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The Living Planet Index | Earth Wise

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The World Wildlife Fund and the Zoological Society of London recently published the latest Living Planet Index, which is designed to measure how animal populations are changing through time.  The purpose is to provide an assessment of the health of ecosystems and the state of biodiversity.

The LPI only looks at the population of vertebrates:  birds, mammals, reptiles, amphibians, and fish.  The latest survey looked at how populations have changed between 1970 and 2018.  The results are that populations of these animal groups have declined by an average of 69% over that 48-year period.

This result highlights a very real and very severe crisis of biodiversity loss.  However, it does not mean that there are 2/3 fewer animals today than 48 years ago.  The way the index is calculated is to look at the changes in individual populations of over 5,000 different species.  Then these individual relative declines are averaged to get the result.  

There are shortcomings in the LPI.  For example, individual species that have seen massive population declines will bring the average down.  But even removing the outliers both of a negative and a positive impact does not dramatically change the result.

There is no perfect indicator for biodiversity and ecosystem health.  The Living Planet Index is nonetheless a useful metric and indicates that many species around the world are in decline.  Policymakers and environmental advocates need to make decisions about conservation and protection measures and this index is one tool they can use.

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There’s a frightening new report about wildlife declines. But many are getting the story wrong.

Photo, posted October 12, 2019, courtesy of Visit Rwanda via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Turning Plastic Into Protein | Earth Wise

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Our planet is choking on plastic.  According to the United Nations, 79% of the 6.3 billion tons of plastic produced every year accumulates in landfills.  Half of all plastic produced is actually designed to be used just once and thrown away.  But plastic is not only accumulating on land.  In fact, the world’s oceans are projected to contain more plastic by weight than fish by the year 2050.     

According to new research, solving the plastic waste issue could help address another prominent global issue: hunger.  A multidisciplinary team of engineers, chemists, and biologists led by researchers from Michigan Tech University has developed a process to break plastics down to be recycled into useful products, including edible protein powder.

The research team’s process converts plastic into compounds using heat and a reactor that deconstructs the material’s polymer chains. The oil-like substance is then fed to a community of oil-eating bacteria.  The bacteria grow rapidly on the oily diet, producing more bacterial cells composed of roughly 55% protein.  This majority-protein byproduct is then dried out and turned into an edible powder.   The end result doesn’t look like plastic at all.  In fact, it resembles a yeast byproduct that comes from brewing beer. 

This research is funded by an award from the US Department of Defense.  The DoD often deploys soldiers in areas where access to food is challenging.  Converting plastic to protein could be part of a solution to that problem. 

While eating something that began as plastic might take some getting used to, it could be part of the solution to both plastic pollution and global hunger.

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Turning Trash Into Treasure: The Plastic to Protein Powder Solution

Beat Plastic Pollution

Photo, posted February 2, 2022, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Snail Darter Is Safe | Earth Wise

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The snail darter is a three-inch-long snail-eating fish that was once only found in the Little Tennessee River.  When that river was going to be dammed by the Tellico Dam under construction in the 1970s, the snail darter was listed on the endangered species list and the little fish subsequently became the subject of a legal battle that made it all the way up to the U.S. Supreme Court.   With the dam project 95% complete in 1978, the Supreme Court blocked further construction, citing the Endangered Species Act.  A year later, Congress exempted the project from the requirements of the Act, thereby clearing the way for the completion of the dam.

In order to save the snail darter, biologists transplanted the fish into several other nearby rivers and waterways.  In addition, the Tennessee Valley Authority modified the operation of the Tellico Dam to release more oxygen-rich water downstream.  Beyond those measures, the river cleanup under the Clean Water Act further aided the fish’s recovery.

In 1984, the snail darter was removed from the endangered species list and was listed as threatened or vulnerable.  Recently, the U.S. Department of the Interior officially removed the snail darter from the federal list of threatened and endangered wildlife. 

The snail darter is the fifth fish species to be delisted because its population has recovered.  It is the first in the eastern United States.  With better management of water releases at dams, many other imperiled aquatic species could be recovered.

Overall, more than 50 plants and animals have recovered under federal protection, including American alligators, humpback whales, peregrine falcons, and bald eagles.

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Once at Center of Controversial Case, the Snail Darter Fish Is No Longer Threatened

Photo, posted July 22, 2015, courtesy of The U.S. Fish and Wildlife Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pacific Bluefin Tuna On The Rebound | Earth Wise

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The Pacific Bluefin Tuna is a commercially valuable species that is especially prized in Japan.  The fish is particularly valued for sashimi and sushi and large specimens have been known to fetch enormous prices at seafood auctions.

Aggressive fishing reduced the bluefin biomass through the late 1990s and 2000s to only a few percent of its potential unfished levels.  Beginning in 2011, The Western and Central Pacific Fisheries Commission began management measures that reduced the catch of smaller bluefin as well as limited the catch of larger bluefin.  The goal was to allow more fish to grow to maturity.  The Inter-American Tropical Tuna Commission adopted similar resolutions a year later.  Despite these efforts, increasing concern about declining bluefin levels led to a petition to list the species as endangered.  The National Oceanic and Atmospheric Administration’s Fisheries organization determined that while the population was near historical lows, the remaining 1.6 million fish was a sufficient number to avoid the risk of extinction and that the measures in place were sufficient.

A new assessment of the bluefin population has shown that the species is now increasing and includes many younger fish that will help accelerate its rebound.  The assessment by NOAA showed that the bluefin stock was greater than the first rebuilding target set for 2019. 

According to the NOAA Fisheries biologists that performed the assessment, the species has responded exactly as predicted given the actions that were taken.  The bluefin tuna is an amazingly resilient fish and it is continuing to demonstrate that fact.

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International Actions Pay Off For Pacific Bluefin Tuna as Species Rebounds at Accelerating Rate

Photo, posted June 1, 2022, courtesy of Philippe Yuan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rewilding The American West | Earth Wise

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Oregon State University scientists have proposed a series of management changes for western federal lands aimed at re-establishing ecosystems there.  Their proposal would result in more gray wolves and beavers in nearly 200,000 square miles of federal lands in 11 states.

In each of those states, the researchers identified areas containing prime wolf habitat.  Gray wolves were hunted to near extinction in the West but have been gradually reintroduced in some areas starting in the 1990s.  Wolf restoration offers significant ecological benefits by helping to naturally control the population of grazing animals such as elk.  This in turn facilitates the regrowth of vegetation species such as aspen, which ultimately supports diverse plant and animal communities.

Beaver populations, which used to be robust across the West, declined roughly 90% after settler colonialism and are now nonexistent in many areas.  By felling trees and shrubs and constructing dams, beavers enrich fish habitat, increase water and settlement retention, maintain water flows during droughts, and increase carbon sequestration.

According to the researchers, the biggest threat to these western lands is livestock grazing, which has degraded ecosystems to a great extent.  They recommend the removal of grazing on about 30% of the federal lands being used for that purpose and instead would have rewilding efforts go on. 

The American West is going through a period of converging crises including extended drought and water scarcity, extreme heat waves, massive fires, and loss of biodiversity.  Rewilding is a way to reestablish long-standing ecosystems.

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More wolves, beavers needed as part of improving western United States habitats, scientists say

Photo, posted October 1, 2020, courtesy of Tina DaPuglet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Sounds Of Coral Reefs | Earth Wise          

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Coral reefs around the world face multiple threats from climate change, pollution, and other impacts of human activity.  Reef conservation and restoration projects must be able to monitor the health of reefs and that is not such a simple matter.  Surveying reefs generally is labor-intensive and time consuming.  But in a new study, scientists at the University of Exeter in the UK have found a new way to do it.

The fish and other creatures living on coral reefs produce a vast range of sounds.  The meaning of these various sounds is for the most part unknown, but reefs nonetheless have distinctive sonic signatures.

The Exeter researchers decided to make use of machine learning technology.  They trained a computer algorithm using multiple recordings of both healthy and degraded coral reefs.  This essentially taught the computer to learn the difference between them.  A computer can pick up patterns that are undetectable to the human year.  This application of artificial intelligence can tell us faster and more accurately how a reef is doing.

The computer was then used to analyze a set of new recordings, and successfully identified reef health 92% of the time.  The team then was able to use this technique to track the progress of reef restoration efforts.

It is generally much cheaper and easier to deploy an underwater hydrophone on a reef and leave it there instead of having expert divers make repeated visits to a reef to survey its status.  Sound recorders and artificial intelligence could be used around the world to monitor the health of coral reefs and determine whether efforts to protect and restore them are working.

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AI learns coral reef “song”

Photo, posted January 11, 2015, courtesy of Falco Ermert via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Who Can Solve The Plastic Waste Problem? | Earth Wise

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Plastic packaging waste is a global problem.  It collects in the oceans, breaks down into microplastics, which are consumed by fish and in turn by people who eat the fish.  Only 14.5% of U.S. plastic waste is recycled.  Most of it ends up in landfills, where is remains undegraded for hundreds of years. 

A new international study explored the global patterns of plastic packaging waste.  The study found that three countries – the U.S., Brazil, and China – are the top suppliers of waste.  In terms of supply, the Americas generate 41% of the world’s production of plastic waste, Europe 24%, and Asia 21%.

That’s the plastics supply.  As far as the consumers actually creating waste are concerned, the Americas represent 36% of the world’s packaging consumption, Asia 26%, and Europe 23%.

Packaging high-protein food such as meat, fish, and dairy is a major contributor to the waste problem.  Plastic for this purpose is hard to replace and international exports exacerbate the problem, accounting for about 25% of plastic packaging waste.

International agreements typically focus on restrictions and fees on production.  But that mostly creates strong incentives to simply relocate polluting activities to developing countries, which is a zero-sum game.  There need to be incentives for consumers to reduce plastic use such as taxes on waste management, refunds on returning bottles, single-use plastic bans, and so on.

Who can solve the plastic waste problem?  Everyone along the supply chain as well as the final consumers have to be part of the solution for reducing plastic waste.

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Producers and consumers must share burden of global plastic packaging waste

Photo, posted March 29, 2022, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shipping And The Endangered Whale Shark | Earth Wise

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Whale sharks are the largest fish in the world.  While they measure up to 60 feet long and weigh up to 15 tons – larger and heavier than a school bus – whale sharks are actually harmless.  They are a graceful, slow-moving, filter-feeding carpet shark.  They are found in marine environments around the world and play an important role in the marine food web and healthy ocean ecosystems.

Whale sharks are an endangered species.  According to the International Union for Conservation of Nature, growing human pressures are putting whale sharks at an increased risk of extinction.  The numbers of these gentle giants have declined by more than 50% over the last 75 years despite many international protections.  Fishing bycatch, poaching, and collisions with ships are the main drivers of the population decline. 

According to new research from marine biologists from the Marine Biological Association and the University of Southampton in the U.K., lethal collisions between whale sharks and large ships are vastly underestimated, and could be the reason why populations are continuing to fall.  Whale sharks spend a large amount of time in surface waters in coastal regions, and the research team theorized that collisions with ships could be causing significant whale shark deaths. 

In the study, researchers tracked the global movements of both ships and whale sharks, and then mapped so-called hotspots where their movements overlapped.  The research team found that more than 90% of whale shark movements fell under the footprint of shipping activity.

While many conservation measures have been taken to protect whale sharks, no international regulations currently exist to protect them from ship collisions.  The researchers say it’s time for that to change. 

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Shipping poses significant threat to the endangered whale shark

Whale sharks (Rhincodon typus)

Global collision-risk hotspots of marine traffic and the world’s largest fish

Photo, posted July 8, 2010, courtesy of Marcel Ekker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Is It Too Late To Save The Vaquita? | Earth Wise

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The vaquita porpoise, the world’s smallest marine mammal, is on the brink of extinction.  Scientists estimate that just 10 or fewer vaquitas are left despite international conservation efforts. Found only in Mexico’s Upper Gulf of California, the vaquita is the most endangered marine mammal on the planet. 

According to the International Committee for the Recovery of the Vaquita, the number one threat facing vaquitas is gillnets. The porpoises get trapped in these nets and drown.  Gillnets are often used illegally in the region to catch shrimp and fish, including the critically-endangered totoaba.  The totoaba’s swim bladder is considered a delicacy in Asia and can fetch thousands of dollars.  Despite Mexico banning both totoaba fishing and the use of gillnets in the vaquitas’ habitat, many say the bans are not always enforced.  

But there is a reason to be hopeful.  According to a genetic analysis led by researchers at UCLA, the critically-endangered species actually remains relatively healthy and can potentially survive if illegal fishing practices cease immediately. 

In the study, which was recently published in the journal Science, the research team analyzed the genomes of 20 vaquitas between 1985 and 2017 and ran simulations to predict the species’ extinction risk over the next 50 years.  The researchers concluded that if gillnet fishing ends immediately, the vaquita has a very high chance of recovery.  If the practice continues, however, even moderately, the likelihood of a recovery plummets. 

According to the research team, the surviving vaquitas are actively reproducing and seem healthy.  But poachers’ gillnets will continue to pose an existential threat to the species until more measures are taken to protect the vaquita. 

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Only 10 vaquita porpoises survive, but species may not be doomed, scientists say

Photo, posted October 18, 2008, courtesy of Paul Olson / NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Assessing Human-Caused Wildlife Mortality | Earth Wise

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Bycatch is the fishing industry term used to describe the deaths of non-target fish and ocean wildlife during the fishing process.  Some bycatch species are thrown away because regulations prohibit them from being kept.  Others are thrown out because they won’t fetch high enough prices.  According to some estimates, global bycatch amounts to about 10% of the world’s total catch. 

Approximately half of global bycatch is a result of trawling.  Trawling is a method of commercial fishing that involves pulling or dragging a fishing net – called a trawl – through the water or across the seabed in hopes of catching fish.  Commercial fishing companies favor towing trawl nets because large quantities of fish can be caught.  But the method is destructive to the seafloor and leads to the indiscriminate catch of all sorts of species, including whales, dolphins, porpoises, sharks, seals, rays, turtles, and seabirds. 

Researchers have developed a new method to assess the sustainable levels of human-caused wildlife mortality.  When this method is applied to a trawl fishery in Australia, it shows that the dolphin capture is not sustainable.  The study, led by scientists at the University of Bristol in the U.K. and United Arab Emirates University, modeled different levels of dolphin capture, including those reported in logbooks and those reported by independent observers.  According to the findings, which were recently published in the journal Conservation Biology, even the lowest recorded dolphin capture rates are not sustainable. 

The new approach is extremely adept at assessing human-caused mortality to wildlife, and can be applied to fisheries bycatch, hunting, lethal control measures, or even wind turbine collisions.

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Wasted Catch

Dolphin bycatch from fishing practices unsustainable, study finds

Photo, posted May 18, 2011, courtesy of Pete Markham via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lighted Nets Protect Marine Wildlife | Earth Wise

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Gillnets are walls or curtains of netting that hang in the water to trap fish.  They are one of the most extensively used fishing gear in coastal regions throughout the world’s oceans.  While they are very effective at catching targeted fish species, they are not discriminating.  As a result, they carry significant risk of bycatch – the accidental capture of unwanted species as well as other interactions with various marine animals.

Researchers from The Wildlife Conservation Society, NOAA Fisheries, Arizona State University, and the National Fisheries and Aquaculture Institute of Mexico have recently published a study showing that using lighted gillnets reduced overall bycatch by 63%, including a 95% reduction in sharks, skates, and rays, and an 81% reduction in Humboldt squid. 

Gillnets often catch endangered, threatened, and protected species such as sharks, sea turtles, marine mammals, and seabirds, as well as unwanted species and non-marketable juvenile target fish species.  The bycatch animals are often dead or injured and are generally dumped overboard.

Illuminating gillnets with LED lights has emerged over the past decade as an effective tool to reduce bycatch of endangered sea turtles.  The new study is the first detailed examination of the effectiveness of illumination for other vulnerable species.

Gillnets are ubiquitous because they are inexpensive and catch everything that passes them.  Global populations of sharks, skates, and rays have declined as a result of bycatch and illegal fishing. The results of this study are encouraging because they provide a practical solution for increasing the selectivity of gillnets and avoiding bycatch. 

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Lighted Nets Dramatically Reduce Bycatch of Sharks and Other Wildlife While Making Fishing More Efficient

Photo, posted September 19, 2015, courtesy of Jim Bahn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And The World’s Fisheries | Earth Wise

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According to a new study, approximately 70% of the world’s oceans could be suffocating from a lack of oxygen by 2080 as a consequence of climate change.  This has the potential to impact marine ecosystems all around the world.  

The study, which was recently published in the journal Geophysical Research Letters, is the first to use climate models to predict how and when deoxygenation will occur throughout the world’s oceans outside of its natural variability. 

According to the findings, significant and potentially irreversible deoxygenation of the ocean’s middle depths began occurring last year.  The models predict that deoxygenation will begin affecting all zones of the ocean by 2080.

According to the study’s models, mid-ocean depths are already losing oxygen at unnatural rates. Globally, the ocean’s middle depth – known as the mesopelagic zone – is home to many of the world’s commercially fished species.  This makes these new findings a potential harbinger of economic hardship, seafood shortages, and environmental disruption. 

Just like land animals, aquatic animals need oxygen to breathe.  As climate change warms the oceans, the water holds less oxygen and is more buoyant than cooler water.  This leads to less mixing of oxygenated water near the surface with deeper waters, which naturally contain less oxygen.  Warmer water also raises oxygen demand among living organisms, resulting in less availability for marine life. 

The researchers also found that oceans closer to both the North Pole and the South Pole are particularly vulnerable to deoxygenation.  While they are not yet sure why, accelerated climate warming could be the culprit. 

These findings should add new urgency to climate change mitigation efforts. 

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Climate change has likely begun to suffocate the world’s fisheries

Photo, posted January 28, 2019, courtesy of Joseph Gage via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Capturing Methane To Feed Fish | Earth Wise

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Methane in the atmosphere is an extremely potent greenhouse gas.  Its warming potential is about 85 times that of carbon dioxide over a 20-year period.  It also worsens air quality by increasing atmospheric ozone.  Many human activities add methane to the atmosphere, notably emissions from landfills and oil and gas facilities.

Capturing methane from these sources for subsequent use is currently uneconomical but new research from Stanford University analyzes the market for using the methane to feed bacteria to produce fishmeal.

Methane-consuming bacteria called methanotrophs can be grown in chilled, water-filled bioreactors containing pressurized methane, oxygen, and nutrients.  The bacteria produce a protein-rich biomass that can be used as fishmeal in aquaculture.  This could offset demand for fishmeal made from small fish or plant-based feeds that require land, water, and fertilizer.

Some companies already do this using natural gas provided by utility pipelines, but it would be far better for the environment to use methane emitted at large landfills, wastewater treatment plants, and oil and gas facilities.

Consumption of seafood has more than quadrupled since 1960, depleting wild fish stocks.  Farmed fish now provide half of all the animal-sourced seafood we eat.

The Stanford research analyzed the cost of methanotrophic fishmeal production under various scenarios and found it to be very competitive with and in some cases considerably cheaper than current market prices for fishmeal. 

According to the study, this process could profitably supply total global demand for fishmeal with methane captured in the U.S. alone.

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Stanford researchers reveal how to turn a global warming liability into a profitable food security solution

Photo, posted April 30, 2017, courtesy of Artur Rydzewski via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Marine Heatwaves And Fish | Earth Wise

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Marine heatwaves are periods of abnormally high temperatures in the ocean that can trigger devastating impacts on ecosystems, including coral bleaching, toxic algal blooms, and mass mortality events.  Marine heatwaves can occur in any ocean and in any season.  They are defined based on the differences between actual and expected temperatures for the location and time of year.     

According to several studies, even under moderate climate warming scenarios, oceans will experience more frequent and longer-lasting marine heatwaves in the years to come.

Researchers from the University of British Columbia’s Institute for the Oceans and Fisheries in Canada have found that extremely hot years will wipe out hundreds of thousands of tons of fish globally this century.  These losses are in addition to the projected decreases to fish stocks from long-term climate change. 

Under a worst-case scenario where no action is taken to curb greenhouse gas emissions, the research team’s model predicts a 6% drop in the amount of potential catches per year.  In addition, the biomass (or amount of fish by weight) is projected to decrease in 77% of exploited species due to the extreme temperatures.

As a result of climate change and these extreme heat events, the research team projected that fisheries’ revenues would decrease by an average of 3% globally, and employment would fall by 2% globally – a loss of likely millions of jobs.

The research team says active fisheries management is critical.  Catch quotas, for example, need to be adjusted in years when fish stocks are suffering from marine heat events.  In severe cases, the fisheries may need to be shuttered in order to allow fish stocks to rebuild.  

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Fevers are plaguing the oceans — and climate change is making them worse

Marine heatwaves could wipe out an extra six per cent of a country’s fish catches, costing millions their jobs

Photo, posted October 11, 2016, courtesy of Kahunapule Michael Johnson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coral Reefs And Ecosystem Services

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A new study led by the University of British Columbia provides the first comprehensive look at what climate change, overfishing, and habitat destruction of coral reefs mean for their ecosystem services.  For humans, this means how the global decline in coral reefs has affected their ability to provide essential benefits including food, livelihoods, and protection from storms.

The study found that global coverage of living corals has declined by about half since the 1950s and the diversity of reef species has declined by more than 60%.  So, it is no surprise that there has been a significant loss in the ability of reefs to provide ecosystem services.

The study analyzed data from coral reef surveys around the world, fisheries catches, indigenous consumption, and more.  Apart from the declines in reef coverage and biodiversity, the study found that fish catches on coral reefs peaked in 2002 and has steadily declined since then, despite increased fishing efforts.

The findings of the study led the researchers to conclude that continued degradation of coral reefs in the years to come threaten the well-being and sustainable development of millions of people in communities on the coast that depend on coral reefs.  Fish and fisheries provide essential nutrients in places with few alternative sources of nutrition.  Coral reef biodiversity and fisheries have added importance for indigenous communities, where important cultural relationships exist with reefs.

The study’s authors say that the results are a call to action.  The level of destruction happening all over the world’s coral reefs is threatening people’s culture, their daily food, and their history.  It is not just an environmental issue; it is a human rights issue.

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Photo, posted September 22, 2010, courtesy of David Burdick / NOAA Photo Library via Flickr.

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Coral Reefs And Fish Survival | Earth Wise

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The precarious state of the world’s coral reefs has been a highly visible subject for a decade or more.  Mostly what we hear about is the loss of some of the most beautiful sights on the planet. But there is far more at stake than scenic wonders.

The warming and acidifying of ocean waters are causing corals to increasingly bleach and often die.  Corals provide a unique food source for some species of fish and a three-dimensional habitat for many others.  The fish that depend on corals are often prey for fish that don’t depend directly on corals and so on up the food chain.

What happens to fish when coral reefs disappear?  The fish species that feed on corals will starve while others will seek alternative rocky habitats.

A new study by the University of Helsinki uses statistical methods to predict how fish diversity will respond to declines in coral diversity. It concludes that a future coral loss might cause a 40% reduction in reef fish diversity globally.  This is more than a loss of colorful sights for snorkelers; reef fishes provide essential protein for millions of people around the world.

The estimate of potential loss of fish species greatly exceeds the number of species known to depend directly or even indirectly on coral.  The implication is that coral reef food webs will begin to unravel if corals go extinct.  This unraveling is expected to be worse in some places than others.  The Central Pacific, for example, could lose 60% of its reef fish.

For both snorkelers and for the millions who depend upon reef fishes for food, the need for greater efforts to conserve and restore coral reefs is apparent.

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A fu­ture ocean that is too warm for cor­als might have half as many fish spe­cies

Photo, posted September 27, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Gulf Of Mexico Dead Zone | Earth Wise

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Every summer, a so-called dead zone forms in the Gulf of Mexico.  It is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. 

When these excess nutrients reach the Gulf, they stimulate excess growth of algae, which eventually die and decompose, depleting oxygen as they sink to the bottom.  These low oxygen levels near the Gulf bottom cannot support most marine life.  Animals that are sufficiently mobile – such as fish, shrimp, and crabs – generally swim out of the area.  Those that can’t move away are stressed or killed by the low oxygen.

A team of scientists funded by the National Oceanic and Atmospheric Administration issues an annual forecast for the dead zone based upon a suite of models that incorporate river flow and nutrient data. 

The 2021 forecasted area is somewhat smaller than, but close to, the five-year measured average for the dead zone, which is 5,400 square miles, roughly the size of the state of Connecticut.   Each year, these forecasts are reported as comparisons to long-term averages, but the problem is that the long-term average is unacceptable.

The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force has set a goal of reducing the size of the dead zone to a five-year average of 1,900 square miles – about a third of the current average.

Large reductions in nutrient loads have been called for in federal and state action plans for nearly 20 years, but clearly these reductions have not yet been sufficient. The Interagency Task Force continues to provide information for managing nutrient loads in the Mississippi River Basin. 

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Average-sized ‘dead zone’ forecast for Gulf of Mexico

Photo, posted October 6, 2020, courtesy of Christine Warner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The World’s Largest Harmful Algal Bloom | Earth Wise

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Brown sargassum seaweed floats in surface water in a bloom that stretches all the way from West Africa to the Gulf of Mexico.  Sargassum provides habitat for turtles, crabs, fish, and birds.

The stuff carpets beaches along the tropical Atlantic, the Caribbean Sea, the Gulf of Mexico, and the east coast of Florida disrupting tourism.  Florida’s Miami-Dade County alone spends $45 million a year cleaning up sargassum.  Annual Caribbean clean-up is in excess of $120 million.

A study by Florida Atlantic University has discovered dramatic changes in the chemistry and composition of sargassum which has transformed the so-called Great Atlantic Sargassum Belt into a toxic dead zone.

The findings of the study suggest that increased nitrogen availability from both natural and human-generated sources, including sewage, is supporting blooms of sargassum and turning a critical marine nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health.

The study found that today’s sargassum tissues compared with those of the 1980s have 35% more nitrogen content and 42% less phosphorus.  Much of the nitrogen increase is a result of agricultural and industrial runoff from the Congo, Amazon, and Mississippi Rivers. 

The fact that the bloom itself has expanded so tremendously was already suspected to be the result of significant changes in the ocean’s chemistry.  Given the negative effect that the Great Atlantic Sargassum Belt is having on the coastal communities, additional research is essential to guide mitigation and adaptation efforts.

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Sargassum now world’s largest harmful algal bloom due to nitrogen

Photo, posted June 5, 2016, courtesy of J Brew via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Biodiversity And Trawling Bans | Earth Wise

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Trawling is a method of commercial fishing that involves pulling or dragging a fishing net – called a trawl – through the water or across the seabed in hopes of catching fish.  Commercial fishing companies favor towing trawl nets because large quantities of fish can be caught in one go.  

However, the trouble with trawling is that it’s destructive to the seafloor and indiscriminate in what it catches.  When towing these large trawl nets, the largest of which is reportedly big enough to catch thirteen 747 jets, everything that happens to be in the way gets caught.  As a result, trawling results in lots of bycatch, a fishing industry term used to describe the deaths of non target species during the process. 

In 2012, the Hong Kong government implemented a territory-wide trawling ban in its waters in hopes of rehabilitating the marine benthic habitat.  The benthic zone refers to the ecological region at the bottom of the ocean. 

Researchers from City University of Hong Kong collected sediment samples from 28 locations six months before the trawl ban and two and a half years after the trawl ban to see whether such interventions can facilitate ecosystem recovery. 

According to the study, which was recently published in the journal Communications Biology, the ban on trawling significantly improved marine biodiversity.  The researchers observed substantial increases in the richness of species and the abundance of benthic marine organisms following the trawling ban.  And since small benthic organisms are the main source of food for large species like fish and crabs, the trawling ban actually helps support fisheries.

More governments should consider a trawl ban to promote sustainable fisheries and marine biodiversity conservation.

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Research confirms trawl ban substantially increases the abundance of marine organisms

Photo, posted December 4, 2018, courtesy of John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Oil Platforms And Biodiversity | Earth Wise

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We have previously reported on the important role that offshore oil platforms seem to play for fish.  In short, the support structures of offshore oil platforms that often rise hundreds of feet through the water column create essentially a prefabricated reef for marine life.

According to a new study recently published in the British journal Ecological Solutions and Evidence, the large gatherings of fish around oil and gas platforms attract harbour porpoises searching for food – despite the fact that noise from industrial activities normally scares porpoises away.    

Harbour porpoises are one of the smallest whale species and the only whale species that’s known to breed in Danish waters.  The species has been protected in Danish waters since 1967.  Previous studies have demonstrated that underwater noises from sources like shipping and industry typically scare porpoises away. 

But according to new research from scientists at Aarhus University in Denmark, there are actually more porpoises around the largest Danish oil platform – Dan F – in the North Sea than there are within the three to ten kilometers surrounding the platform.  The research team found that the platform acts as a natural reef where porpoises can find favorable habitat and food. 

Currently, the international OSPAR convention requires that all decommissioned oil and gas platforms be removed from the ocean.  But according to researchers, leaving the old platforms in the ocean to serve as artificial reefs is actually more beneficial to the marine environment. 

In the Gulf of Mexico, the United States program Rigs to Reefs has converted 558 oil and gas platforms into artificial reefs.

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Harbor porpoises attracted to oil platforms when searching for food

Photo, posted March 26, 2008, courtesy of Dave Herholz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)