Overview
This lecture covers the major types, characteristics, and global significance of aquatic biomes, focusing on species adaptations and the role of various freshwater and marine environments.
Key Characteristics of Aquatic Biomes
- Salinity measures the salt level in water, determining species survival and water suitability for drinking.
- Depth affects sunlight penetration and photosynthesis below the surface.
- Flow refers to water movement, influencing plant survival and dissolved oxygen availability.
- Temperature impacts the amount of dissolved oxygen; warmer water holds less oxygen, supporting less aquatic life.
Freshwater Biomes
- Rivers have high dissolved oxygen due to flowing water mixing air and nutrients from sediments.
- Lakes are standing bodies of freshwater and are important sources of drinking water.
- Water zones include:
- Littoral: shallow edge with emergent plants (e.g., reeds, cattails).
- Limnetic: open, well-lit area where photosynthesis occurs.
- Profundal: deep, dark zone with no photosynthesis.
- Benthic: nutrient-rich bottom supporting invertebrates.
Freshwater Wetlands
- Wetlands have soil submerged/saturated for part of the year, supporting emergent vegetation.
- Plants must be adapted to submerged roots (e.g., cattails, lily pads, reeds).
- Wetlands absorb excess water, recharge groundwater, filter pollutants, and provide diverse habitats.
- Types:
- Swamp: features cypress trees adapted to saturated soil.
- Marsh: contains reeds and cattails.
- Bog: acidic soil supporting spruce trees and mosses.
Estuaries
- Estuaries are where fresh and saltwater mix, creating nutrient-rich, highly productive habitats.
- Salt marshes occur in temperate areas and serve as breeding grounds for fish and shellfish.
- Mangroves are tropical estuaries with trees that stabilize shorelines, absorb floodwaters, and provide fish habitat.
Marine Biomes
- Coral reefs in warm, shallow water are the most biodiverse marine ecosystems, featuring a mutualism between coral (animal) and algae (plant).
- Intertidal zones are coastal areas exposed to changing tides, requiring adaptations to resist wave action and desiccation.
- Open ocean (pelagic zone) is less productive per unit area, but large enough to supply much of Earth's oxygen and absorb carbon dioxide.
Ocean Zones
- Photic zone: sunlight penetrates, allowing photosynthesis.
- Aphotic (abyssal) zone: too deep for sunlight, where organisms use adaptations like bioluminescence and withstand high pressure.
Key Terms & Definitions
- Salinity — amount of salt in water.
- Emergent plants — rooted in soil, extend above water surface.
- Estuary — mixing zone of freshwater and saltwater.
- Bioluminescence — organisms producing their own light.
- Mutualism — both organisms benefit from their relationship.
Action Items / Next Steps
- Practice FRQ: Choose an aquatic organism and explain its unique adaptation to its biome.