A third of the stuff Memorize for Oceans Test 2025

Surface Currents: flows of ocean water on the surface of the ocean.

Ocean currents are affected by global winds, the Coriolis effect, land, the gravitational pull of the moon, and density differences—but surface ocean currents are primarily caused by wind.

Global Winds: the large-scale movement of air.

Coriolis Effect: the deflective force of Earth’s rotation on all free-moving objects, including the atmosphere and oceans.

The coriolis effect causes surface currents to veer right in the Northern Hemisphere and left in the Southern Hemisphere

3-Celled Model: a simplified model of global wind currents.

Gyre: large circular flows of water caused by global winds that are found in each ocean basin.

5 world oceans: Atlantic Ocean, Pacific Ocean, Indian Ocean, Arctic Ocean, Southern Ocean.

Salinity: the amount of salt present in ocean water, measured in ppt or PSU, OR the proportion of dissolved salts to pure water in a water-like substance.

Thermocline: the change in temperature of ocean water with depth OR the layer of rapid temperature change between the evenly warm top layer and the deep cold layer (after the thermocline, it doesn’t get much colder).

Thermohaline Circulation (Global Conveyor Belt): a large-scale stream of ocean water both in the Surface Ocean and Deep Ocean caused by density differences of cold and warm water.

Halocline: the change in salinity of ocean water with depth OR a layer that is like the thermocline and is in a similar place, but it is the layer of rapid salinity change between the high salinity top layer and the low salinity bottom layer (which also doesn’t change that much).

Pycnocline: the change in density of ocean water with depth. (Is there a layer for this?)

parts per thousand (ppt): a unit for measuring salinity similar to a percent, but out of 1,000 instead. Symbol: ‰.

Upwelling: the rising of cold water from deeper layers to replace warmer surface water.

Trophic level: the position of an organism in a food chain or web.

Producer: an organism that uses photosynthesis or chemosynthesis to produce its own food.

Consumer: An organism that must eat to gain necessary nutrients and energy. 

Food web: a diagram which depicts feeding connections (what eats what) in an ecological community.

Temperature and salinity affect ocean water density. 

Cold, salty water is more dense.

Temperature is a more influential factor than salinity in determining density.

PSU is a Practical Salinity Unit, which is a measure of salinity measured from an electrical conductivity test. 1 PSU roughly is 1 ppt.

Throughout the ocean, salinity ranges from 32‰ to 37‰, with the average salinity being around 35‰, but in marginal seas the salinity can be more extreme..

Thermo-: relating to temperature.

Haline-: relating to salinity.

Salinities:

• Equator: air rises=precipitation and high temperature=evaporation, average salinity

• 30 degrees: air sinks=dry and warm temperature=evaporation, high salinity

• 60 degrees: air rises=precipitation and cool temperature=not as much evaporation, lower salinity

• Higher latitudes: very cold=not as much evaporation and global warming=more melting than freezing, low salinity

  • Mr. Mixer says that in these latitudes, it depends the most on the seasons.

Ocean water is the most saline at 30 degrees North and South.

Ocean water is the most cold at high latitudes near the poles.

Ocean water is the most dense at high latitudes near the poles.

The most dense water in the ocean is found near the poles in the Atlantic, because near the poles is the coldest and the Atlantic is the saltiest.

Three layer system for classifying the ocean, based on depth, with descriptions of what affects each layer:

• Surface mixed layer: the layer of the ocean stirred up by the wind that has similar (high) temperature and salinity throughout; dependent on latitude.

• Intermediate layer: temperature, salinity, and density change here; dependent on latitude.

• Deep layer: cold with a low salinity; it comes from NADW, which gives it its characteristics.

Water masses: bodies of water with similar temperature and salinity throughout.

Garbage Patch: regions of the ocean with high concentrations of plastic pollution.

Density: how compact a substance is, mass/volume.

Latitude: the distance north or south of the Earth’s equator.

Global: involving the entire world.

Current: a continuous, directed motion of the ocean.

Ecology is the study of how organisms interact with one another and their surrounding environments.

The biosphere is a category that includes all organisms on Earth.

Biomes are the next-to-largest categories, and are of groups of plants and animals that occupy areas of similar climates.

Ecosystems are the largest categories within biomes, and they are of small groups of organisms that interact with each other.

Within the categories of an ecosystem there are abiotic (non-living) and biotic (living) factors.

Terrestrial biomes are based on temperature and precipitation.

Oceanic biomes are based on temperature, proximity to land, and amount of sunlight.

Marine life zones based on the availability of light:

• Photic zone: the upper part of the ocean into which sunlight penetrates.

• Euphotic zone: the part of the photic zone near the surface where the sunlight is bright enough for photosynthesis to occur.

• Aphotic zone: the area with no sunlight that is completely dark except for some bioluminescent life-forms.

Marine life zones based on the distance from shore:

• Intertidal zone: the area that is sometimes covered by water and sometimes not.

• Neritic zone: further out than the intertidal zone, and it is made of the ocean near the continent before the shelf break.

• Oceanic zone: further away from the shore, beyond the shelf break.

Marine life zones based on depth:

• Pelagic zone: open ocean of any depth.

• Benthic zone: any seafloor surface in the ocean.

• Abyssal zone: subdivision of the benthic zone that is many kilometers below the ocean surface with high pressure, low temperature, low oxygen, low nutrients, and no sunlight.

Symbiosis: the interaction between organisms within an ecosystem.

There are three types of symbiosis:

• Mutualism: both organisms benefit.

• Parasitism: one organism benefits while the other is harmed.

• Commensalism: one species benefits while the other is unaffected.

Trophic levels:

• Primary producers: organisms like plants that convert the sun’s energy into chemical energy.

• Primary consumers: organisms that get energy by eating primary producers.

• Secondary consumers: organisms that get energy by eating primary consumers.

• Tertiary consumers: organisms that get energy by eating secondary consumers.

• Decomposers: organisms that get energy from any trophic level by breaking down the remains of other living things, breaking down waste into nutrients, some which goes to the primary producers (often plants).

10% rule: only 10% of energy from an organism is transferred to the next level in the food chain.

The HIPPO acronym is a way of categorizing ecological effects of human behavior:

• Habitat Destruction

• Invasive Species

• Pollution

• Population (Human)

• Overconsumption

Chemistry breakdown (because this confuses me):

• Carbon (C): a solid element.

• Carbon dioxide (CO₂): a compound that involves carbon.

• Water (H₂O): a compound.

• Carbonic acid (H₂CO₃): an element that can be formed by reactions between carbon dioxide and an element that lowers the pH of ocean water, which increases the acidity.

• Carbonate (CO₃^2_): a compound is oceans that organisms use to build shells and structures.

• Calcium carbonate (CaCO₃): a compound that coral shells are made of.

Zooxanthellae is the name for the algae that coral relies on.

Dead Zone: an area without oxygen or marine life.

Coral bleaching: the process where coral turn white because their algae leaves them.

Thermal Expansion: the process where global warming warms water, which causes the water to physically take up more space.

Plankton breakdown (because this confuses me):

• Plankton are tiny organisms that are the start of the ocean’s food chain.

• Phytoplankton are plants, and they turn sunlight into energy via photosynthesis, and they are eaten by zooplankton, small fish, and invertebrates.

• Zooplankton are animals, and they eat phytoplankton, and they are eaten by larger species like fish, whales, and crustaceans.

Oceanography is a scientific field that uses methods and knowledge from biology, chemistry, physics, and geology to study oceans in the world.

The tropics are between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S).

The subtropics are the zones immediately to the North and South of the tropics, with middle latitudes from the tropics to approximately 35° to 40° North and South.

Desalination is the removal of salts and other chemicals from seawater to produce low-salinity “fresh” water.

Continental margins are portions of the sea floor next to continents.

Passive continental margins aren’t next to plate boundaries.

Active continental margins are where an oceanic plate is being subducted beneath a continent.

Seafloor vocab:

• The continental shelf is a flat-ish flooding extension of a continent that is not very steep and underwater. (See picture in Chapter 12.)

• The continental slope is a steep part of the seafloor that marks the boundary between the continental crust and oceanic crust (varying steepness, usually narrow, at the end of the continental shelf).

• The continental rise is the gently sloping surface at the base of the continental slope (usually goes into the sea for hundreds of kilometers).

• Deep-sea fans are cone-shaped deposits at the bases of continental slopes.

• Submarine canyons are deep, steep-sided valleys that cut into the continental slope and extend across the entire continental rise into the deep-ocean basin.

• Turbidity currents are downslope movements of dense, sediment-laden water.

• Turbidites are deposits from turbidity currents.

• Graded bedding is the phenomenon where turbidites are characterized by a decrease in sediment grain size from bottom to top.

The ocean basin floor is between the continental margin and the mid-ocean ridge. Features:

• Deep-ocean trenches are narrow crack-like features that are the deepest parts of the ocean.

• Abyssal plains are incredibly flat underwater regions.

• Seamounts are isolated volcanic peaks that rise at least 1000 meters above the deep-ocean floor.

A mid-ocean ridge is a continuous mountainous ridge on the floor of all the major ocean basins that is formed by divergent plate boundaries.

Rift valleys are deep down-faulted structures along the axis of some segments of the mid-ocean ridge.

An estuary is a partially enclosed coastal water body that is connected to the ocean.

Coral reefs are structures that consist primarily of the calcite-rich remains of corals as well as the limey secretions of algae and the hard parts of many other small organisms.

Atolls are continuous or broken rings of coral reef that surround lagoons.

Sediments on the seafloor are mixed together from three different sources:

• Terrigenous sediments are derived from land.

• Biogenous sediments are derived from organisms.

• Hydrogenous sediments are derived from water.

• (Extra) Volcanic sediments and outgassing.

• (Extra) Cosmogenous sediments (from space).

Wave vocab:

• Crests are the tops of waves.

• Troughs are the low separations between waves.

• The wave height is the vertical distance between the trough and crest of a wave.

• The wavelength is the horizontal distance between crests.

• The wave period is the time interval between the passage of successive crests at a stationary point.

• Fetch is the distance that wind has traveled across open water.

• Waves of oscillation are waves in the ocean where the form of the wave moves but the water itself doesn't. 

• Waves of translation are advancing water caused by breaking waves.

• The surf is the turbulent water created by breaking waves.

The height, length, and period of waves are affected by wind speed, how long the wind has blown, and fetch.

Abrasion is the sawing and grinding action of water armed with rock fragments.

Wave refraction is the bending of waves.

Beach drift is the transport of sediment in a zigzag pattern along a beach caused by the uprush of water from obliquely breaking waves.

Oblique waves are waves that hit a beach indirectly, at an angle.

A longshore current is a near-shore current that flows parallel to the shore.

Shoreline terms:

• Wave-cut cliffs are seaward facing cliffs along steep shorelines formed by wave erosion at its base and mass wasting.

• Wave-cut platforms are benches or shelfs in the bedrock at sea level, cut by wave erosion.

• Sea arches are arches formed by wave erosion when caves on opposite sides of a headland unite.

• Sea stacks are  isolated masses of rock standing just offshore, produced by wave erosion of a headland.

• Spits are elongated ridges of sand that project from the land into the mouth of an adjacent bay.

• Baymouth bars are sandbars that completely cross bays, sealing them off from the open ocean. 

• Tombolos are ridges of sand that connect islands to the mainland or to other islands. 

• Barrier islands are low, elongated ridges of sand that parallel the coast.

Shoreline erosion has different effects in different places, and is affected by how close rivers with a lot of sediment are, how much tectonic activity there is, the topography and composition of the land, wind and weather patterns, and how the coastline and near-shore areas are shaped.

Shoreline erosion vocab:

• A groin is a barrier built at a right angle to the beach to trap sand that is moving parallel to the shore. 

• A breakwater is a structure that protects a near-shore area from breaking waves. 

• Seawalls are barriers constructed to prevent waves from reaching the area behind the seawall, and they are built to defend property from the force of breaking waves.

• Beach nourishment is a strategy to offset losses caused by wave erosion that involves adding large quantities of sand to a beach system.

An emergent coast is a coast where land that was formerly below sea level has been exposed either because of crustal uplift or a drop in sea level or both.

A submergent coast is a coast with a form that is largely the result of the partial drowning of a former land surface either because of a rise of sea level or subsidence of the crust or both .

Shorelines are all very different and affected by rock types, size and direction of waves, frequency of storms, tidal range, submarine profile, recent tectonic events, and changes in sea level.

Biomagnification: the increase in toxic material through a food chain.

The two sources of salts (salinity) (minerals) in the ocean are outgassing from black smokers and deep sea vents and erosion of weathered rock and minerals deposited in the ocean by river runoff.

Tsunami are waves with very long wavelengths caused by the displacement of large volumes of water. Wavelengths range from 150 km -1000 km.

Four causes of tsunamis:

• Plate tectonic movements along the ocean floor (sometimes part of the upper plate gets stuck on the converging plate, and then when the upper plate springs back up it displaces a lot of water).

• Landslides and rock slide along the coast that displace large amounts of water.

• Ocean volcanic eruptions.

• Meteorite/asteroid impacts. 

In polar regions, evaporation doesn’t happen very much, so melting/freezing is more important.

Subtropical gyres are centered near 30 degrees latitude in the North and South Atlantic, the North and South Pacific, and the Indian Ocean.

Ekman transport, which is caused by the Coriolis effect deflecting water to the right, describes how the net movement of the top layer of water is 90° to the right in the Northern Hemisphere and 90° to the left in the Southern Hemisphere of the wind direction. It influences the movement of surface currents, because the surface currents are caused by the wind and then deflected by Ekman transport. 

Subtropical gyres are centered near 30 degrees latitude in the North and South Atlantic, the North and South Pacific, and the Indian Ocean.

Photoautotrophs include plants, algae, cyanobacteria, and phytoplankton—they are organisms that use sunlight to make organic compounds.

When the wind is blowing one direction in the Northern Hemisphere, the very surface layer will move 45 degrees to the right and the new water movement will be 90 degrees to the right.

Rings form in the Gulf Stream when the current meanders. Meanders on the North side of the Gulf Stream can pinch off, where they rotate clockwise and contain warm waters from the other side of the Gulf stream. These are warm core rings.  In warm core rings, water is moved inwards and water piles up and causes downwelling.

Cold core rings form when meanders on the southern side of the Gulf Stream pinch off, where they rotate counterclockwise and contain the colder waters from the other side of the Gulf Stream, so these are the cold core rings.  In cold core rings, water is moved outwards and water has to move up to replace it, so there is upwelling.

Albedo is the fraction of light that a surface reflects.

Climate is the 30 year average of weather patterns.

Arid means dry.

The high specific heat capacity of water is very high.