Aquatic Biomes

Aquatic biomes

Categorized by salinity, depth, and water flow; divided into freshwater and marine biomes.

Freshwater biomes

Low salinity; include streams, rivers, lakes, ponds, and freshwater wetlands.

Marine biomes

High salinity; include estuaries, salt marshes, mangrove swamps, intertidal zones, coral reefs, and the open ocean.

Water distribution on Earth

97% salt water, 3% fresh water; most fresh water is frozen; less than 1% accessible to humans.

Streams and rivers

Flowing fresh water from springs, rain, or melting snow; streams are narrow, rivers wider.

Stream ecology

Fast streams have high oxygen and few plants; rely on organic matter from land; slow rivers have sediment and rooted plants.

Lake and pond characteristics

Standing water; too deep for emergent plants; lakes larger than ponds.

Littoral zone

Shallow, near shore; sunlight reaches bottom; supports algae and emergent plants.

Limnetic zone

Open water, sunlight penetrates; contains phytoplankton; photosynthesis occurs here.

Profundal zone

Deep water below limnetic zone; no sunlight; low oxygen levels.

Benthic zone

Muddy bottom of lake, pond, or ocean; decomposers live here.

Lake productivity

Oligotrophic (low nutrients, clear), Mesotrophic (moderate nutrients), Eutrophic (high nutrients, turbid water).

Freshwater wetlands

Saturated or submerged at least part of the year; support emergent vegetation.

Swamps

Wetlands with trees (e.g., bald cypress); found in warm, humid regions.

Marshes

Wetlands with nonwoody plants like cattails and sedges.

Bogs

Acidic wetlands with mosses (sphagnum) and shrubs; low nutrients.

Wetland importance

Absorb excess rainwater, reduce flooding, filter pollutants, recharge groundwater, habitat for birds.

Estuaries

Where freshwater meets salt water; very productive; filters pollutants; nursery for fish/shellfish.

Salt marshes

Found in temperate climates within estuaries; nonwoody vegetation; important fish habitat.

Mangrove swamps

Tropical/subtropical coasts; salt

Intertidal zones

Between high and low tide; organisms adapt to drying, waves, and temperature changes.

Coral reefs

Warm, shallow, tropical marine biome; high biodiversity; corals have symbiotic algae.

Coral bleaching

Algae inside corals die → corals turn white; caused by heat, pollution, low pH.

Open ocean

Deep water far from shore; divided into photic and aphotic zones.

Photic zone

Sunlit surface; photosynthesis by phytoplankton produces oxygen, absorbs CO₂.

Aphotic zone

Deep, dark layer; no sunlight or photosynthesis; some bacteria use chemosynthesis.

Chemosynthesis

Bacteria use methane and hydrogen sulfide to generate energy; base of deep

Summary

Freshwater biomes: streams/rivers, lakes/ponds, wetlands. Marine biomes: estuaries/salt marshes, mangroves, intertidal, coral reefs, open ocean.