Chapter 52: Aquatic Biomes and Lake Turnover (Vocabulary)

Vocabulary flashcards covering key terms related to aquatic biomes, lake turnover, and zonation in marine and freshwater environments.

Seasonal turnover

The seasonal mixing of lake waters that oxygenates deeper layers in spring and autumn; in winter and summer, stratification reduces mixing, causing oxygen to decline with depth.

Thermocline

A narrow vertical zone of abrupt temperature change that separates warm surface water from colder deeper water.

Photic zone

The upper layer of water that receives enough light for photosynthesis.

Aphotic zone

The deeper layer where little or no light penetrates.

Pelagic zone

The open-water region of aquatic environments, comprising both the photic and aphotic zones.

Littoral zone

The nearshore, shallow part of a lake or ocean where light reaches the bottom.

Limnetic zone

The open-water zone of a lake away from shore where photosynthesis can occur.

Benthic zone

The ecological region at the bottom of a body of water, consisting of sediments and hosting benthos.

Benthos

The community of organisms that live on or in the bottom substrates of aquatic environments.

Detritus

Dead organic matter that rains down from productive surface waters and serves as a major food source for benthic communities.

Abyssal zone

The deep ocean zone roughly 2,000–6,000 meters below the surface.

Intertidal zone

Coastal area exposed to air and submerged with the tides, between high and low tide lines.

Neritic zone

The shallow part of the ocean over the continental shelf.

Oceanic zone

The portion of the ocean beyond the neritic zone, encompassing deeper waters.

Continental shelf

The submerged edge of a continent that provides the shallow boundary of the ocean.

Zonation

The arrangement of aquatic habitats into distinct layers or zones based on depth, light penetration, distance from shore, and whether the environment is open water or bottom.

Aquatic biomes

Diverse and dynamic aquatic ecosystems that cover much of Earth's surface and are shaped primarily by physical and chemical conditions rather than latitude.

Marine biomes

Saltwater biomes, typically with about 3% salinity.

Freshwater biomes

Biomes with low salinity, usually less than 0.1%.

Plankton

Drifting or weakly swimming organisms that inhabit the water column, including phytoplankton and zooplankton.

Phytoplankton

Photosynthetic plankton that act as the dominant primary producers in many oceanic and freshwater pelagic zones.