feb 2018 17.00 GMTLast modified on Wed 14 Feb 2018 22.41 GMT

Marine scientists are lobbying the federal government to ensure protection for Australia’s most endangered – but least known – ocean ecosystem.

Shellfish reefs, formed by millions of oysters or mussels clustering together in or near the mouths of estuaries, have declined by up 99% since British colonisation.

Yet they are not formally recognised as a threatened ecosystem under Australian environmental law.

A study led by the Nature Conservancy Australia and published in the peer-reviewed open access journal Plos One on Thursday found that the number of reefs formed by Australian flat oysters, Ostrea angasi, had declined 99% from 118 found in historical records to just one, in Tasmania’s Georges Bay.

The number of reefs formed by rock oysters, Saccostrea glomerata, which are found on coastal banks around Sydney, declined 90% from 60 known historical locations to six surviving reefs.

It is even more drastic than the decline in the Great Barrier Reef, which suffered unprecedented mass bleaching events in 2016 and 2017 that are believed to have killed up to half of the coral, and the shrinking of kelp forests, which have declined 90% off the coast of Western Australia due to successive marine heatwaves.

Read on  

Oysters and mussels produce 'ridiculous' levels of gasses causing climate change

 Henry Bodkin 

13 OCTOBER 2017 • 6:24PM

Populations of mussels, clams and oysters produce “ridiculous” levels of climate-warming gasses on a par with herds of cattle, a new study shows.

Scientists have warned the ocean creatures are producing large amounts of the strongest greenhouse gases - methane and nitrous oxides - from the bacteria in their guts.

This methane bubbles out of the water contributing to global warming as it as 28 times greater warming potential than carbon dioxide.

These small yet very abundant animals may play an important, but so far neglected, role in regulating the emissions of greenhouse gases in the seaDr Stefano Bonaglia, Stockholm University

The finding are significant as it is proposed to expand the farming of oysters, mussels and clams to help feed growing populations.

Read on  

Ocean acidification slurps up oysters

Editor’s note: We’re publishing a series from The Story Group that shows Americans on the front lines of climate change. The videos put faces to the warnings in the latest National Climate Assessment.

“The ocean is so acidic that it is dissolving the shells of our baby oysters,” says Diani Taylor of Taylor Shellfish Farms in Shelton, Wash. She and her cousin Brittany are fifth-generation oyster farmers, and are grappling with ocean waters that are more acidic and corrosive than their fathers, grandfathers, and great-grandfathers knew.

Read more and video

Oysters And Crabs ‘Stuck In The Middle’

May 12, 2014

By Angela Herring, Northeastern University

Northeastern University ecologist David Kimbro claims to have watched a lot of TV growing up, particularly The Brady Bunch. “You could kind of get a flavor for how an episode was going to turn out based on how Jan or Peter were faring—you know, the middle kids,” said Kimbro, an assistant professor in the Department of Marine and Environmental Sciences.

He and his colleagues—associate professor Jon Grabowski and assistant professor Randall Hughes, ecology experts with labs at Northeastern’s Marine Science Center—think a similar pattern shows up in oyster reefs, where the behavior of the “middle child” in the predator-​​prey food chain plays a strong role in determining how the reef as a whole will fare. New research from the team, published online on Tuesday in the journal Ecology Letters, gives that hunch even more support.

The work complicates the evolution of a paradigm that has pervaded ecology since the 1960s, namely that the species at the top of the food web dic­ate the welfare of the entire system simply by eating.

For instance, observations in the Aleutian Islands in the 1970s showed that when sea otters were doing well, the nearby kelp forests below the ocean’s surface also thrived. This was due, theory said, to the fact that the otters’ feeding patterns naturally managed the sea urchin population, which feeds on kelp.

Fast-​​forward four decades and one sees a large body of evidence indicating that predators do more than eat; they frighten too. In the early 2000s, Grabowski showed that having a predatory fish scare the middle child has the same effect as predation itself. Like­wise with the sea otters—just swimming around scares the urchins enough to send them into hiding and stop eating kelp.

Read more at

Oysters' Future Imperiled as Oceans Acidify

Monterey, Calif. — Oysters, those slimy mollusks whose juices are thought to boost sexual desire, may be losing their comfy sea homes.

The reason? Global oceans are becoming more acidic as they absorb carbon dioxide pumped into the air from burning fossil fuels, which makes it difficult for calcifying organisms like oysters to create their shells.

The ocean is now 30 percent more acidic than it was before the Industrial Revolution.

At the Ocean Acidification meeting here this month, Anneliese Hettinger of UC Davis presented new research showing that Olympia oysters are smaller after being exposed, as larvae, to a high carbon-dioxide environment. The negative impacts of early exposure to carbon dioxide stuck with the juvenile oysters for at least four months into their lives, stunting their growth.

"We have to take a holistic approach when looking at the oyster instead of only focusing on one life stage," Hettinger said at the meeting.

Read more:  http://www.livescience.com/23903-oysters-future-imperiled-oceans-acidify.html

Oysters Are 'Functionally Extinct'

The Huffington Post
Dean Praetorius
First Posted: 02/ 4/11 04:21 PM

Oysters aren't disappearing from the dining table anytime soon, but they may be disappearing from our oceans.

A recent study published in BioScience has shown that the mollusks, declared "functionally extinct," are disappearing quickly as 85 percent of their reefs have been destroyed through disease or over-harvesting, according to the AFP. 75 percent of the remaining wild oysters can be found in 5 locations in North America.

So what does "functionally extinct" mean?

Oysters no longer play almost any significant role in their ecosystems.

From the AFP:

"Oyster reefs are at less than 10 percent of their prior abundance in most bays (70 percent) and ecoregions (63 percent)," said the study.

"They are functionally extinct -- in that they lack any significant ecosystem role and remain at less than one percent of prior abundances in many bays (37 percent) and ecoregions (28 percent) -- particularly in North America, Australia and Europe."

While the study didn't include parts of South Africa, China, Japan, North Korea, and South Korea, other studies suggest that there's been a significant decrease in oysters in these regions as well, according to the authors.

http://www.huffingtonpost.com/2011/02/04/oysters-are-functionally-_n_818870.html

Louisiana oyster beds remain empty after BP disaster

By Paul Adams

BBC News, Louisiana

Louisiana's oyster beds have not recovered from the US's worst environmental catastrophe, the Deepwater Horizon oil-rig disaster, and some fishermen fear they never will.

We were fishing at the end of the world- or at least a place that felt like it.

Grand Isle is one of the final precarious fragments of land where the myriad bayous of the Mississippi delta give way to the open water of the Gulf of Mexico.

Around us, hungry frigate birds watched as we headed for the oyster beds.

Pelicans swooped by in formation, low and effortless, and a pair of dolphins raced just ahead of the bow, daring each other to get closer and occasionally rolling sideways to check we were suitably impressed.


We were less than 100 miles (160 km) from the wreck of the Deepwater Horizon but everything looked pristine under a blazing sun.

And the oysters! As big as the palm of my hand, succulent and briny.

It was still early and so, for the first time in my life, I had oysters for breakfast. But the atmosphere aboard the boat was sombre.

The oysters were good but hardly plentiful. At this, the season of peak demand, far too many were simply dead.

Not, as you might think, coated in sticky oil or even poisoned by chemical dispersants but killed off, as luck would have it, by fresh water.


Millions of gallons from the Mississippi River were hurriedly diverted into the bays and marshes of the delta to keep the oil from rolling in, earlier in the year - but this upset the delicate balance of fresh and salty conditions the oysters need to survive.

Nick Collins is a fourth generation oyster-man, with a rich gumbo of an accent to match.

His business had only just recovered from the ravages of Hurricane Katrina, five years ago, and Nick was looking forward to a bumper year.

But if the first setback was an act of God, the second was an act of industry - an industry that is much bigger and more commercially important to Louisiana than Nick's delicious oysters, an industry that sits off this fragile, mysterious landscape of channels and marshes, and produces the stuff that Americans really cannot get enough off.

Microbe army
At nearby Port Fouchon beach, the shallow-water rigs, tens of them, sit as little as a mile offshore.

Oil arrived here in the weeks after the spill and BP's clean-up continues.


Armies of contract workers, mostly from Central America, make their steady, painstaking way along the sand.

Wave after wave of them, in bright yellow boots, stooping slightly over shovels and brushes, scooping up tiny tar balls, covered in sand.

They pause, scour the patch in front of them and then - to the sound of "Vamonos!" ("Let's go!") - move on a few paces.

Not all the oil is from the Macondo well. Studies show that some of it comes from elsewhere, perhaps from the rigs we can see, perhaps even from the natural seepage that goes on all the time in the oil-rich Gulf of Mexico - and which has, over the eons, created an army of microbes that like nothing more than to feast, like Pac-Men, on energy-rich hydrocarbons.

Organisms that just might clean up whatever muck lurks out of sight, all by themselves.


So the clean-up is not just about the Deepwater Horizon but about every company that has ever sought to make a fortune extracting the black stuff and bringing it ashore.

BP, it seems, is making amends for all of us.

Fading hopes
But back to the oysters and another family business struggling with the fallout.

On the edge of New Orleans' legendary French quarter, the P & J Oyster Company has been in business for more than 130 years.

Like Nick Collins, Al Sunseri wonders if he has what it takes to recover.

The ice which gushes noisily into his giant coolers every eight minutes has very little to cool and the high, whitewashed-stone shucking tables are deserted.

He has laid off all but two temporary workers who keep a trickle of customers happy with oysters from nearby Texas.


Al also had to deal with Katrina, downsizing and waiting for the oyster beds to replenish themselves.

He was confident, as everyone was, that it was just a matter of time before the oysters reappeared and everyone was happy again.

But now he wonders about his son, who has experienced depression and has not been working for a couple of months.

He says he remembers his own anxiety as a young man, taking over a business with such a long tradition to uphold.

He thinks about Alaska and the herrings that disappeared from Prince William Sound three years after the Exxon Valdez spill, never to return.

More than seven months after the blowout on the Deepwater Horizon, the full ramifications of this disaster are still hard to gauge.

The uncertainty gnaws at everyone who depends on the sea. Is it possible, they wonder, that the worst days may still lie ahead?


http://news.bbc.co.uk/1/hi/programmes/from_our_own_correspondent/9254859.stm

Oysters at risk in acid oceans

THEY have formed a succulent and nutritious part of the human diet for thousands of years. But a new report is warning that plentiful supplies of oysters and mussels could disappear over the next century because the oceans are becoming increasingly acidic.

Dr John Baxter, the co-editor of an international report into the acidification of the world's seas, said increasing levels of carbon dioxide being released into the atmosphere by industrialised countries was gradually changing the acid level of waters across the world.


If the trend continued, the shells of thousands of species would be eroded and the creatures eventually wiped out - creating a huge knock-on effect on other fish and marine life.

As lobsters and crabs have shells with a different chemical composition, it is not clear how they will be affected by increasingly acidic sea water, the report says.

But as well as shellfish eaten by humans, certain types of plankton at the bottom of the marine food chain and coral reefs would also face serious ecological damage.

The first major marine areas to be affected, says the report, are the northern oceans, which are home to a wide variety of important marine life.

The Arctic Ocean is expected to be the first to reach a dangerous level of acidification with 10 per cent of its area hitting the threshold at which damage will occur by the end of this decade.

Dr Baxter, the principal adviser in marine ecology for Scottish Natural Heritage, presented the report, Ocean Acidification: Questions Answered, at a scientific meeting last week. SNH co-funded the report, alongside Natural England, the UK Ocean Acidification Research Programme and the Prince Albert II of Monaco Foundation.

Baxter said: "The only way around this is for the amount of CO2 being released into the atmosphere to be reduced.

"To a certain extent, this can be done by carbon capture - when carbon released from power stations is trapped underneath the seabed and stopped from being released into the atmosphere - but, other than that, we just have to start using less fossil fuel.

The alternative is pretty worrying."


He said that while some animals and plants may adapt to the new environment, many would be wiped out.

"We just don't know what species adapt, if any," Baxter said, adding that the last time there had been serious ocean acidification, 55 million years ago, around 80 per cent of sea species had become extinct.

While ocean acidification occurs naturally, studies show it has increased far more rapidly in the past 150 years.

More than 440 billion metric tons of CO2 has been released into the atmosphere since the end of the first industrial revolution in the 1830s - with half of this generated in the past 30 years.

As atmospheric CO2 increases, more of it is dissolved in the oceans, causing chemical changes which make sea water more acidic. While it is unlikely the world's seas will ever become positively acidic - like lemon juice or vinegar - even a fairly mild level of acidification would have a significant effect on the world's ecosystem.

"Carbonate levels in sea water, which are presently high enough to allow calcium carbonate structures like shells and skeletons to stay intact, can drop to levels that will mean these hard structures will begin to dissolve," the reports says.

"If levels of atmospheric and oceanic CO2 continue to rise at current rates… by 2100 it is likely that the entire Arctic Ocean will be in a state that can dissolve unprotected calcium carbonate structures."

Evidence had already been found that the shells of one species - the planktonic foraminifera - are already 30-35 per cent lighter than their pre-industrial-era counterparts, demonstrating that the effect has already begun.

Environmental groups said acidification was a growing danger to marine life. Richard Dixon, director of WWF Scotland, said: "Climate change would already be much worse if the oceans weren't absorbing huge amounts of the carbon dioxide we are spewing into the atmosphere, but the consequence is that the planet's seas are becoming more and more acidic. This is potentially disastrous for marine life around the globe, devastating much of the base of the food chain and further endangering fish-stocks that many human populations rely on.

"We spend a lot of time worrying about droughts, floods and ice caps, but what's happening to the oceans may actually be the most dangerous impact of climate change."

Duncan McLaren, chief executive of Friends of the Earth Scotland, added: "Ocean acidification threatens not only coral reefs and marine biodiversity, but also the commercial fisheries that depend on them."



By Jane Bradley


http://scotlandonsunday.scotsman.com/environment/Oysters-at-risk-in-acid.6615795.jp

Water firms blamed for poisoned oysters

BRITAIN’S water companies have been accused of contaminating oysters and putting restaurant diners at risk by dumping raw sewage into rivers and the sea.


The number of people suffering food poisoning from raw oysters has risen dramatically, with 230 customers becoming ill in just a three-month period, according to new figures.

The Sunday Times revealed last week how six water companies have fought off an attempt by the Environment Agency to impose regulations on 4,200 overflow pipes that pump out raw sewage.

The scandal of contaminated oysters follows an outbreak of norovirus, which causes vomiting and diarrhoea, at Heston Blumenthal’s Fat Duck restaurant in Bray, Berkshire, last year. Chefs at Raymond Blanc’s Le Manoir aux Quat’ Saisons, which has two Michelin stars, were so concerned that they took oysters off the menu for almost a year.

Britain’s oyster industry is worth about £30m a year, with the main fisheries in the Thames estuary and on the Essex coast, in the Solent off the Isle of Wight and in the River Fal in Cornwall.

Producers fear their livelihoods are being jeopardised by food poisoning incidents linked to oysters. They point out that norovirus, which contaminates the oysters, originates in humans and so the source must be sewage being discharged into rivers and the sea.

“Some Third World countries use better technology than we do to treat sewage,” said David Jarrad, assistant director of the Shellfish Association of Great Britain. “We are as much the victims in this as the consumer.”

The Food Standards Agency has written to councils this year warning of an increase in suspected norovirus outbreaks linked to oysters. Its figures for December 2009 to February 2010 show that 32 restaurants and hotels were hit by outbreaks, with 230 people falling ill.

Norovirus is killed at high temperatures but oysters are typically eaten raw. In February last year Blumenthal was forced temporarily to close the Fat Duck, which has three Michelin stars, after 529 diners fell ill over a seven-week period. A Health Protection Agency report found sewage in oysters was most likely to blame. “Oysters harvested from sewage-contaminated waters will feed on the faecal residues,” it said.

Graham Larkin, operations manager at Colchester Oyster Fishery, which supplied the Fat Duck, said the vast majority of oysters were safe to eat but action needed to be taken.

“Fisheries are being affected by this all over the country. We want to see the water cleaned up,” Larkin said.

He now conducts rigorous tests for norovirus on oysters from the River Colne in Essex. Anglian Water has sewage treatment works on the river, which flows through Colchester, and overflow pipes which can discharge sewage during very wet weather.

Gary Jones, executive head chef at Blanc’s Le Manoir in Oxfordshire, said the restaurant now only served oysters that had been through a purification process and had been tested for norovirus. “We have to be confident that what we put on the menu is not going to harm anyone,” he said.

Jones said there was “not a shadow of a doubt” that oyster contamination was caused by sewage and the water companies should be held to account over discharges. “What we are doing to the seas is horrific. We should be taking this more seriously,” he said.

Water companies are allowed to dump raw sewage into rivers and the sea during wet weather to stop it backing up into homes, but oyster producers want to see more investment to limit the amount that is discharged.

Anglian Water said there was no proven link between its sewage discharges and contaminated oysters. Water UK, which represents water companies, said the industry had spent billions of pounds to improve the sewer system and as a result water quality in rivers and bathing areas had significantly improved.

Jon Ungoed-Thomas
http://www.timesonline.co.uk/tol/news/environment/article7114086.ece