Overview
This lecture covers the main types of aquatic biomes, key environmental factors affecting them, notable adaptations of their organisms, and the ecological roles they play.
Aquatic Biome Characteristics
- Aquatic biomes are determined by salinity, depth, water flow, and temperature.
- Salinity determines which organisms can survive and if water is drinkable.
- Depth affects how much sunlight penetrates for photosynthesis.
- Flow increases dissolved oxygen via mixing; high flow supports more aquatic life.
- Higher water temperatures reduce dissolved oxygen, limiting aquatic organisms.
Freshwater Biomes
- Rivers have high dissolved oxygen and nutrient-rich sediments due to flow.
- Lakes are standing bodies of freshwater and key sources of drinking water.
- Lake zones include: littoral (shallow, emergent plants), limnetic (photosynthesis), profundal (no light, no photosynthesis), and benthic (nutrient-rich bottom).
- Freshwater wetlands are areas with saturated soil and emergent vegetation, providing flood control, groundwater recharge, water filtration, and diverse habitats.
Types of Freshwater Wetlands
- Swamps: dominated by cypress trees adapted to submerged soils.
- Marshes: contain reeds and cattails adapted to submersion.
- Bogs: feature acidic soil with spruce trees and sphagnum moss adapted to acidity.
Estuaries & Transitional Biomes
- Estuaries are where rivers mix with the sea, with nutrient-rich soils and high productivity.
- Salt marshes (temperate) and mangroves (tropical) provide critical habitats and shoreline protection.
Marine Biomes
- Coral reefs in warm, shallow water have the highest marine biodiversity and depend on mutualism between coral and algae.
- Intertidal zones experience shifting tides and host organisms adapted to resist drying and strong waves.
- Open ocean (pelagic zone) has low productivity per area but is vital for global oxygen and COâ‚‚ absorption.
Oceanic Zones & Adaptations
- Photic zone: sunlight penetrates, allowing photosynthesis.
- Aphotic/abyssal zone: no sunlight, organisms use bioluminescence and withstand high pressure.
Key Terms & Definitions
- Salinity — Salt concentration in water.
- Flow — Movement of water in a biome.
- Dissolved Oxygen — Oxygen present in water, essential for aquatic organisms.
- Littoral Zone — Shallow near-shore area with emergent vegetation.
- Limnetic Zone — Open water area with photosynthesis.
- Profundal Zone — Deep, unlit lake area without photosynthesis.
- Benthic Zone — Bottom layer of a water body with high nutrients.
- Wetlands — Areas with saturated soil supporting emergent plants.
- Estuary — Region where freshwater mixes with saltwater.
- Salt Marsh — Temperate coastal wetland in estuaries.
- Mangrove — Tropical estuarine wetland with stilt-rooted trees.
- Coral Reef — Marine ecosystem with mutualism between coral and algae.
- Intertidal Zone — Area between high and low tide lines.
- Photic Zone — Sunlit region of a water body.
- Aphotic/Abyssal Zone — Deep, dark region without sunlight.
Action Items / Next Steps
- Practice FRQ: Identify an aquatic organism and explain its biome-specific adaptation.