Week 13: Uses and abuses of the ocean Flashcards
Renewable resource
Naturally replaced by the growth of marine organisms or by other natural physical processes
Non-renewable resources
Oil, gas, solid mineral deposits are present in ocean in fixed amounts and cannot be replenished over time spans as short as human lifecycles
Types of marine resources
- Physical
- Biological
- Energy
- Non-extractive
Physical marine resources
Deposition, precipitation, accumulation of useful substances in ocean (mineral deposits, oil, gas, water)
Biological marine resources
Animals, plants and algae collected for human usage or used as feed for other animals
Energy marine resources
Extraction of energy from ocean water
Non-extractive marine resources
In place use of the ocean (transportation, recreation, waste disposal)
Types of physical marine resources
- Hydrocarbon deposits
- Sand/gravel and mineral deposits
- Freshwater- extracted from sea water
Types of biological marine resources
- Carrageenan- red algae (rhodophyta): binds food together ex. dog food, chocolate and toothpaste
- Alginate - brown algae (phaeophyta): used to make water based products thicker or creamier ex. ranch dressing and hand creams
- Agar- red algae: food thickener and jelling agent
Are present day fisheries sustainable?
Some… BUT
- 90% of worldwide stocks of tuna, cod etc have disappeared bc of overfishing
Bycatch
Unwanted species caught in fishing net and thrown overboard
What is marine pollution?
When substances or energy are introduced into the ocean by nature or humans and it changes the quality of water or affects the physical, chemical or biological environment
What is a pollutant?
Something that causes damage by interfering directly or indirectly with the biochemical processes of an organism (naturally occurring or man-made)
Response of an organism to a pollutant
Depends on its sensitivity to the quantity and toxicity of that pollutant
Marine pollution - OIL
One of the most widely reported and recognizable forms of pollution
What percentage of natural oil seeps occur?
47%
Crude oil
Not easily dissolvable, form insoluble layers on surface
The dissolvable components are harmful to juvenile marine organisms
Larger in volume and more frequent
Refined oil
Contains synthetic chemicals which are biologically active components
Present for longer periods of time
What is a common key stone species?
Sea otters
Why are sea otters considered key stone species?
Critical to maintaining health of ecosystem
Eat sea urchins which eat holdfasts of kelp
If sea otter population decreases, kelp dies, biodiversity is lost
What species can be harmed by oil pollution?
Whales, sea otters, tuna larvae
How do we clean up oil spills?
- Dispersion (chemicals break it up)
- Burning
- Skimming
- Wave action- forms tar bars
- Consumed by bacteria
- Photooxidation
Biomagnification/ bioaccumulation
A pollutant builds up and is amplified as organisms each organisms with have been in contact w the pollutant
The mercury cycle
Mercury cycles through Earth’s atmosphere, ocean and rock
In ocean, mercury is converted to monomethyl mercury (MMhg), a neurotoxin that moves up food chain and becomes highly concentrated in tuna, swordfish, seafood
Where are MMhg levels highest in ocean?
Near top of low oxygen zone btwn 100 and 400 metres below the surfaceB
Biomagnification and the Hg cycle
- Ionized mercury in seawater and sediments cannot enter bacterial cells
- Some bacteria use sulphate for respiration when O2 is low, expelling sulphide
- Sulphide combines w ionized mercury in seawater to from mercuric sulphide which can diffuse into bacterial cells
- Inside bacterial cells, monomethyl mercury is created and diffuses into seawater to be taken up by phytoplankton
Minamata disease
Severe Hg poisoning
Neurological damage
Congenital
Persistent organic pollutants (POPs)
Harmful organic compounds
Stable, low biodegradability
Sources from pesticides, industrial chemicals and solvents
What is marine debris?
Any persistent solid material that is manufactured or processed
Directly or indirectly, unintentionally or intentionally disposed of or abandoned into the marine environment
Most common type of marine debris
Plastic
Plastics
Not biodegradable
Attract other toxic substances
Differing buoyancies (float and/or sink)
Ghost net
Lost, abandoned, discarded nets/ fishing gear
Turtles and plastic
Eat it, think their full, die of starvation
Grey whales and plastic
Baleen whales feed on ocean bottom by scooping everything up
Microplastics
Microfibres and microbeads
Too small to be filtered out
**hard for organisms to differentiate btwn phytoplankton and microplastics as food
Open ocean and plastics
Surface circulation concentrates buyoant plastics into subtropical gyres
ex. Western garbage patch and eastern garbage patch
What percentage of marine debris will sink to ocean floor?
70%
How do we know that the ocean water is warming?
Stopping of overall global thermal circulation
Metabolic needs of fish are increasing
Most importantly, sea level rise (sea ice is melting)
Sea level
measure of the average height of the surface of the sea; sea level not uniform
Global (eustatic) sea level
Average height of ocean around world (this is rising)
Local sea level
Height of water measured along coast relative to a specific point on land
Causes of regional diff in sea levels
- Diff temp
- Ocean currents
- Changes to average winds and atmospheric pressure
- Post-glacial rebound
- Changed to amount of water on land
- Gravitational adjustments owing to the loss of ice
Main drivers of sea level rise- eustatic
- Add or remove water (glacial vs interglacial)
- Chang water temp (thermal expansion)
Why can sea level rise or fall regionally?
Changes in land elevation- land moves relative to sea level
- Tectonic (land uplifted or subsides)
- Isostatic adjustment
Sea level fall
Tectonic uplift of mountain is going at a faster rate than rate of sea level rise
Sea level rise
Sea level is rising at a faster rate than tectonic uplift of mountain
Impacts of sea level rise
Coastal flooding
Exacerbates storm impacts
Accelerates coastal erosion
