Essential Principles of Oceanography and Marine Science

Lecture 1: Earth’s Major Reservoirs

• Major Reservoirs: Biosphere, Hydrosphere, Atmosphere, Geosphere.

Lecture 3: Radioactive Decay and Half-Life

• Half-Life: A constant amount of time it takes for half of the radioactive atoms in a sample to decay.

Lecture 4: Mantle Plumes and Volcanism

• Mantle Plumes: Places where there has been continuous volcanism for a long period of time. They do not move, but tectonic plates move over them.

Lecture 5: Plate Tectonics and Ocean Features

• Volcanoes are typically found along the mid-ocean ridge and near trenches.
• Tsunamis are caused by earthquakes at subduction zones, undersea landslides, or volcanic eruptions.
• Passive Margins: Far from plate boundaries.
• Active Margins: Close to plate boundaries.
• Deep Ocean Basins: Characterized by hills, undersea mountains, and islands formed by volcanoes.
• Mid-Ocean Ridges: Continuous volcanic ridges that host hydrothermal vents, supporting unique ecosystems.

Lecture 7: Water’s Unique Properties and Heat

• Water’s Weird Properties:
  • Highest surface tension of all liquids.
  • Dissolves more substances than any other solvent.
  • Unusual thermal properties, crucial for weather.
  • Ice floats.
• Thermal Contraction: As temperature decreases, molecules have less energy, are slower, and occupy less space.
• Specific Heat: The energy needed to raise 1 kg of a substance by 1°C.
• Sensible Heat Flux: Adding or removing energy causes a change in temperature.
• High specific heat gives water a high heat capacity, meaning it can absorb or lose large amounts of heat without significantly changing temperature.
• Large Heat Capacity: Moderates climates by preventing large temperature changes (e.g., land/sea breezes, monsoons).

Lecture 8: Latent Heat, Salinity, and Flux

• Latent Heat Flux: Energy that causes a change in the phase of a substance.
• Energy Needed (Absorption): Evaporation, melting.
• Energy Released (Condensation): Condensation, freezing.
• Large latent heat changes during evaporation and condensation transfer energy around Earth.
• Average Salinity: 35‰ (parts per thousand).
• Increasing Salinity: Caused by evaporation and the formation of sea ice.
• Decreasing Salinity: Caused by precipitation and freshwater discharge.
• Ions Added to Ocean: River discharge, volcanoes, hydrothermal activity.
• Ions Removed from Ocean: Absorption and precipitation, sea spray, biological processes, hydrothermal energy.
• Reservoir: The amount of material of interest in a given form.
• Flux: The amount of material added to or removed from a reservoir.

Lecture 9: Desalination and Seawater Density

Desalination Processes and Impacts

• Desalination: Seawater and energy are used in a separation process to yield pure water and brine.
• Desalination is much more expensive because of the required technology and amount of energy.
• Impacts on the Ocean: Improperly placed high volumes of brine can damage ecosystems. The brine has a salt content greater than the surrounding water, is warmer (which lowers oxygen content), and may contain large chemicals and heavy metals. Increased CO2 leads to increased warming of water and melting of ice.

Seawater Density Structure

• Seawater Density: As temperature increases, density decreases. Maximum density is at the freezing point.
• Thermocline: Depths where temperature changes rapidly.
• Halocline: Depths where salinity changes rapidly.
• Pycnocline: Depths where density changes rapidly.

Lecture 10: Atmospheric Circulation and Coriolis Effect

• The poles are colder.
• Earth’s tilt affects seasons, period of daylight, solar angle, and beam spreading.
• Atmosphere moves due to unequal heating (day/night, equator vs. poles).
• High Pressure: Cool air sinking.
• Low Pressure: Warm air rising.
• Coriolis Effect: An apparent force that changes the direction of moving objects (deflection is to the right in the Northern Hemisphere).

Lecture 11: Ocean Circulation Dynamics

Importance of Ocean Circulation

• Transfers heat from warmer to colder regions.
• Affected prehistoric travel.
• Influences the abundance of life in surface water by affecting nutrient distribution.

Circulation Types and Ekman Transport

• Surface Circulation: Driven by winds.
• Deep Circulation: Driven by density.
• Ekman Spiral: When looking vertically down at the currents, they appear to spiral with depth.
• Ekman Transport: The average flow of water throughout the spiral is approximately 90° to the right (Northern Hemisphere) or left (Southern Hemisphere) of the surface wind direction.
• Warmer Currents: Lead to warmer and more humid climates.
• Cold Currents: Lead to cooler and drier climates.

Lecture 12: Vertical Water Movement (Upwelling and Downwelling)

• Upwelling: Movement of deeper water to the surface, bringing nutrient-rich water vital for marine life.
• Downwelling: Movement of water to the deeper ocean.
• Causes of Vertical Movement: Diverging/converging surface water, interactions of winds and coastlines, bends in coastlines, shape of the seafloor, and lack of a pycnocline.
• Upwelled Water Characteristics: Colder, saltier, and contains more nutrients.
• Lack of Pycnocline: Makes it easier for surface and deeper water to mix at high latitudes.

Lecture 13: Deep Ocean and Thermohaline Circulation

• Deep Ocean Circulation: The result of small density differences in water masses.
• Thermohaline Circulation: Density is affected by temperature and salinity. This circulation is much slower than surface currents.
• Deep Water Formation: Deep water masses form by increasing the density of surface waters (making salty water cold, or making cold water salty).
• Intermediate water formation involves very cold but fresh waters, or warmer but very salty waters.
• North Atlantic Deep Water needs to be dense to sink.
• Circulation is predicted to reduce by up to 30% by 2100.
• Slowdown or Weakening of Thermohaline Circulation: Linked to climate changes in the North Atlantic and changes in how much carbon is stored in the ocean.

Lecture 14: El Niño and Tropical Cyclones

• Effects of El Niño: Can cause deaths, financial problems, and structural damage.
• Effects on Ecosystems: Leads to unusual marine life due to warm ocean temperatures.
• Hurricane/Typhoon/Cyclone: Intense areas of low pressure that form in tropical regions.
• Reasons for Global Distributions: Driven by latent heat as water vapor condenses; lack of Coriolis effect at the equator prevents formation there; strong winds in the upper troposphere can spread hurricanes out.
• Hurricane Damage: Includes tornadoes, heavy rain, severe flooding, and storm surge (winds pile up water near the coast).

Lecture 15: Tidal Forces and Bulges

• Gravitational attraction of the Sun and Moon causes tides.
• Differences between the average gravitational force and the actual gravitational force result in tidal force.
• Solar Bulges: Half the size of lunar bulges because the Sun is further away, resulting in less difference in gravitational force from one side of Earth to the other.
• Interaction between Lunar and Solar Bulges: Results in spring tides (large range) or neap tides (small range).

Lecture 16: Tidal and Wave Energy Generation

Tidal Energy

• The flow of water in and out can turn turbines that generate electricity.
• Advantages: Renewable energy source, reliable, does not produce carbon emissions.
• Disadvantages: Requires building a barrier across a river mouth, which can disrupt ecosystems and shipping, and may cause loss of tourism or housing value due to visual impact.

Wave Energy

• Three Types of Wave Interference: Constructive, destructive, mixed.
• Wave Interference: Creates complex patterns of wave heights and wavelengths.
• Methods to Generate Electricity: Floating turbines, oscillating water columns, pressure-based devices.
• Challenges: Environmental impact (marine life, ecosystems), high cost.

Lecture 17: Coastal Processes and Hazards

• Erosional Shores: Characterized by wave-cut cliffs, wave-cut platforms, sea arches, and sea stacks.
• Depositional Shores: Characterized by deltas, spits, and barrier islands.
• Sediment Transport: Oblique waves produce longshore currents, moving sediment along the coastline.
• Spit: A linear ridge of sediment extending away from land due to deposition by longshore drift.
• Barrier Island: Forms where a spit extends most of the way across a bay.
• Coastal Region Hazards: Coastal erosion, hurricanes, tsunamis, sea level rise.
• Stabilizing Coastlines: Methods include building structures (breakwaters, sea walls), alternative structures, restrictions on new construction, and abandonment and relocation.

Lecture 18: Marine Ecosystem Fundamentals

Characteristics of Living Organisms

• Processes essential and characteristic of all living organisms: Metabolism, growth, reproduction, evolution.

Trophic Levels and Energy Flow

• Autotroph: Self-feeder (energy from the sun or chemical reactions).
• Heterotroph: Other-feeder (suspension feeding, deposit feeding, carnivorous feeding).
• Energy is transferred from organism to organism through food chains.
• Trophic Levels: Organisms classified by how many steps they are away from the original source of energy.
• Flow of Energy in Ecosystems: Energy flow is unidirectional and is converted from chemical energy to heat or mechanical energy. Transfer of energy is very inefficient; therefore, higher trophic levels cannot support as much biomass.

Nutrient Cycling and Primary Production

• Flow of Nutrients in Ecosystems: Cyclical, driven by biogeochemical cycles.
• Important Nutrients:
  • Nitrogen (supplied by specific organisms).
  • Phosphorus (supplied by dust/sediment).
  • Iron and Silica (supplied by dust/sediment).
• Primary Production: Sugar production by autotrophs.
• Measuring Primary Production: Measuring light transmission through water, manually sampling water and analyzing mass/type of life, or satellite observation of ocean color.
• High Primary Productivity Ecosystems: Algae beds, coral reefs, continental shelf, open ocean, upwelling zones, estuaries (where rivers meet the ocean).

Lecture 19: Marine Life Adaptations

• Benthic: Organisms that live on the seafloor (more abundant).
• Pelagic: Organisms that live in the open ocean.

Adaptations in the Light Zone (Near Surface)

• Advantages: Photosynthesis, hunting for prey, finding a mate.
• Disadvantages: Difficult to hide from predators.
• Adaptations: Adopting shapes for photosynthesis, transparency, developing camouflage or countershading, migration from deep water (day) to surface (night).

Adaptations in the Deep Ocean (No Light)

• Advantages: Hide from predators.
• Disadvantages: No photosynthesis, difficult to find prey or mate.
• Adaptations: Huge eyes, sensory devices (antennae, specialized skin), bioluminescence.

Physiology and Transport

• Cold water animals are longer-lived, slower, and reproduce slowly.
• Active Transport: Low concentration to high (e.g., forming shells, nutrient uptake).
• Diffusion: High concentration to low (passive).
• Osmosis: Low salinity to high salinity (passive).

Lecture 20: Plankton and Dead Zones

• Most marine organisms obtain oxygen from water using gills and do not have air pockets (they are water-filled).
• Phytoplankton (Producers): Single-celled, perform photosynthesis.
• Zooplankton (Consumers): Single-celled, often have shells.
• Bacterioplankton (Recyclers).
• Life Cycle:
  • Holoplankton: Spend their whole lives as plankton.
  • Meroplankton: Spend only part of their life as plankton (usually juvenile stage).
• Nutrients are limited in the surface of tropical oceans.
• In polar oceans, nutrients are limited in summer, and light is limited in winter.
• Dead Zones: The addition of fertilizers creates blooms of algae that then decay and use up all the oxygen, causing marine life to suffocate.
• Artificially adding nutrients to the ocean is sometimes proposed to remove carbon.

Lecture 21: Nekton and Marine Mammals

• Nekton stay afloat using internal gas chambers or by actively swimming.
• Poikilothermic (Cold-Blooded) Fish: Same temperature as the environment; slower metabolism.
• Homeothermic (Warm-Blooded) Fish: Higher body temperature than the environment; faster metabolism.

Strategies to Avoid Predation

• Schooling.
• Symbiosis:
  • *Commensalism:* One benefits, no harm to the other.
  • *Mutualism:* Both benefit.
  • *Parasitism:* One benefits at the expense of the other.
• Transparency, speed, secreting poisons, mimicry.

Marine Mammals

• Warm-blooded, breathe air, have fur, bear live young.
• Toothed Whales: Complex social groups, use echolocation.
• Baleen Whales: Larger, feed on low trophic level organisms.

Lecture 22: Benthic Ecosystems

• Benthic ecosystems obtain their food from surface ecosystems (except chemosynthetic communities).
• Primary Producers: Plants (seagrass), seaweeds (red: warm/cold; green: intertidal; brown: large).

Shallow Water Benthic Environments

• Intertidal Rocky Shores Challenges: Strong waves, predators, changing temperature, drying out, lack of space.
• Shallow Rocky Bottoms Offshore: Seaweed kelp forests provide food and shelter.
• Shallow Coral Reefs: Consist of individual polyps that have stinging tentacles and symbiotic relationships with dinoflagellates.
• Large surface coral reefs grow in warm water, strong sunlight, clear water, strong waves/currents, consistent salinity, and on a rocky bottom.
• Coral Reef Importance: Highly diverse (25% of all marine species), protect coastlines from storm waves and tsunamis.

Deep Ocean Benthic Environments

• Deep Ocean Abyssal Plains: Dark, cold, high pressure, limited food supply.
• Deep Ocean Hydrothermal Vents: Found along mid-ocean ridges (volcanic activity). Organisms carry out *chemosynthesis*, using chemicals (like hydrogen sulfide) to produce sugars from H₂O, CO₂, and O₂. They typically last for a few decades.
• Deep Ocean Cold Seeps: Microbes carry out chemosynthesis using hydrogen sulfide or methane. These are longer lasting than hydrothermal vents.

Lecture 23: Ocean Policy and Pollution

• Territorial Waters: Extend 12 miles out from land.
• Exclusive Economic Zone (EEZ): Extends 200 miles from land, granting control over mineral resources, fishing, and pollution regulation.

Major Ocean Pollutants and Impacts

• Noise: Shipping and oil/gas exploration increase noise, resulting in changes in whale and dolphin communication.
• Oil: Coats feathers/fur, and is ingested by animals.
• Heavy Metals: Risk depends on how much fish is in the diet, how much toxic substance is in the fish, and how toxic the substance is to people.
• Pesticides (DDT): Causes eggshells to become so thin that eggs are crushed before hatching.
• Habitat Destruction: Loss of coastal wetlands, mangroves, reefs, and destructive fishing practices (bottom trawling, bycatch).
• Overfishing: Removal of entire species from ecosystems can have unexpected consequences on the food web, leading to a reduction in the size of mature fish. This contributes to “shifting baselines,” where our idea of normal constantly shifts with each generation.

Preventing Disastrous Change

• Enforce existing laws.
• Ban harmful fishing practices.
• Establish Marine Protected Areas (MPAs).
• Eliminate fishing subsidies.
• Develop sustainable farming methods.
• Limit pollution.
• Individuals can make informed choices about seafood, avoid over-using chemicals/oils, and support relevant legislation.

Lecture 24: Earth’s Energy Balance and Greenhouse Effect

• Longer wavelength = lower energy; short wavelength = higher energy.
• Everything emits radiation (if temperature is greater than 0 Kelvin).
• Spectrum: Objects emit a range of wavelengths.
• Incoming Energy from Sun (Shortwave): 30% is reflected away by the atmosphere; 70% travels through and is absorbed by the surface or clouds.
• Outgoing Energy from Earth (Longwave/Infrared): Emitted radiation is absorbed by “greenhouse gases” in the atmosphere.
• The greenhouse effect is vital to keep Earth habitable (without it, Earth would freeze).
• Additional greenhouse gases lead to anthropogenic climate change.

Factors Affecting Energy Balance

• Change in Incoming Shortwave Radiation: Changes in aerosols in the atmosphere, amount/type of cloud cover, and type of surface on Earth.
• Change in Outgoing Longwave Radiation Absorbed and Re-radiated: Changes in aerosol or greenhouse gas concentrations in the atmosphere.
• Carbon sources include fossil fuel burning and deforestation.
• Climate change effects include increased sea level, ocean acidification, and rising temperatures.

Lecture 25: Ocean Acidification

• Representative Concentration Pathways (RCPs): Plausible greenhouse gas trajectories for the future based on economic growth, energy sources, and population growth.
• An increase in atmospheric CO₂ will increase dissolved CO₂, resulting in more H⁺ ions (lower pH) and less CO₃²⁻ ions.
• Seawater naturally has fewer H⁺ ions than pure water.
• Ocean Acidification: The amount of H⁺ increases more than other ions, causing ocean pH to decrease.
• Reduction in Carbonate Ions (CO₃²⁻): The ocean tries to balance the increased acidity by reacting H⁺ with CO₃²⁻ to form HCO₃⁻.
• Increased atmospheric CO₂ is causing a reduction in CO₃²⁻ in the ocean, making it undersaturated. If undersaturated with CO₃²⁻, shells start to dissolve.
• Impacts of Increased Acidity/Lower pH on Animals: Affects metabolism, health, and communication, leading to huge uncertainties for marine life.
• Ocean acidification exacerbates the effects of higher temperatures, pollution, invasive species, and poor fishing practices.

Lecture 26: Warming and Sea Level Rise

• Warming is due to extra energy trapped near Earth’s surface because of higher CO₂ in the atmosphere.
• Sea Level Change Causes: Melting glaciers, groundwater removal, thermal expansion of seawater, and melting ice sheets.
• Important Infrastructure at Risk: Ports, power generation, cities, and transport links.
• Risk Posed by Sea Level Rise Depends On: Hazard severity, exposure level, and vulnerability.
• Strategies to Reduce Impact: Protection (building defenses), accommodation (adapting infrastructure), and retreat (moving away from the coast).
• Without greenhouse gas emissions reduction, the world is committed to several meters of sea level rise and continued ocean acidification over the next 100 years.