AP®︎ Environmental Science: Topic 1.3 Flashcards

A water-based ecological system classified chiefly by salinity, movement, depth, light, temperature, turbidity, nutrients, dissolved oxygen, and substrate

A low-salinity aquatic system, including streams, rivers, ponds, lakes, and freshwater wetlands, that provides vital drinking water

A saline aquatic system—including oceans, coral reefs, salt marshes, and estuaries—where algae take up atmospheric CO₂ and generate roughly half the oxygen produced by global photosynthesis

The concentration of dissolved salts in water, commonly measured in parts per thousand (ppt)

Water with intermediate, often variable salinity produced where freshwater and seawater mix

The portion of a body of water receiving enough sunlight for photosynthesis

Water below the photic zone that does not receive enough light to support photosynthesis

Microscopic algae and photosynthetic bacteria that drift in sunlit water and form the producer base of many aquatic food webs

The cloudiness of water caused by suspended particles, which reduces light penetration and may harm aquatic organisms

The supply of nutrients such as nitrogen and phosphorus that limits aquatic producer growth and ecosystem productivity

Oxygen gas present in water and available for aquatic respiration; cold, turbulent water generally holds more than warm, still water

Lotic systems contain flowing freshwater; lentic systems contain standing freshwater

Bodies of flowing freshwater; streams generally carry less water than rivers, but no universal size boundary separates them

The upper beginnings of a river system, typically narrow, cold, clear, fast-moving, and rich in dissolved oxygen

Bodies of standing freshwater; ponds are generally shallower, while lakes are generally larger and deeper

The shallow nearshore lake zone where sunlight reaches the bottom and rooted plants are abundant

The sunlit open-water lake zone away from shore, where phytoplankton are major producers

Deep lake water below the depth at which enough light is available for photosynthesis

The bottom surface and sediments of a body of water, inhabited by bottom-dwelling organisms

A nutrient-poor, low-productivity lake with clear water and usually relatively high deep-water dissolved oxygen

A lake with intermediate nutrient concentrations and biological productivity

A nutrient-rich, highly productive lake with abundant algal or plant growth, often turbid water, and decomposition that can reduce deep-water oxygen

The formation of temperature and density layers in water that resist mixing of heat, oxygen, and nutrients

The warm, less-dense surface layer of a thermally stratified lake

The layer of rapid temperature change separating a lake’s warm epilimnion from its cold hypolimnion

The cold, dense deep-water layer below the thermocline in a stratified lake

Seasonal mixing that occurs when surface and deep water reach similar temperatures and densities, redistributing oxygen and nutrients

An inland area whose soil is covered or saturated by water for part of the year and supports water-tolerant vegetation

A freshwater wetland dominated by nonwoody emergent plants such as grasses, reeds, and sedges

A freshwater wetland dominated by woody vegetation such as trees or shrubs

An acidic, nutrient-poor freshwater wetland that accumulates partially decomposed organic material

The shoreline between average high and low tides, alternately submerged and exposed

The shallow marine water above the continental shelf, often productive because of sunlight, mixing, and nutrient input

The vast marine region beyond the continental shelf, whose sunlit surface often has low productivity because nutrients are scarce

The water column of a marine system rather than its bottom

A partially enclosed coastal body of water where river freshwater mixes with seawater, creating productive brackish habitat

A tidal coastal wetland dominated by salt-tolerant grasses and other nonwoody emergent plants

A tropical or subtropical coastal wetland dominated by salt-tolerant trees and shrubs with dense root systems

A diverse marine ecosystem built by coral polyps in warm, shallow, clear, sunlit, saline water

The movement of nutrient-rich deep water toward the surface, supporting high phytoplankton productivity and fisheries