Digging into the finer details of retired cranberry bog restorations

Cranberry farming was once a prominent industry in southeastern Massachusetts, but now that the cranberry industry is shifting to other areas of the United States and Canada, many New England cranberry bogs are retiring, and efforts are underway to restore some of them as wetlands—a nature-based solution to a number of issues, from flood control to filters of environmental pollutants.

New England’s remaining cranberryfarms are still concentrated in southeastern Massachusetts, where UConn College of Agriculture, Health and Natural Resources Department of Natural Resources and the Environment Ph.D. student Sarah Klionsky focuses her work studying restoration efforts that are increasing the number of wetlands in the region.

When cranberry farms were starting in the area, they were often built on wetlands. Though popularly referred to as “bogs,” Klionsky explains, these areas are usually not technically bogs in the botanical sense, and are more typically a type of wetland known as riparian fens. Restoration of the fens creates habitats for wildlife and plants, and a potential means to remove nitrates from waterways before they reach coastal estuaries.

Nitrates are nutrients, and in excess they lead to a problematic explosion in populations of fast-growing organisms like algae and bacteria, whose accelerated growth can deplete oxygen, resulting in devastating “dead zones” for marine and freshwater wildlife. Nitrates can originate from sources including agriculture and home septic systems, for example.

Determining if and how these restored wetlands remove nitrogen is vital information for future restoration efforts. If restored farms are effective nutrient absorbers, other restorations of retired farms could help increase the wetland area available to improve water quality.

Restoration is no easy task. Cranberry farming is different from tilled-soil farming, says Klionsky, and the methods can drastically alter the landscape and hydrology. Cranberry farms rely on water control features like dams and ditches, and every few years farmers add a few centimeters of sand to help suppress weeds and stimulate growth of the cranberry vines. Over the years, this leads to a thick, heavy layer of sand that compresses the peaty wetland soil below.

Restoration removes a small amount of that sand, but complete removal would be very costly and result in a much lower elevation due to the compression, creating open water instead of wetland, says Klionsky. Restoration also involves the creation of variations in microtopography—slightly higher and lower spots all over the site, including some areas with exposed native wetland soil, culminating in opportunities for diverse plant communities to establish.

“Restoration projects don’t replant or reseed the whole area. They do a little right on the banks of the streams, and a little bit of targeted planting,” says Klionsky. “Most of the plants that come up after the restoration come up on their own.

“One of the really amazing things about these restorations, and a reason they may be particularly attractive, is that we have very, very few invasives and non-native species coming in. They’re here and there, but they make up a very minor percent of the cover of plants afterwards.”

In comparing active restorations to sites that were abandoned, Klionsky says restorations set former cranberry farms on a path to returning to wetlands, whereas abandoned sites often become wooded with upland species.

To begin learning more about the fate of nitrogen in these restored wetlands, Klionsky’s work last summer focused on nitrate removal at the wetland surface.

“I didn’t see a lot of evidence of denitrification happening at the surface,” she says. “We think it’s possible that the surface of the wetlands isn’t in contact with groundwater to help remove the nitrogen from it. Yet, we do think these restored wetlands have a potential to help reduce the amount of nitrogen going downstream.”

Future projects will identify places where there is more contact between the restored wetland soils and the nitrate rich groundwater to see if nitrogen is being removed where groundwater comes to the surface, says Klionsky.

Just as the process of cranberry farming drastically alters the landscape, the process of restoring farms back to wetlands can bring equally drastic changes. As a result, restoration projectsface varying levels of opposition, says Klionsky.

“Cranberry farming is a big identity to those living in this region and the absence of the farms can be something to get used to,” she says.

But a lot of good comes with the changes brought by restoration. Since the areas tend to be quite developed, the newly restored wetlands attract all sorts of wildlife.

“For instance, there have been herring runs restored, which historically were a very important occurrence in southeast Massachusetts,” Klionsky says. “Having more natural space and habitat for different flora and fauna, we see so many different birds and insects and amphibians using the restored sites.”

Klionsky says that if the restorations help with water quality, that would be an another benefit to restoring former cranberry bogs to wetlands.

“What’s been really heartening is to see how the communities use the sites after they’re restored, that they often will have walking paths around the wetlands, and you see a lot of folks coming out and enjoying the spaces.”

FOR MORE INFORMATION:https://phys.org/news/2022-02-finer-cranberry-bog.html

Government guidelines insufficient to protect freshwater ecosystem from salt pollution

Current water quality guidelines aren’t protecting freshwater ecosystems from increasing salt pollution due to road de-icing salts, agriculture fertilizers, and mining operations, according to an international study that included researchers at Rensselaer Polytechnic Institute. Published today in the Proceedings of the National Academy of Sciences (PNAS), the research shows that freshwater salinization triggers a massive loss of zooplankton and an increase in algae—even when levels are within the lowest thresholds established in Canada, the U.S., and throughout Europe.

It’s clear that salt pollution in freshwater lakes, streams, and wetlands, even when constrained to levels specifically chosen to protect the environment, threatens the biodiversity and overall function of freshwater ecosystems. This is a global problem that has the potential to impact ecosystems and human health,” said study co-author Rick Relyea, an expert in the impacts of road salt on freshwater ecosystems, and director of Rensselaer’s Darrin Fresh Water Institute. “The good news, as we’ve seen in our own region, is that communities are learning how to apply road salts in smarter ways while still providing safe roads and saving considerable money in snow and ice removal.”

Dr. Relyea, a member of the Rensselaer Center for Biotechnology and Interdisciplinary Studies and director of the Jefferson Project at Lake George, has conducted extensive research on the impacts of road salt on aquatic environments. His work has helped to establish that road salt masculinizes developing frogs and obliterates circadian rhythm in zooplankton. In recent work, Dr. Relyea has collaborated with an experimental network of 16 sites in four countries across North America and Europe. Earlier this year, Dr. Relyea and that network produced experimental findings led by Canadian scientist Marie-Pier Hébert, which show that lake salinization reduces zooplankton abundance and diversity

The PNAS research, led by The University of Toledo and Queen’s University in Kingston, shows that even at salt concentrations below ranges government regulators have deemed safe and protective of freshwater organisms, significant damage is being done to freshwater lakes.

In particular, increasing salt levels threaten zooplankton, a critical food resource for many young fish, and changes caused by rising salinity could alter nutrient cycling, water quality and clarity, and instigate growth and population declines in economically important fish species.

Researchers say the results indicate a major threat to the biodiversity and functioning of freshwater ecosystems and the urgency for governments to reassess current threshold concentrations to protect lakes from salinization sparked by sodium chloride, one of the most common salt types leading to the salinization of freshwater lakes.

“Salt pollution occurring from human activities such as the use of road de-icing salts is increasing the salinity of freshwater ecosystems to the point that the guidelines designed to protect fresh waters aren’t doing their job,” said Bill Hintz, assistant professor of ecology at The University of Toledo, author, and co-leader of the project. “Our study shows the ecological costs of salinization and illustrates the immediate need to reassess and reduce existing chloride thresholds and to set sound guidelines in countries where they do not exist to protect lakes from salt pollution.”

The lowest threshold for chloride concentration in the U.S. established by the Environmental Protection Agency is 230 milligrams of chloride per liter. In Canada, it’s 120 milligrams of chloride per liter. Throughout Europe, thresholds are generally higher.

It can take less than a teaspoon of salt to pollute five gallons of water to the point that is harmful for many aquatic organisms.

In other countries such as Germany, chloride concentrations between 50 and 200 milligrams per liter are classified as “slightly polluted by salts,” and concentrations between 200 and 400 milligrams per liter are classified as “moderately polluted by salts.” The drinking water guideline is 250 milligrams per liter across much of Europe.

But as the study shows, negative impacts occur well below those limits. At nearly three quarters of the study sites, chloride concentration thresholds that caused a more than 50% reduction in zooplankton were at or below the governments’ established chloride thresholds.

The loss of zooplankton triggered a cascading effect causing an increase in phytoplankton biomass, or microscopic freshwater algae, at almost half of the study sites.

“More algae in the water could lead to a reduction in water clarity, which could affect organisms living on the bottom of lakes as well,” said Shelley Arnott, professor of aquatic ecology at Queen’s University and co-leader of the project and paper. “The loss of zooplankton leading to more algae has the potential to alter lake ecosystems in ways that might change the services lakes provide, namely recreational opportunities, drinking water quality, and fisheries.”

The scientists chose to study zooplankton communities from natural habitats instead of short-duration, single-species laboratory studies because such an approach encompasses a greater diversity of species and naturally occurring predator-prey and competitive interactions over a six-to-seven-week timespan within the zooplankton community.

The study was designed to better understand how the chloride thresholds would hold up in a more natural ecological setting.

They focused on determining if current chloride-based water-quality guidelines protect lake organisms in regions with different geology, water chemistry, land-use, and species pools.

“Many salt-contaminated lakes with chloride concentrations near or above thresholds established throughout North America and Europe might have already experienced food web shifts,” Dr. Hintz said. “This applies to lakes across the globe, not only among the study sites. And the variability in our experimental results demonstrate how new thresholds should integrate the susceptibility of ecological communities at the local and regional scale. While the government guidelines may protect freshwater organisms in some regions, that’s not the case for many regions in the U.S., Canada, and Europe.”

Solutions also include finding ways to strike a careful balance between human use of salt responsible for freshwater salinization with ecological impacts, such as reducing the amount of road salt used to melt winter snow and ice to keep people safe and traffic moving. A previous study led by Dr. Hintz suggests best management practices.

Scientists across the globe contributed to the research “Current water quality guidelines across North America and Europe do not protect lakes from salinization.”

FOR MORE INFORMATION: https://phys.org/news/2022-02-guidelines-insufficient-freshwater-ecosystem-salt.html

Half the world is facing water scarcity, floods and dirty water. Large investments are needed for effective solutions

More than half the world’s population faces water scarcity for at least one month every year. Meanwhile, some people have to deal with too much water, while others have access to only poor water quality. That’s billions of people living with drought in Africa and India, facing flood risks in Bangladesh or lacking clean water due to excessive fertilizer use in the United States, Brazil, China and India.

Climate change exacerbates global water insecurity because it contributes to more frequent and severe droughts, floods and extreme rainfall, accelerated glacier melt, rapid declines in groundwater and the deterioration of water quality. These water-related risks of climate change have negative repercussions for agriculture, energy production, water infrastructure and economic productivity, as well as human health, development and well-being around the world. 

Water is central to the discussions about how societies, economies and governments adapt to climate change, and the vast majority of adaptation strategies already in place are water related. Yet researchers know little about how effective they are. 

As a researcher in the field of climate change and sustainable food systems, I was part of a team that reviewed more than 1,800 case studies for the “Water” chapter of Climate Change 2022: Impacts, Adaptation and Vulnerability, the second part of the Intergovernmental Panel of Climate Change’s Sixth Assessment Report (AR6). This newly released report is the most comprehensive review of climate impacts and how much we can adapt to them since 2014

Water at the center of climate change strategies

The United Nations defines water security as having sustainable access to enough water of adequate quality to support people’s well-being, livelihoods and health, without jeopardizing ecosystems. Water insecurity covers a spectrum of issues—too much, too little, too dirty. 

Unsurprisingly, a large majority of countries have listed water as the priority for adaptation in their climate change plans. In our review of more than 1,800 climate change adaptation strategies, we found that over 80 percent were water-related. Some were in response to water hazards (droughts, floods, groundwater depletion, glacier depletion). In others, the response itself was water-related (irrigation, rainwater harvesting and wetlands conservation).

Yet when we looked at the outcomes of these water-based adaptation strategies, we found that only 359 had been analyzed for effectiveness, meaning that we do not know if most of these strategies actually reduce the impacts of climate change and improve health, well-being and livelihood. 

Adaptation strategies that are enacted without adequate investigation of their effectiveness not only waste scarce resources, but can also distract us from taking more relevant actions that carry larger benefits for the affected population.

Are the strategies working?

Of those 359 strategies, most targeted the agriculture sector. Agriculture accounts for 80 to 90 percent of total water consumed globally and provides water for to 70 percent of people in developing countries with their livelihoods. 

Many of these water-focused approaches included changing the timing and arrangement of crops, choosing better crop varieties and farming techniques, expanding access to irrigation and adopting water conservation practices. 

Non-agricultural water-based adaptations to climate change included adopting better fishery techniques in Ghanaplanting salt-resistant trees in Bangladeshsetting up desalination plants for urban water use in Spain, building flood-resilient housing in Guyana, among others. 

We also found that local, traditional and Indigenous knowledge play an important role in shaping many adaptation responses. For instance, some farmers in Sri Lanka successfully adapted to the 2014 drought by practicing bethma, a traditional technique where the community temporarily reallocated agricultural land among farmers so that each would have similar access to the limited water supply.

Combining local, traditional and Indigenous knowledge with a technical understanding of climate change can lead to the development and implementation of more acceptable and successful climate change adaptation strategies. This not only ensures equitable and inclusive adaptation actions, but also increases the proposed solutions’ effectiveness at minimizing climate change impacts.

Largest number of the adaptation responses, especially those in the agriculture sector, were implemented and led by individual households and civil society bodies. Schemes by governments at various levels of administration—from local to multi-national—comprised the second largest chunk of adaptation strategies.

So far, the role of the private sector has been negligible. Private financing is a minor source of adaptation financing that has mostly focused on developed and emerging economies. Local needs, especially those of the economically disadvantaged communities, have not been adequately addressed by private financing until now. 

At the recent climate change conference in Glasgow, Scotland, global financial firms agreed to fund projects that address climate change mitigation. The translation of these promises into action remains to be seen, but adaptation projects in low- and middle-income countries could benefit a lot from this.

Limited utility and unintended consequences

But we also found that the strategies that work now, might not work in the future. The success of irrigation, soil and water conservation or other agricultural adaptations is contingent on how much warming occurs. 

The benefits of these practices are mostly incremental—the have short-term rewards—and may not always lead to transformative outcomes, such as enabling a community to shifts its livelihood to one with reduced exposure to climate hazards.

We found that some responses have co-benefits: they not only help adapt to ongoing climate change, but also help mitigate (or reduce) future climate change. For example, reusing wastewater for irrigation can have adaptive and mitigative co-benefits. If implemented properly, such projects can not only provide a reliable water source throughout the year, but also reduce the pressure on water treatment infrastructure.

Some adaptation strategies, however, can have long-term negative impacts, called maladaptations. An often-quoted example is that of groundwater overuse for irrigation in India, which currently supports intensive agriculture but is depleting the limited groundwater reserves at a rapid pace.

Adaptation strategies can work, but we need to have a better understanding of their costs and benefits. If the world continues down a high-emissions pathway, these adaptation strategies will start becoming less effective in response to increasingly complex and severe water security issues. 

Water is central to everyone’s health, well-being and livelihood. We must focus on adapting to climate change and mitigating its effects immediately and simultaneously if we are to lessen the hardships of the world’s 10 billion people by 2050. The longer we delay aggressive actions, the higher will be the adaptation costs and smaller will be the opportunity window to undo past actions.

FOR MORE INFORMATION: https://phys.org/news/2022-03-world-scarcity-dirty-large-investments.html

Study reveals trade-offs between ecosystem resistance and resilience to tropical cyclones

In a new study of the ecological impacts of hurricanes, an international research team addresses a question that people have asked for centuries: when confronted by a storm, is it better to be resistant like an oak or resilient like a willow?

The team’s findings, reported in the March 2nd issue of Science Advances, can help guide managers as they plan for climate change and a growing coastal population threatened by tropical storms that are more intense and track farther into temperate latitudes. The findings also provide a framework for guiding management decisions related to other disturbances, such as nutrient pollution or wildfires.

The study’s lead author, Dr. Christopher Patrick of William & Mary’s Virginia Institute of Marine Science, says “We found that coastal ecosystems display consistent tradeoffs between resistance and resilience to tropical cyclones. Our findings emphasize that managing for increased resistance may result in decreased resilience, and vice versa. That knowledge is key for coastal decision making, particularly as climate change alters the risk profile with stronger, more frequent mid-latitude storms.” 

Patrick illustrates these management trade-offs with an example from his role as director of the Seagrass Monitoring and Restoration Program at VIMS. “In the Chesapeake Bay,” he says, “eelgrass tends to be more stable through time than widgeon grass, but takes longer to recover from disturbances such as hurricanes. This trade-off, which would also apply to diebacks from water quality or heat stress, is an important consideration for coastal managers when choosing which species of seagrass to restore.”

The research team comprises 23 scientists from 11 states, Puerto Rico, and Taiwan. Their study is linked to a research coordination network funded by the National Science Foundation to synthesize knowledge concerning ecosystem responses to hurricanes. Joining Patrick as co-authors and members of the network’s leadership team are Drs. John Kominoski of Florida International University, Bill McDowell of the University of New Hampshire, and Beth Stauffer of the University of Louisiana at Lafayette.

FOR MORE INFORMATION: https://phys.org/news/2022-03-reveals-trade-offs-ecosystem-resistance-resilience.html

Office buildings with infrequent water use may have poor water quality

Low-consumption office buildings with infrequent water use could have chemical and microbiological safety issues, according to a study published in PLOS Water by Andrew Whelton at Purdue University, Indiana, United States, and colleagues. The research could have implications for office buildings used less frequently during pandemic lockdowns, and suggests that regular water testing in commercial buildings may be needed.

Many office buildingshave decreased occupancy during weekends and holidays—and recently, during pandemic lockdowns—increasing water stagnation in plumbing. Green buildings are designed to reduce water consumption using efficient fixtures and alternative water supplies. However, due to the combination of lower building water use and low occupancy periods, the safety of water from green buildings is unknown. To better understand chemical and microbiological quality in a green commercial office building plumbing after weekend stagnation, researchers sampled water from a ten-year-old, three story, LEED-certified office building in Indiana between January and February 2020. Samples from all water sources in the building were tested for pH, metals, ions, as well as bacterial strains of Legionella.

Researchers found that copper and lead levels increased over the weekend, and that Legionella counts were highest at a fixture which had no use recorded during sampling. Additionally, the concentration of the disinfectant chlorine decreased over the weekend. The study had several limitations as it relied on self-reported data for measurements of fixture use and may have misreported usage frequency at some locations. Future studies are needed to further analyze how water-saving appliances may impact water quality.

Office buildings with infrequent water use may have poor water quality
Copper contamination in drinking water is often overlooked. Credit: Andrew Whelton, Purdue University, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)

According to the authors, “To prepare plumbing to code, water chemical and microbiological testing is not required or recommended. The green office building studied had many features that are increasingly common in new buildings, including low-flow faucets, automatic faucets, and alternative piping systems for major water uses like toilet flushing and irrigation. These design elements can change water temperature profiles and significantly reduce the amount of water used compared to traditional office buildings, raising concerns for water quality degradation”.

The authors add: “The first people in the office on a Monday morning may, in fact, be using contaminated drinking water. To better understand if the water we are using is safe, much more water testing at the faucet must be conducted. Plumbing design standards and codes must also be revised.”

FOR MORE INFORMATION: https://phys.org/news/2022-03-office-infrequent-poor-quality.html

New scoring scale tracks the harmful effects of salt pollution in freshwater streams and rivers

The road salt that makes your drive to work easier on snowy days may be damaging the water quality in local rivers and streams long after winter is over.

A new study led by University of Maryland scientists sheds light on how salinization from winter road saltcombined with other pollutants creates “chemical cocktails” that can jeopardize the ecological balance of waterways, including those in the Washington, D.C. area. The researchers developed a new five-stage scale to track the progression of this damage, a tool that could inform public policy in the future. The study was published online March 14, 2022 in the journal Limnology and Oceanography Letters.

“We realize this is a really diverse problem that’s caused by road salt, but also other sources of salt pollution in our environment—the fertilizers we put on crops, the sewage we put out, the roads that break down,” explained the study’s lead author Sujay Kaushal, a professor in UMD’s Department of Geology and Earth System Science Interdisciplinary Center. “And it’s not just sodium chloride that’s increasing, it’s all these salt ions that are dissolved in water that contribute to salt pollution.”

Over time, many streams and rivers around the world have become saltier and more alkaline. Salt in this case refers to a wide variety of different compounds in water, which can affect drinking water supplies as well as aquatic organisms and biodiversity. It can also enhance the mobilization of pollutants including nitrates, phosphates, radionuclides and metals.

Kaushal has been studying this problem—which he and his team named Freshwater Salinization Syndrome—for nearly two decades. In this new study, they found that road salts combined with other human-made pollutants are creating conditions that periodically exceed certain regional Environmental Protection Agency (EPA) limits for aquatic life and other limits around the world for good drinking water and agriculture.

After analyzing and reviewing data from around the world, the study’s authors identified five major risk factors for Freshwater Salinization Syndrome. The research team defined stages of its progression, developing a five-tier scoring system for the salt pollution that’s making our rivers sick.

“We’ve developed this five-stage system to identify and track unhealthy progression of salinization in our rivers in much the same way we would track an illness or disease like cancer,” Kaushal said. “We have to look at this unhealthy Salinization Syndrome from a systems-level perspective if we’re going to develop guidelines for diagnosing harmful levels and treat the problem.”

Using a combination of data spanning decades in some of the world’s major rivers and sensors that monitor electrical conductivity in streams and rivers around Washington D.C., Kaushal and his team identified major risk factors that make some waterways more susceptible to salt pollution than others.

These fundamental risk factors included climate, geology, flow paths, human activities and time. The research team then developed a five-level scorecard to track the damaging impact of Freshwater Salinization Syndrome and its water quality symptoms based on risk factors:

Stage 0: Highest water quality, minimally disturbed

Stage I: Abnormally elevated concentrations of one or more salt ions across one season

Stage II: Chronically elevated concentrations of salt ions across multiple seasons

Stage III: Formulation of harmful chemical cocktails exceeding water quality thresholds

Stage IV: Systems-level failures in infrastructure and ecosystem functions and services (drinking water and biodiversity)

Kaushal’s research team found D.C.-area waterways have salt levels exceeding water quality thresholds, scoring higher than Stage II at various times during the year.

“If you look at the Potomac River, it can exceed the EPA regional aquatic life criteria for salt, and the Anacostia River can exceed the United Nations salt limit for crop growth,” Kaushal said. “Parts of the Potomac, the Anacostia and Rock Creek waterways are in Stage III on the scale for at least part of the time, depending on weather, road salt and other factors.”

Gene E. Likens, noted ecosystem ecologist from the Cary Institute of Ecosystem Studies and the University of Connecticut, indicated that this new study is an important step forward in understanding the impact on road salts on waterway ecology.

“The identification and analysis of critical state factors is a major advance in our understanding and management of Freshwater Salinization Syndrome,” he said.

The new salinization scorecard could be a useful tool in diagnosing and treating Freshwater Salinization Syndrome in waterways locally and worldwide. Armed with this type of data on salts accumulating in our waterways and new knowledge of environmental symptoms across stages, policymakers could address the issue with regulations to manage winter salt application as well as other forms of salt pollution that contribute to the freshwater salinization problem and its growing impacts on water quality.

The research paper, “Five State Factors Control Progressive Stages of Freshwater Salinization Syndrome,” Sujay S. Kaushal et. al., was published in Limnology and Oceanography Letterson March 14, 2022.


FOR MORE INFORMATION: https://phys.org/news/2022-03-scoring-scale-tracks-effects-salt.html

Starving manatees will face another rough winter next season

When manatees on Florida’s east coast gather next winter, they’re likely to face another season of starvation.

Despite efforts to reduce pollution in the Indian River Lagoon, where record numbers of manatees died in the past two years, the sea cows are unlikely to find enough seagrass to get through next winter without help. Proposals to improve water quality and protect seagrass died in the Republican-dominated state Legislature, although lawmakers did budget more money for manatee habitat restoration and rescues.

Such rescues appear likely to be needed next winter, as wildlife officials say they expect to mount another emergency feeding operation, in which they supplement the manatees’ natural diet with handouts of lettuce.

“We’re not going to solve the seagrass issue in the Indian River Lagoon over the summer,” said Tom Reinert, south regional director for the Florida Fish and Wildlife Conservation Commission. “So we’ll have to see, but it feels likely we may have to do this again.”

More than 55 tons of romaine and butter leaf lettuce were distributed to manatees near the Florida Power & Light plant in Brevard County, where manatees congregate during the cold months of winter. Unable to tolerate water temperatures below 68 degrees, manatees have learned to come to power plant discharge zones for warmth.

But when manatees concentrate in such numbers, they quickly strip the surrounding area of food, a problem worsened by the loss of vast fields of seagrass in the Indian River Lagoon, a 156-mile-long body of water enclosed by barrier islands that runs from northern Palm Beach County to Volusia County. When fertilizer chemicals such as nitrogen or phosphorus reach the lagoon, they stimulate the growth of algae that blocks sunlight, killing seagrass.

At least 420 manatees have died so far this year from all causes, although malnutrition is thought to be the biggest cause. While this number is lower than the 456 that died during the same period last year, it’s still far higher than the death rate in a normal year.

Mark Perry, executive director of the Florida Oceanographic Society, a conservation group that focuses on the state’s east coast, said water quality may be improving in parts of the lagoon.

For about a year, the lagoon has been spared discharges from Lake Okeechobee, a major source of algae-laden water. In communities around the lagoon, septic tanks are being replaced by sewer systems, reducing another source of pollution. And wetlands have been constructed that extract nutrients from water washing off farms and lawns.

But even if the lagoon’s water quality improves and it gets through the summer without another horrific episode of toxic algae, Perry said seagrass takes time to grow.

“Even if we could correct the water quality problems, get the water right for seagrass to grow,” he said. “It’s going to be a long time, a couple of years. It’s going to be slow, so we’ll still see some elevated mortality.”

Since 2009 the seagrass acreage in the lagoon has decreased by 58%. And the remaining seagrass beds have fallen sharply in productivity, with seagrass cover thinning by 89%, according to the St. Johns River Water Management District.

Water quality showed improvement this year, however, said Ashley Evitt, spokeswoman for the water management district. But while many projects are in the works to reduce incoming pollution and cleanse the lagoon, it will take years for seagrass to recover, she said.

“The district anticipates the need for several years of good water quality to see a substantial response in seagrass restoration; and unfortunately, it isn’t possible to predict water quality for next year or beyond,” she said in an email. “… It would be a fair assumption that until the amount of seagrass in the [Indian River Lagoon] increases, manatees may continue to struggle next winter.”

Three environmental groups have filed formal notice of intent to sue the Environmental Protection Agency for allowing Florida to impose what they considered to be weak water-quality standards with lax enforcement that allowed pollution to build up in the lagoon.

Jaclyn Lopez, Florida director for the Center for Biological Diversity, said Florida does little to enforce standards intended to reduce the amount of fertilizers and other pollutants washing off farms, ranches and lawns.

“We have a bunch of laws and regulations through the Clean Water Act and through Florida’s version of that that are intended to address land use in a way that there isn’t really bad runoff that just pushes all these nutrients into the water,” she said. “Those laws are not being followed and they’re not being enforced. So we have a compliance issue and we also have an enforcement issue.”

The Florida Department of Environmental Protection did not respond to a request for comment.

State Sen. Linda Stewart, D-Orlando, introduced a bill intended to improve water quality by implementing recommendations of the state’s Blue-Green Algae Task Force. These included standards for septic tanks, including inspections every five years and pump-outs of failing systems, as well as other measures to reduce pollution washing off land.

But the bill never made it through the process, with Stewart blaming a difficult legislative session in which the process was slowed by COVID and dominated by social issues that were Republican priorities.

“That would have been a big help if we could have gotten it passed,” Stewart said. “So many things that were important to people of Florida did not get through the process. We had some crazy social issues that seemed to have a higher priority.”

The budget approved by the state Legislature, which is still awaiting the signature of Gov. Ron DeSantis, includes more than $30 million for manatees, paying for expansion of rehabilitation centers, restoration of habitat and additional rescues workers.

Although a repeat of this year’s unprecedented feeding operation, which distributed more than 55 tons of lettuce to hungry manatees, appears likely, it’s not certain. Reinert, of the state wildlife commission, said experts need to analyze the current operation to see whether it was effective before deciding to set up a similar operation next winter.

Pat Rose, executive director of Save the Manatee Club, said the feeding operation needs to be improved, with lettuce offered nearer to where the majority of manatees congregate by the warm-water discharges of the power plant. He said officials need to monitor manatees’ conditions over the summer and should consider beginning the feeding program earlier, in areas where they congregate before temperatures hit bottom.

He said there’s a chance there may be more seagrass available to them next year, even if the improvement is modest.

“None of this is going to change dramatically in a year,” he said. “But we’re seeing some signs of seagrass availability. There are indications that water quality in some of the river systems is getting a little better. That may or may not stay that way.”

FOR MORE INFORMATION: https://phys.org/news/2022-03-starving-manatees-rough-winter-season.html

Team studies greenhouse gas emissions from Appalachian streams

Freshwater ecosystems can be substantial sources of greenhouse gases to the atmosphere, but it can be difficult to figure out how unique aquatic habitat arrangements and connections influence carbon cycling at different scales.

In mountain streams, carbon cycling is affected by many interwoven factors, such as precipitation and the productivity of the surrounding forest. A team of researchers from Virginia Tech studied freshwater greenhouse gas emissions in the mountains of North Carolina to try to better understand how carbon moves through connected streams and wetland networks. 

Kristen Bretz, a Ph.D. candidate, and Erin Hotchkiss, an assistant professor of biological sciences in the Virginia Tech College of Science, recently worked with three undergraduate researchers who have since graduated, on a two-year study at the U.S. Forest Service Coweeta Hydrologic Laboratory.

They found that greenhouse gas emissions from streams and wetlands at Coweeta could be highly variable, but that the presence of a vernal pool, or a small freshwater temporary wetland, in a stream corridor could increase overall emissions.

“This project was an awesome opportunity to envelop several wonderful undergraduate research efforts into the long tradition of Virginia Tech stream research at Coweeta Hydrologic Laboratory,” said Bretz.

Bretz and Hotchkiss, who are both members of the Global Change Center, an arm of the Fralin Life Sciences Institute, published their findings in the Journal of Geophysical Research: Biogeosciences.

“The coolest thing about this paper is that it shows how complex carbon emissions are at small scales—even within a single basin like Coweeta. Zooming in on a landscape can complicate the picture, but we were able to find an interesting linkage between temporary pools and stream emissions of two greenhouse gases: carbon dioxide and methane,” said Bretz.

As parcels of water move through a watershed, they pick up terrestrial materials and flow along pathways in the landscape created by erosion. The biological processes that occur in water moving into and through streams are affected by both soil properties and the arrangements of landscape features, or patches, in and near the channel.

The patches in this study included temporary (vernal) pools, hillside slopes along the streams, stream surface waters, and dry stream beds where the water flows underground.

The exciting results of this research project would not have been feasible without the help of three dedicated undergraduate researchers: Alexis Jackson, Jonathon Monroe, and Sumaiya Rahman. The three recent graduates from the Department of Biological Sciences received numerous accolades for research excellence during their time at Virginia Tech.

In 2019 and 2020, Monroe and Jackson received Undergraduate Research Grant Awards from Virginia Tech’s Global Change Center. Jackson and Rahman conducted their research that contributed to this paper while working as National Science Foundation Research Experience for Undergraduates fellows.

“Their contributions allowed us to move beyond the single-ecosystem approach typical of most research in our field,” said Hotchkiss.

Inspired by her work in the Hotchkiss lab, Jackson recently entered the University of Florida’s environmental engineering Ph.D program as a National Science Foundation Graduate Research fellow.

“The Hotchkiss lab was the foundation to my love for field workand interest in wetland biogeochemistry. Being mentored and surrounded by such skilled, supportive, and innovative women and men has made all the difference in my life and directly impacted my career choice in becoming a wetland ecologist,” said Jackson.

Monroe, now a research assistant at the Mayo Clinic Vaccine Research Group, reflects on his time in the lab. “My time in the Hotchkiss lab was incredibly important in my decision to pursue a career in research,” said Monroe. 

At Virginia Tech, Bretz and Hotchkiss will continue to address knowledge gaps about the water quality and biology of streams in creative ways that will have both local and global implications in the face of climate change.

“Our work provides a unique perspective on how the presence and arrangement of different ecosystems within a landscape control the sources and emissions of carbon gases from mountain stream corridors,” said Hotchkiss.

The study in Coweeta sets the stage for ongoing research, led by Bretz, on how carbon cycling changes as streams dry and rewet and what that means for downstream water quality and food webs.

As climate change is expected to cause longer periods of drought coupled with more intense storms, “work characterizing the variability in freshwater ecosystems will provide critical information about the consequences of those changes on freshwater carbon cycling and water quality,” said Hotchkiss.

FOR MORE INFORMATION: https://phys.org/news/2022-03-team-greenhouse-gas-emissions-appalachian.html

Critical threshold of dissolved oxygen for survival of blue mussel determined

The blue mussel Mytilus edulis, which is a common species of the family Mytilidae, is widely distributed and cultured in coastal waters. It plays an important role in the food web and carbon cycle.

However, as coastal eutrophication rapidly worsens in many regions, both the intensity and duration of hypoxic events increase tremendously, posing a great threat to blue mussels. But how hypoxic stress influences mussel survival as well as their population densitiesremains unknown. 

Recently, a research team led by Prof. Sun Song from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) has determined the critical threshold of dissolved oxygen (DO) concentration for the survival of blue mussel through an experiment covering the DO range of 0.5–2.0 mg L-1during 16-day exposure.

They further assessed the impact of DO fluctuations and poor water quality, and analyzed the responses of metabolic rate and several key enzymes to identify possible physiological stresses. 

The study was published in Marine Environmental Research on Mar. 15.

According to the results, the critical threshold of DO for experimental mussels exposed to 16 days of hypoxia was 0.7–0.8 mg L-1, below which survival dropped drastically from nearly 80% to less than 38%. When hypoxia was combined with DO fluctuations or with poor water quality, the threshold could further rise as the mussels under combined threats suffered higher mortality than those under the single stress of hypoxia. 

In the following physiological and biochemical analysis, the researchers found that the blue mussel was an oxygen conformer that depressed its respiration rate as well as the individual’s total energy requirement when the DO concentration fell below 5–6 mg L-1.

Among all the enzymes analyzed, acid phosphatase and alkaline phosphatase were the most sensitive ones, suggesting that a compromised immune response was another important factor challenging the survival of blue mussel in addition to energy deficiency.

In general, the blue mussel has a strong tolerance against hypoxia, and a moderate hypoxia event is less likely to cause mass mortality. “However, it is worth noting that the survival rate was significantly lower when the DO was at a moderate level of 1.0 mg L-1, but the experimental conditions included a doubled population density, no water change, no water purifier, and no Ultraviolet lamp illumination,” said Li Qiao, first author of the study. “Thus, we strongly recommend that both the DO concentration and the spread of pathogens should be closely monitored in blue mussel mariculture, and that the stocking density should be relatively low under a risk of hypoxic conditions.”

“The findings will help to predict the fate of blue mussels under increased hypoxic events and provide scientific advice for mariculture management,” said Prof. Sun.

FOR MORE INFORMATION: https://phys.org/news/2022-03-critical-threshold-dissolved-oxygen-survival.html

Testing how seaweed biofilters could improve Great Barrier Reef water quality

An innovative new solution using seaweed to help improve water quality on the Great Barrier Reef is progressing to the next exciting phase of research, with on-water trials beginning next month.

Researchers will test whether native seaweed species placed in strategic locations are effective at soaking up damaging pollutants from the water.

The Australian Seaweed Institute developed the nature-based solution, which has already been recognized by the World Economic Forum as one of the top global innovations for protecting oceans.

What affects Reef water quality?

Every year thousands of metric tons of excess nutrients, such as nitrogen and phosphorous from fertilizers, run off the land and out onto the Reef. This can cause harmful algae blooms, reducing light and smothering corals.

The impacts of rising greenhouse gas emissions are also causing the water to become more acidic as the ocean absorbs higher levels of carbon dioxide—threatening the survival of coral reefs and their marine life.

How can seaweed help?

Seaweed has shown promising potential to act as an effective biofilter, controlling pollution by capturing and breaking down these harmful pollutants. Seaweed is ideal because it absorbs carbon, nitrogen and phosphorous from the water to help it grow and provides habitat for marine life.

Both functions could significantly improve the quality of water and marine biodiversity, improving conditions for the entire Reef ecosystem.

What’s been achieved so far?

In 2020 the first stage of work on seaweed biofilters, the concept design phase, identified three native seaweed species that absorb high levels of nutrients—Asparagopsis taxiformis, Sargassum spp and Gracilaria edulis. Researchers also explored the optimal methods for growing these species and carried out in-tank trials.

This work was a collaboration between the Australian Seaweed Institute and Central Queensland University. They found seaweed biofilters have the potential to remove thousands of metric tons of dissolved inorganic nitrogen—a key Reef pollutant—from the water every year.

What’s next?

Under the second stage of research, the proof of concept phase, small seaweed “bio-pods” containing the target seaweed species will be installed in a river estuarine location. These plants will be monitored to see how well they grow and how much nitrogen they absorb. Researchers will then model how the biofilters are likely to perform in various locations across the Reef.

FOR MORE INFORMATION: https://phys.org/news/2022-03-seaweed-biofilters-great-barrier-reef.html