Contaminants and conservation
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Contaminants and Conservation. Contaminant Impacts . Key difficulty for measuring contaminant impacts is that most if not all systems impacted by contaminants are also affected by other human-mediated changes

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Contaminant Impacts

  • Key difficulty for measuring contaminant impacts is that most if not all systems impacted by contaminants are also affected by other human-mediated changes

  • Coastal systems typically experience multiple impacts and contaminants may not even be the most important stressor

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Multiple Contaminants

  • Petroleum

  • Radionucleotides

  • Pesticides

  • Herbicides

  • Heavy metals

  • Nutrient inputs (eutrophication)

  • Sediments

  • Salinity

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Integrating Across Levels

  • Need to integrate across levels

  • Biomarkers and bioindicators have different strengths and weaknesses

  • Focus on organismal level with bioindicators at population and community level with biomarkers at suborganismal levels

  • Population, community and ecosystem levels will be today’s focus

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Measuring Impacts

  • In order to measure changes, you need to conduct some type of environmental monitoring

  • Make periodic measurements of a set of attributes in a location of set of locations

  • The goal is to compare the condition of either contaminated sites vs. uncontaminated (less) sites or across a gradient of sites with varying levels of contamination

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Measuring Impacts

  • Can’t compare everything nor measure everything

  • Focus on particular taxa

    • Birds, fish, invertebrates, algae

  • Focus on particular habitats

    • Salt marshes, mangroves, coral reefs

  • Focus on particular groups

    • Predators, grazers, decomposers, primary producers (plants)

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Measuring Impacts

  • Impacts of contaminants usually have a short-term (acute) and long-term (chronic) components

  • Spatial and temporal scales of impacts are not typically known

  • Subtle changes in the short-term that may ultimately have large long-term effects may be difficult to separate from other environmental variation

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Measuring Impacts

  • What properties or fractions of the contaminants that are causing harm is even difficult to determine

  • Mercury is relatively inert in an inorganic phase but very toxic in an organic phase

  • Bioavailability for many compounds is difficult to determine

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Measuring Impacts

  • Some compounds may be stored by and organism, others metabolized

  • Levels of contaminant in an organism may not be a good indicator of either exposure or toxicity

  • Chemical interaction among different compounds may change bioavailability or toxicity

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Time Scale of Response

(from Adams 2002)

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Antifouling Paint: Tributyl Tin (TBT)

  • For many years, commercial, military and recreational boaters used increasingly toxic bottom paints (copper, tin) to prevent fouling

  • Organotin compounds were found to be very effective but very toxic

  • Although TBT is now banned except for military ships, TBT is still present in sediments in many harbors

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TBT Exposure and Imposex

  • Although there have been many documented lethal effects of TBT, sublethal effects can be damaging

  • At very low concentrations, TBT can result in female molluscs changing into males (not reproductive)

  • Particularly in snail,s TBT can turn females into a nonreproductive males in a state called imposex

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TBT Exposure and Imposex

Oehlmann et al. 1991

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TBT Exposure and Imposex

Bettin et al. 1996

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TBT Exposure and Imposex

Bettin et al. 1996

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Pesticides: Pyrethroids

  • Pyrethroids and related pesticides are common components of urban and surburban runoff

  • They are extremely toxic to insects and other arthropods, and stable in aquatic systems

  • This can accumulate on sediments and result in very toxic effects on copepods, mysids, etc. as well as fish

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Bollmohr et al. 2007

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Bollmohr et al. 2007

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Creosote and PAHs

  • Among the many compounds introduced in bays and harbors is creosote used to preserve wooden piers and pilings

  • Polynuclear aromatic hydrocarbons (PAHs) are among the compounds released from creosote (PAHs have other sources too)

  • PAHs can accumulate in toxic levels in harbors and estuaries causing lesions and tumors in marine organisms

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Creosote and PAHs

Pickney and Harshbarger 2006

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Creosote and PAHs

Pickney and Harshbarger 2006

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Creosote and PAHs

Pickney and Harshbarger 2006

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Other Marine Contaminants

  • Carbaryl (Sevin) is a pesticide used in terrestrial, aquatic and marine systems to kill arthropods (insects)

  • In Pacific northwest estuaries, it is used to kill burrowing shrimp that disrupt oyster production

  • Many other species are killed including crabs and shrimps, but the long-term effects are uncertain

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Other Marine Contaminants

  • Eradication of invasive estuarine plants involves applying herbicides like Imazypyr

  • Although the herbicide is low toxicity, the surfactant that is used to apply the herbicide may be more toxic

  • These are being applied over large areas of San Francisco Bay to eradicate Spartina, with hopefully minimal impacts

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Petroleum: Large Scale Impacts

  • Few contaminants are moved in marine systems in quantities equal to oil

  • Large oil spills have occurred in many different habitats

  • In most cases, effects of even large oil spills are hard to measure

  • Typically few data are available prior to event to compare with post-spill data

  • Sediment and tissue levels are hard to correlate with impacts

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Cosco Busan Oil Spill

Alcatraz Island

San Francisco Bay

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Cosco Busan Oil Spill

Dead oiled seabird

Muir Beach cleanup

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Panama Oil Spill

  • There was an oil spill (3.2 million gallons) in in Panama 1968 near the Smithsonian Institution’s Goleta lab

  • Studies following that oil spill as well as many ongoing scientific studies (not oil related) create substantial baseline to measure effects

  • Larger oil spill (8 million gallons) in 1989 occurred as the result of a ruptured land-based storage tank

  • Oil affected mangrove forests, sea grass beds and coral reef habitats

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Panama Oil Spill

  • Best data was available for mangroves and subtidal corals (pre-spill data from oiled an unoiled sites) less for reef flats and seagrasses

  • Highest concentrations of oil in mangroves and sea grass areas occurred within a few kilometers of the spill

  • Areas affected by wind driven currents were more affected by oil accumulation

  • Low tides after the spill contributed to high oil concentrations at seaward borders of reef flats

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Panama Oil Spill

Coral Reef


Jackson et al. 1989

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Panama Oil Spill

Reef Flat


Jackson et al. 1989

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Panama Oil Spill

Reef Flat


Jackson et al. 1989

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Panama Oil Spill




Jackson et al. 1989

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Panama Oil Spill Five Years After

  • Studies were conducted for the next five years in mangroves to determine long-term effects (Garrity et al. 1994, Burns et al. 1994, Levings et al. 1994)

  • Effects included reduced length of mangrove forest (fringe)

  • Also reduced length and number of mangrove prop roots: important structural habitat

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Panama Oil Spill Five Years After

Garrity et al. 1994

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Panama Oil Spill Five Years After

Levings et al. 1994

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Panama Oil Spill Five Years After

Burns et al. 1994

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Panama Oil Spill Five Years After

  • Sediment cores looking at presence of dead mangrove roots allowed analysis of even longer term effects

  • Also degradation of oil in deep muds was found to be very slow

  • Burns et al. (1994) concluded that toxic effects of oil in mangrove muds could continue for at least 20 years after oil spills

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Oil in New England Salt Marsh

  • In 1969, a large oil spill of number 2 fuel oil spilled in West Falmouth Harbor, MA

  • Large changes took place as measured 5 years afterward

  • Teal et al. (1992) went back and assessed changes 20 years later

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Oil in New England Salt Marsh

  • They found that most of the oil had disappeared except for one of the most heavily oiled sites

  • Most of the organisms sampled had only remant levels of contamination (not much above background levels)

  • Conclusion is that the oil has largely broken down and that the system is functioning relative normally

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Oil in Alaska

  • In 1989, the Exxon Valdez dumped 11 million gallons of crude into northern Prince William Sound, AK

  • It contaminated nearly 2000 km of coastline and as far as 750 km from the spill site

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Oil in Alaska

  • Many acute or short-term impacts (Peterson et al. 2003) including deaths of:

    • 1000-2800 northern sea otters

    • 250,000 sea birds

    • 300 harbor seals

  • Many other immediate impacts on fisheries that were harder to quantify particularly lost recruitment

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Oil in Alaska

  • Long-term impacts as well (Peterson et al. 2003)

  • Rate of oil degradation slowed down markedly from 56% per year up to 1992 to about 20% per year by 2001

  • Depositional refuges and areas protected from sun and wave energy contribute to this remainder

  • Compounds like PAHs that derive from weather oil were still in abundance years later

    • Toxic to pink salmon larve at <20 ppb

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Oil in Alaska

  • Recovery of sea otters was much slower in oiled areas of Prince William Sound

    • Feed on clam and mussels that still have measurable levels of oil toxicity (for as much as 30 years)

  • Harlequin ducks and Barrow’s goldeneye’s also show no recovery in oiled areas

    • Feed on intertidal invertebrates that show elevated enzyme levels due to contamination

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Oil in Alaska

  • Juvenile pink salmon that had been exposed to sublethal doses of PAHs in lab showed only half the survival rate in the next 1.5 years in a mark-release-recapture experiment

  • Exposure to sublethal doses during sensitive life stages can have significant impacts months to years later

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Direct vs. Indirect Effects of Contaminants

  • Contaminants rarely affect single species in natural systems

  • Contaminants will effect multiple species with varying results

  • By impacting some species more than others, contaminants will have both direct and indirect effects on species abundances

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Indirect Effects of Contaminants

(from Fleeger et al. 2003)

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Indirect Effects of Contaminants

  • Direct effects usually lead to reduced abundances of organisms

  • Indirect effects can result in either increased or decreased abundances

  • A review of 150 studies that reference indirect effects of contaminants showed such effects in 60% of the studies (Fleeger et al. 2003)

  • The most common result was an increase in primary producers (plants) (trophic cascade)

  • Some evidence for competitive release, but few studies have tested this