Environmental Systems: Ecosystems, Energy & Material Flow

Vocabulary flashcards covering key terms from the Environmental Systems lecture, including ecosystem structure, energy flow, biogeochemical cycles, biome classifications, and factors influencing ecosystem health.

Ecology

The scientific study of interactions among organisms and their environment; literally “the study of one’s house.”

Ecosystem

A community of interacting organisms and their physical, chemical, and energy environment where materials are exchanged cyclically.

Biotic Components

The living parts of an ecosystem (plants, animals, microbes).

Abiotic Components

The non-living physical and chemical factors of an ecosystem (soil, air, water, temperature, minerals).

Environment (ecological)

Everything that affects an organism during its lifetime.

Atmosphere

Earth’s realm composed of the layer of gases surrounding the planet (air).

Hydrosphere

All water—liquid, solid, and vapor—found on, under, or over Earth’s surface.

Lithosphere

Earth’s outer solid layer of rocks and soil.

Biosphere

The global sum of all ecosystems; zone where life exists.

Photosynthesis

Process by which producers convert CO₂, water, and radiant energy into high-energy molecules (carbohydrates) and oxygen.

Aerobic Respiration

Process in which high-energy molecules are broken down with oxygen to release energy, CO₂, and water.

Producers (Autotrophs)

Organisms (mainly plants and algae) that manufacture their own food through photosynthesis.

Consumers (Heterotrophs)

Organisms that obtain energy by eating other organisms.

Decomposers

Organisms (bacteria, fungi) that break down dead matter, releasing nutrients back into the ecosystem.

Food Chain

Linear sequence of energy transfer from one trophic level to another via consumption.

Biogeochemical Cycle

Cyclic movement of chemical elements between living organisms and the physical environment.

Carbon Cycle

Global circulation of carbon atoms through photosynthesis, respiration, decomposition, combustion, and sedimentation.

Nitrogen Cycle

Pathways through which nitrogen moves via fixation, assimilation, ammonification, nitrification, and denitrification.

Phosphorous Cycle

Movement of phosphorus through rocks, soil, water, and living organisms; lacks a gaseous phase.

Sulfur Cycle

Circulation of sulfur through weathering, atmospheric oxidation, deposition, and biological uptake.

Hydrologic Cycle

Continuous movement of water through evaporation, condensation, precipitation, runoff, and infiltration.

Biome

Large geographic region defined by specific climate conditions and characteristic flora and fauna.

Terrestrial Biome

Land-based biome categorized by temperature and precipitation patterns (e.g., tundra, forest, desert).

Tundra

Cold, treeless biome with permafrost and low precipitation.

Forest Biome

Biome dominated by trees; includes tropical, temperate, and boreal forests.

Savanna

Warm grassland with scattered trees and seasonal rainfall.

Chaparral

Shrub-dominated biome with Mediterranean climate—mild, wet winters and hot, dry summers.

Grassland

Biome of grasses and few trees; moderate rainfall and periodic fires.

Desert

Arid biome with very low precipitation and temperature extremes.

Aquatic Biome

Water-based biome classified by salinity, depth, temperature, and proximity to shore.

Plankton

Tiny, free-floating organisms in water columns that drift with currents.

Phytoplankton

Photosynthetic planktonic plants/algae forming the base of aquatic food webs.

Zooplankton

Non-photosynthetic animal plankton, including larval stages of larger species.

Nekton

Active swimming aquatic animals such as fish, whales, and turtles.

Benthos

Bottom-dwelling aquatic organisms (e.g., crabs, clams, sea stars).

Flowing-Water Ecosystem

Freshwater bodies with moving water (rivers, streams) where organisms adapt to currents.

Standing-Water Ecosystem

Lakes, ponds, and wetlands with non-flowing or slow-moving water.

Littoral Zone

Shallow, near-shore area of a lake or pond; most biologically productive.

Limnetic Zone

Open-water area of a lake where light penetrates; supports plankton.

Profundal Zone

Deep, dark zone of large lakes where decomposers break down sinking organic matter.

Wetland

Land saturated with water either permanently or seasonally; highly productive and provides ecosystem services.

Estuary

Transitional ecosystem where fresh river water mixes with seawater; characterized by fluctuating salinity.

Intertidal Zone

Marine area between high and low tide marks; experiences wave action and tidal changes.

Pelagic Zone

Open-ocean water column away from shore and seafloor.

Neritic Province

Part of pelagic zone extending from shore to 200-m depth.

Oceanic Province

Pelagic waters deeper than 200 m beyond the continental shelf.

Euphotic (Photic) Zone

Upper ocean layer (~0–150 m) where sufficient light supports photosynthesis.

Bathyal (Aphotic) Zone

Ocean layer from the base of the photic zone to ~4,000 m; no photosynthesis.

Abyssal Zone

Deep ocean floor between 4,000–6,000 m; perpetually dark and cold.

Benthic Zone

Ocean floor environment inhabited by sediment-dwelling organisms.

Hydrothermal Vent

Seafloor fissure emitting hot, mineral-rich water; supports chemosynthetic communities.

Coral Reef

Highly productive marine ecosystem formed by accumulations of calcareous coral skeletons in symbiosis with zooxanthellae.

Fringing Reef

Coral reef closely attached to a shoreline.

Barrier Reef

Coral reef separated from land by a lagoon.

Atoll

Ring-shaped coral reef encircling a lagoon, formed around a submerged volcano.

Habitat

The physical environment where a species lives or can live.

Niche

An organism’s functional role and position within an ecosystem.

Keystone Species

Species whose impact on its ecosystem is disproportionately large relative to its abundance.

Invasive Species

Non-native species that establishes and threatens natural biodiversity.

Biodiversity

Variety of life at genetic, species, and ecosystem levels.

Habitat Diversity

Range of different habitat types within an ecosystem.

Genetic Diversity

Variation in DNA among individuals of a population or species.

Species Diversity

Combination of species richness and species evenness in a community.

Poaching

Illegal hunting or capture of wildlife.

Bioaccumulation

Build-up of a chemical in an organism through ingestion and environmental exposure.

Bioconcentration

Direct absorption of a chemical from water into an organism without dietary intake.

Utilitarian Value (of biodiversity)

Importance of biodiversity for practical benefits such as medicines, food, and ecosystem services.

Food Energy in Terrestrial vs. Aquatic Biomes

Carbohydrates dominate terrestrial plants; proteins dominate aquatic primary producers.