What Forms of Pollution are Especially Harmful

in Ecosystems? • Air pollution

– Particulates and Heavy Metals• Industrial sources (ex. steel plants) and car exhaust• Can be toxic, decrease immunity, and aggravate asthma

– Acid rain: from nitric acid (car exhaust) and sulfuric acid (coal)• Acids increase solubility of some toxic heavy metals• Forests decline: Eastern Europe, U.S. Midwest (crosses boundaries)

• Water pollution: point and non-point sources– Biomagnification: heavy metals and persistent organic pollutants (POP’s) are difficult

to metabolize and/or detoxify concentrate in livers, fats of top predators (ex. DDT with egg-thinning effects endangered bald eagles and pelicans); others weaken immune systems or cause feminization (ex. fish in Lake Mead)

– Eutrophication and Sedimentation: excess plant nutrients lead to algal blooms; when algae die, leads to excess decomposition and thus high biological oxygen

demand (BOD); can lead to fish kills; excess sediment smothers corals and mucous-feeding invertebrates; sewage treatment reduces both problems

– Garbage: dumping in ocean outlawed in United States; plastics build up in central Pacific Ocean (center of gyre) and eaten by loggerhead turtles

(mistake for jelly- fish); seabirds ingest and feel full, regurgitate garbage to their offspring

Figure 55.19

Figure 55.20

Figure 55.18

Noise Pollution Affects Marine Mammals (Acoustic Umwelt)

Finally – Proof of Deafness!

Are Introduced Species a Form of Pollution?

• Exotic, non-native species (vs. indigenous species)• The only pollution that creates more of itself

– Can be accidental (ex. ship ballast introduces marine species via larvae) or purposeful (ex. mongoose in Hawaii; many fishes)

– Can have large effects on ecosystems since native species have not co-evolved competitive or anti-predation mechanisms

– Main causes of species extinctions and endangerment in Hawaii and Puerto Rico (including many endemic species)

– Often controversial regarding removal or treatment: poisoning of Lake Davis (CA) to remove pike; shooting

goats on Catalina Island– Other examples: Africanized (“killer”) bees; brown tree

snake (Guam); zebra mussels; “Med Fly”

Figure 56.8

How do Species Become Endangered, and How are They Protected?

• Common Characteristics of Endangered Species: small, localized ranges (including islands), fragmented populations (often due to human activities), low reproductive success

• U.S. Endangered Species Act (ESA): 1973; enforced by U.S. Fish and Wildlife Service or National Marine Fisheries Service – Endangered status: in “imminent danger of extinction throughout all or

significant part of its range”• Protects habitat; can be applied to a specific sub-population

– Threatened status: in “forseeable risk” of extinction• Examples: white shark (Calif. ESA) with naturally low populations and

targeted fisheries for sport/jaws; polar bear recent listing

– Listings: umbrella species chosen to protect entire ecosystem (ex. spotted owl chosen to protect old-growth forests); flagship

species (high profiles, ex. panda, bald eagle); sentinel (bellweather) species first to show effects of environmental stress (ex. amphibians exposed to air and water pollution); keystone species

– Controversies: populations difficult to measure; some listings seem “crazy” (ex. fly in Colton); is it effective? (few de-listings);

habitat protection often conflicts with private-land ownership

Figure 56.4

Figure 56.10

Is Aquaculture the Solution for the Over-fishing Problem?

• Over-fishing: 90% of fisheries over continental shelves; led to 200-mile exclusive-use zones; international fisheries

include Bering Sea, Gulf of Alaska, Grand Banks, Southern Capes (Good Hope, Horn)– Due mainly to increased technology: spotter planes, satellite data,

larger nets and longer long-lines– Biggest problems: bycatch; fishing at low trophic levels; subsidization

and flags of convenience (escape international treaties)• Trawling degrades habitat and has high level of bycatch

– Shark fisheries: mainly for shark-fin soup finning• Sharks do not support fisheries due to low reproductive potential

– Reserves replacing quotas and size limits; easier to enforce and evidence that they work (most fishes with planktonic larvae)

• Aquaculture and Mariculture (marine aquaculture)– Shrimp, salmon, lobster mainly for feeding relatively wealthy; all use

fish meal and contribute to over-fishing (net loss of biomass)– Tilapia and shrimp farms often destroy coastal wetlands/mangroves– Dense populations lead to disease antibiotics enter ecosystems– Escapes common; concern over effects on natural gene pools

Figure 56.9

Figure 54.24

Is the Ozone Layer Still Threatened?

• Stratospheric Ozone Depletion– Ozone a component of smog in lower atmosphere; in

upper atmosphere, shields Earth from UVB radiation– Chlorofluorocarbons (CFC’s) lighter than air, rise to

upper atmosphere, where they stick to ice crystals; each molecule able to destroy many ozone molecules

(most during summer); Antarctic ozone hole detected in 1985, Arctic ozone hole detected in early 1990’s; global ozone declining (ex. Toronto, UV increased 5.3% per year from 1989-1993)

– Effects of UV: skin cancers, stress immune systems, coral bleaching, reduces productivity of phytoplankton

– International Response: Montreal Protocol (1987) phased out production of CFC’s, but existing CFC’s stable (long-lived; ex. freon)

Figures 55.23-55.25

What Evidence Supports the Theory of Global Warming?

• A theory, supported by multiple lines of evidence (that current observed warming trend is due largely to human-caused influences)

– Greenhouse Effect: greenhouse gases trap warm air in lower atmosphere (esp. carbon dioxide, methane, and carbon monoxide)

– Combustion of fossil fuels adds CO2 to atmosphere; deforestation is often via burning (combustion) and loss of trees reduces uptake of carbon dioxide; more cattle more methane (proposal for effort to measure this effect laughed out of

U.S. Congress as “cow-fart study”)– Observed: rise in atmospheric CO2; global atmospheric and

oceanic warming; rising sea levels (Tuvalu, Kiribati, other Pacific islands flooding); retreat of mountain glaciers,

Arctic ice thinned, Antarctic ice shelves apparently breaking up; tropical diseases and insects spreading; regional climates

shifting, affecting species ranges and causing extinctions; widespread coral bleaching; lower heating costs on the “bright side”

Figure 55.21

What are the Predicted Effects of Global Warming and the International Response?

– Predicted: approx. 6°C rise by 2100; warming of tundra releases more CO2, melting of polar ice reduces reflection of energy by white

ice and accelerates melting (vicious cycles); melting of West Antarctic ice sheet would raise sea level by 20 feet, flooding London, New York, Florida, New Orleans (among others); cooling of Northern Europe due to likely disruption of Gulf Stream current by melting Arctic (more icebergs will also endanger ships); rise in intensity of tropical cyclones due to warmer water temperature

– Debate among specialists is mainly regarding the ocean’s role in the absorption of CO2 (but note that levels steadily rising in

atmosphere, corresponding to steady rise in combustion/emissions)– Public debate mainly regarding Earth’s natural cycles of warming/cooling

and lack of “definite proof”; also regarding economic costs of reducing carbon emissions

– International Response: Rio Earth Summit (1992) – agreed that Global Warming is serious problem and response needed by year 2000 (George Bush Sr. signed); Kyoto Accord (1998) – signed by

nearly all nations; Copenhagen (Dec. 2009); Adapt (?): sea walls planned in Thailand and Bangladesh