APES
Notes: Aquatic Biodiversity
Key Factors Determining Biodiversity in Aquatic Systems
Types of Organisms
Phytoplankton
Plankton
Zooplankton
Nekton
Benthos
Decomposers
Ultraplankton
MARINE
Biological Zones in the Open Sea
• Euphotic zone: brightly lit surface layer.
– Nutrient levels low, dissolved O2 high, photosynthetic activity.
• Bathyal zone: dimly lit middle layer.
– No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at night.
• Abyssal zone: dark bottom layer.
– Very cold, little dissolved O2.
Estuaries and Coastal Wetlands: Centers of Productivity
• Estuaries and coastal marshes provide ecological and economic services.
– Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants.
– Reduce storm damage by absorbing waves and storing excess water produced by storms and tsunamis.
– Provide food, habitats and nursery sites for many aquatic species.
Pelagic/Open Sea Zones
Netritic
Oceanic
Abyssal
FRESHWATER
1. Lakes & Ponds
Lake - Large natural
bodies of standing water formed when precipitation, runoff, or groundwater seepage fills
depression in earth’s surface.
Ponds – Shallow, Sunlight penetrates, usually only one zone.
Plant Nutrients
Oligotrophic
Poorly nourished - clear
Mesotrophic
Moderately nourished
Eutrophic
well nourished – excessive plant growth
Cultural Eutrophication:
2. Rivers & Streams
Zones
Source
(headwaters)
Transition
Floodplain
3. Marshes & Swamps
Marshes & Swamps: Covered by shallow water at least part of the year. Waterlogged, anaerobic, rich in organic material
Marshes:
Swamps:
Importance of Wetlands:
Human Impact
• Fragmentation by dams, diversions, or canals
• Flood control levees and dikes
– Alter or destroy aquatic habitats
– Disconnect rivers and floodplains
– Eliminate wetlands
• Draining or filling of wetlands
• Cities and farmlands add pollutants and excess plant nutrients to streams and rivers.