Blog #290 Ospreys Warn Us of Environmental Dangers

It’s dangerous living at the top—being an apex predator and a bioaccumulator means an Osprey gets mega-doses of whatever contaminants are in the water. In doing so,  they are the bellwether of the environment and of enormous importance to residents of  Cayuga Lake. Orpheus and Ophelia are living indicators of our lake’s healthy eco system and water quality. 

Advertisement promoting DDT, courtesy of the Science History Institute. 

Ospreys as Bioaccumulation  

During the 1950-60s, Osprey populations in the US crashed, going nearly extinct  because of the pesticide DDT (dichloro-diphenyl-trichloroethane) in water. DDT  bioaccumulation or gradually built up in an Osprey’s fatty tissues occurs after eating

Spraying DDT cavalierly in suburban and swimming pools, courtesy of Science History Institute. 

contaminated fish. Such bioaccumulation began when zooplankton incorporated DDT  from the water supply into their cells. Fish grazed upon the zooplankton, concentrating  DDT in their tissues. Larger fish ate the grazers storing even larger amounts of DDT in  

their fatty tissues. Osprey, the apex or top predator of the food chain, are piscivores,  eating only fish and lots of them. The more fish they ate, the more DDT was stored in  their fatty tissues. When it came time to lay eggs, DDT reared its ugly head and blocked  calcium from incorporating in the egg shells making them too brittle to incubate.  

DDT blocks calcium from making the eggshell strong. Courtesy of the Science History Institute.

The drastic decline of Osprey, Bald Eagles, and Peregrine Falconsv by 1972 spurred  the government to ban DDT in the US, establish the Environmental Protection Agency, and enact the Clean Water Act. Americans suddenly became aware of what was in  their water supply. A concerted effort by researchers and volunteers helped  reestablish healthy Osprey populations and prevented their extirpation, as well as that  of the Peregrine and Bald Eagle, from the Atlantic seaboard. A national tragedy was  averted, but we still have not learned our lesson about water pollution. 

Lessons Not Learned 

During the last twenty years, North America’s Ospreys, particularly in the industrial  Pacific Northwest, have been facing new assaults from high levels of contaminants in  rivers and lakes. Besides finding high levels of DDT in these waters, alarming levels of  polychlorinated biphenyls (PCBs), pulp mill dioxins, flame retardants, stain-resistant  compounds, urban runoff, mining wastes, prescription drugs, and mercury are  routinely detected.  

Perched on top of the aquatic food web, Ospreys are living depositories for these  hazardous substances in their water supply. Their fat stores retain all of the hazardous  chemicals contained in every fish they have ever eaten. As one chemical is banned,  another new one takes its place in threatening the environment. How do we know this

is occurring? The ospreys tell us. 

The Ospreys’ health mirrors the water quality. 

  

Cosmopolitan Ospreys rely on human-built substrates to locate their nests and are  remarkably tolerant of living among humans. Because of this, they make their homes  along some of the more industrially polluted waters in the States, including the  Columbia River and Chesapeake Bay.  

The ultimate locavores, or animal whose diet consists only of locally produced food.  Ospreys offer a precise gauge of contaminants released in their hunting grounds.  They also consume, via the food chain, hazardous chemicals brought into their habitat  from thousands of miles away via winds and currents. Although they do migrate,  Orpheus and Ophelia return to the same nest each spring to lay their eggs. As a  result, the health of their eggs and chicks are a direct reflection or rather a snapshot of  the pollution in the environment. 

Poisoned Prey

Since the banning of DDT, new threats have emerged and old threats linger.  Chemicals from manufacturing pesticides and everyday household items like furniture,  plastics, cleaners, and pharmaceuticals are polluting the natural world and their long term impact on wildlife and humans remained a question. We’ve already seen that  high doses of DDT impair the ability of birds of prey to reproduce. Limited studies in  other wildlife have found that hazardous chemicals can interfere with everything from  the hatching eggs to liver development in embryos. 

Toxins in the water accumulate in the fish, and are magnified in the Osprey, courtesy of Howard Arndt. 

Ospreys not only mirror how much pollution is in our lake, they also indicate if it  matters—for the osprey and for us. In most places, Osprey populations bounced back from the 1970 population crashes, but the birds living near the mouth of the Columbia  River felt DDT's persistent effects until 2001, when that population finally recovered. 

Superfund Cleanup 

In Missoula, Montana, researchers use Ospreys to help gauge the success of a  massive Superfund cleanup on the Clark Fork River. Crews removed decades' worth  of toxic sludge accumulated from a gargantuan copper mine upstream. The cleanup  proved successful: Osprey eggs taken downstream of the Superfund site had very low  levels of the "big five"—arsenic, copper, zinc, cadmium, and lead—targeted by the 

cleanup. The shocker was the extremely high quantities of mercury levels in the eggs. Osprey chicks in Missoula had 300 micrograms of mercury per liter of blood. (To  prevent birth defects pregnant women are limited to 5.8 micrograms per liter.) Humans  ingesting more mercury risk “cognitive dysfunction.” Consumption of high-mercury  seafood by pregnant women has been linked to reduced IQs in their offspring. 

Toxins in the water can affect the physical and mental development of the nestlings. 

Does this mean the Osprey chicks in Missoula are stupid? That's an important  question, but no one knows. Young ospreys have to learn how to hunt and migrate  thousands of miles on their own. Researchers are placing GPS satellite transmitters  on Missoula fledglings in high- and low-mercury areas to track them and gauge any  deficiencies. To date, researchers have determined that there is a 50 percent  reduction in hatching success in high-mercury areas contaminated by mining in the  region. The implications for human health are serious for those that eat fish from the  same waters.  

Besides PBDEs, scientists working in the Columbia River are concerned about the  hundreds of new pollutants now found in the street runoff and treated sewage and  discharged into the Columbia. Dozens of contaminants accumulating in the river's  

sediment, including contaminants that mimic or block hormones, are released into the  system during floods and dredging, rendering the local fish inedible. And the more  industrial and crowded the area becomes, the more contaminants, from cleaners to  soaps to coatings, enter the river system.

Three- and Four- Letter Dangers 

PBDE DDT 

 

 PFC PFOS 

Over the years, pollutants threatening Ospreys have changed: first DDT (dichloro diphenyl-trichloroethane), then PCBs (Polychlorinated biphenyls), then PBDEs (Polybrominated diphenyl ethers), and now PFCs (perfluorinated compounds). The  only constant is that new ones are constantly invented. While PFCs—chemicals used  widely to make products stain resistant and to manufacture everything from nonstick  cookware to firefighting foam—aren't stored in fat like DTT, It still takes the body years  to evacuate it while damaging the liver and kidneys, lowering testosterone levels, and  reducing embryo viability. 

Perfluorooctane sulfonate, or PFOS, used in Scotchgard until 2002, is found in  Osprey eggs at levels exceeding health requirements and are becoming a global  issue: Toxic amounts have been found worldwide in Osprey eggs from the  Chesapeake and Delaware bays to Japan and Norway. 

What does this mean for Ospreys? It’s too early to know the effects of newly emerging  contaminants on people or birds. Little is known about PFCs tolerance in birds, but  there is evidence that this isn't just a bird concern: Elevated levels of perfluorinated  compounds, including PFOS, are associated with kidney disease, lower testosterone  levels, and other health effects in humans. 

Ospreys recently alerted us to prescription drugs, which are found in sewage  discharge. A hypertension medication was found in all Ospreys that were tested at the  Chesapeake Bay. For several drugs, its calculated that Ospreys will exceed human 

Fledgling Osprey in a local rehabilitation facility. 

therapeutic doses after only three to seven days of ingesting fish, although the effects  on Ospreys is still unknown. 

The bottom line? It's hard to keep track of all the new compounds polluting our  waterways in the Us and their impacts on wi ldlife and  humans. We must look to the Osprey to be a reflection of the health of Cayuga Lake. 

Eyes to the sky!  

Candace  

Candace E. Cornell  

Friends of Salt Point  

Lansing, NY  

cec222@gmail.com

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