contaminants and conservation. contaminant impacts key difficulty for measuring contaminant impacts...

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

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

Multiple Contaminants

• Petroleum• Radionucleotides• Pesticides• Herbicides• Heavy metals• Nutrient inputs (eutrophication)• Sediments• Salinity

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

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

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)

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

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

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

(from Adams 2002)

Time Scale of Response

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

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


Oehlmann et al. 1991


Bettin et al. 1996

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

Pesticides

Bollmohr et al. 2007

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

Creosote and PAHs

Pickney and Harshbarger 2006

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

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

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

Cosco Busan Oil Spill


San Francisco Bay

Alcatraz Island


Muir Beach cleanup

Dead oiled seabird

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

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

Panama Oil Spill

Panama Oil Spill

Coral ReefCommunitiesJackson et al. 1989

Panama Oil Spill

Reef FlatCommunitiesJackson et al. 1989

Panama Oil Spill

MangroveRootCommunitiesJackson et al. 1989

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


Garrity et al. 1994


Levings et al. 1994


Burns et al. 1994


• 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

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


• 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


Teal et al. 1992

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

Oil in Prince William Sound, AK

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

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

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

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

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

Indirect Effects of Contaminants

(from Fleeger et al. 2003)

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

contaminants and conservation. contaminant impacts key difficulty for measuring contaminant impacts...

Documents

toxicalthough tbt

imposextbt exposure

different compounds

harborstbt exposure

multiple impacts

foulingorganotin compounds

impactssome compounds

community level