abiotic factor

nonliving thing, such as water, temperature, and minerals, that affects an ecosystem

benthic zone

the surface of the floor, including some subsurface region, at the bottom of a body of water


number and variety of species in a given area

biogeochemical cycle

cyclic transfer of a chemical, such as carbon, between organisms and the environment


type of ecosystem defined by climatic, physical, and biotic characteristics


all living things and their ecosystems on Earth

biotic factor

a living thing that influences an ecosystem, such as prey, predators, and pathogens

carbon sequestration

storage of carbon dioxide or organic carbon to remediate climate change


long-term, wide-range weather patterns

climate change

long-term change in weather patterns


all organisms living in a given area


the study of interactions among organisms and between organisms and their environments


all organisms living in one geographic region and all the environmental factors that affect those organisms


the location where a river meets the ocean; place where fresh and salt water mix tidally


algal bloom caused by excessive nutrients, leading to a drop in dissolved oxygen

greenhouse gas

atmospheric gas that reflects the Sun's rays back to Earth, trapping heat

hydrothermal vent

deep-sea fissure releasing extremely hot fluid that contains hydrogen sulfide

nitrogen fixation

the conversion of atmospheric nitrogen into ammonia, a form that is more usable by plants

photic zone

upper portion of an aquatic environment where light can penetrate


an interbreeding group of individuals of the same species

rain shadow

effect of air movement over a mountain range that causes wet conditions on one side of the mountain range and dry conditions on the other side


seasonal mixing that redistributes oxygen and nutrients in a body of water