Study demonstrates seagrass’ strong potential for curbing erosion

Most people’s experience with seagrass, if any, amounts to little more than a tickle on their ankles while wading in shallow coastal waters. But it turns out these ubiquitous plants, varieties of which exist around the world, could play a key role in protecting vulnerable shores as they face onslaughts from rising sea levels.

New research for the first time quantifies, through experiments and mathematical modelling, just how large and how dense a continuous meadow of seagrass must be to provide adequate damping of waves in a given geographic, climatic, and oceanographic setting.

In a pair of papers appearing in the May issues of two research journals, Coastal Engineering and the Journal of Fluids and Structures, MIT professor of civil and environmental engineering Heidi Nepf and doctoral student Jiarui Lei describe their findings and the significant environmental benefits seagrass offers. These include not only preventing beach erosion and protecting seawalls and other structures, but also improving water quality and sequestering carbon to help limit future climate change.

Those services, coupled with better-known services such as providing habitat for fish and food for other marine creatures, mean that submerged aquatic vegetation including seagrass provides an overall value of more than $4 trillion globally every year, as earlier studies have shown. Yet today, some important seagrass areas such as the Chesapeake Bay are down to about half of their historic seagrass coverage (having rebounded from a low of just 2 percent), thus limiting the availability of these valuable services.

Nepf and Lei recreated artificial versions of seagrass, assembled from materials of different stiffness to reproduce the long, flexible blades and much stiffer bases that are typical of seagrass plants such as Zostera marina, also known as common eelgrass. They set up a meadow-like collection of these artificial plants in a 79-foot-long (24-meter) wave tank in MIT’s Parsons Laboratory, which can mimic conditions of natural waves and currents. They subjected the meadow to a variety of conditions, including still water, strong currents, and wave-like sloshing back and forth. Their results validated predictions made earlier using a computerized model of individual plants.

Researchers used a74-foot-long wave tank at MIT, loaded with simulated seagrass plants, to study how seagrass acts to attenuate waves under various conditions. In this video, the simulated plants are exposed to strong waves.

In further tests in the MIT tank, simulated seagrass plants are subjected to very low-velocity waves.

The researchers used the physical and numerical models to analyze how the seagrass and waves interact under a variety of conditions of plant density, blade lengths, and water motions. The study describes how the motion of the plants changes with blade stiffness, wave period, and wave amplitude, providing a more precise prediction of wave damping over seagrass meadows. While other research has modeled some of these conditions, the new work more faithfully reproduces real-world conditions and provides a more realistic platform for testing ideas about seagrass restoration or ways of optimizing the beneficial effects of such submerged meadows, they say.

To test the validity of the model, the team then did a comparison of the predicted effects of seagrass on waves, looking at one specific seagrass meadow off the shore of the Spanish island of Mallorca, in the Mediterranean Sea, which is known to attenuate the force of incoming waves by a factor of about 50 percent on average. Using measurements of meadow morphology and wave velocities collected in a previous study led by Professor Eduardo Infantes, currently of Gothenburg University, Lei was able to confirm the predictions made by the model, which analyzed the way the tips of the grass blades and particles suspended in the water both tend to follow circular paths as waves go by, forming circles of motion known as orbitals.

The observations there matched the predictions very well, Lei says, showing the way wave strength and seagrass motion varied with distance from the edge of the meadow to its interior agreed with the model. So, “with this model the engineers and practitioners can assess different scenarios for seagrass restoration projects, which is a big deal right now,” he says That could make a significant difference, he says, because now some restoration projects are considered too expensive to undertake, whereas a better analysis could show that a smaller area, less expensive to restore, might be capable of providing the desired level of protection. In other areas, the analysis might show that a project is not worth doing at all, because the characteristics of the local waves or currents would limit the grasses’ effectiveness.

The particular seagrass meadow in Mallorca that they studied is known to be very dense and uniform, so one future project is to extend the comparison to other seagrass areas, including those that are patchier or less thickly vegetated, Nepf says, to demonstrate that the model can indeed be useful under a variety of conditions.

By attenuating the waves and thus providing protection against erosion, the seagrass can trap fine sediment on the seabed. This can significantly reduce or prevent runaway growth of algae fed by the nutrients associated with the fine sediment, which in turn causes a depletion of oxygen that can kill off much of the marine life, a process called eutrophication.

Seagrass also has significant potential for sequestering carbon, both through its own biomass and by filtering out fine organic material from the surrounding water, according to Nepf, and this is a focus of her and Lei’s ongoing research. An acre of seagrass can store about three times as much carbon as an acre of rainforest, and Lei says preliminary calculations suggest that globally, seagrass meadows are responsible for more than 10 percent of carbon buried in the ocean, even though they occupy just 0.2 percent of the area.

While other researchers have studied the effects of seagrass in steady currents, or in oscillating waves, “they are the first to combine these two types of flows, which are what real plants are typically subjected to. Despite the added complexity, they really sort out the physics and define different flow regimes with different behaviours,” says Frédérick Gosselin, professor of mechanical engineering at Polytechnique Montréal, in Canada, who was not connected to this research.

Gosselin adds, “This line of research is critical. Land developers are quick to fill and dredge wetlands without much thinking about the role these humid environments play.” This study “demonstrates how submerged vegetation has a precisely quantifiable effect on damping incoming waves. This means we can now evaluate exactly how much a meadow protects the coast from erosion. … This information would allow better decisions by our lawmakers.”

The work was funded by the U.S. National Science Foundation.

from MIT News - Oceanography and ocean engineering http://bit.ly/2J9qiOw
via IFTTT

Tapping fresh water under the ocean has consequences

The last place most people would expect to find fresh groundwater is tens to hundreds of kilometers offshore in the ocean. Yet not only is that exactly where freshwater can be found, in the ground of the continental shelf beneath the ocean, but simulations have shown that it could be a common occurrence across a range of geologic systems.

These offshore groundwater resources could be exploited for uses such as drinking, agriculture and oil recovery, but new research from the University of Delaware's Holly Michael and Xuan Yu, who worked as a postdoctoral researcher at UD, suggests that tapping into those resources could lead to adverse onshore impacts.

The research was published in Geophysical Research Letters and is part of Michael's National Science Foundation CAREER Award.

Through simulations and computer modeling, the research explores how using offshore freshwater resources could threaten onshore aquifer systems, lead to diminished onshore groundwater availability and cause widespread land subsidence.

Coastal communities may consider using these offshore groundwater resources as populations increase and the limited freshwater resources are degraded by overuse and pollution, but a more immediate use of the offshore fresh and brackish groundwater is to enhance oil recovery.

Water is used in oil drilling by what is known as waterflooding, in which water is injected to support oil-reservoir pressure and to move oil into producing wells.

Salinity is a major factor controlling the amount of oil that can be recovered from a zone that has been waterflooded and a technique known as low-salinity waterflooding -- using freshwater to waterflood these offshore oil wells instead of the readily available saltwater -- has been shown to increase oil recovery by 14 percent on average.

One of the problems with using these offshore freshwater resources for low-salinity waterflooding in offshore oil production is that the offshore freshwater sources are connected to the freshwater sources on land. That onshore groundwater is filling in the pores of sediment and helping to hold up the surface on which coastal towns are built.

"If you build a city on land surface, you add weight, and you add pressure to the aquifer -- the sediments and water underground. When a building is built, geotechnical tests are done to make sure this added pressure will not cause the land surface to sink," said Michael, the Unidel Fraser Russell Career Development Chair for the Environment and an associate professor in the Department of Geological Sciences. "The pressure of the water in those pores creates an upward force and contributes to rigidity in the system."

If that water is pumped out for low-salinity waterflooding, the pressure is changed underground and it can reduce the ability of the aquifer to support the weight of the city.

Subsidence has been seen in megacities with the constant extraction of water below ground, with examples being Venice, Italy and Tokyo, Japan. Pumping offshore freshwater resources for low-salinity waterflooding could have this same affect.

"This affect can hardly be simulated when a simple geologic structure is assumed," said Yu, who is now an associate professor in the school of civil engineering at Sun Yat-sen University in China. "Our model results suggested that the magnitude of subsidence in homogenous and layered geology is much smaller than the heterogeneous cases."

In addition to land subsidence, another possible consequence of oil companies tapping into these offshore freshwater resources is that the freshwater aquifers on-land could experience increased salinization, again through the connection between the offshore freshwater and the freshwater on-land.

The reduction in onshore fresh groundwater from low-salinity waterflooding can also have an impact on coastal population centers, especially in locations where oil reservoirs lie offshore of highly populated cities, such as those in Southeast Asia and the Mediterranean Basin.

Michael said that because scientists are just now realizing that this freshwater exists offshore, the purpose of the paper was to demonstrate the potential for offshore pumping to have devastating effects on coastal communities, before the practice becomes widespread.

"What we are saying in this paper is, 'Wait a minute, the cities on shore might have no idea that offshore activities could potentially affect their resources,'" said Michael. "Offshore pumping of fresh groundwater could cause subsidence on land, which can cause a range of problems, especially in populated areas. And then there are the fresh, groundwater resources that are being used up that could potentially be a resource for humans in the future."

Story Source:

Materials provided by University of Delaware. Note: Content may be edited for style and length.

from Oceanography News -- ScienceDaily http://bit.ly/2VDYqJc
via IFTTT

Arsenic-breathing life discovered in the tropical Pacific Ocean

Arsenic is a deadly poison for most living things, but new research shows that microorganisms are breathing arsenic in a large area of the Pacific Ocean. A University of Washington team has discovered that an ancient survival strategy is still being used in low-oxygen parts of the marine environment.

"Thinking of arsenic as not just a bad guy, but also as beneficial, has reshaped the way that I view the element," said first author Jaclyn Saunders, who did the research for her doctoral thesis at the UW and is now a postdoctoral fellow at the Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology.

The study was published this week in the Proceedings of the National Academy of Sciences.

"We've known for a long time that there are very low levels of arsenic in the ocean," said co-author Gabrielle Rocap, a UW professor of oceanography. "But the idea that organisms could be using arsenic to make a living -- it's a whole new metabolism for the open ocean."

The researchers analyzed seawater samples from a region below the surface where oxygen is almost absent, forcing life to seek other strategies. These regions may expand under climate change.

"In some parts of the ocean there's a sandwich of water where there's no measureable oxygen," Rocap said. "The microbes in these regions have to use other elements that act as an electron acceptor to extract energy from food."

The most common alternatives to oxygen are nitrogen or sulfur. But Saunders' early investigations suggested arsenic could also work, spurring her to look for the evidence.

The team analyzed samples collected during a 2012 research cruise to the tropical Pacific, off the coast of Mexico. Genetic analyses on DNA extracted from the seawater found two genetic pathways known to convert arsenic-based molecules as a way to gain energy. The genetic material was targeting two different forms of arsenic, and authors believe that the pathways occur in two organisms that cycle arsenic back and forth between different forms.

Results suggest that arsenic-breathing microbes make up less than 1% of the microbe population in these waters. The microbes discovered in the water are probably distantly related to the arsenic-breathing microbes found in hot springs or contaminated sites on land.

"What I think is the coolest thing about these arsenic-respiring microbes existing today in the ocean is that they are expressing the genes for it in an environment that is fairly low in arsenic," Saunders said. "It opens up the boundaries for where we could look for organisms that are respiring arsenic, in other arsenic-poor environments."

Biologists believe the strategy is a holdover from Earth's early history. During the period when life arose on Earth, oxygen was scarce in both the air and in the ocean. Oxygen became abundant in Earth's atmosphere only after photosynthesis became widespread and converted carbon dioxide gas into oxygen.

Early lifeforms had to gain energy using other elements, such as arsenic, which was likely more common in the oceans at that time.

"We found the genetic signatures of pathways that are still there, remnants of the past ocean that have been maintained until today," Saunders said.

Arsenic-breathing populations may grow again under climate change. Low-oxygen regions are projected to expand, and dissolved oxygen is predicted to drop throughout the marine environment.

"For me, it just shows how much is still out there in the ocean that we don't know," Rocap said. Saunders recently collected more water samples from the same region and is now trying to grow the arsenic-breathing marine microbes in a lab in order to study them more closely.

"Right now we've got bits and pieces of their genomes, just enough to say that yes, they're doing this arsenic transformation," Rocap said. "The next step would be to put together a whole genome and find out what else they can do, and how that organism fits into the environment."

Co-author Clara Fuchsman collected the samples and led the DNA sequencing effort as a UW postdoctoral research scientist and now holds a faculty position at the University of Maryland. The other co-author is Cedar McKay, a research scientist in the UW School of Oceanography. The study was funded by a graduate fellowship from NASA and a research grant from the National Science Foundation.

Story Source:

Materials provided by University of Washington. Original written by Hannah Hickey. Note: Content may be edited for style and length.

from Oceanography News -- ScienceDaily http://bit.ly/2VFB0CV
via IFTTT

New clues to coastal erosion

New research has uncovered a missing nutrient source in coastal oceans, which could promote better water quality and sand management on popular beaches.

While the release of nutrients buried in the seabed 'feeds' coastal marine ecosystems, the latest research at Flinders University has found a new physical mechanism which erodes seabed sediment at depths up to 20 metres, well outside (between 10km and 20km) from the surf zone closer to shore.

This powerful natural process that is energetic enough to erode seabed sediment at up to 20 m, also adds to the nutrients stirred and moved by breaking surface waves nearer the beach, according to the new hydrodynamic modelling.

"This new knowledge has significant implications for coastal sediment management practices such as dredging," says Flinders University oceanographer Associate Professor Jochen Kaempf.

The study reveals that major sediment erosion follows from coast-parallel winds in an oceanic situation known as downwelling.

"Such winds trigger a swift coastal current -- left-bounded by the coast in the Southern Hemisphere -- that is accompanied by a vigorous stirring zone in nearshore waters," Associate Professor Kaempf says.

While this finding explains the high proportion of recycled nutrients in coastal ecosystems, it incidentally also points to a new mechanism of wind-driven sediment drift in coastal oceans that complements the well-known littoral drift in the surf zone.

"Along the Adelaide metropolitan coastline, for example, the wind-driven sediment drift tends to be predominantly southward and opposite to the northward sediment drift in the surf zone," explains Dr Kaempf.

"On the other hand, high turbidity levels following a seabed erosion event negatively impact the health of seagrass beds, and the sudden nutrient release can also trigger potentially harmful toxic algae blooms," says Dr Jochen Kaempf, who also is South Australian branch president of the Australian Meteorological and Oceanographic Society.

Dr Kaempf's latest paper calls for more field research and the development of reliable ocean forecasting models to study and predict the occurrence of such erosion events.

Story Source:

Materials provided by Flinders University. Note: Content may be edited for style and length.

from Oceanography News -- ScienceDaily http://bit.ly/2IVz1EM
via IFTTT

New mathematical approach tested for the search of flight MH370

The 2014 disappearance of Malaysia Airlines Flight MH370 remains ones of the biggest mysteries in aviation. More than $150 million has been spent so far to identify where the plane carrying 239 passengers crashed into the Indian Ocean, with no success. Recent efforts combining satellite data with a new mathematical approach aim to make headway in the search for plane crashes.

An international team of researchers has developed a new mathematical approach to analyzing how debris moves around the ocean that has been able to identify a potential crash site. Using what are known as Markov chain models, they have narrowed down a potential crash location substantially north of the region where most search efforts have concentrated.

A Markov chain model predicts the behavior of complicated systems by determining the probability of each outcome from the current state of what is being studied. They have been used to power Google search algorithms and model financial markets.

In the study, reported in the journal Chaos, from AIP Publishing, the group used data from the Global Drifters Program, a publicly available dataset that uses satellites to track spherical buoys as the ocean's currents, waves and wind push them along paths over time.

In true Markovian fashion, each aimless buoy's next turn is an independent event from every other movement it has made in the past. The buoys were then placed on a grid with more than 3,000 virtual squares to simulate where plane debris would float to.

One issue is that very little debris has been found so far.

"Surprisingly, after more than three years, there is only a handful of confirmed debris recovered from the airplane," said Philippe Miron from University of Miami and the lead author on the paper. "This increases the errors of the model."

Seasonal variation in the Indian Ocean also required the team to develop three separate models to accurately predict debris movement during the protracted search effort.

"The monsoon in the Indian Ocean has important effects on the circulation of the region," Miron said.

After the analysis, the team's estimated search area was from 33 to 17 degrees south latitude along the arc of the last satellite to contact the downed plane, whose northern edge has remained largely unscrutinized.

Miron said he hopes the group's approach will encourage future efforts to deploy more trackable devices in the ocean to provide more data to solve similarly vexing problems. He looks to use mathematical models to further understand how drifting objects move in the ocean, including the flow of hydrocarbons following undersea oil spills.

Story Source:

Materials provided by American Institute of Physics. Note: Content may be edited for style and length.

from Oceanography News -- ScienceDaily http://bit.ly/2VH3fRP
via IFTTT

Chemical records in teeth confirm elusive Alaska lake seals are one of a kind

Hundreds of harbor seals live in Iliamna Lake, the largest body of freshwater in Alaska and one of the most productive systems for sockeye salmon in the Bristol Bay region.

These lake seals are a robust yet highly unusual and cryptic posse. Although how the seals first colonized the lake remains a mystery, it is thought that sometime in the distant past, a handful of harbor seals likely migrated from the ocean more than 50 miles (80 kilometers) upriver to the lake, where they eventually grew to a consistent group of about 400. These animals are important for Alaska Native subsistence hunting, and hold a top spot in the lake's diverse food web.

Scientists now know these "colonizing" seals must have found the lake suitable enough to stay and raise their offspring. Generations later, the lake-bound seals appear to be a genetically distinct population from their ocean-dwelling cousins -- even though they are still managed as part of the larger Eastern Pacific harbor seal population.

But if the lake seals are distinct and show signs of local adaptation to their unique ecological setting, this would mean that their conservation -- especially in the face of the rapidly changing climate of western Alaska and proposed industrial developments -- should differ from that of nearby marine populations.

Lifelong chemical records stored in their sequentially growing canine teeth show that the Iliamna Lake seals remain in freshwater their entire lives, relying on food sources produced in the lake to survive. In contrast, their relatives in the ocean are opportunistic feeders, moving around to the mouths of different rivers to find the most abundant food sources, which includes a diverse array of marine food items in addition to the adult salmon returning to Bristol Bay's nine major watersheds. These findings are described in a paper published online in March in Conservation Biology.

"We clearly show these seals are in the lake year-round, throughout their entire lives," said lead author Sean Brennan, a postdoctoral researcher at the University of Washington's School of Aquatic and Fishery Sciences. "This gives us critical baseline information that can weigh in on how we understand their ecology, and we can use that information to do a better job developing a conservation strategy."

This new study comes at a time when federal agencies are considering whether to permit mining activities in Bristol Bay, a region teeming with wildlife, including Alaska sockeye salmon. Iliamna Lake, and the seals and other animals that live there, is located in the heart of the proposed Pebble Mine project.

The U.S. Army Corps of Engineers this spring released a draft environmental impact statement that analyzes the project's proposal, presents alternative plans and gives the public a chance to comment. Ultimately, the document will help decide whether the controversial mine is approved.

Because of their current conservation status, the Iliamna Lake harbor seals aren't assessed as a distinct and ecologically significant population in the project's draft environmental impact analysis. If the seals are determined to be a distinct population, that has important implications for how the Iliamna Lake system is managed, the study's authors said. The lake and its resident fishes would then be considered critical habitat for seals.

Separately, federal regulators have considered whether the lake seals should be named a distinct population, but scientists have been unable to agree on whether the seals are both distinct, and ecologically and evolutionarily significant, mainly because little is known about their ecology -- including whether adult lake seals potentially migrate to the ocean to feed each year.

Brennan was a doctoral student at the University of Alaska Fairbanks when he heard about early efforts to evaluate whether the lake seals were a distinct population. Chemical tracing methods he was using to track the life patterns of salmon could also work for the seals, he realized.

"The light just went off in my head," Brennan said. "What I was doing for salmon was directly applicable to this population of seals."

Brennan and collaborators at the UW, University of Utah and University of Alaska Anchorage looked at the chemical signatures present in the teeth of lake seals during each year of their life to better understand where they moved and what they ate. Specifically, the scientists drilled into the growth lines of the seals' canine teeth, then measured the ratio of heavy and light isotopes of carbon, oxygen, and strontium present in each growth layer.

Because of the young bedrock geology of the Kvichak (QUEE-jak) River watershed, which encompasses Iliamna Lake, strontium isotope levels in the ocean are consistently much higher than in the lake. Unlike other elements, strontium signatures in mammal teeth directly reflect what animals assimilate from their environment, in particular, what they eat. Therefore, by looking at the strontium isotope ratios over the course of a seal's life, the researchers saw that the ratios were consistent with lake signatures -- meaning these seals only live in Lake Iliamna, depend principally on fish produced within the lake, and do not migrate to the ocean.

They also determined that young seals eat very little adult sockeye salmon. But later in life, the seals shift to supplement their diets with the seasonally abundant sockeye salmon that return each summer to the lake.

The researchers say this method could be used to better understand the life patterns of other elusive mammals around the world, such as river dolphins in the Amazon or the Mekong Basin. Broadly, marine mammals in coastal regions are among the most endangered animals on Earth, Brennan said.

"In terms of the broader picture of aquatic mammal conservation across the globe, I think we show that strontium isotopes can be really powerful because they collapse a lot of uncertainty. This method is completely underutilized across the world," Brennan said.

from Oceanography News -- ScienceDaily http://bit.ly/2PEVBlz
via IFTTT

Scientists track giant ocean vortex from space

Researchers have found a new way to use satellites to monitor the Great Whirl, a massive whirlpool the size of Colorado that forms each year off the coast of East Africa, they report in a new study.

Using 23 years of satellite data, the new findings show the Great Whirl is larger and longer-lived than scientists previously thought. At its peak, the giant whirlpool is, on average, 275,000 square kilometers (106,000 square miles) in area and persists for about 200 days out of the year. Watch an animation of the Great Whirl's evolution here.

More than being just a curiosity, the Great Whirl is closely connected to the monsoon that drives the rainy season in India. Monsoon rains fuel India's $2 trillion agricultural economy, but how much rain falls each year is notoriously difficult to forecast. If researchers can use their new method to discern a pattern in the Great Whirl's formation, they might be able to better predict when India will have a very dry or very wet season compared to the average.

"If we're about to connect these two, we might have an advantage in predicting the strength of the monsoon, which has huge socioeconomic impacts," said Bryce Melzer, a satellite oceanographer at Stennis Space Center in Mississippi and lead author of the new study in AGU's journal Geophysical Research Letters.

A swirling sea

The Great Whirl is a huge whirlpool that forms every spring off the coast of Somalia, when winds blowing across the Indian Ocean change direction from west to east. English geographer Alexander Findlay first described the Great Whirl in his navigational directory for the Indian Ocean in 1866.

According to Findlay, Lieutenant Taylor of the British Royal Navy described a "great whirl of current" circulating clockwise at about the same latitude at Xaafuun, Somalia. "A very heavy confused sea is created by this whirl," Findlay wrote. The phenomenon became known as the Great Whirl, and sailors have long been wary of its strong waves and intense currents.

The Great Whirl starts to form in April but its currents are deepest and strongest from June to September, during the official Indian monsoon season. A 2013 study using satellite data found that at its peak, the Whirl can grow to more than 500 kilometers (300 miles) wide, making it wider than the Grand Canyon is long.

The Great Whirl's circular currents extend hundreds of meters downward and can go farther than 1 kilometer (0.6 miles) deep in some areas. The inertia it generates keeps the Whirl going well past the end of monsoon season in September, until typically disappearing late in the fall.

Studying the Whirl from afar

Scientists have been interested in the Great Whirl for years but have had difficulty studying it directly. Monitoring the Whirl requires many repeat observations taken over a long period of time, but rampant piracy off the Somali coast has prevented researchers from venturing near it or placing instruments in the ocean to observe it.

And because the Whirl is so large, it doesn't behave the way smaller whirlpools do, and scientists have difficulty defining its boundaries. As a result, scientists don't fully understand how the Whirl varies from year to year or exactly when it forms and when it disappears.

Researchers have recently turned to satellites to see if they can monitor the Whirl from afar. In the new study, Melzer and his colleagues developed a new way to use satellite measurements of sea levels to better define the Great Whirl's boundaries and track it over time. The center of the Great Whirl actually rises higher than sea level and the currents spin around this "hill" of water.

The researchers analyzed sea level satellite data from 1993-2015 to understand how the Whirl changes from year to year and what it looks like under different climate conditions.

They found the Great Whirl is larger than previous thought. The average size of the Whirl over those 23 years was 275,000 square kilometers (106,000 square miles), making it larger than the state of Colorado.

They also found there's a lot of variability in when the Great Whirl forms and how long it lasts. But on average, it lasts for 198 days -- six and a half months -- considerably longer than previous estimates of 166 and 140 days.

The vast amount of inertia it generates keeps the Whirl spinning well past the official end of monsoon season in September. The researchers found the Whirl persists well into November and even December, and there were three years -- 2000, 2005, and 2010 -- when it persisted into the new year. The longest it lasted was 256 days -- more than eight months -- in 1997.

The researchers haven't yet found a pattern in the Great Whirl that could help them predict the Indian monsoon. But they hope to also apply their method to tracking whirlpools in other areas. Whirlpools in the Gulf of Mexico, for example, have very strong currents that could affect oil drilling operations in the area.

from Oceanography News -- ScienceDaily http://bit.ly/2Vzjb8P
via IFTTT