CHAPTER 11The Coastal Ocean

Overview

Coastal waters support about 95% of total biomass in ocean

Most commercial fish caught within 320 km (200 m) from shore

Important also for shipping, oil and gas production, and recreation

Many pollutants found here – that’s a problem!

http://www.safmc.net/Portals/0/shrimp%20trawler2.jpg

Ocean ownership 1609 sea is free to all (mare liberum = free)

Assumed fish resources are inexhaustible

1702 territorial sea under coastal nation’s sovereignty (3 nautical miles from shore)Distance of cannon shot

http://www.kid-friendly-family-vacations.com/image-files/fort_sumter.jpg

Fort Sumter, Charleston harbor, South Carolina

United Nations and ocean laws 1958-1982 United Nations

Law of the SeaLaw of the Sea ConferencesNational sovereignty extends 12

nautical milesExclusive Economic Zone (EEZ)Exclusive Economic Zone (EEZ)

200 nautical miles (370 km) from land (mineral and fishing resources)

Right of free passage for shipsOpen ocean mining regulated by

International Seabed Authority○ This has changed, still very

contentiousUnited Nations arbitrates disputes

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EEZ of the U.S.--about 30% more than land area of entire U.S.

Fig. 11.1

Characteristics of coastal waters Adjacent to land (to edge of

continental shelf) Influenced by river runoff, wind,

tides Salinity variable

Freshwater runoffWindsMixing by tides

http://upload.wikimedia.org/wikipedia/commons/5/58/Outer_Continental_Shelf_map.png

Characteristics of coastal waters Temperature variable

Low-latitudes: restricted circulation, very warm

High-latitudes: sea iceMid-latitudes○ Seasonal changes○ Prevailing winds

Types of coastal waters EstuaryEstuary

Partially enclosed coastal area with ocean water and freshwater (runoff) mixing

Coastal wetlandCoastal wetlandEcosystem with water table close to

surface Lagoon – type of estuaryLagoon – type of estuary

Shallow coastal water separated from ocean

Marginal seaMarginal seaRelatively large semi-isolated body of water

Estuaries - Origin of estuaries Rising sea level “drowns”

what was once land Coastal plain estuaryCoastal plain estuary

Former river valley now flooded with seawater

FjordFjord Former glaciated valley now flooded

with seawater Bar-built estuaryBar-built estuary

Lagoon separated from ocean by sand bar or barrier island

Tectonic estuaryTectonic estuary Faulted or folded down-dropped area

now flooded with ocean

Estuaries - Classification of estuaries4 types - Based on mixing of freshwater and

saltwater

Vertically mixedVertically mixed Shallow, low volume Salinity uniform

Slightly stratifiedSlightly stratified Deeper than previous Upper layer less salty; lower layer more salty Estuarine circulation

Highly stratifiedHighly stratified Deep, relatively strong halocline

Salt wedgeSalt wedge Deep, high volume Strong halocline Typical at mouths of deep, high volume rivers

Figure 11.8

Severely effected by human activity, freshwater wedge can be traceable far out to sea

Indian River Lagoon Estuary Well-mixed due to winds

and shallow depths Seasonal changes in

salinity, temperature, dissolved oxygen

Most biologically diverse estuary in north america…over 4,000 species of plants and animals

Threats: habitat destruction, stormwater runoff, and invasive exotic species

http://www.indianriverlagoon.org/docs/irlmap.html

Sebastian Inlet

Chesapeake Bay Estuary

Anoxic conditionsAnoxic conditions below pycnocline in summer Runoff of sewage and fertilizer cause algae bloom when these organisms die, increased decomposition causes

anoxic conditions Decrease in oxygen levels in water

Major kills of commercially important marine animals

Coastal Wetlands - Types of coastal wetlands

o Ecosystems that are saturated with watero Swamps, tidal flats, coastal

marshes, bayous

o Salt marsho Any latitude

o Mangroveso Low latitude

Characteristics of coastal wetlands Efficiently cleanse polluted water Absorb water from coastal flooding

during storms Protect shores from wave erosion

http://soundwaves.usgs.gov/2008/03/WetlandLG.jpg

Coastal Wetlands - Loss of coastal wetlands Half of U.S. coastal

wetlands lost to development (housing, industry, agriculture)

U.S. Office of Wetland Protection, 1986Minimize loss of

wetlandsProtect or restore

wetlands

http://www.on.ec.gc.ca/wildlife/factsheets/images/glfs-coast-stress.jpg

Lagoons Freshwater zone Transition zone of brackish water Saltwater zone Hypersaline in arid regions

Marginal seas Mostly from tectonic events

Ocean crust between continents, e.g., Mediterranean Sea

Behind volcanic island arcs, e.g., Caribbean Sea

Shallower than ocean Connected to ocean

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Caribbean Sea On Caribbean plate defined by Greater

and Lesser Antilles – volcanic island arc Relatively shallow marginal sea – deepest

is Cancun Trough at 7,686 m (25,220 ft) Underlain by oceanic crust

http://woodshole.er.usgs.gov/project-pages/caribbean/images/PBATHY1.GIF

Mediterranean Sea Remnant of Tethys Sea – when all the continents

were together Deeper than usual marginal sea Underlain by oceanic crust Thick salt deposits – almost dried up about 6

million years ago

Fig. 11.14a

Mediterranean circulation

High rates of evaporation Mediterranean Intermediate Water very

salty

Fig. 11.14b

Marine pollution Any harmful substance or energy put into

the oceans by humansHarmful to living organisms○ Standard laboratory bioassay – concentration of pollutant

that causes 50% mortality among test organisms

Hindrance to marine activities (e.g., fishing)Reduction in quality of sea water

Waste disposal in ocean Diluting pollutants with huge volume of

ocean water Long-term effects not known Debate about dumping wastes in ocean

None at all ??Some, as long as properly disposed and

monitored ??

Main types of marine pollution Petroleum Nutrient excess

○ Sewage sludge○ Fertilizer runoff

DDTs and PCBs Mercury Non-point-source pollution and trash

○ Drainage from roads, canals, etc.

Petroleum Biodegradable Biodegradable

hydrocarbonshydrocarbonsRecovery faster than

expected○ Exxon Valdez oil

spill, 1989But many organisms

killed outrightLong-term

consequences uncertain○ Research is still

being done in this area, some animal populations have not completely recovered

Fig. 11.16

BP Deepwater Horizon Oil Spill in Gulf of MexicoApril 20, 20104.9 MILLION barrels of oil were leakedWhat are future effects?

Cleaning oil spills Natural

processesVolatilizationPhoto oxidationEmulsificationBiodegration by

pelagic organisms

Biodegration by benthic organisms

Artificial processesOil dispersantsIsolate spill with

boomsSkimming or

absorbing surface oil slick

Bioremediation by “hydrocarbon-eating” bacteria

Preventing oil spills Double hulled oil tankers by

20151990 Oil Pollution Act

Burn oil before it spreads1999 M/V New Carissa

http://www.modelshipmaster.com/products/ocean_liners/tube.jpg

http://www.ec.gc.ca/EnviroZine/images/aerial.jpg

Sewage sludge

Semisolid material after treatment No dumping of sludge in ocean after

1981Clean Water Act, 1972

HOWEVER - many exceptions/waivers

New York’s sewage sludge disposal

First, shallow water sites

Then (1986), deeper water site

Adverse effects on fish 1993 all sewage

disposed on land

Fig. 11.25

DDT and PCBs Pesticide DDT and industrial chemicals

PCBs (polychlorinated biphenyls)○ DDT – pesticide that was widely used○ PCBs – used in transformers and other areas of

industry

Widespread in oceans Persistent organic pollutants

ToxicLong life dissolved in seawaterAccumulated in food chain

Bioaccumulation – it’s happening in us, also!

Bioaccumulation and biomagnification BioaccumulationBioaccumulation – organisms

concentrate pollutant from seawater BiomagnificationBiomagnification – organisms gain

more pollutant by eating other organisms

DDT

Decline in bird populations and thin eggshells Long Island osprey California brown

pelican

DDT banned in U.S. in 1972

Some marine bird populations rebounded

Mercury and Minamata disease

Methyl mercury toxic to most living organisms

Chemical plants, Minamata Bay, Japan, released mercury in 1938

By 1950 first reported ecological changes By 1953 humans poisoned

Neurological disorder

Bioaccumulation and biomagnification

Safe levels of mercury determined byRate of fish

consumption by people

Mercury concentration in fish consumed

Minimum ingestion rate of mercury to cause damages

Non-point-source pollution and trash Not from underwater pipelines

Hard to regulateFor example, from storm drainsPesticides and fertilizersRoad oil Trash

Trash from dumping Some trash can be legally

dumped far from shoreBiodegradable (e.g., food) orSinkable (e.g., glass, metal)

Some trash cannot be dumpedPlastic○ Lightweight (floats)○ Not easily biodegradable○ Plastic can incorporate

pollutants, such as DDT and PCBs

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It is up to us!

Don’t throw trash out your car window Don’t leave trash on the beach Don’t throw trash off the side of your

boat Don’t use fertilizers irresponsibly Don’t just dump things down the drain

without reading about proper disposal Get onto people you know that do this!

○ Think of your kids and grandkids!

Problems with Contaminants in Oceans Research into immunosuppression

and reproductive problems in many species

Chemicals that are banned in US and other countries are still used in others – it is 1 ocean, doesn’t matter where it is dumped○ It will effect us all!

All drains lead to the ocean!

Fig. 11.32a,b

Misconceptions Science and technology can solve all of our

problems. The Earth can absorb and neutralize any amount of

waste and pollution over time. Dilution is the solution to the problem. Microorganisms are not important to human survival. Local people cannot improve their environments; it is

out of their hands. If we run out of oil and gas we will just find more. Earth is both an endless supply of resources and a

limitless sink for the waste products of our society.

Ocean Literacy Principles 1.d - Sea level is the average height of the ocean relative to the

land, taking into account the differences caused by tides. Sea level changes as plate tectonics cause the volume of ocean basins and the height of the land to change. It changes as ice caps on land melt or grow. It also changes as sea water expands and contracts when ocean water warms and cools.

1.h - Although the ocean is large, it is finite and resources are limited.

5.f - Ocean habitats are defined by environmental factors. Due to interactions of abiotic factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not evenly distributed temporally or spatially, i.e., it is “patchy”. Some regions of the ocean support more diverse and abundant life than anywhere on Earth, while much of the ocean is considered a desert.

5.i - Estuaries provide important and productive nursery areas for many marine and aquatic species.

Sunshine State Standards SC.6.E.6.1 - Describe and give examples of ways in which Earth's surface is built up and torn down by

physical and chemical weathering, erosion, and deposition. SC.6.E.6.2 - Recognize that there are a variety of different landforms on Earth's surface such as coastlines,

dunes, rivers, mountains, glaciers, deltas, and lakes and relate these landforms as they apply to Florida. SC.912.E.6.6 - Analyze past, present, and potential future consequences to the environment

resulting from various energy production technologies. SC.912.L.17.2 - Explain the general distribution of life in aquatic systems as a function of chemistry,

geography, light, depth, salinity, and temperature. SC.912.L.17.3 - Discuss how various oceanic and freshwater processes, such as currents, tides, and

waves, affect the abundance of aquatic organisms. SC.912.L.17.8 - Recognize the consequences of the losses of biodiversity due to catastrophic events,

climate changes, human activity, and the introduction of invasive, nonnative species. SC.912.L.17.11 - Evaluate the costs and benefits of renewable and nonrenewable resources, such as

water, energy, fossil fuels, wildlife, and forests. SC.912.L.17.13 - Discuss the need for adequate monitoring of environmental parameters when making

policy decisions. SC.912.L.17.16 - Discuss the large-scale environmental impacts resulting from human activity, including

waste spills, oil spills, runoff, greenhouse gases, ozone depletion, and surface and groundwater pollution.

SC.912.L.17.20 - Predict the impact of individuals on environmental systems and examine how human lifestyles affect sustainability.