APES midterm

Demography

The study of human populations and population trends.

Demographer

A scientist in the field of demography.

Immigration

The movement of people into a country or region, from another country or region.

Emigration

The movement of people out of a country or region.

Crude birth rate (CBR)

The number of births per 1,000 individuals per year.

Crude death rate (CDR)

The number of deaths per 1,000 individuals per year.

Doubling time

The number of years it takes a population to double.

Total fertility rate (TFR)

An estimate of the average number of children that each woman in a population will bear throughout her childbearing years.

Replacement-level fertility

The total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size.

Developed country

A country with relatively high levels of industrialization and income.

Developing country

A country with relatively low levels of industrialization and income.

Life expectancy

The average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate in that country.

Infant mortality

The number of deaths of children under 1 year of age per 1,000 live births.

Child mortality

The number of deaths of children under age 5 per 1,000 live births.

Net migration rate

The difference between immigration and emigration in a given year per 1,000 people in a country.

Age structure diagram

A visual representation of the number of individuals within specific age groups for a country, typically expressed for males and females.

Population pyramid

An age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries.

Population momentum

Continued population growth after growth reduction measures have been implemented.

Theory of demographic transition

The theory that as a country moves from a subsistence economy to industrialization and increased affluence it undergoes a predictable shift in population growth.

Affluence

The state of having plentiful wealth including the possession of money, goods, or property.

Family planning

The practice of regulating the number or spacing of offspring through the use of birth control.

IPAT equation

An equation used to estimate the impact of the human lifestyle on the environment: Impact = population affluence technology.

Gross domestic product (GDP)

A measure of the value of all products and services produced in 1 year in one country.

Urban area

An area that contains more than 385 people per square kilometer (1,000 people per square mile).

Population

The individuals that belong to the same species and live in a given area at a particular time.

Community

All of the populations of organisms within a given area.

Population ecology

The study of factors that cause populations to increase or decrease.

Population size (N)

The total number of individuals within a defined area at a given time.

Population density

The number of individuals per unit area at a given time.

Population distribution

A description of how individuals are distributed with respect to one another.

Sex ratio

The ratio of males to females in a population.

Age structure

A description of how many individuals fit into particular age categories in a population.

Limiting resource

A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size.

Density-dependent factor

A factor that influences an individual's probability of survival and reproduction in a manner that depends on the size of the population.

Carrying capacity (K)

The limit of how many individuals in a population the environment can sustain.

Density-independent factor

A factor that has the same effect on an individual's probability of survival and the amount of reproduction at any population size.

Population growth models

Mathematical equations that can be used to predict population size at any moment in time.

Population growth rate

The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period.

Intrinsic growth rate (r)

The maximum potential for growth of a population under ideal conditions with unlimited resources.

Exponential growth model (Nt = N0e^rt)

A growth model that estimates a population's future size (Nt) after a period of time (t), based on the intrinsic growth rate (r) and the number of reproducing individuals currently in the population (N0).

J-shaped curve

The curve of the exponential growth model when graphed.

Logistic growth model

A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.

S-shaped curve

The shape of the logistic growth model when graphed.

Overshoot

When a population becomes larger than the environment's carrying capacity.

Die-off

A rapid decline in a population due to death.

K-selected species

A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity.

r-selected species

A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.

Survivorship curve

A graph that represents the distinct patterns of species survival as a function of age.

Type I survivorship curve

A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age.

Type II survivorship curve

A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span.

Type III survivorship curve

A pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood.

Corridor

Strips of natural habitat that connect populations.

Metapopulation

A group of spatially distinct populations that are connected by occasional movements of individuals between them.

Inbreeding depression

When individuals with similar genotypes—typically relatives—breed with each other and produce offspring that have an impaired ability to survive and reproduce.

Community ecology

The study of interactions between species.

Symbiotic relationship

The relationship between two species that live in close association with each other.

Competition

The struggle of individuals to obtain a shared limiting resource.

Competitive exclusion principle

The principle stating that two species competing for the same limiting resource cannot coexist.

Resource partitioning

When two species divide a resource based on differences in their behavior or morphology.

Predation

An interaction in which one animal typically kills and consumes another animal.

Parasitoid

A specialized type of predator that lays eggs inside other organisms—referred to as its host.

Parasitism

An interaction in which one organism lives on or in another organism.

Pathogen

A parasite that causes disease in its host.

Herbivory

An interaction in which an animal consumes a producer.

Mutualism

An interaction between two species that increases the chances of survival or reproduction for both species.

Commensalism

A relationship between species in which one species benefits and the other species is neither harmed nor helped.

Keystone species

A species that that is not very abundant but has large effects on an ecological community.

Ecosystem engineer

A keystone species that creates or maintains habitat for other species.

Ecological succession

The predictable replacement of one group of species by another group of species over time.

Primary succession

Ecological succession occurring on surfaces that are initially devoid of soil.

Secondary succession

The succession of plant life that occurs in areas that have been disturbed but have not lost their soil.

Pioneer species

A species that can colonize new areas rapidly and grow well in full sunshine.

Climax community

Historically described as the final stage of succession.

Threatened species (IUCN)

According to the International Union for Conservation of Nature (ICUN), species that have a high risk of extinction in the future; according to U.S. legislation, any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

Near-threatened species

Species that are very likely to become threatened in the future.

Least-concern species

Species that are widespread and abundant.

Intrinsic value

Value independent of any benefit to humans.

Instrumental value

Worth as an instrument or a tool that can be used to accomplish a goal.

Provision

A good that humans can use directly.

Native species

Species that live in their historical range, typically where they have lived for thousands or millions of years

Exotic species

A species living outside its historical range. (Also known as "alien species.")

Invasive species

A species that spreads rapidly across large areas and causes harm.

Lacey Act

A U.S. act that prohibits interstate shipping of all illegally harvested plants and animals.

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

A 1973 treaty formed to control the international trade of threatened plants and animals.

Red List

A list of worldwide threatened species.

Marine Mammal Protection Act

A 1972 U.S. act to protect declining populations of marine mammals.

Endangered species

A species that is in danger of extinction within the foreseeable future throughout all or a significant portion of its range.

Threatened species (U.S.)

According to the International Union for Conservation of Nature (ICUN), species that have a high risk of extinction in the future; according to U.S. legislation, any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

Convention on Biological Diversity

An international treaty to help protect biodiversity.

Edge habitat

Habitat that occurs where two different communities come together, typically forming an abrupt transition, such as where a grassy field meets a forest.

Biosphere reserve

Protected area consisting of zones that vary in the amount of permissible human impact.

Species richness

The number of species in a given area.

Species evenness

The relative proportion of individuals within the different species in a given area.

Phylogeny

The branching pattern of evolutionary relationships.

Evolution

A change in the genetic composition of a population over time.

Microevolution

Evolution below the species level.

Macroevolution

Evolution that gives rise to new species, genera, families, classes, or phyla.

Gene

A physical location on the chromosomes within each cell of an organism.

Genotype

The complete set of genes in an individual.

Phenotype

A set of traits expressed by an individual.

Mutation

A random change in the genetic code produced by a mistake in the copying process.

Recombination

The genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division.

Evolution by artificial selection

The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind.

Evolution by natural selection

The process in which the environment determines which individuals survive and reproduce.

Fitness

An individual's ability to survive and reproduce.

Adaptation

A trait that improves an individual's fitness.

Gene flow

The process by which individuals move from one population to another and thereby alter the genetic composition of both populations.

Genetic drift

A change in the genetic composition of a population over time as a result of random mating.

Bottleneck effect

A reduction in the genetic diversity of a population caused by a reduction in its size.

Extinction

The death of the last member of a species.

Founder effect

A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals.

Geographic isolation

Physical separation of a group of individuals from others of the same species.

Allopatric speciation

The process of speciation that occurs with geographic isolation.

Reproductive isolation

The result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring.

Sympatric speciation

The evolution of one species into two, without geographic isolation.

Genetically modified organism (GMO)

An organism produced by copying genes from a species with a desirable trait and inserting them into another species.

Range of tolerance

The limits to the abiotic conditions that a species can tolerate

Fundamental niche

The suite of abiotic conditions under which a species can survive, grow, and reproduce.

Realized niche

The range of abiotic and biotic conditions

Distribution

Areas of the world in which a species lives.

Niche generalist

A species that can live under a wide range of abiotic or biotic conditions.

Niche specialist

A species that is specialized to live in a specific habitat or to feed on a small group of species.

Mass extinction

A large extinction of species in a relatively short period of time.

Core

The innermost zone of Earth's interior, composed mostly of iron and nickel. It includes a liquid outer layer and a solid inner layer.

Mantle

The layer of Earth above the core, containing magma.

Magma

molten rock

Asthenosphere

The layer of Earth located in the outer part of the mantle, composed of semi-molten rock.

Lithosphere

The outermost layer of Earth, including the mantle and crust.

Crust

In geology, the chemically distinct outermost layer of the lithosphere.

Hot spot

In geology, a place where molten material from Earth's mantle reaches the lithosphere.

Plate tectonics

The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle.

Tectonic cycle

the sum of the processes that build up and break down the lithosphere

Subduction

The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.

Volcano

A vent or fissure in the Earth's surface through which magma and gases are expelled

Divergent plate boundary

an area beneath the ocean where tectonic plates move away from each other

Seafloor spreading

The formation of new ocean crust as a result of magma pushing upward and outward from Earth's mantle to the surface.

Convergent plate boundary

an area where plates move toward one another and collide

Transform fault boundary

An area where tectonic plates move sideways past each other.

Fault

A fracture in rock caused by a movement of Earth's crust.

Seismic activity

the frequency and intensity of earthquakes experienced over time

Fault zone

a large expanse of rock where a fault has occurred

Earthquake

The sudden movement of Earth's crust caused by a release of potential energy along a geologic fault and usually causing a vibration or trembling at Earth's surface.

Epicenter

the point on the Earth's surface directly above the focus of an earthquake

Richter scale

a scale that measures the largest ground movement that occurs during an earthquake

Tsunami

A series of waves in the ocean caused by seismic activity or an undersea volcano.

Rock cycle

The geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosion, among other processes.

Igneous rock

rock that forms when magma cools and solidifies

Intrusive igneous rock

igneous rock that forms when magma rises up and cools in a place underground

Extrusive igneous rock

rock that forms from the cooling and solidification of lava at Earth's surface

Fracture

In geology, a crack that occurs in rock as it cools.

Sedimentary rock

Rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments.

Metamorphic rock

Rock that forms when sedimentary rock, igneous rock, or other metamorphic rock is subjected to high temperature and pressure.

Physical weathering

the mechanical breakdown of rocks and minerals

Chemical weathering

The breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both.

Acid precipitation

Precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere

Erosion

The physical removal of rock fragments from a landscape or ecosystem.

Parent material

The underlying rock material from which the inorganic components of a soil are derived.

Soil degradation

The loss of some or all of a soil's ability to support plant growth

Horizon

A horizontal layer in a soil defined by distinctive physical features such as texture and color.

O horizon

The organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition

Humus

The most fully decomposed organic matter in the lowest section of the O horizon.

A horizon

Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together.

E horizon

A zone of leaching, or eluviation, found in some acidic soils under the O horizon or, less often, the A horizon

B horizon

A soil horizon composed primarily of mineral material with very little organic matter

C horizon

The least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material.

Cation exchange capacity (CEC)

the ability of a particular soil to absorb and release cations

Base saturation

the proportion of soil bases to soil acids, expressed as a percentage

Crustal abundance

The average concentration of an element in Earth's crust

Ore

A concentrated accumulation of minerals from which economically valuable materials can be extracted.

Metal

An element with properties that allow it to conduct electricity and heat energy, and to perform other important functions.

Reserve

in resource management, the known quantity of a resource that can be economically recovered

Strip mining

the removal of strips of soil and rock to expose ore

Mine tailings

unwanted waste material created during mining including mineral and other residues that are left behind after the desired metal or ore is removed

Open-pit mining

a mining technique that uses a large visible pit or hole in the ground

Mountaintop removal

a mining technique in which the entire top of a mountain is removed with explosives

Placer mining

the process of looking for minerals, metals, and precious stones in river sediments

Subsurface mining

Mining techniques used when the desired resource is more than 100m (328 feet) below the surface of Earth.

Environmental Studies

The field of study that includes environmental science and additional subjects such as environmental policy, economics, literature, and ethics

Biotic

Living

Abiotic

Nonliving

Environmentalism

a social movement that seeks to protect the environment through lobbying, activism, and education

Ecosystem

A particular location on Earth with interacting biotic and abiotic components

Environmental Science

The field of study that looks at interactions among human systems and those found in nature

Fossil Fuel

A fuel derived from biological material that became fossilized millions of years ago

Environment

The sum of all the conditions surrounding us that influence life

Fracking

Hydraulic fracturing, a method of oil and gas extraction that uses high-pressure fluids to force open cracks in rocks deep underground

Ecosystem Services

The processes by which life-supporting resources such as clean water, timber, fisheries, and agricultural crops are produced

Sustainable Development

Development that balances current human well being and economic advancement with resource advancement resource management for the benefit of future generations

Biophilia

Love of Life

Development

Improvement in human well-being through economic advancement

Environmental Indicator

An indicator that describes the current state of an environmental system

Species

A group of organisms that is distinct from other groups in its morphology, behavior, or biochemical properties

Sustainability

Living on Earth in a way that allows humans to use it resources without depriving future generations of those resources

Ecological Footprint

A measure of how much an individual consumes, expressed in an area of land

Speciation

The evolution of new species

Species Diversity

The number of species in a region or in a particular type of habitat

Anthropogenic

Derived from human activities

Background Extinction Rate

The average rate at which species become extinct over the long term

Greenhouse gases

Gasses in Earth's atmosphere that trap heat near the surface

Ecosystem Services

The processes by which life-supporting system resources such as clean water, timber, fisheries, and agricultural crops are produced

Per Capita

Amount per each person in a country or unit of population

Null Hypothesis

A prediction that there is no difference between the groups or conditions that are being compared

Scientific Method

An objective method to explore the natural world, draw interference from it, and predict the outcome of certain events, processes or changes

Uncertainty

An estimate of how much a measured or calculated value differs from a true value

Replication

The data collection procedure of taking repeated measurements

Natural Experiment

A natural event that acts as an experimental treatment in an ecosystem

Theory

A hypothesis that has been repeatedly tested and confirmed by multiple groups of researchers and has reached wide acceptance

indpedent variable

A variable that is not dependent on other factors

Control Group

In a scientific investigation, a group that experiences exactly the same conditions as the experimental group, except for the single variable under study

Sample size (n)

The number of times a measurement is replicated in data collection

Hypothesis

A testable conjecture about how something works

Accuracy

How close a measured value is to the the actual value

Variable

Any categories, conditions, factors, or traits that differ in the natural world or in experimental situations

Dependent Variable

A variable that is dependent on other factors

Precision

How close the repeated measurements of a sample are to one another

Biosphere

The region of our planet where life resides, the combination of all ecosystems on Earth.

Producer

An organism that uses the energy of the Sun to produce usable forms of energy. (Also known as "autotroph.")

Photosynthesis

The process by which producers use solar energy to convert carbon dioxide and water into glucose.

Cellular Respiration

The process by which cells unlock the energy of chemical compounds.

aerobic respiration

The process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Anaerobic respiration

The process by which cells convert glucose into energy in the absence of oxygen.

Consumer

An organism that is incapable of photosynthesis and must obtain its energy by consuming other organisms. (Also known as "heterotroph.")

Herbivore

A consumer that eats producers. (Also known as "primary consumer.")

Carnivore

A consumer that eats other consumers.

Secondary Consumer

A carnivore that eats primary consumers.

Tertiary Consumer

A carnivore that eats secondary consumers.

Tropic Level

The successive levels of organisms consuming one another.

Food Chain

The sequence of consumption from producers through tertiary consumers.

Food Web

A complex model of how energy and matter move between trophic levels.

Scavenger

An organism that consumes dead animals.

Detritivore

An organism that specializes in breaking down dead tissues and waste products into smaller particles.

Decomposers

Fungi and bacteria that convert organic matter into small elements and molecules that can be recycled back into the ecosystem.

Gross primary productivity (GPP)

The total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time.

Net primary productivity (NPP)

The energy captured by producers in an ecosystem minus the energy producers respire.

Biomass

The total mass of all living matter in a specific area.

Standing crop

The amount of biomass present in an ecosystem at a particular time.

Ecological efficiency

The proportion of consumed energy that can be passed from one trophic level to another.

Trophic pyramid

A representation of the distribution of biomass, numbers, or energy among trophic levels.

Biogeochemical cycle

The movements of matter within and between ecosystems.

Hydrologic cycle

The movement of water through the biosphere.

Transpiration

The release of water from leaves during photosynthesis.

Evapotranspiration

The combined amount of evaporation and transpiration.

Runoff

Water that moves across the land surface and into streams and river

Carbon cycle

The movement of carbon around the biosphere.

Macronutrient

One of six key elements that organisms need in relatively large amounts: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Limiting nutrient

A nutrient required for the growth of an organism but available in a lower quantity than other nutrients.

Nitrogen cycle

The movement of nitrogen around the biosphere.

Nitrogen fixation

The process that converts nitrogen gas in the atmosphere (N2) into forms of nitrogen that producers can use.

Nitrification

The conversion of ammonia (NH4+) into nitrite (NO2-) and then into nitrate (NO3-).

Assimilation

The process by which producers incorporate elements into their tissues.

Mineralization

The process by which fungal and bacterial decomposers break down the organic matter found in dead bodies and waste products and convert it into inorganic compounds.

Ammonification

The process by which fungal and bacterial decomposers break down the organic nitrogen found in dead bodies and waste products and convert it into inorganic ammonium (NH4+)

Denitrification

The conversion of nitrate (NO3-) in a series of steps into the gases nitrous oxide (N2O) and, eventually, nitrogen gas (N2), which is emitted into the atmosphere.

Leaching

The transportation of dissolved molecules through the soil via groundwater.

Phosphorus cycle

The movement of phosphorus around the biosphere.

Algal bloom

A rapid increase in the algal population of a waterway.

Hypoxic

Low in oxygen

Dead zone

When oxygen concentration become so low that it kills fish and other aquatic animals.

Sulfur cycle

The movement of sulfur around the biosphere.

Disturbance

An event, caused by physical, chemical, or biological agents, resulting in changes in population size or community composition.

Resistance

A measure of how much a disturbance can affect flows of energy and matter in an ecosystem.

Resilience

The rate at which an ecosystem returns to its original state after a disturbance.

Restoration ecology

The study and implementation of restoring damaged ecosystems.

Watershed

All land in a given landscape that drains into a particular stream, river, lake, or wetland.

Intermediate disturbance hypothesis

The hypothesis that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels.

Climate

The average weather that occurs in a given region over a long period of time.

Weather

The short-term conditions of the atmosphere in a local area, which include temperature, humidity, clouds, precipitation, and wind speed.

Troposphere

A layer of the atmosphere closest to the surface of Earth, extending up to approximately 16 km (10 miles).

Stratosphere

The layer of the atmosphere above the troposphere, extending roughly 16 to 50 km (10-31 miles) above the surface of Earth.

Albedo

The percentage of incoming sunlight reflected from a surface.

Saturation point

maximum amount of water vapor in the air at a given temperature

Adiabatic cooling

The cooling effect of reduced pressure on air as it rises higher in the atmosphere and expands.

Adiabatic heating

The heating effect of increased pressure on air as it sinks toward the surface of Earth and decreases in volume.

Latent heat release

The release of energy when water vapor in the atmosphere condenses into liquid water.

Atmospheric convection current

Global patterns of air movement that are initiated by the unequal heating of Earth.

Hadley cell

A convection current in the atmosphere that cycles between the equator and 30° N and 30° S

Intertropical convergence zone (ITCZ)

The latitude that receives the most intense sunlight, which causes the ascending branches of the two Hadley cells to converge.

Polar cell

A convection current in the atmosphere, formed by air that rises at 60° N and 60° S and sinks at the poles, 90° N and 90° S.

Ferrell cell

A convection current in the atmosphere that lies between Hadley cells and polar cells.

Coriolis effect

The deflection of an object's path due to the rotation of Earth.

Rain shadow

A region with dry conditions found on the leeward side of a mountain range as a result of humid winds from the ocean causing precipitation on the windward side.

Gyre

A large-scale pattern of water circulation that moves clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Upwelling

The upward movement of ocean water toward the surface as a result of diverging currents.

Thermohaline circulation

An oceanic circulation pattern that drives the mixing of surface water and deep water.

El Niño-Southern Oscillation (ENSO)

A reversal of wind and water currents in the South Pacific.

Terrestrial biome

A geographic region categorized by a particular combination of average annual temperature, annual precipitation, and distinctive plant growth forms on land.

Aquatic biome

An aquatic region characterized by a particular combination of salinity, depth, and water flow.

Habitat

An area where a particular species lives in nature.

Tundra

A cold and treeless biome with low-growing vegetation

Permafrost

An impermeable, permanently frozen layer of soil.

Boreal forest

A forest biome made up primarily of coniferous evergreen trees that can tolerate cold winters and short growing seasons.

Temperate rainforest

A coastal biome typified by moderate temperatures and high precipitation.

Temperate seasonal forest

A biome with warm summers and cold winters with over 1 m (39 inches) of precipitation annually.

Woodland/shrubland

A biome characterized by hot, dry summers and mild, rainy winters.

Temperate grassland/cold desert

A biome characterized by cold, harsh winters, and hot, dry summers.

Tropical rainforest

A warm and wet biome found between 20° N and 20° S of the equator, with little seasonal temperature variation and high precipitation.

Tropical seasonal forest/savanna

A biome marked by warm temperatures and distinct wet and dry seasons.

Subtropical desert

A biome prevailing at approximately 30° N and 30° S, with hot temperatures, extremely dry conditions, and sparse vegetation.

Littoral zone

The shallow zone of soil and water in lakes and ponds where most algae and emergent plants grow.

Limnetic zone

A zone of open water in lakes and ponds.

Phytoplankton

Floating algae.

Profundal zone

A region of water where sunlight does not reach, below the limnetic zone in very deep lakes.

Benthic zone

The muddy bottom of a lake, pond, or ocean

Oligotrophic

Describes a lake with a low level of productivity.

Mesotrophic

Describes a lake with a moderate level of productivity.

Eutrophic

Describes a lake with a high level of productivity.

Freshwater wetland

An aquatic biome that is submerged or saturated by water for at least part of each year, but shallow enough to support emergent vegetation.

Salt marsh

A marsh containing nonwoody emergent vegetation, found along the coast in temperate climates.

Estuary

An area along the coast where the fresh water of rivers mixes with salt water from the ocean.

Mangrove swamp

A swamp that occurs along tropical and subtropical coasts, and contains salt-tolerant trees with roots submerged in water.

Intertidal zone

The narrow band of coastline between the levels of high tide and low tide.

Coral reef

The most diverse marine biome on Earth, found in warm, shallow waters beyond the shoreline.

Coral bleaching

A phenomenon in which algae inside corals die, causing the corals to turn white.

Open ocean

Deep ocean water, located away from the shoreline where sunlight can no longer reach the ocean bottom.

Photic zone

The upper layer of ocean water in the ocean that receives enough sunlight for photosynthesis.

Aphotic zone

The deeper layer of ocean water that lacks sufficient sunlight for photosynthesis.

Chemosynthesis

A process used by some bacteria in the ocean to generate energy with methane and hydrogen sulfide.