Ecosystems, Energy Flow, and Ecological Impacts

Vocabulary flashcards covering ecological organization, thermodynamics, energy flow, productivity, ecological pyramids, and human-driven environmental impacts such as persistent pollutants and microplastics.

Levels of Organization

The hierarchical ecological structure consisting of Individual, Population, Community, Ecosystem, Biome, and Biosphere.

Community

A group of populations living and interacting with each other in a common habitat, encompassing only the biotic components of an ecosystem.

Population

A group of organisms of a single species living together in a specific area.

Habitat

The physical location in which a community, species, population, or organism normally lives.

Ecosystem

A community and the physical environment it interacts with, functioning as a system of biotic factors (living organisms) and abiotic factors (physical environment).

Marine Ecosystem

An aquatic ecosystem—including seas, estuaries, salt marshes, and mangroves—characterized by water that has a high concentration of salt.

Freshwater Ecosystem

An aquatic ecosystem—including rivers, lakes, and wetlands—characterized by a low concentration of salt in the water.

Steady State Equilibrium

A natural condition of ecosystems where inputs and outputs are balanced over time.

Geographic Information Systems (GIS)

A technology system that provides satellite data and spatial analysis tools (such as Global Forest Watch) to aid in ecological investigations.

Keystone Species

A species that is vital for the continued functioning of an ecosystem, such that the ecosystem would collapse without it (e.g., the agouti dispersing Brazil nut seeds).

Biodiversity Intactness Index (BII)

The average abundance of originally present species relative to an undisturbed, intact ecosystem, assessed geographically across biomes and major marine zones.

First Law of Thermodynamics

The principle stating that energy flowing through an ecosystem can be transformed from one form to another, but cannot be created or destroyed, keeping total system energy constant.

Second Law of Thermodynamics

The principle stating that energy transformations are not $100\%$ efficient and that energy degrades from a concentrated form to dispersed heat, reducing available work and limiting trophic levels.

Photosynthesis

The process by which autotrophs convert solar energy, $\text{CO}_2$, and $\text{H}_2\text{O}$ into chemical energy in the form of glucose ($\text{C}_6\text{H}_{12}\text{O}_6$) and release $\text{O}_2$.

Cellular Respiration

The biochemical process in which living cells oxidize glucose and other organic molecules with $\text{O}_2$ to release energy for life functions and heat, discharging $\text{CO}_2$ and $\text{H}_2\text{O}$.

Detritivore

A heterotroph that ingests dead organic matter and digests it internally within its body (e.g., earthworms, dungworms, and snails).

Saprotroph

A decomposer (such as fungi or bacteria) lacking an internal digestive system that secretes enzymes directly onto dead organic matter to absorb digested nutrients.

Gross Productivity (GP)

The total gain in biomass or energy assimilated by an organism or trophic level.

Net Productivity (NP)

The amount of biomass or energy remaining after deducting losses from cellular respiration: $\text{net productivity} = \text{gross productivity} - \text{cellular respiration}$.

Maximum Sustainable Yield

The net productivity of an organism or trophic level that can be extracted without diminishing its future availability or stock.

Pyramid of Numbers

A graphical ecological model that displays the exact count or estimate of individual organisms coexisting at each trophic level.

Pyramid of Biomass

A graphical model that quantifies the standing stock or dry mass present at each trophic level at a specific point in time, measured in $\text{g/m}^2$ or $\text{J/m}^2$.

Pyramid of Energy

A graphical model illustrating the flow and rate of energy generation through trophic levels over time (measured in $\text{g}\,\text{m}^{-2}\,\text{year}^{-1}$ or $\text{J}\,\text{m}^{-2}\,\text{year}^{-1}$), which cannot be inverted due to thermodynamics.

Biomass

The mass of an organism excluding its water content, obtained by drying a sample in an oven at $80\,^\circ\text{C}$ until constant mass is achieved.

Dichlorodiphenyltrichloroethane (DDT)

A persistent synthetic organochlorine pesticide widely used during World War II against typhus and malaria vectors, later restricted due to ecological damage.

Bioaccumulation

The continuous build-up of persistent or nonbiodegradable pollutants within an individual organism or trophic level over time due to an inability to metabolize or excrete them.

Biomagnification

The increasing concentration of a persistent chemical pollutant per unit of biomass at successively higher trophic levels along a food chain.

Microplastics

Small synthetic plastic particles that measure up to $5\,\text{mm}$ in diameter.