Aquatic Life Zones

1. Aquatic Life Zones Saltwater and freshwater aquatic life zones cover 75% of the Earth’s surface

2. Aquatic Life Zones: The Basics The key factors determining biodiversity in aquatic systems are • temperature • dissolved oxygen content • availability of food • availability of lightand nutrients necessary for photosynthesis.

3. Most of the Earth Is Covered with Water • Aquatic life zones • Saltwater: marine • Oceans and estuaries • Coastlands and shorelines • Coral reefs • Mangrove forests • Freshwater • Lakes • Rivers and streams • Inland wetlands

4. Aquatic Trophic Structure • Plankton Floats • Phytoplankton • Zooplankton • Nanoplankton • Nekton Swims • Benthos Bottom • Decomposers

5. Distribution of Marine Life Availability of light and nutrients needed for photosynthesis Euphotic - light Disphotic - twilight Aphotic - dark • Temperature • Dissolved oxygen • Availability of food

6. Importance of Marine Aquatic Systems • Irreplaceable reservoirs of biodiversity • Provide major ecological and economic services.

7. Marine Ecological and Economic Resources • Reservoirs of diversity in three major life zones • Coastal zone • Usually high NPP • Open sea • Ocean bottom

8. Highly Productive Coastal Zones • Estuaries and coastal wetlands • River mouths, Inlets, Bays, Sounds, Salt marshes • Mangrove forests • High NPP • Nutrients, Light • O2 can be limited • Seagrass Beds • Support a variety of marine species, stabilize shorelines, reduce wave impact • High NPP • Nutrients, Light, O2

9. Intertidal Zones • High NPP • Nutrients • Dissolved O2 • Light • Rocky & Sandy shores • barrier beaches • Organisms must adapt to deal with daily salinity and moisture changes

10. Coral Reefs • Extremely high NPP • Marine equivalent of tropical rain forests • Habitats for one-fourth of all marine species • Tropical • Temperature • Light • Nutrients • O2

11. Pelagic and Benthic Zones • Pelagic = Open Ocean • Vertically Stratified • Light & Nutrients • Euphoticzone • Plankton & Nekton • Bathyalzone • Deposit feeders • Filter feeders • Abyssal zone: • Deposition of CaCO3 • Upwellings • NPP is variable

12. Freshwater Ecosystems • Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.

13. Lentic and Lotic Systems • Standing (lentic) bodies of freshwater • Lakes • Ponds • Inland wetlands • Flowing (lotic) systems of freshwater • Streams • Rivers

14. Lentic Systems • Formation of lakes • Geologically short-lived • Four zones based on depth and distance from shore • Littoral zone • Limnetic zone • Profundal zone • Benthic zone

15. Lentic Nutrient Levels • Oligotrophic lakes • Low levels of nutrients and low NPP • Eutrophic lakes • High levels of nutrients and high NPP • Mesotrophiclakes • Intermediate • Cultural eutrophication leads to hypereutrophiclakes

16. Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans • Watershed, drainage basin • Surface water runoff • Groundwater storage • Three aquatic life zones • Channel • Riparian • Floodplain

17. Freshwater Inland Wetlands • Marshes • Swamps • Prairie potholes • Floodplains • Arctic tundra in summer • Intense Nutrient Cycling and Storage • High NPP

18. What impacts aquatic life zones? Marine Fresh water Agriculture Logging Mining Waste Disposal Dams Diversions Groundwater withdrawal • Agriculture • Logging • Mining • Waste Disposal • Dams • Overfishing • Plastic • Melting ice caps and glaciers