Aquatic Biomes Notes

Aquatic Biomes

  • Aquatic organisms rely on organic matter and nutrients suspended in the water.
    • Example: Filter feeders like oysters, clams, and barnacles consume detritus.
  • Water's Importance:
    • Disperses gametes and larvae to new areas.
    • High thermal capacity moderates temperature, reducing energy expenditure for organisms.
    • Screens out UV radiation.
  • Types of aquatic biomes:
    • Antarctic
    • Marine
    • Lake
    • Wetlands
    • Rivers and Streams

Antarctic Biome

  • Low terrestrial biodiversity.
  • Highly productive seas due to abundant phytoplankton and long summer daylight.
    • Phytoplankton feeds krill, a crucial food source.
  • Environmental Threats:
    • Climate change
    • Extraction of minerals, oil, and gas
    • Fishing
    • Invasive species (e.g., rats)
    • Ocean acidification
    • Pollution (including CFCs)
    • Tourism
  • Solutions:
    • Address climate change
    • Prevent invasive species through monitoring and rapid eradication
    • Limit fishing
  • Climatograph: graph of temperature and precipitation.
  • Antarctic Food Web includes phytoplankton, krill, and shrimp.

Hemispheric Differences and Heat Transfer

  • Northern Hemisphere is dominated by land, while the Southern Hemisphere is dominated by oceans.
  • Temperature differences between summer and winter are greater in the Northern Hemisphere because land warms/cools quicker than water.
  • Heat transfer from the equator to the poles occurs through:
    • Air currents
    • Oceanic water currents
  • Surface ocean currents are driven by wind patterns (warmer, higher pressure to cooler, lower pressure).
  • The Great Ocean Conveyor Belt involves deep-water ocean currents driven by water temperature and density (thermohaline).
    • Gulf Stream Ocean Circulation is a key component.

Ocean/Marine and Freshwater Zones

  • Ocean/Marine zones: high in salinity
  • Freshwater ponds and lake zones: low in salinity
  • Salinity is the amount of salt (sodium chloride) dissolved in water.
  • Oceans cover 75% of Earth’s surface and supply oxygen from algae and photosynthetic bacteria.
  • Oceans absorb a significant amount of CO2CO_2.
  • Photosynthesis primarily occurs in the photic (ocean) and littoral zones (freshwater).
  • Zones in Aquatic Biomes: Profundal zone (also called aphotic) and Open ocean

Aquatic Zones

  • Intertidal Zone
  • Photic Zone: where photosynthesis occurs.
  • Benthic Zone: ocean floor.
  • Aphotic Zone: sunlight doesn’t penetrate.

Freshwater Zones

  • Littoral Zone: emergent, rooted plants, MOST photosynthesis.
  • Limnetic Zone: floating plants, less plants, LESS photosynthesis occurring here.
  • Profundal Zone
  • Benthic Zone

Intertidal Zones

  • Coastline existing between high tide and low tide.
  • Ranges from steep, rocky areas to sloping mudflats.
  • Organisms have adapted to hold on to rocks and resist being washed away by waves.

Open Ocean

  • Photic Zone: upper layer of ocean receiving enough sunlight for photosynthesis.
  • Aphotic Zone: deeper layer of water lacking sufficient sunlight for photosynthesis.
    • Some bacteria use chemosynthesis.

Coral Reefs

  • Corals are marine invertebrates.
  • They usually live in compact colonies.
  • Exoskeleton made out of CaCO3CaCO_3.
  • They can catch small fish and plankton using stinging cells on tentacles.
  • Mostly get energy from zooxanthellae (photosynthetic unicellular dinoflagellates - algae) in a mutualistic relationship.
  • Threats:
    • Ocean acidification: thinner CaCO3CaCO_3 skeleton.
    • Rising ocean temperatures: destroys relationship between coral and symbiotic microalgae, leading to coral bleaching (death).

Lakes

  • Large, natural bodies of freshwater from rain, runoff, or groundwater seepage.
  • Classified by their production of organic matter.
  • Types of lakes:
    • Oligotrophic (young lake): nutrient-poor, clear, blue water.
    • Mesotrophic (middle-aged lake): clear, blue water with intermediate nutrients.
    • Eutrophic (old lake): murky (turbid) with nutrient-rich, dark water.
  • Turbidity: the clarity of liquid.

Lake Stratification

  • Stratification: layers of water based on density changes caused by temperature.
  • Epilimnion: top layer, receives sunlight, warmer.
  • Thermocline: division of upper and lower layers (drastic change in temperature).
  • Hypolimnion: bottom layer.

Seasonal Turnover

  • Water exchange between surface and bottom water.
  • Fall & spring turnover in lakes.
  • Summer: Epilimnion (22°C), Thermocline (20°C-18°C), Hypolimnion (8°C-6°C).
  • Spring Turnover: 4°C throughout.
  • Fall Turnover: 4°C throughout.
  • Winter: Ice (0°C near surface), Epilimnion (2°C), Thermocline, Hypolimnion (4°C).

Wetlands

  • Areas covered with water at some point in a year.
  • Supports aquatic plants.
  • Water can be freshwater, saltwater, or brackish (mix of salt/fresh) water.
  • High biodiversity.
  • Examples:
    • Ballona Wetlands in Playa del Rey, CA
    • Florida Everglades
  • 3 main types:
    • Swamps - have trees
    • Marshes - no trees
    • Bogs & Fens (peatlands)
      • Bog: Groundwater
      • Fen: Rainwater
  • Ecosystem services of wetlands include:
    • Filter pollutants and contaminants from water
    • Flood regulation
    • Groundwater recharge (for freshwater wetlands)
    • Habitat for organisms

Estuaries/Salt Marshes (Temperate)

  • Areas along the coast where freshwater mixes with saltwater (brackish) from the ocean.
  • Productive places for plants and algae, with plant life helping to filter contaminants out of the water.
  • Contain nonwoody emergent vegetation.

Mangroves (Tropical)

  • Trees that exist in brackish water.
  • Ecological importance:
    • Filter water
    • Habitat
    • Flood control, slows down water flow
  • Threats:
    • Cut down to use the land for agriculture/aquaculture
    • Ex: shrimp farms in southeast Asia

Rivers and Streams

  • River - constant flow of freshwater due to gravity.
  • Stream - faster flow rate than a river, less volume.
  • Zones:
    • Source - the beginning of the formation of a river - the mountain.
    • Transition - lower in elevation, water moves slower, water is less clear, greater species diversity
      • Tributaries - rivers that join other rivers
    • Floodplain - lowest in elevation, leads to sea, water is the most turbid
      • Estuaries - where rivers connect to oceans

River Zones Details

  • Tributary
  • Flood plain
  • Meander (curves) - due to erosion (one side of the river will flow faster than the other).
  • Oxbow lake
  • Delta - mouth of river, constant flow of water, transporting sediment
  • Estuary - ocean/lake floods into river, less sediment

Delta Examples

  • Okavango Delta, Botswana
  • Mississippi River Delta
    • Dead zones

Riparian Areas (buffer zones)

  • Land next to freshwater sources such as rivers, streams, creeks, lakes
  • Flora:
    • Hydrophilic (water-loving) plants and trees
    • Ferns, sedges, willows
  • Fauna:
    • Birds, beavers, river otters, ducks, frogs, salamanders, snakes, fish
  • Ecosystem services of riparian areas include:
    • Filtering pollutants and water contaminants (similar to wetlands)
    • Flood regulation
    • Provides a habitat for organisms

General Summary

  • Freshwater (low salinity):
    • Ponds and Lakes, Streams and Rivers.
    • Freshwater Wetlands
  • Marine (high salinity):
    • Open Ocean
    • Coral Reefs (tropical regions)
  • Mix of freshwater and saltwater (brackish):
    • Estuaries/salt marshes in temperate regions
    • Mangrove swamps in tropical regions
    • Intertidal zones
  • Flowing water: Streams and Rivers
  • Standing water, deep water (standing = doesn’t flow): Ponds and Lakes, Open Ocean
  • Standing water, shallow water: Freshwater Wetlands
  • Fluctuating water depths: Intertidal zones