Aquatic Biomes

Abiotic Conditions in Aquatic vs. Terrestrial Biomes

• Aquatic Abiotic Factors:

  • Depth-dependent environmental variables:
  • Light penetration
  • Temperature
  • Water velocity and currents
  • Salinity
  • Dissolved Oxygen ($D.O.$)
  • Nutrient availability: Primarily Nitrogen ($N$) and Phosphorus ($P$)
  • Bottom substrate type: Muddy, sandy, or rocky

• Terrestrial Abiotic Factors (for Comparison):

  • Overlaid daily temperature fluctuations
  • Annual average temperature
  • Seasonal and diurnal temperature variations
  • Rainfall and precipitation
  • Topography
  • Wind speed

Classification of Aquatic Biomes

• Freshwater Biomes:

  • Lotic Systems (Flowing Water):
  • Streams
  • Rivers
  • Lentic Systems (Still Water):
  • Ponds
  • Lakes
  • Wetlands (Partially Flooded Environments):
  • Marshes: Characterized by non-woody, herbaceous plants.
  • Swamps: Characterized by forested, woody vegetation.
  • Bogs: Highly acidic environments containing moss or sphagnum moss and peat.

• Marine Biomes:

  • Intertidal zones (coastal shorelines)
  • Open ocean (pelagic zone)
  • Deep ocean (benthic/abyssal zone)
  • Marine marshes (open-watery wetlands)
  • Estuaries (brackish water environments where fresh and salt water mix)
  • Coral reefs

Productivity and Nutrient Dynamics

• High Productivity and Biodiversity Biomes:

  • Coral reefs and estuaries represent the biomes with the highest primary productivity and biodiversity in aquatic ecosystems.

• Low Productivity per Unit Area:

  • The open ocean and deep ocean, along with certain freshwater biomes, exhibit low primary productivity per unit of area.

• Nutrient Distribution and Upwelling Mechanisms:

  • Concentrations of nitrogen and phosphorus nutrients are significantly higher along coastlines due to terrestrial runoff entering rivers and flowing into estuaries.
  • Nutrients are transported from the deep ocean floor up to the surface via upwelling, providing critical nutrients for photo-autotrophs.
  • When aquatic organisms die, their biomass sinks to the ocean floor, where benthic decomposers break down the matter and recycle the nutrients.

• Secondary Productivity and Dissolved Oxygen:

  • Secondary productivity can be substantially high in cold water aquatic environments due to an increased dissolved oxygen pattern.

Global Water Distribution

• Most Water on Earth: Oceans (saline water)
• Most Fresh Water: Ice caps and glaciers

Terminology and Definitions

• Primary Productivity: The rate at which primary producers (such as plants and algae) synthesize biomass or energy through photosynthesis.
• Secondary Productivity: The rate at which consumers (herbivores and carnivores) construct new biomass from the organic matter consumed.
• Intertidal Zone: A narrow coastal band of land along the shoreline that experiences continuous daily shifts in sunlight exposure, temperature, and water levels due to tidal movement.
• Sphagnum Moss: The dominant species residing around acidic freshwater bogs.