| Term | Definition |
| ecology | the scientific study of the interactions between organisms and their environments |
| abiotic components | nonliving chemical and physical factors |
| biotic components | living chemical and physical factors |
| ecological time | minutes, months, years |
| evolutionary time | decades, centuries, millennia |
| organismal ecology | morphological, physiological, and behavioral ways in which an individual organism meets the challenges posed by their (a)biotic environments |
| population | group of individuals of the same species living in a particular geographic area |
| population ecology | factors that affect how many individuals of a particular species live in an area |
| community | all the organisms of all the species that inhabit a particular area |
| community ecology | interacting species in a community |
| ecosystem | all the abiotic factors in addition to the entire community of species that exist in a certain area |
| ecosystem ecology | energy flow and the cycling of chemicals among the various biotic and abiotic components |
| landscape ecology | ecosystems and how they are arranged in a geographic region |
| biosphere | the global system - the sum of all the planet's ecosystems |
| precautionary principle | a guiding principle in making decisions about the environment |
| biogeography | study of the past and present distribution of individual species |
| dispersal | the distribution of individuals within geographic population boundaries |
| climate | the prevailing weather conditions at a locality |
| biomes | major types of ecosystems that occupy broad geographic regions |
| microclimate | climate that varies on a fine scale |
| photic zone | place where there is sufficient light for photosynthesis |
| aphotic zone | place where little light penetrates |
| thermocline | rapid temperature change |
| benthic zone | bottom of all aquatic biomes |
| detritus | dead organic matter |
| littoral zone | shallow, well lit waters close to the shore |
| limnetic zone | well lit, open surface waters father from the shore |
| profundal zone | deep aphotic region |
| oligotrophic | deep and nutrient poor |
| eutrophic | shallow and nutrient high |
| wetland | area covered with water that supports aquatic plants |
| estuary | area where a freshwater stream or river merges with the ocean |
| intertidal zone | where land meets water |
| neritic zone | shallow regions over the continental shelves |
| pelagic zone | open water of any depth |
| abyssal zone | very deep, benthic communities |
| permafrost | permanently frozen stratum |