[CHAPTER 8]
Pollution Destabilizes Ecosystems
What if ocean pollution were to result in death of the tiny planktonic plants? These phytoplankton are the producers of the ocean. They are the basis of the marine trophic pyramid! Elimination of these plants would result in extinction of life in the oceans. Such a catastrophe is unthinkable.
—WILLIAM MASON AND GEORGE FOLKERTS, Environmental Problems
“Very nice country . . . Walked from town & fell asleep beneath a tree.” These remarks were penned by Charles Darwin in his field notebook on Tuesday, 16 February, 1836, about his final “pleasant little excursion” along the banks of the Derwent River before leaving Tasmania (Banks and Leaman 1999).
The Derwent Estuary was one of Australia’s finest deepwater ports and was also the center of the Southern Ocean whaling industry. But alas, like so many places in the far corners of the map, most people have never heard of it. It’s at the southern end of the southern corner of the southern island of the southern continent in the Southern Hemisphere. Rotate your globe to Australia . . . now go down . . . no, farther down . . . if you get to Antarctica, go back up a smidgen. Or go to New Zealand and turn left.
Tasmania is a wild and magical place. The mystery of the striped and toothy thylacine: forever gone or master of stealth. The Tassie devil’s contagious disease, passed during face-to-face romance or combat. Spotted quolls and naked-nosed wombats roaming without fear of predators. Tasmania is a land of orchids and carnivorous plants and rainbows. Lots of rainbows.
Based on EPA estimates, in one week a 3,000-passenger cruise ship generates about 210,000 gallons of sewage; 1,000,000 gallons of gray water (shower, sink, and dishwashing water); 37,000 gallons of oily bilge water; more than 8 tons of solid waste; millions of gallons of ballast water containing potential invasive species; and toxic wastes from dry cleaning and photo-processing laboratories (PEW 2003).
A recent US National Academy of Sciences study estimates that the oil running off our streets and driveways and ultimately flowing into the oceans is equal to an Exxon Valdez oil spill—10.9 million gallons—every 8 months (PEW 2003).
In the United States, animal feedlots produce about 500,000,000 tons of manure each year, more than three times the amount of sanitary waste produced by the human population. More than 13,000 US beaches were closed or under pollution advisories in 2001, an increase of 20 percent from the previous year (PEW 2003).
Tasmanians are fervent “greenies.” And that’s a good thing, because somebody has to preserve this little corner of wonder. But underwater is a different story. The ravages of industrialization have taken their toll—perhaps it’s a case of out of sight, out of mind.
In 1974, the Derwent was declared the most polluted river in the world (Bennett 1999). Zinc- and cadmium-contaminated oysters. Mercury-contaminated fish. Acids from a paper mill. Untreated or poorly treated effluent from thirteen sewage outfalls. Half a state’s worth of agricultural waste funneling into the catchment. Too many decades of industrial dumping.
The major issues identified in the 1997 State of the Derwent Report include heavy metals, introduced species, high sedimentation rates, pathogens, loss of seagrass and wetlands, elevated nutrients, resin acids and low dissolved oxygen, and accumulated sludge deposits (Bennett 1999). Once inviting enough for Darwin himself to take a snooze along her shores, the Derwent is now a shocking story of power struggles, secrecy, fat-cat profits, and wanton disregard for the environment and the services it provides.
The Derwent is a microcosm for just about every estuary, bay, harbor, and coastal waterway in the world. We have been using rivers as giant colons to rid our urban waste (see plate 10). Beaches have become repositories for our soda bottles, beer cans, plastic bags, and used syringes. Ships’ ballast tanks have become essentially comfy aquariums for travel-minded flora and fauna. This chapter and the next focus on these issues and what happens next, after we have abused and insulted our seas.
The morning of 19 September 2009, surely must have seemed like any other. Except on that day, 498,818 volunteers from 108 countries and locations picked up 10,239,538 items of marine debris, totaling some 7.4 million pounds (Ocean Conservancy 2010). Over 2 million cigarette butts and filters—just 15 seconds’ worth of worldwide consumption. Over 1 million plastic bags. Nearly 1 million food wrappers and containers. Over 900,000 caps and lids. Beverage bottles. Cutlery. Cans. Straws. Stirrers . . . In one day. Please reread this paragraph, then pause for a moment before continuing. Let it sink in. Let yourself be shocked.
Pollution is, in the broad sense, any substance or object introduced into the ecosystem that has or can have a harmful effect. Many types of pollution come from nonpoint sources, such as wind-blown debris, automobile exhaust, and agricultural or urban runoff. There are essentially two main types of pollution: nutrient and nonnutrient. Nutrient pollution includes substances that are natural in the marine environment but are in unnaturally excessive amounts (eutrophic conditions) or severely limiting (oligotrophic conditions). We examined the issues relating to nutrient pollution in the preceding chapter; we shall now turn our attention to nonnutrient pollution. Both types are highest in coastal areas, an outcome of increasing urbanization. And both types can cause phytoplankton blooms, leading to hypoxia or anoxia, in turn leading to jellyfish blooms.
Nonnutrient pollution includes the garbage and toxic substances that are not natural in the marine environment and have a deleterious effect on marine life, such as petroleum hydrocarbons, heavy metals, plastic debris, and toxic waste. Marine pollution can be obvious, such as an oil spill or plastic drink bottles and beer cans along a coastline, but often the most harmful pollutants are those we cannot see. Some chemicals react in such a way as to deplete oxygen from the water, causing anoxia. Many types of toxic chemicals diffuse into the seawater or adhere to tiny particles that are taken up by filter-feeders or deposit-feeders. Stored in flesh or fat, these toxins concentrate over time or magnify up the food chain, eventually ending up on our dinner table either directly through contaminated fish or indirectly through fish meal in animal feeds, transferring to us through meat and dairy products.
. . .
A gobsmacking array of pollutants makes its way into the marine ecosystem. Some dissipate quickly, while others accumulate on the surface of sediments until they are taken into the food chain or resuspended from the sediments by trawlers, bioturbating invertebrates, or storm action. Many types of heavy metal and organic pollutants concentrate in the tissues of higher predators (a process called “biomagnification”), where they become hazardous to the predator or to humans as their predator.
Pesticides. Herbicides. Fungicides. Hydrocarbons. Fluorocarbons. Oil spills. Leaching plastics. Radioactive waste. Chemical weapons dumping. Endocrine disruptors and various gender-benders. Antibiotics triggering microbial resistance. In fact, about 70,000 man-made chemicals currently surround us in building materials, personal care products, lawns and gardens, the water we drink, the air we breathe, and the food that we eat (McTaggart 2000).
These contaminants come from a wide variety of sources. Industrial factories discharge chemical waste directly into waterways or incinerate it into airborne particles that eventually settle. Crop-based agriculture is a rich source of pesticides, whereas stock-based agriculture often uses huge quantities of antibiotics and growth hormones. Urban roadways are a substantial source of oil and rubber residues. Medications, cosmetics, micro-scrubbers, disinfectants, and a stupefying array of household contaminants make their way into sewer systems, septic tanks, and rivulets and waterways through residential drains.
Nonnutrient pollution often follows the same routes into the oceans as excess nutrients, and as one might expect, those regions with the highest eutrophication often suffer from the highest levels of chemical contaminants. Oil spill residues in the Gulf of Mexico. Routine fish consumption advisories for mercury, PCBs, herbicides, insecticides, and endocrine disruptors in the Chesapeake. Complex cocktails of pesticide residues, petroleum hydrocarbons, synthetic organic compounds, and heavy metals in Boston Harbor and the Gulf of Maine, where tumors and diseases in fish and shellfish are above the national average. Nearly 50,000 containers of radioactive waste at the Farallones off San Francisco. Carcinogenic DDT and PCBs still lurking in fishes and sediments off Los Angeles. Similarly, concentrations of DDT and PCBs are still readily found in Mediterranean mammals, birds, and invertebrates, despite having been banned more than 30 years ago. The Canadian Inuit have been harvesting beluga whales for thousands of years, but today the whales are so heavily contaminated that they are no longer safe to eat. . . or even to touch—when they are found washed up dead on beaches, they have to be removed by HazMat teams (DFO 2012).
In Japan, mercury and Minimata disease, fallout from Hiroshima and Nagasaki, nuclear waste dumping by Russia in the Sea of Japan, toxic whale meat, toxic tuna, and the Fukushima nuclear meltdowns are just a few of the concerns. Coastal waters and sediments around Japan remain heavily polluted with contaminants including dioxins, PCBs, butyltin compounds, heavy metals, floating litter, bauxite residue, and radionuclides.
“Just as the speed and scale of China’s rise as an economic power have no clear parallel in history, so its pollution problem has shattered all precedents” (Kahn and Yardley 2007). In the East China Sea, 81 percent of the sea area has been rated category 4 for pollution on a scale of 1–5; half of the red tides in China are from this region, and are blamed on petrochemical waste and heavy metal sediments. Currently, China is completing construction on new coal-fired power plants at the breakneck pace of 2–3 per week (Harrabin 2007). This adds even more pollution, not to mention carbon dioxide, on top of the nation’s already severely polluted air and water.
In the Northern Indian Ocean, a persistent brownish haze covers about 10 million square kilometers (4 million square miles)—roughly the same area as the continental United States—and is as dense as the smog one might expect to find in the most polluted cities (SIO 1999). Preliminary data indicated that the scatter effect of the aerosols reduced the amount of energy absorbed by the ocean surface by up to 10 percent, impacting photosynthesis and the amount of moisture evaporating from the ocean and therefore altering the entire rainfall cycle.
In Australia, herbicides and other pesticides are pouring into the Great Barrier Reef from sugar cane farming and other agriculture, heavy metals persist in the Derwent Estuary, the fish at Gladstone have become so toxic as to close fishing, and the world’s highest levels of mercury were found in a dead dolphin in 1999 off Adelaide (Grady and Brook 2000). Despite input reductions, continued input and persistent concentrations of heavy metals, PCBs, DDT, and other harmful organic compounds, as well as radionuclides, are still high in the Baltic (HELCOM 2007). Contaminants that cause illness in fish, including lymphocystis, liver nodules, skeletal deformities, parasites, and skin ulcers, the latter of which were found in 43 percent of cod, continue to plague the North Sea (Lang 2008).
If your head is spinning from all the chemical names and medical and ecological effects, welcome to the club. It is head-spinning: that’s the point. An astonishing number of chemicals are causing an astounding array of problems. So much so that for most of us, tuning out seems like our only option. And so the problem continues to grow.
Bioaccumulation and Biomagnification
Although they sound similar, these two concepts are fundamentally different. “Bioaccumulation” is the buildup over time of toxic substances in the body of an organism. “Biomagnification” is where these accumulated substances are passed up the food chain, and compounded through repeated ingestion of contaminated organisms.
The health of organisms—and indeed, the human organism at the top of the food chain—can be affected by pollution directly through acute toxicity poisoning or indirectly through these substances being concentrated in prey. But these processes can and do also affect community composition in marine ecosystems through their cumulative effects on higher levels of the food chain.
The Dirty Dozen
Twelve persistent organic pollutants have been identified by the United Nations Environmental Programme as being the worst of the worst: polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene, dioxin, furans, dieldrin, aldrin, endrin, chlordane, heptachlor, toxaphene, and mirex (Alessi et al. 2006). These chemicals share certain characteristics that make them particularly hazardous. They are toxic to both humans and wildlife. They resist breaking down, remaining intact for a long time. They are highly soluble in lipids (fats), and so are able to accumulate in the bodies of humans, marine mammals, and other wildlife. They concentrate up the food chain. They pass from mother to fetus through the womb and to the child through breast milk. They cause nervous system damage, immune system diseases, reproductive and developmental disorders, and cancers. Singly, they are toxic. In synergy, we have no idea.
Pesticide Residues
Warning signs are posted on fishing piers and fences along the coastlines of Southern California, alerting fishermen not to eat white croaker (see plate 10). White croakers are common from San Francisco to Mexico. In fact, they are so easy to catch that they are often considered a nuisance to fishermen trying to catch a more sporting fish. But that’s the problem. Many of the fishermen aren’t there for sport; they are fishing to feed their families. And because the white croakers are so plentiful and easy to catch, they make an easy meal. And they’re toxic.
In 1987, Donald Malins and his colleagues from the National Marine Fisheries Service found high concentrations of DDT and PCBs, as well as liver carcinomas and other lesions, in tissue samples from white croakers in the Los Angeles area (Malins et al. 1987). By examining over 100 fish as well as sediment samples from 5 sites, they found that these chemicals were in higher concentration in prey items in the croakers’ stomachs, including fish, squid, worms, crabs, shrimp, and clams, than in the sediments. It was clear that the prey were concentrating the toxins and passing them along to the fish.
DDT and PCBs are not natural in the marine environment. They got there through surface water, groundwater, and aerial emissions from industrial plants, such as Montrose Chemical Corporation near the Los Angeles Harbor. Montrose manufactured DDT, the new “wonder pesticide,” at its Torrance plant from 1947 to 1982. Wastewater was disposed into the county sewer system, which emptied into the ocean, while storm water that ran off over the contaminated soils and sediments in and near the site and aerial emissions exposed drinking water aquifers that served more than 100,000 people. An estimated 1,700 tons of DDT were discharged just between the late 1950s and early 1970s.
In 1948, the Nobel Prize was awarded for the discovery of DDT as an insecticide. But the 1962 book Silent Spring by Rachel Carson brought attention to a more sinister side to the chemical as an environmental hazard. As a result of the environmental movement largely spawned by the book, agricultural use of DDT was banned by the United States in 1972, and eventually worldwide by the Stockholm Convention in 2004.
The Environmental Protection Agency issued an administrative order on 6 May 1983 requiring Montrose to cease all discharges of DDT, but sediments remain contaminated. DDT is an effective toxin against many kinds of arthropods, not only insects; crustaceans in the sea are also poisoned by the powerful neurotoxin. Worms and other small organisms living in the soils ingest and absorb these toxins too; fish and other organisms eat many worms, and bigger fish eat many small fish, and the toxins concentrate in fatty tissues up the food chain.
DDT also affects fish-eating birds like eagles by causing their eggshells to be very thin and brittle, leading to premature breakage and the death of developing chicks. In humans, DDT is linked with a range of unpleasant health effects, including:
• an increased occurrence of diabetes and cancers of the liver, pancreas, and breast;
• developmental and reproductive toxicity, such as premature birth and “disruption in semen quality, menstruation, gestational length, and duration of lactation” (Rogan and Chen 2005, 770);
• interference with thyroid function;
• neurological problems including Parkinson’s; and
• asthma.
DDT stores in the body fat and has a half-life of 6–10 years. Testing by the Centers for Disease Control and Prevention in 2005 detected DDT and its derivatives in almost all human blood samples (Eskenazi et al. 2009), while Food and Drug Administration tests commonly detect DDT in our food (USDA 2009).
In 1990, the state and federal governments filed a lawsuit against 10 companies, including four DDT-manufacturing plants, for damages relating to release of DDT and PCBs into the marine environment near Los Angeles. The chemicals were released in contaminated sewage up until the 1970s.
In December 2000, the US Department of Justice and the California Attorney General announced a settlement with Montrose Chemical Corporation of California and other polluters totaling about $140 million to fund cleanup of the DDT contamination and restoration of the marine environment.
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Ocean sediments near populated areas often contain persistent organic pollutants like DDT, PCBs, and PAHs (polycyclic aromatic hydrocarbons, a group of over 100 chemicals that are produced during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances). These residues of industrial burning and pesticide use from decades past are relatively safe while sequestered in the sediments. But when resuspended, they are introduced back into the food chain and into our food supply. In particular, storms and human activities like bottom-trawling, dredging in shipping channels, and coastal construction (for example, the building of marinas), stir up the sediments on the seafloor, causing the finer particles to resuspend in the water column as a plume that may drift with the current for great distances. As they settle out, these fine particles can be harmful to filter-feeding, bottom-dwelling organisms, such as clams, mussels, sponges, and tunicates. The nutrient phosphorus also often concentrates in shallow sediments and when resuspended, as we have seen, can contribute to phytoplankton blooms, thereby hastening dead zones.
The increase in turbidity caused by bottom-trawling also reduces light penetration, which can impact on photosynthetic organisms, such as kelps and corals. As we have seen earlier, turbidity can also reduce the ability of visual predators to see their prey, thus favoring tactile predators like jellyfish.
Petroleum Hydrocarbons
Of all the various types of pollutants in the sea, one of the most visible—and emotive—certainly must be oil spills. Crude oil is essentially a cocktail of substances that range from sticky to tarry, soluble to glob-forming, smelly to noxious to seriously poisonous. The blackened sand, slick water, and drowned birds are just the tip of the iceberg. The fractions, or chemical components, that often do the most biological damage are those that we can’t see; they dissolve into the water or evaporate away, leaving only their toxic residues.
Hydrocarbons, the product of decomposed organic matter from eons past, occur naturally in crude oil. The purpose of refining oil is to purify these substances for our use. Asphalt, propellants for aerosol sprays, solvents, gasoline, and jet fuel are just a few of the uses of various hydrocarbons. Methane. Propane. Butane. Hexane. Octane. Toluene. Xylene. Naphthalene. We hear these terms in various contexts of daily life. Many of them cause cancer or nerve disorders or affect the blood, immune system, lungs, skin, eyes, liver, kidneys, or developing fetuses.
When these compounds enter the environment, undesirable outcomes often occur, particularly when they affect the base of the food chain. Experiments with numerous types of phytoplankton exposed to low concentrations of hydrocarbons have shown that some species are strongly stimulated to grow, while others are moderately stimulated, while still others are actually inhibited (Dunstan, Atkinson, and Natoli 1975).
Therefore, it seems clear that even low concentrations of oil in the marine environment can alter the growth or cause the demise of certain phytoplankton species. Even minor alterations low in the food chain can be anticipated to have major cascading effects on species further up. The “elephant in the room,” so to speak, since the BP oil spill in the Gulf of Mexico, is what effect the disaster will have on the local ecosystem, and, more importantly, on the gulf fisheries, America’s second largest next to Alaska, a business on which many people’s livelihoods rest.
According to industry experts (Patton 2010), shrimpers’ catches were down by 75 percent from normal in the first month of shrimping season after the spill. The shrimp harvest in the western Gulf of Mexico for that year was projected to fall some 20 percent below the historical average. If the Exxon Valdez damage is anything to go by, it can be a long road back: that spill destroyed billions of salmon and herring eggs, and those fisheries are still at reduced levels. Part of the problem is the stimulating effect that oil spills have on microbial activity, “spawning an explosion of bacteria that feed on crude.” As the bacteria decompose the oil, their respiration processes suck the oxygen out of the water, creating or enhancing dead zones.
It will be many years before a clear picture emerges on the economic damage to the fishing industry from the spill, but what about the immediate ecosystem damage? What about the birds, the invertebrates, the algae?
Crude oil coats everything it touches with a shiny, tarry, smelly film. Every rock. Every feather. Every hair. Every gill. Every root. Every grain of sand. Images of oil-coated birds following spills are ubiquitous. Even thin films of oil will usually prove deadly to birds, because any spot of oil acts like a pinhole in their natural waterproofing and insulation barrier. Once that barrier is broken—it doesn’t matter how broken—hypothermia is inevitable. Preening only makes things worse, hastening death through poisoning by ingestion.
When the Exxon Valdez ran aground in Alaska in March 1989, only 17,000 barrels of 257,000 were recovered. Thirteen hundred miles of shoreline were impacted, along with outright deaths of “250,000 seabirds, 2,800 sea otters, 300 harbor seals, 250 bald eagles, 22 killer whales, and billions of salmon and herring eggs” (NPS 2009, 1). The timing seemed like it could not have been worse: seabirds were gathered in prebreeding aggregations and fish were spawning. . . The Deepwater Horizon spill in the Gulf of Mexico, however, is worse, having spanned both mating and nesting season.
Marine mammals don’t fare well, either. Those with fur, for example, seals and otters, become coated in oil, losing their insulating properties and becoming at risk of hypothermia. Several hundred harbor seals are believed to have died from inhalation of toxic fumes (Peterson et al. 2003). Cetaceans can have trouble breathing if their blow holes become clogged with oil. Even those not directly affected may still eat contaminated food or face stiffer competition from losses through the food chain.
Once thought to break down through rapid dispersion and microbial degradation, it is now clear that spilled oil has both an acute mortality effect and a chronic sublethal effect. A study conducted nearly 20 years after the Exxon Valdez spill found that 98,000 liters (26,000 gallons) of oil were still trapped in the sediments along the Alaskan shoreline (Walsh 2009). These hidden remnants continue to leach toxins into the water year after year. Even low level chronic exposure, such as from persistent subsurface oil, is now known to have a range of deleterious effects, including:
• ongoing deformities and mortality of fish embryos in oiled estuaries and stream banks;
• concentrated contamination in filter-feeding clams and mussels that becomes toxic to their mammalian predators (including humans); and
• a lengthened recovery process for the entire affected ecosystem due to compromised health, depressed reproduction, and enhanced mortality overall, and the trophic cascades stemming from it (Peterson et al. 2003).
Some of the most profound effects are found in the “other” species—the less charismatic ones without the fur and feathers. Macroalgae and bottom-dwelling invertebrates suffer from a combination of chemical toxicity, smothering, and physical displacement and scalding by pressurized water used in the cleanup effort. These lead to cascades of indirect effects that can last for decades and slow the recovery process of the entire ecosystem (Peterson et al. 2003). Loss of the protective cover of the structural algal canopy reduces the survival of young algae trying to recolonize. This in turn reduces the habitat for grazing snails and their predators, thus opening up niche space for opportunistic and weedy species like green algae and barnacles.
Heavy Metals
Recall the highly polluted Derwent Estuary in Tasmania. In 1974, the heavy metal loads were so high that the sediments were saturated. A follow-up study in 1996 found that there was little reduction in heavy metal levels since the original investigation—the toxins were continuing to leach from the sediments, and the fish and shellfish were continuing to concentrate them to dangerous levels (Whitehead et al. 2010). Today, fishing bans are still in place and regular warnings are still issued about water safety.
Heavy metals, often called toxic metals, are a worrying source of pollution. These include elements, such as mercury, cadmium, lead, chromium, zinc, copper, and arsenic, among others. Some are required in minute amounts for human health, while others, even in small amounts, can cause severe health problems or death.
Unlike organic pollutants, heavy metals do not decay over time. They can accumulate in sediments and be stirred up later by trawling or dredging activities, storms, or bioturbating organisms. Of greatest risk to us is when heavy metals are taken into the food chain by deposit-feeding organisms and concentrated through bioaccumulation or biomagnification. Heavy metals can cause changes to tissue matter, reproductive and growth abnormalities, and behavioral alterations.
Heavy metal pollution arises from various sources. For example, chromium and cadmium are used in electroplating, while mercury pollution typically comes from metal smelting, as well as chlorine and cement plants and coal-fired power plants. Common sources of copper pollution include erosion of overhead cables by railway traffic, combustion of waste, and automobile brakes. Large amounts of lead were emitted by automobile exhaust until it was banned in fuels in 2000.
The plight of mercury poisoning was brought to the world’s attention in 1972 with the publication of a black-and-white photograph, Tomoko Uemura in Her Bath, by American photojournalist W. Eugene Smith. The startling image depicts a mother cradling her severely deformed, naked daughter in a traditional Japanese bathtub. Tomoko suffered from a form of mercury poisoning known as Minamata disease, named for the region in Japan where it was discovered. Tragically, she was poisoned by methylmercury while still in the womb through her mother, who had eaten local fish and shellfish that had been contaminated by discharges from a local chemical plant. Unknown at the time, the congenital form of Minamata disease occurs when the placenta removes the mercury from the mother’s bloodstream and concentrates it in the fetus.
From 1932 to 1968, the Chisso Corporation’s chemical factory at Minamata released methylmercury into Minamata Bay and the Minamata River, causing the deaths of more than 600 people and giving rise to claims of illness by over 21,000 people. Thousands of residents of Minamata and nearby regions suffered the effects of mercury poisoning from consuming contaminated fish and shellfish from this region. Mercury poisoning causes a severe neurological syndrome, including walking and coordination difficulties, numbness in the hands and feet, muscle weakness, and damage to vision, hearing, and speech; many victims also experience rapid onset of insanity, paralysis, coma, and death.
Another source of mercury poisoning, ironically, can be found in Japanese school lunches. Whale meat is obtained as a byproduct of an annual harvest for “scientific purposes” of about 1,000 whales and 20,000 dolphins. The meat is fed to school children “as an effort to pass ‘traditional food culture’ down to children,” the Wall Street Journal reports (Twaronite 2011). But the World Wildlife Fund calls the “scientific purposes” argument a sham to circumvent the international moratorium on whaling (ABC 2005). Apparently, so too is the “traditional food culture” argument. While a few coastal communities have been eating whale since the 1700s, for most it is a recently acquired taste, becoming popular as a cheap source of protein in the postwar years (Head 2005). About 20 percent of schools in Japan serve whale meat, which they buy at deeply discounted prices from the Institute of Cetacean Research, which carries out the government’s whaling program (Parsons 2010; “Whale Meat Increasingly Back on Menu” 2010). However, samples of the short-finned pilot whale tested at 10–12 times the level of mercury that is considered safe (Reuters 2007), far higher than even tuna, which is on most “do not eat” lists.
Outside of Japan, mercury is a common heavy metal that we get from eating fish, particularly large, predatory fish like tuna, swordfish, king mackerel, and shark. Mercury in the oceans is primarily derived from the exhaust of coal-fired power plants then dispersed into the atmosphere, shunted toward the poles by circulation patterns, and settled into the oceans (Jackson 2010).
There is no “safe” level of mercury. The Food and Drug Administration suggests a limit of 1 ppm of mercury in fish and seafood. To put this into context, the highest category of contaminated fish, which includes, ahi tuna, swordfish, and shark, reveal concentrations of more than 0.5 ppm of mercury; general guidelines suggest limiting the consumption of these fish to no more than 400 grams (14 ounces) per week, or 200 grams (7 ounces) if they have 1 ppm of mercury. These suggested limits do not take into consideration mercury buildup from occupational sources or contamination by drinking water, inhalation, other contaminated foods, or cosmetics.
In comparison with fish, whale meat is far more toxic, because the whales live longer, eat more contaminated fish and squid, and concentrate more toxins in their fatty tissues. It was reported in New Scientist in 2002 that tests on whale meat for sale in Japan revealed extremely high levels of mercury: 2 of the liver samples in 26 tested contained over 1,970 ppm of mercury, nearly 5,000 times the government’s contamination limit of 0.4 ppm.
At these concentrations, a 60-kilogram adult eating just 0.15 grams [less than 1 ⁄1º the weight of a US dime] of liver would exceed the weekly mercury intake considered safe by the World Health Organization. . . Rats suffered acute kidney poisoning after a single mouthful of the most highly contaminated liver. . . On average, concentrations of mercury in whale and dolphin livers were 370 [ppm], 900 times the government limit. Average levels in kidneys and lungs were also high, about 100 times the limit. None of the samples was below the limit. . . While levels were lower in muscle, on average it still contained 2.5 to 25 times the limit. (Coghlan 2002)
Plastic Debris
Plastics made up 80–85 percent of the seabed debris in Tokyo Bay, an impressive figure considering that most plastic debris are buoyant.
—JOSÉ DERRAIK, “The Pollution of the Marine Environment by Plastic Debris: A Review”
Not all that long ago, the question “Paper or plastic?” was about sensitivity toward forests—or about conveniently sized plastic liners for bathroom waste baskets. Then came reports about turtles mistaking plastic bags for jellyfish. But the true extent of the plastics problem remains off most people’s radar. And each year, only 5 percent of the 1 trillion plastic bags produced in the United States alone get recycled (Sivan 2011).
We like plastics because they are lightweight, strong, durable, and cheap—but these very same properties are the reasons they pose a serious hazard to the marine environment (Derraik 2002). It’s not just about turtles. Nobody really knows how long plastics will last in the marine environment. According to Dr. Tony Andrady of the Research Triangle Institute in North Carolina, “Except for a small amount that’s been incinerated, every bit of plastic manufactured in the world for the last 50 years or so still remains. It’s somewhere in the environment” (Weisman 2008, 126). The problem is that plastics don’t “degrade” or “break down” in the sea, they only “break apart.” As they become smaller and smaller, it is easy for us to think that they have gone away, but they don’t. Powder-sized particles are taken up by tiny filter-feeding organisms and make their way into the food chain. On land, ultraviolet light and warm temperatures break down the plastics, but water reduces the UV penetration and buffers temperature change. These effects are particularly reduced in the deep sea, where many of the plastics are accumulating (Macfadyen, Huntington, and Cappell 2009).
Vast regions of accumulated floating and drifting plastic debris span thousands of miles in the mid-ocean gyres: drink bottles, beach sandals, food containers, rubber boots, laundry baskets, children’s toys, toothbrushes, rubber duckies. Ship captains have dubbed an area midway between San Francisco and Hawaii, the “eastern garbage patch” (not to be confused with the western garbage patch, off Japan, or others in other gyres). This area, where plastic vastly outnumbers plankton, is a slowly rotating clockwise swirl of plastic flotsam about twice the size of Texas, possibly the world’s largest dump (Weiss 2006).
It is impossible to accurately estimate the amount of plastic debris accumulating in the oceans and seas, but the limited studies that exist suggest that the problem is (as the saying goes) “bigger than Ben Hur.” A review on pollution by plastics in the marine environment included the following:
In 1975 the world’s fishing fleet alone dumped into the sea approximately 135,400 tons of plastic fishing gear and 23,600 tons of synthetic packaging material. [Another study] estimated that merchant ships dump 639,000 plastic containers each day around the world, and ships are therefore, a major source of plastic debris. Recreational fishing and boats are also responsible for dumping a considerable amount of marine debris, and according to the US Coast Guard they dispose approximately 52% of all rubbish dumped in US waters. (Derraik 2002, 843)
But don’t rush to blame just the fishermen and coast guard. In 1982, it was estimated that more than 8 million debris items per day were entering the sea, made up of about 8 percent plastics; however, as our love affair with plastic products has increased, so too has its accumulation in the sea, which is estimated to have risen severalfold (Thompson et al. 2004; Barnes 2005; Gregory 2009).
For many marine species, plastic debris has become essentially another food group. Turtles mistake plastic bags for jellyfish. Seabirds mistake disposable lighters for fish. Fish mistake Styrofoam particles for plankton. These are some of the effects of plastic waste in the oceans.
• Turtles often mistake plastic grocery carry bags and food wrappers for their jellyfish prey. Feeding experiments demonstrate that sea turtles actively select colorful plastic items over colorless, and that plastic items accumulate in the gut for many months (Lutz 1990), clogging their digestive tracts and blocking the passage of food and waste. A study of 371 leatherback necropsies since 1968 found over 37 percent contained plastic in the gut (Mrosovsky, Ryan, and James 2009); interestingly, the study also found a rapid increase in the incidence of plastic ingestion from the 1960s to the 1980s, with a leveling off after that.
• Penguins, pelicans, albatrosses, shearwaters, auklets, seagulls, and other seabirds, as well as seals and dolphins, ingest plastics or become entangled in plastics. Netting, fishing line, ropes, and other debris can become entangled around the neck, legs, wings, flippers, tails, and flukes, leading to strangulation, cutting and infection, amputation, drowning, and asphyxiation, as well as dragging during swimming. Seals in particular are curious and playful and will often poke their heads into loops and holes; however, while loops slip on easily, the lay of their hair keeps collars from slipping back off (Derraik 2002). Birds that prey on plankton are vulnerable to confusion of plastic pieces for copepods, krill, or squid, while fish-eating birds like albatrosses often mistake larger, colorful plastic debris for their prey; intestinal obstruction and diminished hunger signals are among the most harmful effects (Azzarello and Vleet 1987).
• Planktivores mistake tiny drifting plastic particles for their prey. Samples from the North Pacific central gyre in 1998 revealed that plastics outweighed plankton 6 to 1 (Moore et al. 2001); however, by 2008, this figure had risen to a whopping 46 to 1 (Algalita 2009). The majority of fragments found were thin films like those from sandwich bags and pieces of monofilament or polypropylene line—all those shining and glinting little bits must look like a ticker-tape parade or a Thanksgiving feast. Even jellylike salps were found with plastic fragments embedded in their tissues, a startling find given their brief lifespan.
• Suspension-feeding or filter-feeding animals like mussels, clams, anchovies, and sardines have been shown to ingest and accumulate microscopic plastic fragments. Experiments with mussels demonstrated that a brief pulse of particles accumulated in the gut, then translocated to the circulatory system within 3 days and persisted for over 48 days (Browne et al. 2008). Given these results, it is not hard to imagine that longer-term exposure to microplastics could have deleterious effects.
• Deposit-feeding organisms have also been shown to be affected by micro-plastics. Experiments with sea cucumbers have demonstrated that up to twentyfold more PVC fragments and over a hundredfold more fragments of nylon line were ingested than were expected from the concentration in the sediments (Graham and Thompson 2009). It therefore appears that these organisms were preferentially selecting plastic particles over sediment grains.
• Toxic additives leaching from plastics are a big concern, particularly in the acidic environment of stomach acids and digestive fluids. Furthermore, plastics readily act as both a magnet and a sponge for attracting and absorbing PCBs, DDT, and other organic pollutants from the marine environment, then act like a toxic bullet as they enter into the food web and concentrate up the food chain (GESAMP 2010).
Consider the northern fur seals of the Pribiloff Islands in the Bering Sea. In 1969, 100 percent of the seals returning to rookeries were free of plastic entanglement. In 1973, 38 percent were entangled. In 1976, scientists estimated that up to 40,000 fur seals each year were being killed by entanglement in plastics (Derraik 2002).
Dr. Jennifer Lavers of the University of Tasmania has studied the flesh-footed shearwaters (also called mutton birds) at Lord Howe Island. She found that 96 percent of the birds breeding on the island have plastic in their digestive tracts. In April 2011, one bird was found with 276 pieces of plastic in its stomach—15 percent of the bird’s body mass—the equivalent of an average human ingesting 11 kilograms (25 pounds) of plastic. According to Lavers, “Once ingested, plastic can block or rupture the digestive tract and leak contaminants into the bird’s blood stream resulting in stomach ulcerations, liver damage, infertility, and in many cases, death” (Lavers 2011).
But there is an even more sinister side to the picture. The process of attraction of contaminants to plastics is called “adsorption.” Dr. Hideshige Takada, a geochemist at Tokyo University, has studied adsorption of toxins onto micro plastics, and found that PCBs and DDE (a breakdown product of DDT) build up on floating plastics and can eventually accumulate concentrations up to 1 million times those in the surrounding seawater (Raloff 2001; Mato et al. 2001).
Speaking at a conference on the problem of plastics in the Mediterranean in 2011, Maria Damanaki, European commissioner for Maritime Affairs and Fisheries, stated, “Last July a Franco-Belgian research team announced the results of their research; there were almost 250 billion small pieces of plastic in the Mediterranean and an additional 500 tones [sic] of dissolved plastic litter on the surface of our sea” (Damanaki 2011, 2). To combat the plastics problem, the European Union has unveiled a program in May 2011 to subsidize Mediterranean fishermen to catch plastic rather than fish. The aim of the plan is to provide fishermen with an alternative income while reducing pressure on dwindling fish stocks (Harvey 2011). Of course, there is still bycatch. . . .
For many years, startling photographs and stories have raised our awareness about turtles confusing plastic bags for their jellyfish prey, seabirds with plastic 6-pack holders twisted around their necks, otters and sea lions choked by tangles of fishing line, and once-beautiful beaches strewn with plastic drink bottles, food wrappers, flip-flops, cigarette lighters, and children’s toys.
But what we haven’t seen is what happens to those plastics as they break down. They fragment. They shred. They break into teeny little pieces. Sounds good? Nope: keep reading.
Larger pieces of plastic are often eaten by larger animals or become entangled with them, while smaller fragments are eaten by smaller animals, which are in turn eaten by larger animals. Plastics stay in the gut. They don’t break down. Debris like bread wrappers, potato chip bags, and garbage can liners block the digestive tract. Or animals feel full from accumulated particles and accidentally starve. Seabirds regurgitate plastic debris into the begging mouths of their young, which cannot regurgitate and so choke and die. By the tens of thousands.
The problem is much worse with microplastics. Microplastics come primarily from two sources: first, the microscopic particles resulting from physical and chemical breakdown of plastic waste in the oceans, and second, manufactured microscopic resin pellets (called “nurdles”) and cosmetic and industrial scrubbers. They even come from our cozy polar fleece jackets, which release thousands of tiny plastic threads every time they are laundered (Leschin-Hoar 2011). Microplastics are particularly abundant in subtidal sediments (Thompson et al. 2004). One particularly revealing study compared the density of plastics found in 2 groups of surface-water samples from 5 sites sequentially offshore from Southern California, the first sampling after 2 months without rain, and the follow-up sampling just after a storm with 9 centimeters (3-1/2 inches) of rainfall (Moore et al. 2002). The average density of plastics was 8 pieces per cubic meter (1 piece per 4 cubic feet); after the storm it was 7 times higher. Furthermore, the average mass of plastic was 2-1/2 times higher than the mass of plankton, and even higher after the storm.
Experiments with different types of feeding animals (e.g., filter-feeders, deposit-feeders, detritus-feeders), have demonstrated that these particles are readily taken up by animals who cannot differentiate them from food (Thompson et al. 2004). Visual predators are often attracted to the colorful specks. The precise effects of these plastics in the food chain are not yet well understood. However, it seems plausible that the toxins in and on plastics may be capable leaching out during the digestion process, and perhaps concentrating up the food chain. It also seems likely that as plastic particles accumulate in guts and tissues of animals, these particles may concentrate in the guts and tissues of the animals that eat them.
While the effect of large plastic items is quite obvious—we see trash on the shoreline and entanglement of marine animals—the effects of microplastics may be much more difficult to identify. The blockage of gut or circulatory systems by microscopic particles can happen slowly, and the types of animals most affected by microplastics are typically off most people’s radar, for example, worms, plankton, sea cucumbers, bivalves. However, as toxins enter the food chain via these animals and concentrate in their predators, we may see effects that we previously could not have imagined.
Dirty Little Secrets: Nuclear Waste
Lawyers, Liars, and Liabilities
Nuclear radiation is a bit of a hot topic at the moment, with the Fukushima disaster exploding into the world news in early 2011. But long before Fukushima rattled our feeling of safety, hundreds of thousands of tons of dumped nuclear waste were a percolating problem for marine life. Authorities on the Fukushima incident say that “release of [11 million liters of] radioactive water into the ocean . . . shouldn’t pose a widespread danger to sea animals or people who might eat them” (Australian AP 2011), citing dilution as the reason. However, from the information below, these conclusions seem worth pondering. And questioning.
Between 1946 and 1982, when ocean dumping of radioactive waste was legal, some 1.7 million curies (Ci) were disposed of at sea in containers designed to last only 100 years. A curie is a nonmetric unit of measurement of radioactivity that is roughly the activity of 1 gram of the radium isotope 226Ra; it is also used to measure the quantity of material containing the number of atoms that would produce 1 Ci of radiation. The metric unit of radioactivity is the becquerel (Bq), which equates to 1 decay per second. One curie is equal to approximately 37 gigabecquerels. Therefore, 1.7 million Ci is a lot.
Radioactivity is classified into three types relating to strength. So-called alpha emitters, such as plutonium and americium, are very strong in their ionizing ability but not very strong in terms of distance. Beta emitters, such as strontium, caesium, cobalt, and iodine, are weaker in terms of ionizing power but travel greater distances. Alpha radiation is the most dangerous because the ionizing process essentially rips cells to bits; beta radiation is safer, in that it only damages cells, but it can reach more cells that it only damages a bit, and can be very dangerous in this respect. A third category, gamma radiation, is a type of invisible, very high-energy light. The legal ocean dumping of radioactive waste contained about 99 percent beta emitters. Alpha emitters were also present in low quantities. What do we expect to happen as these containers degrade and bleed their contents into the food chain?
The London Dumping Convention came into force in 1975, making it illegal to dump high-level radioactive waste and requiring permits for low-level waste dumping. Low-level waste is defined as radioactive waste that does not require shielding during normal handling and transport, whereas high-level waste requires shielding at all times. A 1983 amendment to the convention suspended all radioactive dumping at sea.
According to Dominique Calmet of the Nuclear Fuel Cycle and Waste Management division of the International Atomic Energy Agency, the main objective of radioactive waste disposal in the deep sea is “to isolate it from man’s surrounding environment for a period of time long enough so that any subsequent release of radionuclides from the dumping site will not result in unacceptable radiological risks . . . sea dumping is essentially a strategy of dispersion/dilution rather than one of containment” (Calmet 1989, 47, 48).
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Back to Fukushima: the real question isn’t “will the effect be widespread,” because the answer is subjective (Atlantic species are unlikely to be severely affected, but the fallout plume has spanned the Pacific). The real questions should be, “What is the potential for toxic transfer to local organisms, how long will the danger in the ocean persist, and in what ways might radioactivity be passed up the food chain and affect the ecosystem dynamics as a whole?”
On 27 March 2011, the Environmental Protection Agency RadNet testing program found 422 pico-curies per liter of iodine-131 in rainwater from Boise, Idaho (EPA 2011); this is more than 14,000 percent the limit for safe drinking water; dozens of other cities have also tested many times the safe limit for radiation (Higgins 2011). The following day, 28 March, CNN reported that radioactive iodine had been detected in milk in both California and Washington, prompting increased testing across the United States. Then curiously, it was considered a step forward for the crisis-plagued Fukushima nuclear plant when, on 5 April 2011, CNN reported that in the preceding days, the radiation readings had decreased from “7.5 million times the legal limit . . . to [only] 5 million times the norm” (CNN 2011). That same day, the Japanese chief cabinet secretary announced that radioactive iodine had been found in fresh fish, prompting the same regulation measures for seafood as had earlier been applied to vegetables.
In another example, two different experts quoted by Australian Geographic on the same day indicated a problem but dismissed it outright (Australian AP 2011). One said, “Very close to the nuclear plant—less than 800 m or so—sea creatures might be in danger of genetic mutations if the dumping goes on a long time,” while the other said, “It’s not even clear in what way marine life could be affected, because the level of radiation isn’t yet well understood. Fish would probably escape such an effect anyway, because unlike static species such as oysters, they move around and would avoid continuous exposure.”
It seems that these experts are thinking in terms of instant vaporization, like in the movies, or perhaps just the type of radiation that penetrates through like a microwave and causes instant damage. But neither seems to be considering the more likely effect of radioactivity making its way into the food chain through worms, clams, plankton, and other lower food sources . . . or the half-life of the elements being dumped . . . or the ongoing dumping . . . or the long-term effects. . . .
In fact, Anders Møller of the Université Pierre et Marie Curie in Paris has been studying the ongoing effects of the Chernobyl nuclear disaster over the past 25 years. Møller has shown consequences of radiation exposure for a range of bird species that are permanent residents around Chernobyl and also for migrants through the area (Møller et al. 2007; Møller and Mousseau 2009). As top predators, seabirds are often used as sentinels of the marine environment. Symptoms of exposure from Chernobyl have included sperm abnormalities, reduction in brain size, infertility, and, as an “early warning system,” the development of albino feather patches within 3 months of exposure.
Within months of Fukushima, researchers in Australia began to notice similar white feather patches on flesh-footed shearwaters (see plate 10), a long-lived seabird species which breeds in Australia, but spends the winter months in the Sea of Japan (Jennifer Lavers, personal communication). The source of the radiation poisoning likely originates through the prey ingested by the birds. It is estimated that the cleanup of Fukushima will take more than a decade, but the problem will persist long after in the environment both in Japan and abroad as radioactive elements are transported around the globe for the next 20–30 years (the average half-life of cesium and strontium).
Amid Japan’s struggles with whether to bring back online its nuclear power plants that were shut down in response to Fukushima, and facing decades to know the full impact of the meltdowns on the food chain, Russia announced in August 2012 that it had dumped in Arctic waters “some 17,000 containers of radioactive waste, 19 ships containing radioactive waste, 14 nuclear reactors, including five that still contain spent nuclear fuel, 735 other pieces of radioactively contaminated heavy machinery, and the K-27 nuclear submarine with its two reactors loaded with nuclear fuel” (Digges 2012). The containment status of these dumped items is unknown.
The Effect of Pollution on Ecosystems
The reality is that if we want to have coral reefs in the future, we’re going to have to behave that way and recognize the magnitude of the response that’s necessary to achieve it. (Scripps News 2008)
No shortage of examples exists to demonstrate the effects of pollution on ecosystems; in fact, the hard part is deciding which examples to use. The Exxon Valdez oil spill in 1989 drowned, suffocated, chilled, and poisoned hundreds of thousands of birds, sea otters, whales, seals, and fish from acute toxicity, oil saturation, and hypothermia. Untold numbers of invertebrates and algae were killed from the oil or the cleanup effort, leading to further complications. In addition, 20 years on, tens of thousands of gallons of oil are still embedded in shallow sediments, continuing to release toxins in sublethal but chronic levels, causing depressed reproduction and recovery.
The Gulf of Mexico oil spill in 2010 certainly must have caused unprecedented losses to wildlife, but sadly, it’s just too soon to tell. “Exact counts of killed or sickened animals are impossible, given that the majority of carcasses sink into the ocean, rot unseen in marsh grasses or are consumed after death by predators,” according to a spokesperson for the Center for Biological Diversity, an environmental group based in Tucson, Arizona (Calkins 2011). Official government data on the acute effects included 1,146 endangered sea turtles, 8,209 birds, and 128 dolphins and whales. However, the center estimates the harm in far more confronting numbers based on studying animals the following season: about 6,165 sea turtles, 82,000 birds (comprising 102 species) and as many as 25,900 marine mammals (including 4 species of dolphins and whales). Even these numbers do not take into account the massive number of invertebrates on which the larger animals depend, nor are other factors considered, such as chronic exposure, nesting on oil-contaminated sediment, toxic effects of the chemical dispersant, the fate of the 35-kilometer-long plumes that lie below the surface, and the effects to the spring bloom of plank-tonic invertebrate larvae that coincided with the accident.
Vast tracks of cold-water corals living in the deep sea in the Gulf of Mexico were found dead and dying in December 2010, coated with a “black, fluffylike substance,” believed to be from oil. Researchers at the University of Florida described the strong toxic response as more of a “smoking cannon” than a smoking gun. “It could be the tip of the iceberg of all kinds of weird things we’re going to see in the Gulf of Mexico in the next three to five years [due to the oil spill]” (Jones 2010).
While different species tend to react differently to various pollutants, in general, pollution tends to favor weedy species over others. Studies have demonstrated that flagellates flourish in waters treated with low concentrations of DDT or copper, whereas diatoms do not (Menzel, Anderson, and Randke 1970; Thomas and Seibert 1977).
Eggs and larvae aside, it appears that planktonic ecosystems barely blink when oil spills occur. One study found that zooplankton reestablished within 5 days (Johansson, Larsson, and Boehm 1980), while others have found that microbes and flagellates are stimulated by oil (Davenport 1982). The planktonic response to oil spills and the preliminary response to the Deepwater Horizon spill were reviewed as part of a term paper assignment by students at Scripps Institution of Oceanography, who concluded that “early research shows that the planktonic community [of the Gulf of Mexico] exhibits an encouraging level of resilience” (Abbriano et al. 2011, 295).
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Earlier the subject of habitat damage by bottom-trawling was raised. One of the more insidious effects of bottom-trawling is the stirring up of sediments (see plate 9). Each pass of the trawl resuspends miles of chemical residues, DDT, PCBs, hydrocarbons, mercury, radioactive particles, and a confetti of plastics. All the harmful substances that have finally settled and been buried beyond reach of the food chain are once again made active. And these toxic clouds spread for many miles, diffusing into the water like fine dust, back into the food chain.
An interesting example of the effects of chemical residues is found in the sea otters of Southern California, where high levels of DDT and PCBs are associated with a high frequency and variety of diseases (McKay and Mulvaney 2001). Similarly, a recent population decline in orcas (killer whales) of Puget Sound in Washington is thought to be linked to high levels of PCBs detected in tissue samples.
A mass mortality event of bottlenose dolphins occurred in 1987–1988 along the Atlantic coast of the United States, where approximately 2,000 dolphins died. The cause of death was believed to have been a virus, although environmental contamination and algal toxins likely contributed to the severity. Other similar disease-related mortalities and morbidities have occurred in the Indian River Lagoon in Florida, including about 50 bottlenose dolphins killed within a 3-month period in 1982; 5 bottlenose dolphins found with severe skin disturbances in 2001; more than 150 sick or dead loggerhead turtles in 2000–2001; and an ongoing high prevalence of disease in sea turtles (McKay and Mulvaney 2001).
Nuclear Pollution and Ecosystems
Nuclear power is often marketed to the public as a “clean energy.” And it is, in many respects. None of that nasty carbon dioxide that we’ve been hearing so much about. But nuclear plants have those occasional pesky meltdowns, alas.
As we’ve seen above, accidents as well as decades of radioactive waste dumping have left several chances for potential catastrophe. There’s the obvious pathway up the food chain to our dinner tables. But there’s also the less obvious pathway of causing disease in the bigger animals as they eat contaminated smaller animals, and this upsetting the balance in a way similar to overfishing.
There’s also the issue of thermal pollution caused by nuclear reactors and the effect of unnatural heat in confined ecosystems. For every unit of electrical energy generated by a nuclear power plant, 2 units of heat energy are generated and released into the environment. Apparently nobody has yet worked out a way to harness this extra energy. Many nuclear power plants use what’s known as a “once-through cooling system” to remove the excess heat and keep the reactors operating properly. A typical plant of this type draws in more than 1 billion gallons of water a day, or 500,000 gallons a minute, for each reactor. The water is drawn in through massive pipes, cycled through the power generating station, then discharged back into the same body of water at temperatures up to 25°F hotter than it came in (Gunter et al. 2001).
In addition to the obvious and heart-tugging problem of sucking in manatees, turtles, and other charismatic estuarine megafauna, there are the not-so-small problems of sucking in microfauna and creating a tropical lagoon “microclimate” where it doesn’t belong.
Entrainment of microfauna and microflora. If large animals can get sucked into the intakes—and they do—in addition to jellyfish ingress incidents, of which there are plenty, one can only conclude that smaller plankton must be entrained in tremendous quantities. There doesn’t seem to be any data on this, no records, no estimates . . . But imagine a constant vacuum, sucking in a billion gallons of water a day along with its inhabitants—fish eggs and larvae, phytoplankton, invertebrate larvae—instantly cooking them, then discharging them into a warmer-than-normal body of water. Some get pulverized or liquefied in the process, creating more surface area to help speed up the bacterial decay process. Certainly this must be the pressure-cooker means to eutrophication.
A tropical lagoon microclimate. The warm-water effluent from power plants completely alters the local ecosystem. If it’s along an open coastline, then the thermal plume may extend only a matter of hundreds of meters, often turning the affected area into a moonscape. But if it’s in a semienclosed embayment or estuary, the entire ecosystem can be catastrophically changed. The dissolved oxygen concentration is too low for most indigenous species, and many physiological processes have narrow thermal windows in which the controlling enzymes will work properly. A (nonnuclear) natural gas–fired power station at Torrens Island, South Australia, has been supplying Adelaide’s electricity since 1968 (Painter 2011). According to a statement to Australian Parliament:
The plume from the Torrens Island power station discharges into the Angus Inlet, which discharges directly into the Barker Inlet, which is an aquatic reserve and probably South Australia’s most important fish nursery area. The temperature of the Angus Inlet, especially in hot weather . . . will go over 40 degrees Celsius [104°F]. This hot water will extend up to three kilometres into the Barker Inlet aquatic reserve. (Parliament of Australia 1997)
Since at least 1972, perhaps not so surprisingly, the tropical jellyfish Cassiopea ndrosia has taken up residence and appears to be doing quite well there.
The Effect of Pollution on Jellyfish
The most obvious effect of pollution on jellyfish is that it typically causes acute death or chronic toxicity in other species, effectively leaving jellyfish the last man standing. However, jellyfish are not entirely immune to direct effects from pollution. Very few studies have been performed on jellyfish with regard to pollution responses, except a few on hydrocarbons and petroleum. We know from these experiments that oil kills jellyfish and that polyps and young medusae develop abnormally with even low concentrations. In fact, jelly fish polyps have been used as an environmental indicator for hydrocarbon pollution, by monitoring subtle changes in their development and behavior (Spangenberg 1984).
Drifting and resting pieces of plastic must certainly become easily fouled with jellyfish polyps, potentially acting as expansion room for colonies building a seed bank before a bloom event. Similarly, floating and drifting plastic objects are likely to aid in dispersal of polyp colonies over potentially extremely long distances, as long as the plastic stays afloat.
You may be rubbing your chin or scratching your head, trying to figure out what all this toxic and nuclear stuff has to do with jellyfish. That’s the point, probably very little. It seems likely that jellyfish are one of the few predators not affected by radiation and many types of toxins—mind you, there’s no evidence; it just seems reasonable. Other animals around them with muscle and bone and blood and fat will store persistent organic pollutants, radiation, and heavy metals, and presumably be affected by them. Jellyfish, however, because of their watery, clonal, and short-lived nature, probably won’t. First, they don’t have much in the way of tissues to store toxins in. Second, they don’t usually live long enough to build up high concentrations. Third, even if the polyps are storing radioactivity or persistent toxins, so little of the polyp is passed along to each medusa larva that it is probably of little consequence. And fourth, because the medusa is the sexual stage and is ephemeral, the chance of illness or genetic mutation due to radiation or toxins is very slim. So while fish are growing two heads and cancer tumors, whales are dying of leukemia and mercury poisoning, and shearwaters are glowing in the dark and choking on plastics, jellyfish will still be gorging on their plankton banquets just like nothing had ever happened . . . assuming the plankton survive.
Thermal Pollution
In general, warming stimulates greater polyp reproduction and faster medusa growth. However, this is not always the case. Two extremes of the effects of unusually warm water on jellyfish are demonstrated by two examples from Australia. In the first, recall the case of the tropical species Cassiopea thriving in the warm effluent of the power station in the normally chilly waters of South Australia. In the second, a similar thermal plume appears to be driving a local extinction of a different jellyfish species.
Local Extinction Caused by Power Plant? Catostylus mosaicus
Reports of the large and conspicuous blubber jellyfish Catostylus mosaicus (see plate 1) swarming in the Tuggerah Lakes of New South Wales date back to at least 1892 (Scott 1999). It appears that Catostylus was consistently so abundant as to make fishing difficult.
The Munmorah Power Station on the shore of Lake Budgewoi commenced operation in 1967. A report in 1971 included the fact that the jellyfish were so numerous that they blocked the cooling water intake screens. However, by 1974, the jellyfish had virtually disappeared (J. Bell, in Scott, 1999). Several possible explanations have been put forth. First, there is local speculation among fishermen and others that the Power Station put something in the water that killed the jellyfish. The facility is known to release chlorine and heavy metals into the lake system (Kennedy 1997). However, given the lack of further available information, it is impossible to evaluate this hypothesis.
A second possibility is that warm water effluent from the power station altered the temperature of the lakes sufficiently to make them inhospitable to the polyps of Catostylus, thereby killing off the “seed bank” of the population. A third theory is that the warm water effluent altered the temperature enough to disrupt the algae/copepod dynamic of the food chain or the symbiotic algae in the jellyfish’s tissues, essentially causing a “bleaching event” similar to corals, and leaving Catostylus to starve.
A considerable number of studies have been performed on the effect of warm water effluent from power plants on local ecosystems, including in Australia. In some cases, species richness in the discharge plume area has been found to remain unchanged or to increase, while at others, species have been considerably reduced or eliminated altogether. It is thought that these differences could be due to local conditions, such as topography of the discharge area or intensity and duration of the temperature changes (Robinson 1987). However, “species richness” only measures total number and does not take into account whether the species are the same as those present before the disturbance or even whether they are native or heartier, more tolerant introduced forms. Despite the obvious lessening of effect on the local environment if power station effluents were to be discharged directly to the ocean, rather than to enclosed lagoonal areas, many stations continue to be built in shallow estuarine areas.
If indeed, the warm effluent from the Munmorah Power Station was the cause of the disappearance of Catostylus, as seems likely, the implication is intriguing: if Catostylus needs cooler water to survive, projected climate change may well drive the population south into Tasmanian waters, or drive it extinct. But then again, climate change effects would be slower, allowing the species and its associated ecosystem time to move, whereas thermal pollution progresses very fast in comparison.
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Our knowledge of the direct biological effects of pesticides, plastics, and radiation on jellyfish is lacking. However, it seems reasonable to conclude that any type of biological or ecological stress put on an ecosystem as a whole or on some of its inhabitants carries the potential to be favorable to jellyfish, in the same way that overfishing weakens one or more links in the food chain. Overall, pollution is effectively a “dream come true” for jellyfish in most cases, disturbing ecosystems sufficiently to give jellies the competitive edge.
The window for action is narrowing. As the [UNEP] Year Book underlines, persistent issues are in many cases becoming more acute, whilst new ones are emerging.
—ACHIM STEINER, United Nations undersecretary-general and United Nations Environment Programme executive director