19 Environmental Impacts of Industrial Activities and Human Populations Notes for Marine Biology: Function, Biodiversity, Ecology By Jeffrey S. Levinton.

19 Environmental Impacts of Industrial Activities and Human

Populations

Notes for Marine Biology: Function, Biodiversity,

EcologyBy Jeffrey S. Levinton

Human Effects on Marine Environment

• Complex interactions of human impacts often make it difficult to understand the role of various pollutants in degrading the marine environment

Human Effects on Marine Environment

• Pollution may be long term (chronic) or short term (acute)

• Pollution may come from point sources or from a variety of geographic points

Effects on Single Species

• Common species are often chosen as bioassays of pollution effects

• Direct studies can be made on uptake of substances and mortality

• The effects of toxic substances on single species may be measured by constructing models relating toxic substance concentration to population growth

(a) Life history stages of the killifish Fundulus heteroclitus are used to make population projection with stage-specific survival (P), reproductive rate (R) of stages 2, 3, 4, and development of one stage into another; (b) population projections as a function of dioxin and PCB concentrations

Effects on Single Species• The introduction of toxic substances may be

related to uptake by individuals in field populations

• Gene expression may be an effective means of assaying for effects of toxins. Microarrays can be used for expression of many genes in response to toxic substance

• With genetic variation in natural populations and differences in fitness among genotypes, evolution of resistance to toxic substances may occur

Tolerance for polychlorinated biphenyls (PCB 126) of the nonmigratory killifish Fundulus heteroclitus when taken from a range of contaminated areas, as measured by the reciprocal of LC50 after exposure to a given concentration

Toxic Substances

• Noncumulative toxic substances do not increase in concentration in body over time

• Cumulative toxic substances continue to increase in concentration

• Food chain magnification occurs when concentration of substance increases as toxic substance is passed from trophic level to trophic level. Only happens when special chemical conditions occur (e.g., solubility of toxic substance in a common substance such as fatty acids in consumer)

Effects on Biodiversity

• Toxic substances may remove certain species from a community, resulting in lower biodiversity with increased input of toxic substances.

Toxic Metals

• Mercury - toxic when attached to short carbon-chain alkyl group (= methylmercury), strongly neurotoxic, birth defects; biomagnifies up food chain

• Cadmium - from batteries, sewage, electroplating factories, effects on human kidney function, bone deformities

• Lead - from batteries, paints, sewage, fuel additives; neurotoxic effects, mental development of children

Pesticides, Herbicides

• Designed to kill a variety of pests, principally arthropods such as mosquitoes, agricultural pests, but also plants

• Targets are often nonspecific, marine species also killed off

• Pesticide toxicity often affects human health

Some Pesticides, e.g. DDT• DDT - one of many chlorinated hydrocarbons• Used to kill Anopheles mosquito and other agricultural pests• Magnified up the marine food chain to vertebrates, owing to

solubility in fatty tissue• Implicated in declines in 1970s of birds at apex of food web

(marine-feeding bald eagles, osprey, brown pelicans, etc.) - strong effects on reproductive function, egg shell thickness

• DDT banned in many countries, birds have increased in abundance, but still used in many developing countries to fight malaria

• Pesticides used in USA today are less toxic (e.g., malathion)

DDT and other Chlorinated Pesticides

Other Carbon-based Toxic Substances

• Polychlorinated Biphenyls (PCBs) - used as lubricants in industrial machinery, highly toxic - implicated in reproductive failures of marine mammals, human effects; release in NE USA resulted in area closures to fishing, and health advisories. Current controversy over cleanups in Hudson River, other sites

Other Carbon-based Toxic Substances 2

• Polycyclic aromatic hydrocarbons (PAHs) - derivatives from fossil fuels, coming from sewage, and other sources; toxic effects on benthic invertebrates and fishes, effects on hormonal cycles and reproductive effects of fishes

Oil Pollution - Sources

• Leaks from terminals, loading pipes in harbors

• Offshore drilling

• Wrecks of oil tankers

• Washout of oil into storm drains and direct washout to the shoreline

Tanker Accidents 1• Result in catastrophic release of oil• Associated with rough weather, making it difficult to

clean up• Tanker traffic has increased with increasing use of

petroleum around world• Tankers (e.g. large ones carry more than 200,000 tons)

are not maneuverable, take several kilometers to stop• New tankers are double skinned, have multiple holds,

but older ones very vulnerable to puncture and breakup through imbalance of loads

Tanker Accidents 2• Torrey Canyon, off coast of U.K in 1967, released 80

tons of crude oil, tanker bombed to burn oil, use of detergents did much damage to marine life

• Amoco Cadiz, spilled 200,000 tons near French coast in 1978, strong effects on marine life

• Barge Florida near Cape Cod, 1969, small spill of #2 diesel fuel oil, but toxic substances found in shellfish over a year later

• Exxon Valdez, 1989, off coast of Alaska, 11 million gallons, strong effects on marine life, still evident in 2001. Hot water cleanup did much damage

400

300

200

100

0 J F M A M J J

Month in 1978Den

sity

of

amph

ipod

s pe

r 1/

4 sq

uare

met

er

Change in abundance of amphipods followingwreck of tanker Amoco Cadiz near Brittany coast

Oil

Mangroves

Sediment

Stormerosion

Sea grasses

Sediment

Onshore Offshore

Erosion

Coral reef

The cascading effects of oil derived from a 1986spill along the shores of Bahia Las Minas in Panama

Toxic Components of Oil

• Crude oil generally less toxic than refined oil

• Aromatic compounds (compounds with benzene rings) are more toxic; percent aromatics is a good indicator

• Crude oil: < 5 % aromatics, Refined Oil - 40-50 % aromatics

• Aromatics impair cell membrane function, neurotoxic and behavioral effects

Oil - Effects on Seabirds

• Contour feathers interlock and keep water from penetrating down feathers beneath

• Oil coats contour feathers and collapses their interlock, seabirds lose insulation and die of hypothermia

• Birds often ingest toxic oil while preening, and feeding birds (e.g., puffins) are attracted to oil at surface

Structure of a bird’s contour feather, showing how barbules are hooked together to seal spaces between barbs

Birds covered with oil from a spill (above) are washed; cleanup at this point often is futile

Nutrient Input and Eutrophication

• Agricultural activities and sewage add nutrients, as wellas disease organisms, to estuarine and coastal waters.• Eutrophication -Human activities result in large additions of dissolved nutrients to coastal waters. Point sources such as sewer outfalls, storm sewers• The atmosphere can be a major source of nutrientaddition to coastal bays.

Effect of Added Nutrients

• Nutrient stimulation of primary production often resultsin hypoxia or anoxia• Phytoplankton are not all grazed, sink through thermocline and are consumed by bacteria, which also consume oxygen.• Leads to waters of low oxygen (hypoxia) or no oxygen (anoxia)• High nutrient inputs result in large hypoxic or anoxic dead zones in coastal areas throughout the world

Development of hypoxia in an estuary. (a) Normal situation: much of thephytoplankton is grazed and bottom waters are oxygenated; (b) nutrient input from sewage stimulates phytoplankton growth, and some dead phytoplankton sink to bottom waters; bacterial decomposition reduces oxygen, and other material sinks to bottom sediment, where more oxygen is consumed from bottom waters; (c) oxygen is removed from bottom waters and benthos die

Dead zone on shelf off the mouth of the Mississippi River in 1993, 1998

Abating Eutrophication

• Eliminating ocean dumping of solid sewage waste andbetter treatment of sewage before wastewaters arereleased into the coastal zone can abate eutrophication.

Sewage Treatment• Primary treatment: solids are intercepted by screens• Secondary treatment: more toxic nitrogenous organic compounds and colloids are stirred in aerobic tanks so that only phosphates, nitrates, and ammonia will be released into coastal waters; solid residue is then disposed. • Tertiary treatment: even dissolved phosphates, nitrates, and ammonia are removed, by means of anaerobic decomposition processes

Methods of Sewage Treatment

Global Environmental Change and the Ocean

• Industrial activities have caused the net addition ofcarbon dioxide and other greenhouse gases to theatmosphere since the nineteenth century; theseadditions are significant on a geological scale

• Carbon dioxide additions to the atmosphere have causedincreases of sea-surface temperature through at leastthe past 100 years

• Carbon dioxide additions have resulted in a reduction ofseawater pH

(a) Changes in world average temperature anomalies since 1880, which are deviations from the mean temperature of a base period 1951-1980; (b) Global map of mean surface temperature anomalies for the period 2001-2005 (see Hansen et al. 2006, Proc. Nat. Acad. Sci.)

Global Environmental Change at the Organismal Level

• Increases of sea-surface temperature affect physiologicalfunction, migration patterns, and geographical range

Latitudinal shifts of species not entirely coordinated. Nesting birds might lose preferred food in water column nearby

• Increases of sea-surface temperature may affect theimpact of spread of disease

Corals and other species are weakened by temperature increase, increase susceptibility

• Decreases of pH are influencing calcification

Some evidence for corals, calcifying plankton such as coccolithophorids might be affected, although carbon dioxide can also stimulate primary production

Global Environmental Change at the Biodiversity Level

• Changes of pH and sea-surface temperature may causethe loss of foundation species for major communities

• Changes of sea-surface temperature may causeincreases of the success of invasions of alien species andrearrangements of local species abundance

• Overharvesting of species or habitat destruction mayresult in complex negative interactions with globalclimate change impacts

• Sea-level rise and climate change may strongly affectcoral reef survival; reef drowning possible, reefs cannot “escape” to higher latitudes in Pacific oceanic island systems

Global Environmental Change at the Biodiversity Level

• Increased temperature and carbon dioxide may increasebiological productivity, especially in nutrient-enrichedestuaries

• Increase of greenhouse gases and global warmingcould intensify coastal upwelling and increase primaryproduction

• Changes in primary production may occur in the openocean over a few decades, but there is no evidence atpresent that primary production has increased to anydegree over the last 70 years or so

•While upwelling increase is possible, increase in sea surface temperature could stabilize water columns, resulting in nutrient depletion in tropical open sea water columns

The End