A mysterious ocean algae scarcity could have enormous ramifications for the ocean’s food webs

The upper image is courtesy of Norman Kuring, Ocean Color Group, NASA Goddard Space Flight Research Center.

A globally important ocean algae is mysteriously scarce in one of the most productive regions of the Atlantic Ocean, according to a new paper in Deep Sea Research I. A massive dataset has revealed patterns in the regions where Atlantic coccolithophores live, illuminating the inner workings of the ocean carbon cycle and raising new questions.

“Understanding these large-scale patterns helps us understand ocean productivity in the entire Atlantic basin,” said William Balch, a senior research scientist at Bigelow Laboratory for Ocean Sciences and lead author on the paper. “Collecting this dataset has been a superhuman effort for my team that has taken hundreds of days at sea and years of analysis.”

The researchers found that coccolithophores both struggle and thrive in unexpected places throughout the Atlantic Ocean. They are most abundant in subpolar and temperate waters and surprisingly scarce around the equator, where an abundance of nutrients and sunlight create one of the most biologically productive regions of the global ocean.

The team also discovered that some coccolithophore species thrive deep below the surface near the farthest reaches of sunlight – within or just above an important water layer called “Sub-Antarctic mode water.” This distinct feature flows north from the Southern Ocean and provides nutrients to much of the global ocean, including the northern hemisphere. Balch suspects that booming coccolithophore populations in the Southern Ocean are depleting the water layer’s nutrient supply and altering its chemistry – potentially making it inhospitable for coccolithophores by the time it reaches the equator.

“Sub-Antarctic mode water exerts a staggering level of control on much of the global ocean,” Balch said. “If coccolithophores are changing its essential properties, then they could be influencing which species grow in food webs as far away as the equator or even in the northern hemisphere.”

Balch and his team built this vast dataset from measurements collected during 10 45-day research cruises through the Atlantic Meridional Transect program, which crosses the Atlantic Ocean between the United Kingdom and the tip of South America. Their findings also have important applications to observations that rely on NASA ocean color satellites. These powerful oceanographic tools allow scientists to detect coccolithophore populations by measuring the light they reflect back into space, but they require on-the-water measurements to ground-truth the satellite data. NASA was the primary funder of this work.

Coccolithophores build protective crystalline plates from chalk minerals by extracting dissolved inorganic carbon from seawater. The way a species’ plates are shaped impacts how those plates scatter light in the surface ocean, especially after they become detached and begin to sink towards the seafloor. The researchers discovered that not all coccolithophores drop their plates, and that the plates found throughout the water column come from just a few species.

This finding vastly simplifies the calculations needed to measure the carbon that coccolithophores contain from satellite reflectance data. Coccolithophores play a major role in the global carbon cycle, and understanding where they live and how they scatter light is essential to quantifying how this important element moves between the surface ocean and seafloor. Ultimately, that carbon is either broken down by deep-sea bacteria or buried in sediment, effectively sequestering it from the atmosphere for thousands of years.

Balch’s team, along with an international team of investigators, will continue this research in January, when they embark on a National Science Foundation-funded cruise to answer one of the most important questions raised by this study – how coccolithophores in the Southern Ocean alter Sub-Antarctic mode water before it flows north. Their research will elucidate how these changes may affect productivity further north, and why coccolithophores are so scarce at the equator.

“The grand question remains – what is missing from this equatorial water that makes it not conducive to coccolithophore growth in such a fertile region of the world ocean?” Balch said. “The difference in the amount of coccolithophores at temperate latitudes and the equator is profound, and it has enormous ramifications for the ocean’s food webs and the productivity of the entire planet.”

Learn more: Study Reveals Patterns in Globally Important Algae

 

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Overfishing is depleting oceans across the globe, with 90 percent of the world’s fisheries fully exploited or facing collapse

via World Ocean Review

JOAL, Senegal — Once upon a time, the seas teemed with mackerel, squid and sardines, and life was good. But now, on opposite sides of the globe, sun-creased fishermen lament as they reel in their nearly empty nets.

“Your net would be so full of fish, you could barely heave it onto the boat,” said Mamadou So, 52, a fisherman in Senegal, gesturing to the meager assortment of tiny fish flapping in his wooden canoe.

A world away in eastern China, Zhu Delong, 75, also shook his head as his net dredged up a disappointing array of pinkie-size shrimp and fledgling yellow croakers. “When I was a kid, you could cast a line out your back door and hook huge yellow croakers,” he said. “Now the sea is empty.”

Overfishing is depleting oceans across the globe, with 90 percent of the world’s fisheries fully exploited or facing collapse, according to the United Nations Food and Agriculture Organization. From Russian king crab fishermen in the west Bering Sea to Mexican ships that poach red snapper off the coast of Florida, unsustainable fishing practices threaten the well-being of millions of people in the developing world who depend on the sea for income and food, experts say.

But China, with its enormous population, growing wealth to buy seafood and the world’s largest fleet of deep-sea fishing vessels, is having an outsize impact on the globe’s oceans.

Having depleted the seas close to home, Chinese fishermen are sailing farther to exploit the waters of other countries, their journeys often subsidized by a government more concerned with domestic unemployment and food security than the health of the world’s oceans and the countries that depend on them.

Increasingly, China’s growing armada of distant-water fishing vessels is heading to the waters of West Africa, drawn by corruption and weak enforcement by local governments. West Africa, experts say, now provides the vast majority of the fish caught by China’s distant-water fleet. And by some estimates, as many as two-thirds of those boats engage in fishing that contravenes international or national laws.

China’s distant-water fishing fleet has grown to nearly 2,600 vessels (the United States has fewer than one-tenth as many), with 400 boats coming into service between 2014 and 2016 alone. Most of the Chinese ships are so large that they scoop up as many fish in one week as Senegalese boats catch in a year, costing West African economies $2 billion a year, according to a new study published by the journal Frontiers in Marine Science.

Learn more:China’s Appetite Pushes Fisheries to the Brink

 

 

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Fishing for DNA: Free-floating eDNA identifies presence and abundance of ocean life

Image 20170410 31882 15i73lyFish leave bits of DNA behind that researchers can collect.
Mark Stoeckle/Diane Rome Peebles images, CC BY-ND

Mark Stoeckle, The Rockefeller University

Ocean life is largely hidden from view. Monitoring what lives where is costly – typically requiring big boats, big nets, skilled personnel and plenty of time. An emerging technology using what’s called environmental DNA gets around some of those limitations, providing a quick, affordable way to figure out what’s present beneath the water’s surface. The Conversation

Fish and other animals shed DNA into the water, in the form of cells, secretions or excreta. About 10 years ago, researchers in Europe first demonstrated that small volumes of pond water contained enough free-floating DNA to detect resident animals.

Researchers have subsequently looked for aquatic eDNA in multiple freshwater systems, and more recently in vastly larger and more complex marine environments. While the principle of aquatic eDNA is well-established, we’re just beginning to explore its potential for detecting fish and their abundance in particular marine settings. The technology promises many practical and scientific applications, from helping set sustainable fish quotas and evaluating protections for endangered species to assessing the impacts of offshore wind farms.

Who’s in the Hudson, when?

In our new study, my colleagues and I tested how well aquatic eDNA could detect fish in the Hudson River estuary surrounding New York City. Despite being the most heavily urbanized estuary in North America, water quality has improved dramatically over the past decades, and the estuary has partly recovered its role as essential habitat for many fish species. The improved health of local waters is highlighted by the now regular fall appearance of humpback whales feeding on large schools of Atlantic menhaden at the borders of New York harbor, within site of the Empire State Building.

Preparing to hurl the collecting bucket into the river.
Mark Stoeckle, CC BY-ND

Our study is the first recording of spring migration of ocean fish by conducting DNA tests on water samples. We collected one liter (about a quart) water samples weekly at two city sites from January to July 2016. Because the Manhattan shoreline is armored and elevated, we tossed a bucket on a rope into the water. Wintertime samples had little or no fish eDNA. Beginning in April there was a steady increase in fish detected, with about 10 to 15 species per sample by early summer. The eDNA findings largely matched our existing knowledge of fish movements, hard won from decades of traditional seining surveys.

Our results demonstrate the “Goldilocks” quality of aquatic eDNA – it seems to last just the right amount of time to be useful. If it disappeared too quickly, we wouldn’t be able to detect it. If it lasted for too long, we wouldn’t detect seasonal differences and would likely find DNAs of many freshwater and open ocean species as well as those of local estuary fish. Research suggests DNA decays over hours to days, depending on temperature, currents and so on.

Fish identified via eDNA in one day’s sample from New York City’s East River.
New York State Department of Environmental Conservation: alewife (herring species), striped bass, American eel, mummichog; Massachusetts Department of Fish and Game: black sea bass, bluefish, Atlantic silverside; New Jersey Scuba Diving Association: oyster toadfish; Diane Rome Peeples: Atlantic menhaden, Tautog, Bay anchovy; H. Gervais: conger eel., CC BY-ND

Altogether, we obtained eDNAs matching 42 local marine fish species, including most (80 percent) of the locally abundant or common species. In addition, of species that we detected, abundant or common species were more frequently observed than were locally uncommon ones. That the species eDNA detected matched traditional observations of locally common fish in terms of abundance is good news for the method – it supports eDNA as an index of fish numbers. We expect we’ll eventually be able to detect all local species – by collecting larger volumes, at additional sites in the estuary and at different depths.

In addition to local marine species, we also found locally rare or absent species in a few samples. Most were fish we eat – Nile tilapia, Atlantic salmon, European sea bass (“branzino”). We speculate these came from wastewater – even though the Hudson is cleaner, sewage contamination persists. If that is how the DNA got into the estuary in this case, then it might be possible to determine if a community is consuming protected species by testing its wastewater. The remaining exotics we found were freshwater species, surprisingly few given the large, daily freshwater inflows into the saltwater estuary from the Hudson watershed.

Filtering the estuary water back in the lab.
Mark Stoeckle, CC BY-ND
Analyzing the naked DNA

Our protocol uses methods and equipment standard in a molecular biology laboratory, and follows the same procedures used to analyze human microbiomes, for example.

eDNA and other debris left on the filter after the estuary water passed through.
Mark Stoeckle, CC BY-ND

After collection, we run water samples through a small pore size (0.45 micron) filter that traps suspended material, including cells and cell fragments. We extract DNA from the filter, and amplify it using polymerase chain reaction (PCR). PCR is like “xeroxing” a particular DNA sequence, producing enough copies so that it can easily be analyzed.

We targeted mitochondrial DNA – the genetic material within the mitochondria, the organelle that generates the cell’s energy. Mitochondrial DNA is present in much higher concentrations than nuclear DNA, and so easier to detect. It also has regions that are the same in all vertebrates, which makes it easier for us to amplify multiple species.

We tagged each amplified sample, pooled the samples and sent them for next-generation sequencing. Rockefeller University scientist and co-author Zachary Charlop-Powers created the bioinformatic pipeline that assesses sequence quality and generates a list of the unique sequences and “read numbers” in each sample. That’s how many times we detected each unique sequence.

To identify species, each unique sequence is compared to those in the public database GenBank. Our results are consistent with read number being proportional to fish numbers, but more work is needed on the precise relationship of eDNA and fish abundance. For example, some fish may shed more DNA than others. The effects of fish mortality, water temperature, eggs and larval fish versus adult forms could also be at play.

Just like in television crime shows, eDNA identification relies on a comprehensive and accurate database. In a pilot study, we identified local species that were missing from the GenBank database, or had incomplete or mismatched sequences. To improve identifications, we sequenced 31 specimens representing 18 species from scientific collections at Monmouth University, and from bait stores and fish markets. This work was largely done by student researcher and co-author Lyubov Soboleva, a senior at John Bowne High School in New York City. We deposited these new sequences in GenBank, boosting the database’s coverage to about 80 percent of our local species.

Study’s collection sites in Manhattan.
Mark Stoeckle, CC BY-ND

We focused on fish and other vertebrates. Other research groups have applied an aquatic eDNA approach to invertebrates. In principle, the technique could assess the diversity of all animal, plant and microbial life in a particular habitat. In addition to detecting aquatic animals, eDNA reflects terrestrial animals in nearby watersheds. In our study, the commonest wild animal detected in New York City waters was the brown rat, a common urban denizen.

Future studies might employ autonomous vehicles to routinely sample remote and deep sites, helping us to better understand and manage the diversity of ocean life.

Mark Stoeckle, Senior Research Associate in the Program for the Human Environment, The Rockefeller University

This article was originally published on The Conversation. Read the original article.

 

 

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Marine incentives programs work to address multiple ocean threats

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Incentives that are designed to enable smarter use of the ocean while also protecting marine ecosystems can and do work, and offer significant hope to help address the multiple environmental threats facing the world’s oceans, researchers conclude in a new analysis.

Whether economic or social, incentive-based solutions may be one of the best options for progress in reducing impacts from overfishing, climate change, ocean acidification and pollution, researchers from Oregon State University and Princeton University say in a new report published this week in Proceedings of the National Academy of Sciences.

And positive incentives – the “carrot” – work better than negative incentives, or the “stick.”

Part of the reason for optimism, the researchers report, is changing awareness, attitudes and social norms around the world, in which resource users and consumers are becoming more informed about environmental issues and demanding action to address them. That sets the stage for economic incentives that can convert near-disaster situations into sustainable fisheries, cleaner water and long-term solutions.

“As we note in this report, the ocean is becoming higher, warmer, stormier, more acidic, lower in dissolved oxygen and overfished,” said Jane Lubchenco, the distinguished university professor in the College of Science and advisor in marine studies at Oregon State University, lead author of the new report, and U.S. science envoy for the ocean at the Department of State.

“The threats facing the ocean are enormous, and can seem overwhelming. But there’s actually reason for hope, and it’s based on what we’ve learned about the use of incentives to change the way people, nations and institutions behave. We believe it’s possible to make that transition from a vicious to a virtuous cycle. Getting incentives right can flip a disaster to a resounding success.”

Simon A. Levin, the James S. McDonnell distinguished university professor in ecology and evolutionary biology at Princeton University and co-author of the publication, had a similar perspective.

“It is really very exciting that what, until recently, was theoretical optimism is proving to really work,” Levin said. “This gives me great hope for the future.”

The stakes are huge, the scientists point out in their study.

The global market value of marine and coastal resources and industries is about $3 trillion a year; more than 3 billion people depend on fish for a major source of protein; and marine fisheries involve more than 200 million people. Ocean and coastal ecosystems provide food, oxygen, climate regulation, pest control, recreational and cultural value.

“Given the importance of marine resources, many of the 150 or more coastal nations, especially those in the developing world, are searching for new approaches to economic development, poverty alleviation and food security,” said Elizabeth Cerny-Chipman, a postdoctoral scholar working with Lubchenco.  “Our findings can provide guidance to them about how to develop sustainably.”

In recent years, the researchers said in their report, new incentive systems have been developed that tap into people’s desires for both economic sustainability and global environmental protection. In many cases, individuals, scientists, faith communities, businesses, nonprofit organizations and governments are all changing in ways that reward desirable and dissuade undesirable behaviors.

One of the leading examples of progress is the use of “rights-based fisheries.” Instead of a traditional “race to fish” concept based on limited seasons, this growing movement allows fishers to receive a guaranteed fraction of the catch, benefit from a well-managed, healthy fishery and become part of a peer group in which cheating is not tolerated.

There are now more than 200 rights-based fisheries covering more than 500 species among 40 countries, the report noted. One was implemented in the Gulf of Mexico red snapper commercial fishery, which was on the brink of collapse after decades of overfishing. A rights-based plan implemented in 2007 has tripled the spawning potential, doubled catch limits and increased fishery revenue by 70 percent.

“Multiple turn-around stories in fisheries attest to the potential to end overfishing, recover depleted species, achieve healthier ocean ecosystems, and bring economic benefit to fishermen and coastal communities,” said Lubchenco.  “It is possible to have your fish and eat them too.”

A success story used by some nations has been combining “territorial use rights in fisheries,” which assign exclusive fishing access in a particular place to certain individuals or communities, together with adjacent marine reserves. Fish recover inside the no-take reserve and “spillover” to the adjacent fished area outside the reserve. Another concept of incentives has been “debt for nature” swaps used in some nations, in which foreign debt is exchanged for protection of the ocean.

“In parallel to a change in economic incentives,” said Jessica Reimer, a graduate research assistant with Lubchenco, “there have been changes in behavioral incentives and social norms, such as altruism, ethical values, and other types of motivation that can be powerful drivers of change.”

The European Union, based on strong environmental support among its public, has issued warnings and trade sanctions against countries that engage in illegal, unregulated and unreported fishing. In the U.S., some of the nation’s largest retailers, in efforts to improve their image with consumers, have moved toward sale of only certified sustainable seafood.

Incentives are not a new idea, the researchers noted. But they emphasize that their power may have been under-appreciated.

“Recognizing the extent to which a change in incentives can be explicitly used to achieve outcomes related to biodiversity, ecosystem health and sustainability . . .  holds particular promise for conservation and management efforts in the ocean,” they wrote in their conclusion.

Learn more: Marine incentives programs may replace ‘doom and gloom’ with hope

 

 

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High seas fisheries management could recoup losses due to climate change

Photo: Altafalvi, Wikimedia Commons.

Photo: Altafalvi, Wikimedia Commons.

Closing the high seas to fishing could increase fish catches in coastal waters by 10 per cent, helping people, especially the most vulnerable, cope with the expected losses of fish due to climate change, new UBC research finds.

“Many important fish stocks live in both the high seas and coastal waters. Effective management of high seas fisheries could benefit coastal waters in terms of productivity and help reduce climate change impacts,” said lead author William Cheung, associate professor and director of science of the Nippon Foundation-Nereus Program at UBC’s Institute for the Oceans and Fisheries.

The high seas are areas of ocean outside the jurisdiction of any country and cover nearly two-thirds of the ocean’s surface.

Researchers used computer models to predict catches of 30 important fish stocks that live in both the high seas and coastal waters in 2050 under three different management scenarios: closing the high seas to fishing, international cooperation to manage fishing, and maintaining the status quo.

They found that both strengthening governance  and closing the high seas to fishing increased the resilience of coastal countries to climate change, especially in tropical countries where there is a high dependence on fisheries for food and livelihood.

“The scenarios of closing the high seas may greatly reduce the issue of inequity of benefits and impacts among different countries under climate change,” said co-author Vicky Lam, a postdoctoral fellow at UBC’s Institute for the Oceans and Fisheries.

Climate change is expected to disproportionately impact countries in the South Pacific, Indo-Pacific, West African coast and west coast of central America. Previous UBC research shows that if carbon dioxide levels continue to rise on the current trajectory and the Earth warms, these countries could face a 30 per cent decrease in fish stocks as fish migrate to cooler waters.

“The high seas can serve as a fish bank of the world by providing the insurance needed to make the whole global ocean more resilient,” said paper co-author Rashid Sumaila, professor at UBC’s Institute for the Oceans and Fisheries and director of OceanCanada, one of the research funders. “By closing the high seas to fishing or seriously improving its management, the high seas can help us mitigate and adapt to the effects of climate change on marine ecosystems.”

Learn more: High seas fisheries management could recoup losses due to climate change

 

 

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