Module 3: Aquatic Biomes

Characteristics of aquatic biomes

Salinity, flow, temperature, depth

Salinity

How much salt there is in a body of water, determines which species can survive & usability for drinking (Freshwater vs. estuary vs. ocean)

Flow

Determines which plants and organisms can survive, how much O₂ can dissolve into water

Depth

Influences how much sunlight can penetrate and reach plants below the surface for photosynthesis

Temperature

Warmer water holds less dissolved O₂ so it can support fewer aquatic organisms

Water distribution

• 30% = land

• 70% = water

  • 97% = saltwater

    • 78% = above ground

    • 22% = ground water

  • 3% = freshwater

Freshwater biomes

They are categorized as streams and rivers, lakes and ponds, and freshwater wetlands that are widely distributed throughout the world

Rivers

Has high O₂ due to flow mixing water and air, also carries nutrient-rich sediments (deltas & flood plains = fertile soil)

Lakes

Standing bodies of fresh O₂ (drinking water source)

Four layers of rivers and lakes

Littoral, limnetic, profundal, and benthic

Littoral

Shallow water with emergent plants

Limnetic

Where light can reach, minimal sunlight (only phytoplankton can photosynthesize)

Profundal

Too deep for sunlight, zero sunlight

Benthic

Murky bottom where bugs live, nutrient-rich sediments

Oligotrophic lakes

A pond with low nutrient content and low phytoplankton 

Mesotrophic lakes

A pond with moderate nutrient content and moderate phytoplankton

Eutrophic lakes

A pond with moderate nutrient content and moderate phytoplankton

Wetlands

Area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants

Vegetation in wetlands

Plants living here have to be adapted to living with roots submerged in standing water (cattails, lily pads, reeds)

Benefits of wetlands

• Stores excess water during storms, lessening floods

• Recharges groundwater by absorbing rainfall into soil

• Plants filter pollutants from water draining through

• Highly plant growth due to lots of water and nutrients from dead organic matter in sediments

Estuaries

An area where fresh water from the rivers and saltwater from the ocean emerge along the coast that has a lot productivity (plant growth) due to nutrients in sediments deposited in estuaries by river

Salt marsh

• Estuary habitation along the coast in temperate climates

• Breeding ground for many fish and shellfish species

• Supports nonwoody emergent plants

Mangrove swamps

• Estuary habitation along the coast in tropical climates

• Mangrove trees with long, stilt roots stabilize the shoreline & provide habitat for many species of fish & shellfish

Coral reef

A diverse marine biome with warm, shallow water beyond the shoreline in tropical regions

Mutualism between coral and algae

• Coral take CO₂ out of ocean to create calcium carbonate exoskeleton (the reef) & also provide CO₂ to the algae

• Algae live in the reef & provide sugar (energy) to the coral through photosynthesis

• Without the mutualism, coral would die without energy from algae and algae would die from not having a habitat and CO₂ from the coral

Intertidal zone

• A narrow layer of the coastline that coexists between high and low tide

• Organisms must be adapted to survive crashing waves & direct sunlight/heat during low tide

• Shells & tough outer skin can prevent drying out (desiccation) during low tides

• Diff. organisms are adapted to live in diff. Zones

Ocean

• Deep-water source that is located away from the shoreline where sunlight can’t penetrate to the ocean bottom

• Low productivity/area as only algae & phytoplankton can survive in most of ocean

• So large though, that algae & phytoplankton of ocean produce a lot of earth’s O₂ & absorb a lot of atmospheric CO₂

Photic zone

An upper layer of the ocean where it receives enough sunlight for photosynthesis

Aphotic zone

Another layer below the photic zone where it receives sunlight but not enough for photosynthesis

Benthic zone

The ocean floor where sunlight can’t be seen under and has zero light whatsoever

Chemosynthesis

A process that bacteria use as a source of energy from the combination of methane and hydrogen sulfide