Case study of Bioaccumulation and Biomagnification– Orcas - endangered species of Puget Sound

Orcas (a.k.a. killer whales) Scientific name: Orcinus orca Largest member of dolphin family Identifying traits: Height of dorsal fin Saddle patch behind dorsal fin White patches on sides, belly, behind eyes

Orca biology Birth weight: around 400 lbs Adult weight – between 2.5 – 7 tons Males larger than females Lifespan: Females: can live to over 60 years Males: live around 40 years

Natural History Found in all seas, including Arctic and tropics Travel in pods: 3 - >150 individuals Main food: Fish Squid Marine mammals

Transient vs. Resident Orcas 2 major subspecies of orca Transient orcas: Live offshore Feed mostly on marine mammals Small pods of 3-5 individuals Tend to be very quiet Resident orcas: Live near shore Feed mostly on fish (esp. salmon) Large pods: >20 individuals Vocalize often

Puget Sound Resident Orcas Live in extended familial units called pods Pods are matriarchal in structure Oldest female is the grandmother of other orcas in pod Puget sound resident orcas 3 pods – J, K, L Summer around San Juan islands Winter on the outer coast

Status of Southern Resident Orcas 1995-2000: about 20% of southern resident orcas died – now 89 orcas Many females of reproductive age are not producing viable young Young males: dying rapidly Few males left in entire community Listed as endangered species in 2005 – at risk of extinction

Threats to Orcas Decreasing food supply Disturbance wild salmon are also listed as an endangered species Disturbance Physical (harassment by whale watching vessels) Acoustic (low/mid frequency sonar, drilling, dredging) Interferes with echolocation Environmental contamination Bioaccumulation of pollutants Historic threats Hunting Captured for captivity in marine parks

Pollutants Pollutant: any agent that adversely affects the health, survival, or activities of living organisms or that alters the environment in undesirable ways

How do pollutants enter environment? Point source pollution – specific locations of highly concentrated pollutant discharge Factories, power plants, sewage treatment plants Non-point source pollution – scatter, diffuse sources of pollutants Runoff farms, roads, golf courses, homes, etc All pollutants eventually end up in the ocean

Types of pollutants Water soluble pollutants Fat soluble pollutants Move rapidly and widely thru an environment Fat soluble pollutants Inside organisms, they penetrate readily into tissues and cells Stored in lipid deposits Protected from metabolic breakdown Passed via breast milk to young in mammals Tend to have much longer effects

Pollutant persistence Persistence = how long it takes to breakdown and be removed from the ecosystem Some compounds are very unstable and degrade rapidly Concentrations decline rapidly over time Other compounds are specifically designed to resist degradation (don’t break-down easily) Can have severe impacts long after they are introduced

POPs Persistant Organic Pollutants synthetic organic compounds used in various products (from electronics to cars) that resist environmental degradation Include PCBs and DDT Can have very long term effects in affected ecosystems

PCBs: Polychlorinated biphenyls BOTH FAT SOLUBLE AND A POP = very stable and resists degradation Used in: transformers, pesticides, paint, small electric parts, etc from 1929 - 1977 Enter mainly through non-point sources: products with PCBs leak, PCB travels into soil, carried by wind and water into environment (and eventually the ocean) In rats – cause liver cancer, pituitary tumors, leukemia, lymphoma and intestinal cancer In humans, classified as a probable human carcinogen (cancer causer) → banned in 1977

Bioaccumulation Process by which cells selectively absorb and store a great variety of molecules Allows cell to accumulate nutrients and essential minerals (like calcium, phosphorus, etc.) However, same process can also absorb and store harmful pollutants inside an organism Reason some fish are not fit for human consumption (usually because of bioaccumulation of mercury)

Biomagnification Process by which the effects of pollutants are magnified up an ecosystem through food chains When organism consumed by a higher trophic level, only about 10% of energy moves up, however majority of the pollutant is passed on from prey to consumer Therefore – as the pollutant moves up the food chain, the concentration of the pollutant in the body tissue increases dramatically This is especially true for POPs since they persist for long periods of time

Biomagnification Example DDT residues - Long Island Estuary Woodwell, Wurster, Isaacson, 1967 Trophic level Organism DDT (wet weight) Primary Producer Green alga 0.08 ppm (parts per million) Consumer Mud snail 0.26 ppm Secondary Summer Flounder 1.28 ppm Tertiary Ring-billed gull 75.5 ppm

Puget sound orcas affected by PCB’s Our orcas have, on average, the highest measured levels of PCB’s of any marine mammal IN THE WORLD Almost 150 ppm (parts per million) average >10 ppm PCB known to cause immune problems in seals Mother can pass as much as 90% of PCB’s to her offspring via milk and through placenta Female transient orca found dead on Dungeness spit in 2002 had 1000 ppm

Yeah, but there are banned, right? Double whammy for our orcas PCB’s are less harmful when in fat vs. their bloodstream Low salmon runs = orcas use blubber (fat) for energy ↓ PCB’s released into blood PCBs interfere with normal immune function Result: orcas more susceptible to disease and pathogens

Yeah, but PCB’s are banned, right? - other POP’s – the ‘Dirty Dozen’ POP (persistent organic pollutant) Pesticide Industrial Chemical By-product Aldrin √ Chlordane DDT Dieldrin Endrin Heptachlor Mirex Toxaphene Hexachlorobenzene PCBs Dioxins Furans

New era, new threats Many countries still use chemicals that have proven to bioaccumulate Chemicals are stored all over the world and are often not properly disposed of US does not have a law that insists on testing of new chemicals (unless they are used in food) Only 10% of the 85,000 chemicals used in North America have been tested for environmental effects

PBDEs: example of a new threat Polybrominated diphenyl ethers Group of fire-retardant chemicals (they don’t catch fire) A POP: structurally similar to PCB’s Found in furniture, televisions, computers Europe has banned PBDE’s, only state to ban is California There IS an available fire retardant shown not to bioaccumulate

Extra credit Research report on: PBDE’s or another currently used pollutant Use at least 3 different sources (and provide bibliography) Include: Chemical structure What it is used in/ for (pros) Environmental/ health impacts (cons) Statement on whether you believe it should continue to be used or outlawed