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Marine Heat Waves | Earth Wise

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In late July, the ocean temperature measured in Florida Bay, between the southern end of the Florida mainland and the Florida Keys, was 101.1 degrees Fahrenheit, a possible world record for sea surface temperature.  There is no official record keeping for ocean temperatures, but the highest previous reading ever reported was 99.7 degrees in the middle of Kuwait Bay in 2020. 

What is going on is a marine heat wave and marine heat waves can last for weeks, months, or even years.  The current Gulf of Mexico marine heat wave has been present for several months, beginning in February or March.  Experimental forecasts by the National Oceanic and Atmospheric Administration say the extreme ocean temperatures in the area may persist through at least October.

The ocean absorbs 90% of the excess heat associated with global warming.  Therefore, marine heat waves all over the planet are becoming warmer over time.  The current marine heat wave would likely have occurred even without climate change, but because of it, the event is extraordinarily warm.

Marine heat waves cause stress to corals and other marine ecosystems.  Exposure to extreme temperatures for long periods of time causes corals to eject the algae that live inside of them, resulting in white or pale coral.  This coral bleaching leaves the coral without food and will ultimately kill it.

In general, extreme heat can be destructive and deadly for marine ecosystems.  A massive marine heat wave known as “the Blob” took hold in 2013-2016 in the northeastern Pacific Ocean and led to an ecological cascade of fishery collapses, toxic algal blooms, and record numbers of humpback whale entanglements.

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The ongoing marine heat waves in U.S. waters, explained

Photo, posted December 25, 2016, courtesy of Paul Asman and Jill Lenoble via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Oxygen Loss In Lakes | Earth Wise

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Researchers from Cornell University and Rensselaer Polytechnic Institute have found that the continual warming in the world over the past 25 years has been reducing the amount of oxygen in many lakes.

Data from more than 400 lakes – mostly in the United States – shows that lakes with dissolved oxygen losses strongly outnumber those with gains.  Overall, the researchers found that the amount of low oxygen water is increasing by 0.9% to 1.7% per decade on average  and the volume of lake water lacking oxygen has increased by more than 50% from 25 years ago.

In the summer, lake surfaces may be about 70 degrees while the lake bottom may be about 40 degrees.  The colder water is denser than the warmer water which causes resistance to the layers mixing.  It is akin to having oil and vinegar in a cruet.  This is known as stratification.   The result is that oxygen from the atmosphere is prevented from replenishing dissolved oxygen in deep waters.  This is a normal seasonal phenomenon.

However, with winter ending sooner than it used to, seasonal stratification is starting earlier and ending later. As warming continues, it is likely that there will be an increasing number of oxygen-depleted lakes in the future.

Oxygen deprivation in water can lead to hypoxia (low oxygen) and even anoxia (no oxygen), which have negative consequences for fish and other species.  Reducing oxygen in lake water can lead to buildup of methane.   Nutrients from agricultural runoff, released from unsettled lake sediment, increase the likelihood of harmful algal blooms.

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Warming climate prompts harmful oxygen loss in lakes

Photo, posted June 23, 2010, courtesy of Alexander Acker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And The Color Of Lakes | Earth Wise

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According to a new study recently published in the journal Geophysical Research Letters, blue lakes around the world are at risk of turning green-brown if climate change continues unabated. 

For the study, the research team used over five million satellite images of more than 85,000 lakes and reservoirs around the globe between 2013 and 2020 in order to determine each lake’s most common water color.  Since lake color can change seasonally, the researchers assessed the most frequent lake color during those seven years. 

Algae and sediments affect the color of lakes.  But the study found that precipitation, air temperature, lake depth, and elevation also play major roles in determining a lake’s most common water color. 

The research team found that blue lakes account for less than one-third of lakes worldwide.  Blue lakes tend to be deeper and are often found in cool, high latitude regions with high precipitation and winter ice cover.  Meanwhile, green-brown lakes, which account for 69% of all lakes, are found in drier regions, continental interiors, and along coastlines. 

As global temperatures rise, lakes will warm, and warmer water produces more algal blooms.  As a result, the researchers expect the changing climate to decrease the percentage of blue lakes, many of which are found in the Rocky Mountains, northeastern Canada, northern Europe and New Zealand. 

Water color is a simple but viable way to measure water quality that can be done on a global scale using satellites.  This approach provides researchers with a way to study how lakes – even the remote ones – are changing.  

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Climate change is making lakes turn green-brown

Photo, posted August 27, 2011, courtesy of Paul Schultz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Prospects For Floating Solar | Earth Wise

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Countries are trying to figure out how to get enough energy from solar and wind generation to completely decarbonize their economies.  According to some estimates, nations might have to devote between half a percent and five percent of their land area to solar panels to get the job done.  Half a percent is about the amount of the U.S. that is covered by paved roads.  While there is lots of open land in many parts of the country, covering it with solar panels might not be acceptable to farmers, conservationists, or other interested parties.

One way to deploy more solar panels without using up land is the use of floating solar panels.  Floating photovoltaic systems – also known as floatovoltaics – are becoming increasingly common, especially in Asia.  This year, China installed one of the largest floatovoltaic systems in the world on a reservoir near the city of Dezhou.

Floating solar panels stay cooler and run more efficiently than those on land.  The panels also help prevent evaporation from their watery homes and the shading they provide also help to minimize algal blooms.  Solar installations on reservoirs generally puts them near cities, making it easier to feed power into urban grids.

On the other hand, floating solar systems need to be able to withstand water and waves and are generally more expensive to build than land-based systems.

At present, the installed global capacity of floating solar is only about 3 gigawatts, compared with more than 700 gigawatts of land-based systems. However, reservoirs around the world collectively cover an area about the size of France.  Covering just 10 percent of them with floating solar could produce as much power as all the fossil-fuel plants in operation worldwide.

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Solar Takes a Swim

Photo, posted March 7, 2019, courtesy of Hedgerow INC via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Manatees And Pollution | Earth Wise

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Manatees are large, gentle, and curious marine mammals measuring up to 13 feet long and weighing up to 3,300 lbs.  There are three living species of manatees:  The Amazonian Manatee, the West African Manatee, and the West Indian Manatee, which is commonly found in Florida and the Gulf Coast.  Manatees inhabit the shallow, marshy coastal areas and rivers of the Caribbean Sea, the Gulf of Mexico, the Atlantic coast, the Amazon basin, and West Africa. 

The West Indian Manatee, which includes the Florida Manatee, is protected under the Endangered Species Act.  Today, the range-wide population is estimated to be at least 13,000 manatees, with more than 6,500 in the southeastern United States and Puerto Rico.

In Florida, an uptick in nutrient loading from nonpoint sources is triggering algal blooms in Indian River Lagoon and neighboring areas.  These algal blooms have decimated seagrass, manatees’ primary food source. 

As a result , manatees have starved to death by the hundreds along Florida’s east coast.  The state has recorded 974 manatee deaths in 2021, shattering previous annual all-time highs with still approximately two months to go.  Manatees, which need to eat between 100-200 pounds of seagrass daily, are now eating the seagrass roots, which permanently kills the aquatic plants.

Efforts are being made to replant seagrass and to restore clam and oyster beds so that the mollusks can help clean the water.  But manatees face a myriad of additional threats, including collisions with boats and ships, temperature changes, disease, and crocodile predation.

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Florida lawmakers hear Fish & Wildlife agency response to manatee death ‘catastrophe’

West Indian manatee

Preliminary 2021 Manatee Mortality Table by County

Photo, posted May 7, 2010, courtesy of Jim Reid/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfires And Algal Blooms

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Australia is no stranger to wildfires. But the 2019-2020 season proved to be particularly severe: wildfires destroyed 3,100 homes, displaced 65,000 people, and burned more than 72,000 square miles – roughly the same size as Washington State. The season is colloquially referred to as the Black Summer.

According to a new study recently published in the journal Nature, clouds of smoke and ash from these wildfires triggered widespread algal blooms thousands of miles downwind to the east in the Southern Ocean.

The study, which was led by researchers from Duke University, shows that aerosol particles in the smoke and ash fertilized the water as they fell into it.  This provided the nutrients that fueled unprecedented blooms in that region, conclusively linking for the first time a large-scale response in marine life to fertilization by pyrogenic iron aerosols from a wildfire.

This finding raises questions about the role wildfires may play in the growth of phytoplankton, the microscopic marine algae that – through photosynthesis – absorbs large amounts of climate-warming carbon dioxide from Earth’s atmosphere. 

According to the research team, the Australian algal blooms were so extensive that the subsequent increase in photosynthesis may have temporarily offset a substantial portion of the wildfires’ CO2 emissions.  It remains to be seen how much of the absorbed CO2 remains safely stored in the ocean and how much it has been released back into the atmosphere. 

The researchers plan to investigate the fate of the phytoplankton further.  They also plan more research to better predict where and when aerosol deposition will boost phytoplankton growth in the future.  

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Australian wildfires triggered massive algal blooms in Southern Ocean

Photo, posted January 12, 2020, courtesy of BLM-Idaho via Flickr.

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Road Salt Pollution

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Mirror Lake is a popular recreational lake located in the Village of Lake Placid.  It is the most developed lake within the Adirondack Park, which is a publicly protected area that is actually larger than Yellowstone, Yosemite, Glacier, and Grand Canyon National Parks combined.

New research has revealed that road salt runoff into Mirror Lake is preventing natural water turnover which poses a risk to the balance of its ecology.  The study, which was published in Lake and Reservoir Management, found that road salt runoff is preventing spring mixing of the water column.    This creates more anoxic water conditions, meaning there is less oxygen in the water, and limits the ability of the habitat to support the native lake trout. 

Mirror Lake is the first lake in the Adirondack Park to show an interruption in lake turnover due to road salt.  Many lakes in northern climes experience so-called “dimictic turnover”, which is a natural process where wind and less stratified water conditions of spring and fall allow mixing of the water column that redistribute oxygen and nutrients throughout the lake.  High levels of surface-water chloride introduced into the lake from road salt runoff inhibit the mixing of the water column.

The lack of mixing and oxygenation is bad news for fish species such as lake trout, which require cold, oxygenated water to survive.  It may also put the lake at a greater risk of algal blooms.

Mirror Lake is small, surrounded by concentrated development, and receives the direct discharge of stormwater.  So, it is particularly vulnerable to road salt contamination.  Other lakes elsewhere in New York may experience similar conditions.  The researchers are confident that natural turnover conditions could be restored to the lake if road salt application in the watershed is reduced.

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Road salt pollutes lake in one of the largest US protected areas, new study shows

Photo, posted January 5, 2018, courtesy of MTA of the State of NY via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving The Sea From Salt

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The Persian Gulf along with the Red and Mediterranean seas are getting saltier all the time because of the waste products of desalination.   The United Arab Emirates, Saudi Arabia, Kuwait, Qatar, Bahrain and Oman account for 45% of the world’s desalination capacity.  And the byproduct of desalination is brine, which is twice as salty as seawater.   Even advanced desalination plants produce two cubic meters of waste brine for every one cubic meter of clean water.

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Preventing Toxic Algal Blooms

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We have talked about the growing problem of toxic algal blooms on a number of occasions.  The increasing occurrence of these blooms has been associated with rising temperatures and carbon dioxide levels as well as the presence of wastewater nutrients and agricultural fertilizers in rivers, lakes and reservoirs.  The most notable incident occurred in the summer of 2014, when algae contamination in Lake Erie left 400,000 residents in Ohio and Michigan without water for 72 hours.

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Nitrogen Pollution Suffocates Fish

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Atlantic Menhaden

In Riverhead, Long Island the stench of rotting fish is becoming all too familiar. Over the past two months, the Department of Environmental Conservation estimates more than 400,000 Atlantic menhaden, commonly called bunker, have washed up on the shores of the Peconic River – which sits between Long Island’s north and south forks. The culprit: nitrogen pollution.

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