Aquatic Ecosystems
Ocean, shores and estuaries
Freshwater lakes, streams, wetlands
1. Marine Ecosystems
- Pelagic: swim actively, not attached
- Fish, Cetaceans (whales)
- Plankton: weakly swim, carried by current
- Phytoplankton: photosynthesize
- Algae: diatoms, dinoflagellates
- Bacteria: “blue-greens” or cyanobacteria
- Zooplankton: grazers on phytoplankton
- Small crustaceans: copepods, shrimp
- Larvae: fish and other crustaceans
- Benthos: live on the bottom
- Photosynthetic: algae (kelps, rock weeds, other
seaweeds)
- Fauna: crabs, worms, sea stars, other burrowing
animals, fish associated with nesting or hiding on bottom
2. Figure 6.19. Marine Ecosystems:
photosynthetic zone = euphotic
3. Fig. 6.20. Types of Shores: substrate determines the
kinds of organisms
4. Coral Reef ecosystem
- Coral base
- Mutualistic
- Coral animal host makes calcarious skeleton
- Symbiotic algae (zooxanthellae) provide fixed
carbon
- High biodiversity
- Require shallow, clear, warm water
- Slow growing
- Fragile
5. Mangrove Swamp Ecosystem
- Range tropical -> subtropical
- Colonizes areas protected from wave action
- Colonizes areas of high sedimentation
- Colonizes shallow sandy or muddy areas
- Tide range: highest-tide to intertidal and subtidal
- Important natural “seawall”
- Human impacts: removed for shrimp farms, developments
6. Vivipary: mangrove seedlings germinate
on parent tree, then drop into water, get trapped in mud, take root.
7. Map of the Chesapeake Bay System: Estuaries, Seagrass
Meadows and Saltwater Ecosystems
- map from: www.chesapeake.org/SAV/images/baymapnew.gif
8. Estuaries
- Shallow
- Partially enclosed area
- Freshwater enters the ocean
- Tides bring in saltwater
- Highly productive: source for many major fisheries like
shell fish and finfish
9. Chesapeake: some statistics
- Algonquins named it: “Chesepiooc” for great shellfish
bay
- Largest bay in the US: 2,500 mi2
- Longest: 195 mi
- Most tributaries: 150
- Most miles of shoreline: 4,000
- 265 fish species use the estuary for food &
reproduction in summer
10. $ Value of the Chesapeake $
- 20 % of US oyster harvest
- 50 % of US blue crabs & softshell clams
- 200 million # of seafood at a value > $100 million
11. No Submerged Aquatic Vegetation = Ecosystem
dysfunction
- Graphic from:
www.dnr.state.md.us/bay/monitoring/index.html
12. Problems in the Chesapeake:
- Habitat destruction
- Dredged and filled for development
- Erosion of edges by boat traffic
- Marshes “starved” by channelization and freshwater
innudation --> change to Phragmites marshes
- Some destruction by wild horses, pigs
- Water pollution: nutrients from sewage, aqriculture,
sediments from runoff
13. Freshwater Ecosystems
- Lakes and ponds
- Zones equivalent to ocean
- Edges with rooted vegetation: littoral zone
- Emergent plants: above water --> cattails
- Submerged plants: all processes below
surface -->Elodea
- Open water without rooted vegetation: limnetic zone
- Characterized by nutrient/productivity
- Oligotrophic: high in watershed, low nutrients,
clear, deep
- Mesotrophic: middle of watershed, medium nutrients,
less clarity
- Eutropic: lower part of watershed, high in
nutrients, shallow, murky(= turbid)
14. Freshwater Ecosystems
- Flowing waters: streams and rivers
- Most energy comes from outside: leaves, runoff
- Headwaters --> middle reaches --> mouth
- Small fast moving --->large, slow moving
- Wetlands: edges of streams, end of succession of a lake
- Swamps: trees
- Marshes: grasses, wet prairies
- Bogs: Sphagnum moss dominated (like Tannersville
Cranberry Bog), low pH
- Vernal ponds: dry up after spring
15. Fig. 6.23. Lake Ecosystem: how is it
different from the ocean?
16. On your own
- How are freshwater ecosystems impacted by humans?
- How much of following ecosystems have been lost?
- N. American Tallgrass prairie?
- Original primary forest in the US?
- Wild or scenic rivers in the US?
- Original wetlands in the US?