Earth's Ocean Statistics

• About 70% of Earth's surface is covered by water
• Only 1% of the oceans has been explored
• Approximately half the oceans exceed 3km in depth
• More information is known about the Moon's surface than the deep ocean
• The deepest areas of the ocean basin comprise about half of Earth's surface

Ocean Statistics

• The Pacific Ocean has an area of 155.6 million km², an average depth of 4.0 km, a volume of 622.4 million km³, and a greatest known depth of 11.0 km at the Mariana Trench
• The Atlantic Ocean has an area of 76.8 million km², an average depth of 3.9 km, a volume of 299.5 million km³, and a greatest known depth of 9.3 km at the Puerto Rico Trench
• The Indian Ocean has an area of 68.6 million km², an average depth of 3.9 km, a volume of 267.5 million km³, and a greatest known depth of 7.5 km at the Sunda Trench
• The Southern Ocean has an area of 20.3 million km², an average depth of 4.0-5.0 km, a volume of 81.2-101.5 million km³, and a greatest known depth of 7.2 km at the South Sandwich Trench
• The Arctic Ocean has an area of 14.1 million km², an average depth of 1.2 km, a volume of 16.9 million km³, and a greatest known depth of 5.6 km (unnamed)
• The Mediterranean Sea has an area of 3.0 million km², an average depth of 1.4 km, a volume of 4.2 million km³, and a greatest known depth of 4.6 km off the coast of Greece
• The Caribbean Sea has an area of 2.7 million km², an average depth of 2.6 km, a volume of 7.0 million km³, and a greatest known depth of 6.9 km at the Cayman Trench
• The South China Sea has an area of 2.3 million km², an average depth of 1.6 km, a volume of 3.7 million km³, and a greatest known depth of 5.0 km west of Luzon, Philippines
• The Bering Sea has an area of 2.3 million km², an average depth of 1.5 km, a volume of 3.5 million km³, and a greatest known depth of 4.8 km at the Aleutian Trench
• The Gulf of Mexico has an area of 1.6 million km², an average depth of 1.5 km, a volume of 2.4 million km³, and a greatest known depth of 3.8 km at Sigsbee Deep

Ocean Basin Features

• Continental shelves are gently sloping offshore extensions of continents, reaching to the continental slope. They form over millions of years from accumulated inorganic and organic material
• The continental slope marks the point where the continental shelf descends steeply to the deep ocean
• The continental rise is the gently sloping ocean floor located between the continental slope and the abyssal plain
• Abyssal plains are the deepest parts of the ocean covering vast areas, interrupted by submarine mountain chains and trenches
• Seamounts are volcanic peaks rising steeply from the ocean floor, occurring isolated or in chains from mid-ocean ridges or hotspots
• Guyots are flat-topped seamounts with summits below the ocean surface, potentially of volcanic origin from mid-ocean ridges, truncated by wave erosion
• Mid-oceanic ridges are boundaries between diverging oceanic plates, featuring two parallel chains of submarine mountains separated by a graben, offset by transform faults
• Rift valleys are formed by downfaulting between parallel faults, such as the East African Rift Valley and along mid-oceanic ridges
• Seafloor spreading involves the lateral movement of new oceanic crust away from mid-ocean ridges, a key component of continental drift theory
• Paleomagnetism tracks changes in Earth's magnetic field through the alignment of magnetic minerals in sedimentary and igneous rocks
• Subduction zones are tectonic areas at convergent plate margins where an oceanic plate descends into Earth's mantle
• Trenches are narrow, deep depressions on the ocean floor, adjacent to subduction zones
• Grabens are downfaulted sections of a rift valley

Mid-Ocean Ridges

• Mid-oceanic ridges mark the boundary where two oceanic plates diverge
• They consist of two parallel submarine mountain chains separated by a graben and offset by transform faults
• Mid-ocean ridges are large-scale features, reaching widths of up to 1000 km and lengths of 60,000 km
• Mid-ocean ridges are the largest volcanic structure, with a typical ridge crest at 2.5 km below sea level
• They form a global chain of submarine mountains

Hydrothermal Vents and Cold Seeps

• Hydrothermal vents, or black smokers, release sulfur-rich warm waters
• Hydrothermal vents host extremophiles, influence temperature, and provide nutrients and warmth
• Cold seeps are locations where chemicals like hydrogen sulfide, methane, and hydrocarbon-rich fluids escape from the ocean floor
• Marine snow, consisting of dead animals and organic matter, falls through the ocean, serving as a food source

Ocean Nutrients and Productivity

• Biological deserts occur in ocean gyres because they have low levels of nutrients
• Rivers bring high nutrient levels to oceans
• Phytoplankton are the primary producers in the ocean
• Upwelling zones, like the South American coastline, bring high levels of nutrients to the surface

Marine Net Primary Productivity (NPP)

• Coastal regions account for 20% of marine NPP and 10% of global NPP, with an estimated NPP of 250 g/cm²/year
• Deep ocean areas account for 80% of marine NPP and 40% of global NPP, with an estimated NPP of 130 g/cm²/year
• Coastal shelves have high productivity due to runoff from land, wind-blown minerals, and mixing of bed load
• Dissolved nutrients corresponds to higher productivity
• Deep oceans exhibit low productivity
• Ocean gyres characterized as 'biological deserts' lack dissolved nutrients
• Coastal regions have high NPP despite their limited area and depth
• Centers of oceans like the Pacific and Southern are far from land, limiting nutrient availability
• River-supplied nutrients lead to high productivity in coastal areas and estuaries

Coastal Ecosystems and Productivity

• Waves mix minerals and nutrients, clouding the water
• Underwater forests in coastal waters can have NPP nearly as high as a tropical rainforest
• Nitrogen promotes growth in underwater ecosystems
• Sargassum seaweed are a floating type of seaweed that promote an ecosystem
• Food chains are linear diagrams showing a single line of connection within an ecosystem
• Food webs show interconnections, and is part of a region's biodiversity or variety of organisms

Krill in the Southern Ocean

• Antarctic sea ice is a primary nursery for Krill
• Krill may struggle to adapt sufficiently to climate changes because it takes 2 year to reproduce and have 4-5 year lifespan
• Commercial krill harvesting began in the 1970s
• Krill is used in products for human digestion, animal feed and fishing bait
• Chile, China (18%), S Korea (18%), Norway (51%), and Ukraine harvest krill
• Overfishing concerns in the 1970s/80s are similar to whale and seal history depletions

Ecosystem Services

• Provisioning services directly produce food
• Regulating services naturally regulate carbon dioxide
• Cultural services include picturesque views for recreation
• Supporting services support nutrient cycling

Krill Management in the Southern Ocean

• The Conservation of Antarctic Marine Living Resources (CCAMLR) was set up in 1982
• The treaty has 25 member states; AC and EDC countries, whereas no LIDCs fish or are members
• Monitoring/regulating commercial krill interests is the key aim
• CCAMLR set catch limits, hindered by the effect of commercial fishing companies
• Hydroacoustic surveys are used to monitor krill stocks, but evidence stocks have fallen 80%
• The Total Allowable Catch is 620,000 tonnes per year
• Stakeholders in CCAMLR are dominated by ACs like Norway who are actively fishing
• Sustainability informs the management of krill stock
• Antarctic krill brick is marketed heavily in China at $4 per 500 g
• Krill decline has been linked to warming seas
• Krill feed on the underside of sea ice, and the Antarctic peninsula is their breeding ground
• As the ice melts, Krill cannot maintain their numbers
• The TAC is 620,000 tonnes, needing spread across the southern ocean if increased to become viable and avoid honeypots or sacrifices

Oil and Gas Extraction

• Oil booms and animals covered in oil are results of oil spills
• Rising oil demand means exploration happens to the continental shelf edge
• Significant fields are in the Gulf of Mexico, Persian Gulf, and North Seas
• Smaller operations are closer shoreline with greater gas productions in Louisiana more than Texas
• Jackup rigs, steel platforms, and concrete platforms are used in deep and ultra-deep water
• Increased energy demand for electricity, heating, and cars are uses
• Shale gas and resources allow complete natural gas independence in the US
• Fracking agents could leach into groundwater
• Artic nations tap oil reserves, and 30%/13% of undiscovered gas/oil are in the Artic circle
• Oil comes from dead organic material over millions of years

Sea-Bed Minerals and Wave Energy

• Potential energy as water rises/falls creates wave power when coupled with wave energy capture devices
• Waver rollers are a scheme that uses waver rollers to turn a piston that is attached to a generator for electricity to shore
• Wave rollers destroy the benthic ecosystems/requires energy materials
• Carnegie have designed wave energy systems
• Wave energy issues include power/device durability, maintenance, disrupting benthic organisms, and noise
• WaveRollers utilize hinged panels on the seabed, rating from 350kW to 1000kW
• Artificial WaveRoller reefs create new habitats and does not use emissions to produce energy
• Tidal energy is captured from rise/fall based on coastline shape/tidal magnitude
• Coastlines experiencing multiple tides that align with the earth can harness lots of power
• Tidal energy can be harvested by building walls or dams
• Tidal power installation sites must have specific sites/qualifications and powerful high/low tide differences

Climate Change and Fish Populations

• 3.3 billion or one third of the population depend on fish
• 35% UK fishers report violence
• Tension exists between everyone via the common good/self interests
• Ocean resources have little boundaries and are available as ‘everyone's’

Global Commons and Ocean Resources

• Advantage to exploiting resources outweighs individuals cost when costs are shared among people
• It is likely someone will chose to exploit, even where if individual chooses not to
• Multiple treaties, sea floor cables, waste dumping and fishing are all governed
• Ocean acidity is caused by anthropogenic CO2
• The ocean is a major carbon sink with 30% absorbed
• Water temperature increases cause increased CO2
• Aborbed CO2 decreases water by the pH level which causes issues

Coral Reefs

• Coral reefs contain calcium secretion via coral polyps
• Sunlight and water depth increase coral reef biodiversity
• Global warming and mass bleaching causes mortality and prevents recovery

Climate Change and Sea Levels

• Isostatic changes are localized and result from tectonic and ice sheet changes
• Eustatic changes are global and accelerate with all oceans connected
• Over the past few decades, changes have been acclerated
• In 2014, global sea level was 6.6 cm above the 1993 average
• Thermal expansion and ice sheet melting create sea level changes
• Earths wobble and sea floor spread create sea level changes

Rising Sea Levels

• Islands are at risk with water level increasing and will be lost
• Salt water and agriculture contaminate environments

Ocean-Based Globalisation and Transportation

• International migration stems from reasons of conflict/ climate synoptically
• Oceans are key to space/time compression and 96% of 'stuff' across the ocean in invented containers
• The UNCLOS maintains oceanic movements
• Oceans are important for global economics, travel, and cable routes

Pollution and Maritime Regulations

• Oil spills damage all environments
• Invisible infrastructure and laws are necessary for the future
• Decreased sea ice can create heat budget deficits

High Latitude Oceans

• There has never been a plane route from Sydney to London, but there is one coming by 2025

Arctic Sea Ice

• Increased global load and container size requires faster shipping

Influence of Cables

• The world of power and data travels via wires/cables, making locations with cable ports important
• Naval bases need security, logistics, political power and resources

Naval Power and Conflicts

• China invests in ports globally to grow military
• Piracy has links to world trade and migration
• Maritime regulations for refugee safety is an issue