Abiotic Factors
- Life in water depends on:
- Temperature
- Sunlight penetration
  - For photosynthesis
  - Affected by depth and turbidity of water
- Amount of dissolved oxygen
- Salinity
- pH
- Nutrient availability
  - Shallow waters have lots of nutrients
Organisms and Aquatic Life Zones
- Plankton: free floating, weakly swimmers
- Phytoplankton
  - Autotroph
- Zooplankton
  - Heterotroph
- Ultraplankton
  - Autotrophic bacteria
- Nekton: free-swimming
- Benthos: bottom dwellers
- Decomposers
Oceans
- High biodiversity
- 2 zones
- Coastal
  - Warm and nutrient rich area
  - 90% of all marine species
- Open sea
  - Cooler
  - Fewer species
- Ocean bottom
Types of Estuaries
- Mangrove Forests
- Swamps and mangrove forests are dominated by trees, while salt marshes are dominated by grasses
- Coastal Zone
- Enclosed body of water formed where seawater mixes with freshwater from rivers and streams
- Called “marine nurseries”
  - Habitats for many juvenile fish species
- Salt tolerant trees that reduce erosion
Estuaries
- Extremely fertile because the river brings lots of sediments
- Stressful conditions and abundant nutrients result in low species diversity, but great abundance of the species present
Intertidal Zone
- The area between high tides and low tides
- Organisms have some adaptation to withstand wave activity
- Rocky shores
- Areas pounded by waves
- Varieties of algae, snails, crabs, etc.
- Sandy shores
- No plants or algae
- Insects, shorebirds, crabs, and worms
Barrier Islands
- Long, narrow, offshore deposits of sand or sediments that parallel to the coastline
- Aid in protecting mainland, estuaries, and coastal wetlands
- Found along eastern coasts and Gulf of Mexico
- Lots of development
Coral Reefs
- Structure that is formed by coral polyps
- Typically found in warm coastal waters of the tropics and subtropics
- Coral polyps form a hard, stony, exoskeleton made of limestone
Coral Reefs Climate
- Usually found near land in shallow, warm, salty water
Importance of Coral Reefs
- High biodiversity
- Considered the most diverse and productive
- Grow very slowly
- Complex relationships that exist between many organisms
Damage to Coral Reefs
- Very sensitive to environment changes
- Natural disturbances
- Hurricanes or typhoons, and predation by a large starfish
- Anthropogenic disturbances
- Sediment runoff
- Pollution
- Reef fishing
- Coral bleaching
- 300+ reefs are protected as reserves or parks
Freshwater Life Zone
- Cover less than 1% of Earth’s surface
- Low salt concentration
- Less than 1%
- Types
- Flowing
  - Streams
  - Rivers
- Standing
  - Ponds
  - Lakes
  - Inland wetlands
Lake and Pond Zones
- Divided into four zones determined by depth and distance from the shoreline
- Littoral zone
  - Top layer
  - Shallow
  - Near shore
  - High biodiversity
  - Aquatic plants
  - Grazing snails
  - Clams
  - Insects
  - Crustaceans
  - Fish
  - Amphibians
- Limnetic zone
  - Sunlit water
  - Surface layer
  - Main photosynthetic layer
  - Plankton
  - Fish
- Profundal zone
  - Cools and dark layer
  - Low oxygen
- Benthic zone
  - Bottom layer
  - Decomposers and detritivores
Lake Classification
- Oligotrophic
- Newly formed
- Poorly nourished
- Little sediment
- Deep water
- Clear water color
- Low net primary production
- Eutrophic
- Excess supply of nutrients
  - Phosphates and nitrates
- Shallow water
- Murky water color
- High net production
Characteristics of Rivers and Streams
- Bodies of flowing water moving in one direction
- Found everywhere
- Get their start at headwater, which may be springs, snowmelt or even lakes
- Travel all the way to their mouths
- Usually another water channel or the ocean
Freshwater Inland Wetlands
- Lands that are covered with fresh water year round or seasonally and located away from coastal areas
- High biodiversity
- Vary in size
- Important in filtering pollutants, absorbing excess water from storms, and providing habitats
Impacts of Human Activities on Freshwater Systems
- Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats
- Dams, diversions, and canals have fragmented about 40% of the world’s 237 large rivers
- Flood control levees and dikes alter and destroy aquatic habitats
- Cities and farmlands add pollutants and excess plant nutrients to streams and rivers
- Many inland wetlands have been drained or filled for agriculture or urban development