Chapter 8: Aquatic Biodiversity
Coral Reefs
Ecological & Economic Services
- Moderate atmospheric temperatures
- Act as natural barriers protecting coasts from erosion
- Provide habitats
- Support fishing and tourism businesses
- Provide jobs and building materials
- Studied and enjoyed
Degradation and Decline
- Coastal development
- Pollution
- Overfishing
- Warmer ocean temperatures leading to coral bleaching→ Kill algae and thus the polyps
- Increasing ocean acidity
What Is the General Nature of Aquatic Systems?
Most of the Earth Is Covered with Water
- Saltwater includes;
- Atlantic
- Pacific
- Arctic
- Indian
- Freshwater: Any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids.
Aquatic Life Zones
- Saltwater life zones (marine life zones): Oceans, estuaries, coastlands, shorelines, coral reefs, and mangrove forests.
- Freshwater life zones: Lakes, rivers, streams, and inland wetlands
Aquatic Species
- Plankton→ Free floating creatures
- Phytoplankton: Primary producers for most aquatic food webs
- Zooplankton: Primary and secondary consumers. Single-celled to large invertebrates like jellyfish
- Ultraplankton: Tiny photosynthetic bacteria
- Nekton are strong swimmers
- Fish, turtles, whales, etc.
- Benthos: Bottom dwellers
- Oysters, sea stars, clams, lobsters, crabs, etc.
- Decomposers: Mostly bacteria
Key Factors That Determine Types & Numbers of Organisms
- Critical factors in the distribution of organisms
- Temperature
- Dissolved oxygen content
- Availability of food
- Availability of light and nutrients needed for photosynthesis in the eutrophic (photic) zone
- Turbidity: Degree of cloudiness in the water, inhibits photosynthesis
Why Are Marine Aquatic Systems Important?
Oceans Provide Vital Ecological and Economic Resources
- Reservoirs of diversity in three major life zones
- Coastal zone: Warm, nutrient-rich, shallow. Shore to the edge of a continent shelf.
- Open sea
- Ocean bottom
Major Ecological and Economic Services Provided by Marine Systems
- Ecological Services
- Climate moderation
- CO2 absorption
- Nutrient cycling
- Waste treatment
- Reduced storm impact (mangroves, barrier islands, coastal wetlands
- Habitats and nursery areas
- Genetic Resources and biodiversity
- Scientific information
- Economic Services
- Food
- Animals and pet feed
- Pharmaceuticals
- Harbors and transportation routes
- Coastal habitats for humans
- Recreation
- Employment
- Oil and natural gas
- Minerals
- Building materials
Estuaries and Coastal Wetlands
- Estuaries/Coastal Wetlands: Where rivers meet the sea and seawater mixes with freshwater (ex. river mouths, inlets, bays, sounds, salt marshes, and mangrove forests.)
- Very productive ecosystems→ high nutrient levels
- Seagrass Beds: Grow underwater in shallow areas, support a variety of marine species, stabilize shorelines, and reduce wave impact.
- Mangrove forests: Along tropical and subtropical coastlines, 69 different tree species grow in saltwater
Rocky and Sandy Shores Host Different Types of Organisms
- Intertidal zone: Rocky shores or sandy shores which have barrier beaches
Three Zones of the Ocean
- Euphotic zone: Phytoplankton, nutrient level low, dissolved oxygen levels high.
- Bathyal zone: Dimly lit, zooplankton and smaller fishes
- Abyssal zone: Dark and cold, high levels of nutrients, little dissolved oxygen, deposit feeders, filter feeders
How Have Human Activities Affected Marine Ecosystems?
Major threats to marine systems
- Major threats to marine systems
- Coastal development
- Overfishing
- Use of fishing trawlers
- Runoff of nonpoint source pollution
- Point source pollution: Discharge pollutants at specific locations
- Habitat destruction
- Introduction of invasive species
- Climate change from human activities
- Pollution of coastal wetlands and estuaries
Why Are Freshwater Ecosystems Important?
Water Stands in Some Freshwater Systems and Flows in Others
- Standing (lentic) bodies of freshwater: Lakes, ponds, inland wetlant=ds
- Flowing (lotic) systems of freshwater: Streams and rivers
- Littoral zone: Near shore where rooted plants grow, high biodiversity,
- Turtles, frogs, crayfish, and some fish
- Limnetic zone: Sunlight area away from shore, main photosynthetic zone, some larger fish
- Profundal zone: Deepwater too dark for photosynthesis, low oxygen levels, with some fish
- Benthic zone: Decomposers, detritus feeders, and some fish, nourished primarily by dead matter
Major Services Provided by Freshwater Systems
- Ecological Services:
- Climate moderation
- Nutrient cycling
- Waste treatment
- Flood control
- Groundwater recharge
- Habitats for many species
- Genetic resources and biodiversity
- Scientific information
- Economic Services:
- Food
- Drinking water
- Irrigation water
- Hydroelectricity
- Transportation corridors
- Recreation
- Employment
Some Lakes Have More Nutrients Than Others
- Oligotrophic Lakes: Low levels of nutrients and low NPP with very clear water
- Eutrophic Lakes: High levels of nutrients and high NPP and murky water with high turbidity
- Mesotrophic Lakes: Commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients
- Cultural Eutrophication: This occurs when sewage, detergents, fertilizers, and other nutrient sources are introduced into the ecosystem as a result of human water pollution, accelerating the aging process.