All posts by Mark Shepherd

About Mark Shepherd

I work in the environmental movement helping to protect the air we breathe, the water we drink, the land that sustains us and the natural and biological resources we depend on.

Are Insect Populations Declining?

Yellow Scarab Beetle in the Monteverde Cloud Forest, Costa Rica.  Photo by Mark Shepherd

On a recent trip to research insect populations, I visited a small sliver of the Chihuahua desert that runs through the extreme southeast corner of Arizona, I encountered hundreds of eager hover flies.  I say eager, because the flies followed and buzzed around me relentlessly.  While I couldn’t identify any single individual fly, I am certain that a few of them followed me for more than half a mile as I trekked through the dry, rock strewn, dusty desert.  I am not a dancer, but all of the swatting, arm waving, and stumbling probably made me look like I move like Mic Jagger.  Relief came when wind from an approaching thunderstorm forced the flies to land or be blown away.

Of course, the flies were after me because I was a source of water and salt in the middle of a desert.  The flies need both to survive and reproduce.  With a life span measured in weeks, the flies had no time for politeness.  Their tiny biological clocks were ticking.   They were in their golden days, having already lived most of their young lives as larvae and then metamorphosing into the annoying fly stage that zipped just a little too close to my ear canals.  For me it was irritating, but for the swarming flies, it was all-or-nothing; do or die.

Many amazonian insect species were drawn to light.
Many amazonian moths and other insect species can be seen by hanging a sheet and light.  Photo by Mark Shepherd, Peru

Insect Bias

As a group insects get a lot of bad press, when they get any at all.   Biting and stinging insects of course figure prominently in many stories. There are a number of published articles headlining that insects make up a significant number of invasive species, which is partially true.  But the biases against our chitin covered earthmates are largely out of proportion.   Why is large group of caribou called a herd, but a large group of insects is a swarm.  Swarm has a more sinister, negative connotation.  Swarming hover flies are pests.  While many people mourn the loss of the huge buffalo populations that use to wander the western prairies, no one would likely invest in a hover fly reintroduction program if their populations dropped significantly.   Insects are not generally considered a charismatic species, meaning they don’t draw the attention that elephants and polar bears garner.  No one pines for the years when painful, stinging harvester ants were more plentiful in east Texas.  No one has established a non-profit to reintroduce the rocky mountain locust, whose past populations inspired the following letter from E. Snyder of Highland Kansas:

At our place they commenced coming down about 1 O’clock in the afternoon, at first only one at a time, here and there, looking a little like flakes of snow, but acting more like the advance skirmishers of and advancing army; soon they commenced coming thicker and faster, and they again were followed by vast columns, or bodies looking almost like clouds in the atmosphere.  They came rattling and pattering on houses, and against the windows, falling in the feilds, on the prairies and in the waters – everywhere and on everything.  By about 4 o’clock in the afternoon, every tree and bush, buildings fences, fields, roads and everything, except animated beings, was completely covered by grasshoppers. 

The disappearance of the locusts that terrorized the American frontier is noteworthy in that it happened to an insect pest that, at the time, no one believed was vulnerable to extinction.   Why? Because insects appear to be so numerous it is difficult to imagine them being eradicated.  They are described as “R” selected, meaning they have short lifespans and produce enormous numbers of offspring, among other traits.  Such characteristics may seem to make insects invincible, but the truth is many insects are especially vulnerable to habitat loss and invasive species.  Even if insects produce a large number of eggs, they usually have specific habitat requirements necessary to ensure survival.

Researchers have noted insect population declines in many sites across Europe.
Iron clad beetle (Zopherinae sp.) has and extremely tough outer shell, one of the strongest known.  Photo by Mark Shepherd,  Driftwood, Texas.

Declining Populations

A recent article in Science (May 12, 2017) reports that insect biomass captured in traps spread across more than 100 European nature reserves has dropped dramatically since the 1980’s.  Members of the Krefeld Entomological Society, a group of amateur entomologist that have been monitoring insect abundance, raised concern after comparing earlier masses of insects trapped to those in 2013.   Whether similar declines are happening in other locations around the world is difficult to say, because there are too few surveys across multiple years to make anything stronger than a guess.  Also, insect populations can vary significantly from one year to the next, in cycles that may last several years to a decade.  So even if annual surveys were available, for some insect species, it still wouldn’t be enough.  Finally, the lack of public awareness concerning the extinction risk of many insects, other than honey bees and monarch butterflies, means there is likely insufficient funding to conduct surveys.

So why be concerned about declining insect populations?  Because they pollinate most of our food crops, aerate the soil, control other pests, and feed those bat, bird, and fish species we humans so love to photograph.


Vaquita: The World’s Rarest Marine Mammal Is In Trouble

Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, Illustration by Justin Shepherd
Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico. Illustration by Justin Shepherd

Another species of marine mammal is on the verge of extinction.  The Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, is reportedly just 30 individuals away from being lost forever.  The name vaquita is Spanish for “little cow,” and it looks somewhat like a panda mixed with a dolphin.   Because individuals suffer high mortality when trapped in illegal gill nets used by fishermen, the vaquita populations have plummeted since 1997.  Mexico has spent millions trying to stop the illegal practice of using gill nets, but to date has not been able to prevent it completely.

Faced with the imminent loss of the vaquita, the Mexican government approved a conservation plan in April, 2017.  The plan, however, may not be implemented until October, 2017, as there are many logistical hurdles, including building enclosures to house the captive breeding program.  There are also many unknowns, such as whether the vaquita will breed in captivity, how long they live, what age they mature sexually, and the minimum number of individuals necessary to keep the species from going extinct.  It will be tricky to get all of the things needed to save the vaquita by October.  Let’s hope the efforts that the Mexican government is taking, and the recent awareness brought to the issue by Leonardo De Caprio and several wildlife conservation organizations, will help turn things around.   Otherwise, like the Chinese river dolphin, we will lose another unique aquatic species.

Killing Poachers

Many are familiar with the worldwide effort to stop the illegal hunting of endangered wildlife.  Some nations have created wildlife refuges where hunting is limited, while other nations, such as Costa Rica, have banned hunting altogether.  Creating a refuge is challenging enough, but enforcing hunting limitations is far more difficult.  Even in the well protected reserves in Africa, poachers still manage to kill threatened elephant and rhinoceros. The animals are typically killed for their ivory horns and tusks. Recently, several accusations have been leveled that game wardens in India may be going too far by killing poachers.

Wild greater one-horned rhinoceros (Rhinoceros unicornis) standing by a forest track in Kaziranga National Park, Assam, India. Park wardens on bicycles in the background. Photo by Jeremy Richards;
Wild greater one-horned rhinoceros (Rhinoceros unicornis) standing by a forest track in Kaziranga National Park, Assam, India. Park wardens on bicycles in the background. Photo by JeremyRichards

Encountering poachers is dangerous, as they are often organized and armed. Several game wardens who have crossed paths with poachers have been killed in the line of duty.  Nonetheless, accusations have arisen that wardens use excessive force against poachers, sometimes with the tacit approval of conservation minded individuals.  Wildlife guards in India’s famous Kaziranga National Park, in Assam, have recently been accused of using excessive force sanctioned by the Indian Government.  One such accusation was leveled by British Broadcasting Corporation reporter Justin Rowlatt.  In his  film titled Killing for Conservation , Rowlatt reported that guards were given immunity from prosecution for killing or injuring poachers:

“the park rangers were killing an average of two people every month – more than 20 people a year. Indeed, in 2015 more people were shot dead by park guards than rhinos were killed by poachers. Innocent villagers, mostly tribal people, have been caught up in the conflict.”

Officials with India’s National Tiger Conservation Authority (NTCA) dispute that wardens are given authority to kill-on-sight.  The NTCA go further stating that Rowlatt’s film is biased and misleading, and was not submitted for review prior to airing. Moreover, The NTCA has banned BBC from filming in any other tiger reserves for five years.

Several aspects lend credence to the film’s claim that there is a shoot-to-kill policy.  Firstly, the film shows interviews with several guards who state that they have been told to kill any poachers caught in the conservation park.  The film also shows interviews with several individuals from nearby villages who tell stories of family members killed in the park, not because they were not poaching, but because they accidentally strayed into the park.  In one instance, a father describes how his young son was shot in the leg by guards who mistook him for a poacher.  The park management reportedly compensated the family for their mistake.  Even the interviews with park managers appear to support that there is, if not a policy, at least unspoken approval and support for killing poachers on-sight.

There were, however, also several facts that seem to lend credence to the NTCA’s claim that the goal of the film was to sensationalize.  That Rowaltt did not offer  authorities the opportunity to comment on interview statements, prior to broadcasting the film, could be interpreted as biased reporting.  There is nothing that would seemingly have prevented the BBC from airing the film in spite of any objections.  So why did Rowlatt not submit it for review.  In another instance, Rowlatt appears to speak negatively of the World Wildlife Fund, the organization he indicates is providing funds, equipment, and training for the park guards. He asks whether donor would be alright knowing that their donations are going to train these wardens.  The statement seems odd when placed against the gravity of the shoot-to kill accusation.

Left uncertain in the whole affair is whether the number of poachers killed in the last few years is truly a result of a policy that lowers the threshold for using deadly force, or, as also reported, there is an increase in the number of poachers willing to take a risk for the valuable ivory.  It would appear unlikely that individuals willing to poach are unarmed, as it would be difficult to kill an elephant, even a small one, without a weapon.  Thus, any confrontation between poachers and guards is likely to be a high risk situation.  The presence of so many villagers on the outskirts of the park, where there are no fences to mark its perimeter, makes the probability of accidental shootings almost inevitable.


Protecting Elephants

In October of 2016, in what was considered a surprising move, the United States, the European Union and several African nations voted against an all-out ban of the elephant ivory trade;
African Elephant in Kenya Photo by Kevin Lings

In October of 2016, in what was considered a surprising move, the United States, the European Union and several African nations voted against an all-out ban of the elephant ivory trade.  It was a surprising move in that there was strong support in favor of a ban from the countries hosting the two largest elephant ivory markets: the United States and China.

There were several reasons offered as to why the ban failed.  One reason had to do with the technical structure of the ban, which contained a potential loophole giving illegal ivory trading cover under the limited legal trade.  Another reason given was that banning all ivory trading would reduce incentive to protect elephants and to establish effective elephant conservation programs.  A similar argument is used to support hunting of game birds and other animals in the United States, such as duck, alligator, deer, wolves, and more recently, bears.  It is not at all clear, however, that such limited, legal hunting necessarily results in sustainable population sizes.  Also, elephants are a potentially vulnerable because they are a K-selected species, meaning they have large body sizes, are long lived, have few offspring, and don’t usually reach sexual maturity until between 12 and 16 years of age.  That likely means that sustainable hunting may mean very few in the population can be hunted without impacting the ability of elephant populations to remain stable.  Yet another reason given was that populations of elephants are too large to warrant an all-out ban, something that should be afforded to only to species whose populations are teetering on the edge of extinction.

While legal hunting programs have apparently benefited some species of game birds, whether such programs truly work for larger, or even other small species is uncertain.  After all, populations subjected to legal hunting regimes are typically nowhere near the size of populations 30 to 100 years ago.  In addition, it is important to remember that no one really knows what the sustainable population size truly is.  The passenger pigeon reportedly had incredibly large populations only a few years before they completely disappeared.  There are some species with small population sizes that are stable, while others, especially those that exhibit strong social structures, need a much larger populations size than would be recognized as the minimum.

The good news is that both of the two largest markets for elephant ivory have or are set to ban imports and trading.  Last year China, the largest consumer of elephant ivory, announced a ban on imports and trading that will take effect later this year.  The United States finalized regulations last year (July 6, 2016) banning virtually all future imports and trading.  How effective the ban will be depends upon enforcement and whether the risk of illegally obtaining ivory is worth the reward.  In any case, there does seem to be hope for one of the public’s favorite animals, even while lesser known species continue their silent, unmitigated march toward extinction.


Haleakala Flightless Moth

haleakala flightless moth final
Haleakala flightless moth (Thyrocopa apatela). Photo by Mark Shepherd

Many species in the Hawaiian islands are known to be endemic (found nowhere else).   An example is the Haleakala flightless moth. This moth is not just restricted to the Hawaiian Islands, but it can only be found on the windswept western slopes of the summit of Haleakala volcano.  Its scientific name is Thyrocopa apatela.  It is, however, more commonly known as the Haleakala flightless moth or the Haleakala grasshopper moth.


It survives in very harsh, desert-like conditions near the summit, where temperatures average from 50 to 65 degrees Fahrenheit (10-18°C) during the day, and may drop below freezing temperatures at night.  Because the moth lives at elevations above 9,000 feet (2,900 m), the air is thinner and solar radiation is more intense than at sea level; another factor contributing to the harsh conditions of its habitat.  The name Haleakala means “house of the sun” and the thin air means the sun is brighter here.  The thin air is also one of the reasons there is an observatory on the summit of Haleakala, where light from space is less distorted than at lower elevations.  

The summit of Haleakala volcano, Maui, Hawaii. Photo by Mark shepherd

The moth’s restricted habitat appears to be getting even smaller. Surveys during the 1970’s found moths living at altitudes as low as of 5,000 feet (1,524 m) . Recent surveys, however, only found  moths above 9,500 feet (2,895.6 meters), perhaps due to invasive Argentine ants (Iridomyrmex humilis).  The abundance of many native insect species is reduced in areas invaded by Argentine ants.  Theses ants have been named one of the worlds top 100 worst invasive species.

Advantages to Being Flightless

It might seem odd that a moth with wings is flightless, however several winged insects live in aeolian areas, where winds are strong.  In windy habitats , the ability to fly may be a disadvantage.   The obvious disadvantage is the potential injury from being smashed against the dry, rock strewn landscape, reminiscent of the surface of Mars.  A second disadvantage is that strong winds may blow moths away from potential mates.  Remember, these moths are only found near the summit.  A third potential disadvantage is that strong winds blow the insects into rainwater where they can drown.  So there appears to be some advantages to being flightless.

Ecology and Behavior

The Haleakala flightless moth hops in a similar way to crickets, and is able to jump ten times its body length.  Adults are largely scavengers of organic material and the moth caterpillars feed on dead leaves.  Beside this, very little information is available on the ecology of the Haleakala flightless moths.  A quick review on google scholar turned up only three results pages, and most of the studies found provided little more than taxonomic (biological classification) information.

Haleakala flightless moth is able to hop 10 times its body length.
Photo by Mark Shepherd

If you find yourself on the island of Maui, you should make the journey up to the caldera of the now extinct Haleakala volcano to see this remarkable moth and a whole host of other rare species that populate the national park – before they are gone forever.

To see more of the Earths biodiversity, click on the link below to visit MyEarth.

The Still Mysterious Case of Missing Bees

Honey Bee (genus Apis) foraging in the field. Photo by Mark Shepherd
Honey Bee (genus Apis) foraging in the field. Photo by Mark Shepherd

We are just four months shy of the 10-year anniversary when David Hackenberg reported losing two-thirds of his bee hives to a phenomenon now known as Colony Collapse Disorder (CCD).   It was in October of 2006 that Mr Hackenberg, a Pennsylvania bee keeper, noticed that 2000 bee colonies he had transferred to Florida to pollinate crops were devoid of almost all adult bees, except the queen.   Like a scene out of a science fiction movie there were no bodies left to explain what happened.  All of the adult bees took flight from the hive never to return, leaving combs filled with honey and larvae.  In January of 2016, Maryam Henein published a story online noting that David Hackenberg had again lost a large number of bee hives.  This time 90 percent of his colonies.   Mr. Hackenberg was not alone in his losses, with other bee keepers reporting large colony losses.  He is now a part of a civil lawsuit filed against the United States Environmental Protection Agency alleging that the ongoing sale and use of neonicotinoid pesticides have caused rapid honey bee kills with long-term effects leading to bee colony mortality, bird mortality, nationwide water and soil contamination, and other environmental and economic harms.  Other researchers, however, question the role  that neonics, as neonicotinoids are often called in the bee keeper industry, play in CCD.

Neonicotinoids are a group of insecticides used on a variety of crops, such as apples, pears, peaches, walnuts, cucumbers and many others.  The most widely used neonicotinoid is imidacloprid. Mimicking the molecular structure of nicotine that is found in a variety of plants such as tobacco, and that can act as a natural defense against insects, neonics over-stimulate insect nerve cells. The over-stimulation results in the noticeable twitching of insects that are fatally poisoned.

In 2012, researchers led by Chensheng Lu of Harvard University  published a paper indicating that exposing bee hives to  imidacloprid led to the death of colonies in significantly higher numbers than hives not exposed to the insecticide.   In the study, however,  dead bees were found on  the ground near the hives, something not seen in colonies affected by CCD.  Hives affected by CCD were reported to be  empty with few, if any, dead bees found.  The researchers explained that the reason they found dead bees was that their study was conducted in winter conditions, where snow on the ground made finding dead bees easier.  In warmer latitudes, sick bees could fly farther and the bodies might not be found.  So it seemed that the mystery might have finally been solved, right?  Well, no.

In March 2013, the FDA published the results of  a 3-year study indicating that while imidacloprid could cause effects on bee health and colony success, effects were not seen at doses typically encountered in the field.  The FDA report stated that even at some high doses imidacloprid,

“had no significant effects on foraging activity or other colony performance indicators during and shortly after exposure…. Given the weight of evidence, chronic exposure to imidacloprid at the higher range of field doses (20 to 100 μg/kg) in pollen of certain treated crops could cause negative impacts on honey bee colony health and reduced overwintering success, but the most likely encountered high range of field doses relevant for seed-treated crops (5 μg/kg) had negligible effects on colony health and are unlikely a sole cause of colony declines”.  

honey bee on flower (apis melifera) photo by mark shepherd
honey bee on flower (apis melifera)

Further, the FDA and Mary Berenbaum, previously at the National Academy of Sciences, noted that Chensheng Lu, “never tested for the presence of pathogens, so his conclusions dismissing other likely causes don’t follow from his data“.  The FDA also noted that with bee populations in 2015 at a 20-year high, the CCD phenomenon identified in 2006 was likely a cyclical  phenomenon that has occurred several times over the last century,  making CCD less of a concern.  Or does it?  Bear in mind that many of the honey bee populations are started with queens that share a very similar genetic makeup, and thus, are potentially susceptible to similar diseases.  If a virus, bacterium, or mite was the real culprit behind CCD,   having some many queens and colonies with such a similar genetic make up could mean another event like the 2006 CCD phenomenon could have a potentially devastating effect.

The general molecular structure of Imidacloprid, a neonicotinoid insecticide suspected of causing colony collapse disorder.
The general molecular structure of imidacloprid, a neonicotinoid insecticide suspected of causing colony collapse disorder.

For more information see the links below

USDA study concludes neonics not driving bee deaths—As White House set to announce pollinator revival plan’





Diversity among Some Environmental Organizations

A review of board members and executives at several large and well known environmental organizations finds little diversity in leadership positions.
African American Hiker Photo by Mark Shepherd

If the biological world exhibited a similar diversity in the number of species present that several environmental organizations do with regard to minorities in positions of leadership, it would be an extremely impoverished world.   I reviewed the online list of board members and executives at several large and well known environmental organizations, and was very surprised to find that there is very little diversity in leadership positions, and almost no African Americans.  There were only a few Hispanics, Asians, and at one prestigious environmental organization, there were no African Americans.  That’s right, not one!

Diversity Review

To be fair, there are limited positions, though several environmental organizations’ list of board members is long – very long.  You would think that in an organization with a list of nearly 50 board members and executive staff, there would be at least one African American.  Perhaps that is just an artifact of my online survey, which only included active board members in 2016, but I have my doubts.  I am sure that every organization seeks to recruit dedicated talent to their senior level positions, and who wants to be included in an organization solely for the purpose of helping to attain the semblance of diversity.  It was, however, rather odd to see positions such as Managing Director of continents such as Africa, that were no more diverse than, say, a Managing Director of Europe.

Reasons for Low Diversity Among Environmental Organizations

Several reasons have been proffered to account for the lack of diversity among environmentalist, and environmental organizations, including the lack of minority participation as environmental volunteers, the shortage of minorities pursuing science degrees or attaining the skills and experience necessary to make attractive candidates.  I, however, think the issue is much deeper than opportunities.  Marshall Shepherd wrote an excellent piece in Forbes, “Why Do Many Minorities Avoid Science?”   While the issue I am discussing is not specifically about minorities in science, I think the reasons mentioned in the article are related to minority representation in environmental organizations.  In his article, Marshall Shepherd quoted several minority professors and scientists who opined on the lack of minorities in science.  Several opinions focused on lack of exposure to science at an early age, the lack of minority scientists as role models, a low connection of minorities to science, and even a distrust of the system.  All of which seem reasonable, but only deal with one side of the issue, that of the availability of qualified minority professionals.  Only a couple dealt with the other potential issue: perceptions of minorities by the predominantly white leaders of environmental organizations, and in particular perceptions of African Americans.  A quote by Calvin Mackie, President and founder of STEM NOLA (Science, Technology Engineering, and Math – New Orleans, Louisiana) discusses the issue of perceptions.

“It’s a problem because no one sees it as one. Think about it, STEM people are taught to solve problems. ..if the problem exist. .. in their eyes, it’s our problem, own it and solve …without accepting any responsibility that they are the barriers.  It’s mind over matter, we don’t matter because they (the professions) don’t mind!

Involving the Next Generation

To be sure, this is more than an academic issue to me.  I have two children, both of whom are, of course, minorities.  My daughter stands second in her very academically rigorous high school class of nearly 500 plus students, and my son has just finished his second year of college with a 3.9 GPA , while double majoring in Biology and Biochemistry.  I certainly have involved them in my environmental research and they have had numerous experiences with environmental issues, especially during the time period when I was Vice President of Environmental Health and Safety at a fairly large power company.  I also recently decided to volunteer more in a few environmental organizations, something I have done before, though once again in fairness, not for these organizations.  I feel I am doing my part to assure there are well qualified minorities available.  I hope environmental organizations, some of which have finally recognized the issue, will also do the very best they can to be more inclusive.


Shepherd, M. (2016, January 18). Why do many minorities avoid science? Forbes Science.


Link to the article below:


Photo by Mark Shepherd:  African American hiker in Big Bend National Park

Monk Parakeet Populations Growing


Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires);
Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires).
Photo by Rich Lindie

In 1939, nearly 77 years ago, the Carolina Parakeet (Conuropsis carolinensis) was declared extinct.  At the time, it was United States’ only known native parrot.  The cause for its extinction is not certain, but is frequently reported to be the result of deforestation.  Some experts, however, believe deforestation and hunting may have reduced the

populations sufficiently to allow other factors, such as disease, to be the proximate cause of extinction.  Whatever the cause, the species’ population decline appears to have been rapid, occurring sometime between 1896 and 1904.   The last one died in captivity in 1918 at the Cincinnati Zoo (Click on the book cover to the right to get a copy of an excellent book Errol Fuller discussing the Carolina Parakeet and other extinct species titled, “Lost Animals”).

Since 1968, a new parakeet is taking up residence in some habitats formerly occupied by the Carolina Parakeet.  Also known as the Quaker parakeet, the monk parakeet is native to South America, occurring from central Bolivia and southern Brazil, south to central Argentina.  Monk parakeets (Myiopsitta monachus), believed to have been accidentally or intentionally released, are now found in several states of the U.S., and can also be found in Canada, Puerto Rico, Bahamas, West Indies, England, Belgium, Italy, Spain, and Israel.  In the United States breeding populations occur in Texas, Louisiana, Florida, Illinois, New York and as far north as Connecticut.

Here in Austin, as in all major Texas cities, there is an established population of monk parakeets.  They are almost always found in groups, frequently searching the ground for seeds and any fallen fruit, which is reported to be their main diet.  They are also frequently found on electric transmission lines crisscrossing the city.

Monk Parakeets are unique among the psittacines (parrots) in that rather than making their home in cavities, they build large communal nests using sticks, often among those same transmission lines, which is the only potential problem with any increase in their numbers.

Populations of monk parakeets are thought to be growing exponentially, and while they do not seem to pose the same pest problem in United States that they do in their native South America, there is still concern that could change.   One study reports that parakeet populations will likely continue to expand and grow for the foreseeable future (Pruett-Jones et al., 2007).

Click the link below to see a short video of monk parakeets in Austin, Texas

monk parakeets short 2

Pruett-Jones S, Newman JR, Newman CM, Avery ML, Lindsay JR: Population viability analysis of monk parakeets in the United States and examination of alternative management strategies. Human-Wildlife Conflicts. 2007, 1:35-44.

Green Sea Turtle (Chelonia mydas)

Photo by Willyam Bradberry

Green Sea Turtle (Chelonia mydas)

AKA: Pacific green turtle, black (sea) turtle

Green Sea Turtle (click on this link to watch)

While diving off the coast of Hawaii, I encountered multiple green sea turtles in the shallow areas around the shore.  Adult green sea turtles are primarily vegetarians and feed on sea grass and algae.  Juvenile turtles are reported to eat crabs and jellyfish, in addition to sea grass and algae.  When fully grown, green sea turtles may weigh between 300 and 350 pounds, with one very large turtle reportedly weighing nearly 700 pounds.

The name “green sea turtle” refers to the color of its dermal fat (layer of fat beneath the skin).  The turtle’s shell is typically brown in color, as in the video.  In  some parts of the eastern pacific, green sea turtles have shells that are reportedly olive to black.  Greens sea turtles have also been reported to be one of the few turtles to leave the water for reasons other than to lay eggs.  They range across the tropical and subtropical waters of the earth.

In subtropical areas and temperate areas, where shallow water temperatures during the winter are cold, green sea turtles may experience cold stunning.  When this occurs, their hear rate and blood circulation decrease, they become lethargic, and barely move.  They often appear to be “dead” but may be very much alive.  If the turtle remains in a prolonged state of cold stunning, they may die.  Being unable to swim also makes them vulnerable to various types of accidents or drowning.  In 2013, there were a record number of turtles reportedly stranded by cold stunning along the Atlantic coast, but fewer in subsequent years.   Along the Texas gulf coast, cold stunning does not occur as frequently and is not prolonged, but does occur.  Warming sea temperatures may result in fewer cold stunning events, but may also result in other changes more detrimental to green sea turtles.

Green sea turtles are listed as endangered by the IUCN (International Union for the Conservation of Nature), and the U.S. Fish and Wildlife service lists breeding populations along the Florida and Pacific coast of Mexico as endangered. Divers, swimmers and snorkelers may swim and photograph the turtles, but are prohibited from harassing or capturing green sea turtles and their eggs.



Here are a few links for more information:

What are the Health Risks Associated with Fossil Fuel Power: How Much Do You Know?


In the United States, there are approximately 6,997 power plants with a capacity to generate at least one megawatt of electricity (United States Energy Information Agency [EIA], 2013). Each of these power plants may operate one or more electric power generators resulting in an estimated 19,023 individual generators (EIA, 2013). It is estimated that U.S. power plants produced 3.8 billion kilowatt-hours (KWh) of electricity in 2013 (EIA, 2014). Plants combusting fossil fuel (coal, oil, natural gas) supplied approximately 66% of the U.S. electrical energy needs, nuclear power plants provided 19% and renewable energy plants provided another 13% (EIA, 2014).

The public health risks associated with power plants are largely dependent upon pollutants released from the fuel used to generate heat. The primary pollutant emissions from coal combustion include particulate matter, nitrogen oxides, sulfur oxides, carbon monoxide, methane, carbon dioxide, mercury, volatile organic compounds (VOCs), and heavy metals (United States Environmental Protection Agency [EPA], 2013). Natural gas-fired plants also emit nitrogen oxides, carbon dioxide and methane, but in lower quantities than coal-fired power plants. Sulfur oxides and mercury emissions from natural gas combustion are negligible (EPA, 2013a). Nuclear power plants and renewable power plants do not have emissions from combustion; however, nuclear plants discharge large quantities of high temperature water used for cooling. In addition, nuclear power plants generate nuclear waste that is difficult to dispose and remains hazardous for thousands of years (Chapman, 2012).

Here I focus on risks associated with fossil fuel power generation; however, it is important to recognize that risks occur along the entire fuel cycle, from resource extraction to waste disposal. The public and occupational health risk from nuclear power generation is primarily related to radiation exposure during all stages of the fuel cycle (Hamilton, 2011). Secondary health risks include trauma (Hamilton, 2011). Among five renewable energy categories (geothermal, hydropower, photovoltaics, wind, and solar), trauma is the primary occupational hazard during power production operations. Exposure to toxic brines, hydrogen sulfide and radon are also occupational and public health risks at geothermal plants (Hamilton, 2011).


Fuel Type and Carbon Emissions The two charts show the relationship between fuel type and carbon emissions for U.S. energy consumption in 2010. Source: U.S. Energy Information Administration
Fuel Type and Carbon Emissions. The two charts show the relationship between fuel type and carbon emissions for U.S. energy consumption in 2010. Source: U.S. Energy Information Administration

Fossil Fuel Power Benefits and Risks

Fossil fuel power production has allowed unprecedented industrial and population growth from a fairly low dollar cost energy source. Wilkinson et al. (2007) noted that the exploitation of fossil fuels is integral to modern living and has been a key element of the rapid technological, social and cultural changes during the past 250 years.  Their review paper noted that 2.4 billion of the world’s population, disadvantaged by a lack of access to clean energy, are exposed to high levels of indoor air pollutants from inefficient burning of biomass fuels.

Community health risks associated with fossil fuel power plants are unique, not because they are the only sources for certain pollutants, but because of the quantities of pollutants emitted. For instance, according to the EPA 2011 national emissions inventory data, fossil fuel power plants accounted for 69% of all anthropogenic emissions of sulfur dioxide (SO2) (EPA, 2014). The majority of power plant SO2 emissions are from coal (98%), further distinguishing them from natural gas-fired and oil–fired power plants (0.7%). Short-term exposure to SO2 has been associated with an array of adverse respiratory effects, including bronchoconstriction and increased asthma symptoms (EPA, 2014). Fossil fuel power plants emit approximately 51% of all anthropogenic mercury emissions, of which coal-fired plants account for 97% (EPA, 2014).  Mercury may remain in the atmosphere for long periods of time before depositing into the environment where it can bioaccumulate. Fossil fuel power plants also emit other hazardous heavy metal air pollutants, including arsenic (62%), nickel (28%) and chromium (22%) (EPA, 2014).

Risks to the natural environment from fossil fuel power plants include heavy metal discharges into water and ground water from coal pile runoff; leachate from coal ash landfills; discharges related to equipment maintenance and cleaning; cooling tower blowdown; discharges from wastewater treatment; and heavy metal air emissions that deposit into water and onto land surfaces. EPA surveys of groundwater near ash landfills and surface impoundments have demonstrated that arsenic may exceed human health thresholds by more than four orders of magnitude and poses the greatest risk for heavy metal discharges from coal plants (EPA, 1998). At oil-fired plants, arsenic, vanadium, and potentially nickel, are of greatest concern.

Power Plants often use billions of gallons of water for rivers, lakes and the ocean for use in cooling.
Power Plants often use billions of gallons of water from rivers, lakes and the ocean for use in cooling. Photo by Mark Shepherd


Another risk to the natural environment that does not involve a pollutant discharge is that of water withdrawals for cooling. To generate power, many power plants boil water to generate steam. The steam spins a turbine which generates electricity. After the steam passes through the turbine, it must be cooled to be recycled. To cool this water, power plants pull water from streams, rivers and estuaries for use in cooling towers or heat exchangers. A single power plant is able to pull hundreds of millions of gallons of water for use in cooling. In the United States, fossil fuel power plants account for 91% of all cooling water withdrawals (EPA, 2014). Large water withdrawals from lakes, rivers, estuaries and other water bodies may result in aquatic organisms being impinged on screens meant to filter debris. Small fish and eggs may be entrained, leading to a loss of early life stages needed to maintain healthy populations. A majority of power plants (71%) are also located within two miles of water bodies that are impaired due to excess nutrient loadings or other forms of pollution (EPA, 2014g). Thus, impingement and entrainment may exacerbate the loss of species and critical habitat from pollution.

The risks associated with fossil fuel power are not evenly distributed across fuel types or within fuel types. A study of non-climate change-related damages caused by air emissions from 406 coal-fired power plants estimated that 50% of the plants with the lowest damages together produced 25% of the net generation of electricity, while 10% of the plants with the highest damages also produced 25% of the net generation (National Research Council [NRC], 2010). Similarly, a review of 498 natural gas-fired facilities noted that there were major differences in pollution generation. Ten percent of the gas-fired plants accounted for 65% of the damage (NRC, 2010).


Greenhouse Gas Emissions from Fossil Fuel Power Plants

This natural gas-fired power plant along the south Texas coast has lower pollution emissions than similarly sized coal-fired plants.
This natural gas-fired power plant along the south Texas coast has lower pollution emissions than similarly sized coal-fired plants.
Photo by Mark Shepherd

Greenhouse gas (GHG) emissions from power plants have been identified as a long-term risk causing worldwide climate change (Schaeffer et al., 2015). The current and future impact from climate change depends upon a large number of factors, making risk estimation a complex and difficult undertaking. Haines et al. (2000) identified GHG risks to human health that include direct exposure to thermal and weather extremes, and indirect effects that include alterations in vector-borne infectious diseases, water quality and quantity, and changes in agricultural productivity. An example of vector-borne disease risk from climate change includes that of the St. Louis encephalitis virus. The virus, which can cause inflammation of the brain when transmitted to humans, depends on meteorological triggers for virus amplification between mosquitoes and wild birds (Day, 2001). Several researchers reported that climate change has caused an earlier onset of the spring pollen season in the Northern Hemisphere, potentially exacerbating asthma symptoms (D’Amato et al., 2002; Weber, 2002; Beggs, 2004). Other impacts from climate change include regional declines in fish populations (Brooks et al., 2002). Moore et al. (2008) identified potential impacts in marine and fresh water systems that include lower pH, changes to vertical mixing, precipitation and evaporation, and harmful algal blooms.

Forty percent of all greenhouse gases are emitted by fossil fuel power plants (75% of these are from coal-fired plants) (EPA, 2014). As of 2011, fossil fuel power plants in the United States that emit 25,000 tons or more of carbon dioxide equivalent (CO2e) greenhouse gases must report annual emissions to the EPA. The list of chemicals regulated under the program includes carbon dioxide, methane, nitrous oxide, and a number of fluorinated hydrocarbons. Fossil fuel power plants primarily emit carbon dioxide, with smaller quantities of methane and nitrous oxide. While carbon dioxide is the greenhouse gas emitted in large quantities, methane and nitrous oxide have larger global warming potentials (GWP). Methane has a 25 times larger GWP and nitrous oxide has a 298 times larger GWP than CO2.


Occupational Risks

Compared to other industries, occupational injury numbers and rates in the United States are generally low among power generating facilities. The Electric Power Research Institute (EPRI) collects and publishes information on the number of occupational injuries and illnesses reported by participating power facilities. EPRI reported that the most frequent types of injury (1995-2011) was sprains and strains (38.5%); cuts, lacerations and punctures (15.2%); and contusions and bruises (8.5%) (EPRI, 2013). The greatest occupational risks are associated with fossil fuel power plants. The United States Department of Labor (DOL) shows one fatality per year in 2012 and 2013 among fossil fuel electric power generating plants (DOL, 2014). In 2013, 82% of the approximately 2,200 recordable injuries within the power generation industry occurred at fossil fuel power plants. Nonfatal injury incident rates per 100 full-time employees at fossil fuel power plants was 1.4 in 2013, which interestingly is lower than hydroelectric power generation (2.3), but higher than nuclear power generation (0.2) (DOL, 2014). Illnesses such as respiratory conditions, poisonings from chemicals, and skin diseases are generally low at fossil fuel power plants. Hearing loss, however, represents the highest illness category among fossil fuel plants. In 2013, hearing loss incident rates per 10,000 full-time employees at fossil fuel plants was 20.1, or approximately 55% of all the reported illness incidents (DOL, 2014).

Exposure to coal dust at coal-fired power plants has not resulted in illness rates similar to those in coal mines (DOL, 2014). The reason is not completely understood. While coal ash (material remaining after coal combustion) contains many of the same mineral and metal constituents as coal dust, it does not appear to be as toxic (Borm, 1997).



To address these risks the EPA has proposed a number of regulations to protect the community and natural environment, particularly for coal-fired and oil-fired power plants. Many are the result of continuing efforts that began decades ago to further reduce pollutants associated with a number of potential health effects.



Beggs, P.J. (2004). Impacts of climate change on aeroallergens: past and future. Clinical and Experimental Allergy, 34, 1507-1513. doi:10.1111/j.1365-2222.2004.02061.x

Brooks, A. J., R. J. Schmitt and S. J. Holbrook. (2002). Declines in regional fish populations: have species responded similarly to environmental change? Marine and Freshwater Research, 53(2), 189-198. doi:10.1071/MF01153

D’Amato, G., Liccardi, G., D’Amato, M., Cazzola, M. (2002). Outdoor air pollution, climatic changes and allergic bronchial asthma. European Respiratory J., 20, 763-776. doi:10.1183/09031936.02.00401402

Electric Power Research Institute (EPRI). (2013). Occupational health and safety database 2012: annual data reporting years, 1995-2011. Retrieved from

Haines, A., McMichael, A.J., Epstein, P.R. (2000). Environment and health: 2. Global climate change and health. Canadian Medical Association J., 163(6), 729-734.

Moore, S.K., Trainer, V.L., Mantua, N.J., Parker, M.S., Laws, E.A., Backer, L.C., Fleming, L.E. (2008). Impacts of climate variability and future climate change on harmful algal blooms and human health. Environmental Health, 7, 1-12. doi:10.1186/1476-069X-7-S2-S4

Schaeffer, M., Gohar, L., Kriegler, E., Lowe, J., Riahi, K., Van Vuuren, D. (2015). Mid- and long-term climate projections for fragmented and delayed-action scenarios. Technological Forecasting and Social Change, 90, 257–268. doi:10.1016/j.techfore.2013.09.013.

United States Department of Labor. (2014). Industry injury and illness data. Retrieved from Bureau of Labor Statistics website:

United States Environmental Protection Agency. (2014). Cleaner Power Plants Mercury and Air Toxics Standards (MATS) for Power Plants US EPA. Retrieved from

United States Energy Information Agency. (2013). How many and what kind of power plants are there in the United States? FAQ U.S. Energy Information Administration (EIA). Retrieved from
United States Energy Information Agency. (2014). Monthly Energy Review – Energy Information Administration (DOE/EIA-0035(2014/10)). Retrieved from

Weber, R.W. (2002). Mother Nature strikes back: global warming, homeostasis, and implications for allergy. Annals of Allergy Asthma and Immunology, 88, 251-252. doi:10.1016/S1081-1206(10)62004-2