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Lecture 6

GEOG 102 Lecture Notes - Lecture 6: Grand Banks Of Newfoundland, Global Affairs Canada, Biomagnification


Department
Geography
Course Code
GEOG 102
Professor
Faran Ali
Lecture
6

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Week 6
Significance of oceans
• Economic value of marine ecological goods – $21 trillion per year (~70% more than terrestrial
systems) – including transport, waste disposal, fisheries, etc.
• Coastal zones – occupy 18% of the Earth’s surface – 60% of the world’s population lives in
coastal zones – supply about 90% of the global fish catch – account for about 25% of global
primary production
• Fisheries – supply 20% of the world’s annual animal protein supply – more than 1 billion
people rely on fish as primary source of protein – human dimension of fisheries
Oceanic systems
• Limited knowledge of ocean resources (relative to land based resources) – e.g. fish stock
assessment and uncertainties • Oceans cover 70% of the earth’s surface, but account for only
50% of global primary productivity
• Limiting factors: – temperature – nutrients – light
What are the most productive areas of the oceans? i. coastal zones / continental shelf areas •
shallow areas; up to about 200m depth
• light penetration, warmer temperatures, increased photosynthesis ii. areas of nutrient
circulation (upwelling) to the surface • high circulation areas
Ocean management challenges
a. Fisheries b. Habitat destruction c. Pollution d. Industrial activities e. Costal developments f.
Introduction of exotic species g. Climate change
Pollution • About 80% of ocean pollution comes from activities on land, 20% from activities at
sea • 2 main forms of chemical pollution i. toxic materials ii. nutrients
• Pollutants concentrate at the boundary between the sea bed and water; and the boundary
between the water and the atmosphere
• Endocrine disruption is leading to feminization of some marine species; it may also lead to
growth and learning deficits in humans
Example: PCBs • Polychlorinated biphenyls • industrial chemical compounds once used in paint
and electrical transformers • chemically inert and not biodegradable
• ‘bioaccumulate’ in the tissues of animals at the top of the food chain
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