Chapter 11 The Coastal Ocean Essentials of Oceanography 7th Edition

Coastal waters Relatively shallow areas that adjoin continents Heavily used for commerce, recreation, fisheries, and waste disposal Experience dramatic changes in salinity and temperature

Salinity and temperature in the coastal ocean Figure 11-1

Estuaries Estuaries are partially enclosed coastal bodies of water Examples of estuaries include: River mouths Bays Inlets Gulfs Sounds Formed by a rise in sea level after the last Ice Age

Classifying estuaries by origin Coastal plain Fjord Bar-built Tectonic Figure 11-3

Tectonic estuary (San Francisco, CA) Fjord estuary (Norway) Examples of estuaries Tectonic estuary (San Francisco, CA) Fjord estuary (Norway) Figure 11-4

Classifying estuaries by water mixing Vertically mixed Slightly stratified Highly stratified Salt wedge Figure 11-5

Coastal wetlands Coastal wetlands are saturated areas that border coastal environments Brackish water conditions Two most important types of coastal wetlands: Salt marshes (mid-latitudes) Mangrove swamps (low latitudes)

Coastal wetlands: Salt marshes and mangrove swamps Figure 11-8

The value of coastal wetlands Coastal wetlands are highly productive areas that serve as fish nurseries for many important species Effectively filter polluted runoff from land Problem: are viewed as worthless land, so are often replaced with developments (roads, housing, shopping, etc.)

Lagoons Lagoons are shallow coastal bodies of water separated from the ocean by a narrow strip of land such as a barrier island Figure 11-9

Mediterranean circulation The Mediterranean Sea experiences high rates of evaporation Causes inflow of water at the surface and outflow of high salinity water below Figure 11-11b

Pollution in coastal waters Coastal waters are highly affected by pollution because they are: Heavily used Close to sources of pollution Shallow-water bodies Not as well circulated as the open ocean

Marine pollution: A definition The introduction by man, directly or indirectly, of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of sea water and reduction of amenities. (World Health Organization)

Main types of marine pollution Petroleum (oil) Sewage sludge DDT and PCBs Mercury Non-point-source pollution

Marine pollution: Petroleum Oil spills can be caused by: Tanker accidents Intentional dumping Drilling/pumping operations Figure 11-12

Marine pollution: Petroleum Petroleum is biodegradable Many pollution experts consider oil to be among the least damaging ocean pollutants Data from the 1989 Exxon Valdez oil spill shows the recovery of key organisms Figure 11-13

Marine pollution: Petroleum Various processes act to break up and degrade oil in the marine environment Figure 11-18

Marine pollution: Petroleum When oil washes up at a beach, it can negatively affect the marine environment Oil can coat marine organisms and render their insulating fur or feathers useless Oil on the beach from the Exxon Valdez oil spill, Alaska

Marine pollution: Sewage sludge Sewage sludge is the semisolid material that remains after sewage treatment Much sewage sludge was dumped offshore until laws restricted sewage dumping Figure 11-21

Marine pollution: DDT DDT was a widely used pesticide that became concentrated in marine fish DDT caused brown pelicans and ospreys to produce thin egg shells Worldwide, DDT has been banned from agricultural use but is still used in limited quantities for public health purposes

Marine pollution: PCBs PCBs are industrial chemicals used as liquid coolants and insulation in industrial equipment such as power transformers PCBs enter the marine environment through leaks and from discarded equipment PCBs can accumulate in animal tissues and affect reproduction

Marine pollution: Mercury and Minamata disease Mercury has many industrial uses but is extremely toxic A chemical plant released large quantities of mercury into Minamata Bay, Japan Residents who ate highly contaminated fish suffered neurological disease and birth disorders (Minamata disease)

Marine pollution: Non-point- source pollution Non-point-source pollution comes from material washed down storm drains as “poison runoff” Includes fertilizers, pesticides, road oil, and trash Figure 11-26

Current law regulating ocean dumping The only substance that is illegal to dump anywhere in the ocean is plastic Figure 11-27

Plastic in the marine environment Does not biodegrade Floats Has high strength Is ingested by and entangles marine animals Figure 11-28

Essentials of Oceanography 7th Edition End of Chapter 11 Essentials of Oceanography 7th Edition