Aquatic Life Zones
description
Transcript of Aquatic Life Zones
Aquatic Life Zones
Saltwater and freshwater aquatic life zones cover 75% of the
Earth’s surface
Aquatic Life Zones: The Basics
temperature dissolved oxygen
content availability of food availability of light
and nutrients necessary for photosynthesis.
The key factors determining biodiversity in aquatic systems are
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
Aquatic Trophic Structure
Plankton Floats• Phytoplankton• Zooplankton• Nanoplankton
Nekton Swims Benthos Bottom Decomposers
Distribution of Marine Life Temperature Dissolved oxygen Availability of food
Availability of light and nutrients needed for photosynthesis • Euphotic - light• Disphotic - twilight• Aphotic - dark
Importance of Marine Aquatic Systems
Irreplaceable reservoirs of biodiversity
Provide major ecological and economic services.
Marine Ecological and Economic Resources
Reservoirs of diversity in three major life zones• Coastal zone• Usually high NPP
• Open sea• Ocean bottom
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
Intertidal Zones High NPP• Nutrients• Dissolved O2
• Light Rocky & Sandy shores• barrier beaches
Organisms must adapt to deal with daily salinity and moisture changes
Coral Reefs
Extremely high NPP• Marine equivalent of
tropical rain forests• Habitats for one-
fourth of all marine species
Tropical• Temperature• Light• Nutrients• O2
Pelagic and Benthic Zones
Pelagic = Open Ocean Vertically Stratified• Light & Nutrients• Euphotic zone
• Plankton & Nekton• Bathyal zone
• Deposit feeders• Filter feeders
• Abyssal zone:• Deposition of CaCO3
• Upwellings NPP is variable
Freshwater Ecosystems
Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.
Lentic and Lotic Systems
Standing (lentic) bodies of freshwater• Lakes• Ponds• Inland wetlands
Flowing (lotic) systems of freshwater• Streams• Rivers
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
Lentic Nutrient Levels Oligotrophic lakes• Low levels of nutrients and
low NPP Eutrophic lakes• High levels of nutrients and
high NPP Mesotrophic lakes• Intermediate
Cultural eutrophication leads to hypereutrophic lakes
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
Marshes Swamps Prairie potholes Floodplains Arctic tundra in summer
Intense Nutrient Cycling and Storage
High NPP
Freshwater Inland Wetlands
What impacts aquatic life zones?
Marine Agriculture Logging Mining Waste Disposal Dams Overfishing Plastic Melting ice caps and
glaciers
Fresh water Agriculture Logging Mining Waste Disposal Dams Diversions Groundwater withdrawal