Exploring Aquatic Biomes – VOCABULARY Flashcards

A set of vocabulary flashcards covering key terms from the notes on lakes, wetlands, streams and rivers, estuaries, intertidal zones, the open ocean (oceanic pelagic zone), coral reefs, and deep-sea vent ecosystems.

Thermocline

A layer in a body of water where temperature changes rapidly with depth, separating warmer surface water from cooler deeper water; may be year-round in temperate lakes and seasonal in tropical ones.

Oligotrophic

Lakes that are nutrient-poor and generally oxygen-rich, with low decomposable organic matter in bottom sediments and often less surface area relative to depth; can become eutrophic with runoff.

Eutrophic

Lakes that are nutrient-rich and often have oxygen depletion in deep layers during warm periods; high organic matter and decomposition rates.

Littoral zone

The shallow, well-lit region near shore where rooted aquatic plants can grow.

Limnetic zone

The open-water zone away from shore that hosts phytoplankton; where zooplankton graze on the phytoplankton.

Phytoplankton

Photosynthetic organisms in aquatic environments (including cyanobacteria) that form the base of the food web.

Zooplankton

Small drifting heterotrophs in the limnetic zone that graze on phytoplankton.

Benthos/Benthic zone

Organisms living on the bottom of lakes and wetlands; the bottom-dwelling community.

Wetland

A habitat inundated by water at least part of the time and supporting plants adapted to water-saturated soil; some wetlands are permanently flooded, others flood infrequently.

Turnover

Seasonal mixing of water that renews nutrients in the photic zone of temperate lakes.

Estuary

A transition area between river and sea where salinity varies with tides and nutrients make estuaries highly productive.

Saltmarsh grasses

Along with algae, a major producer in estuaries; grasses adapted to saline conditions.

Intertidal zone

The zone that is submerged and exposed by tides twice daily; upper areas experience more air exposure and greater temperature/salinity variation.

Oceanic pelagic zone

The vast open-ocean region, constantly mixed by currents; photic zone extends deeper due to clear water; covers about 70% of Earth's surface.

Photic zone

Sunlit layer of water where photosynthesis can occur; depth varies with water clarity; deeper in clearer open-ocean waters.

Neritic zone

The shallow coastal zone over the continental shelf; the nearshore portion of the marine environment.

Marine benthic zone

The seafloor below the surface waters of the coastal (neritic) zone and the offshore pelagic zone; little sunlight except in shallow areas; temperature decreases with depth and pressure increases.

Abyssal zone

The very deep benthic zone, typically around 3°C, with high pressure and organisms adapted to cold, dark, high-pressure conditions.

Coral reef

Reefs formed largely from calcium carbonate skeletons of corals; shallow, photic tropical waters with high water clarity and oxygen levels.

Corals

Cnidarians that form reef structures and host mutualistic algae; high diversity and productivity on reefs.

Chemoautotrophs

Organisms that obtain energy by oxidizing inorganic molecules (e.g., H2S) and fix carbon; primary producers at hydrothermal vents.

Deep-sea hydrothermal vent

Underwater communities around vents powered by chemoautotrophs that use chemical energy (not sunlight) to fix carbon.

Giant tube worms

A characteristic deep-sea vent organism nourished by symbiotic chemoautotrophic bacteria living in or on their bodies.

Overfishing

Removal of large portions of fish populations, leading to depleted stocks and disrupted marine ecosystems.

Ocean acidification

The lowering of ocean pH due to uptake of atmospheric CO2, harming calcifying organisms and reef systems.

Mangroves

Coastal trees and ecosystems often cleared or modified for aquaculture, impacting spawning and nursery habitats for many species.