1. Plants in Aquatic Ecosystems Environmental Science 4.3

2. Types of Algae Plankton algae – very small type of floating algae ▫When present in large numbers plankton algae give water a brown, yellow, red, or pea-soup green color  Algal bloom Pond scum – floating mat of filamentous algae ▫Filamentous algae grow as long strands Stonewort algae – identified by central stem w/ whorls of branches that can grow 3 ft

3. Importance of Algae Algae are most important producers in any aquatic ecosystem ▫Production of oxygen When there are too many algae competing, many die and decay, creating demand for oxygen ▫Algae can not produce enough oxygen to meet the needs of all aquatic organisms ▫May cause fish kill, either due to lack of oxygen or toxic chemicals produced by the algae

4. Some algal blooms are toxic to humans ▫Anabaena (formerly blue-green algae) Water treatment plants remove algae by filtering water through sand

5. Types of Flowering Plants Submerged plants grow in deep water and grow entirely below surface (except flowers) Emerging plants grow in shallow water ▫Most stems, leaves, and flowers grow above water Floating plants have floating leaves and flowers

6. Importance of Flowering Plants Submerged stems and leaves of flowering plants provide habitats Emerging plants along the shore prevent erosion and provide cover for fur-bearing animals (beaver, muskrats, mink) ▫Seeds provide food Small ponds that dry up in summer are important b/c can not support fish ▫Provides excellent salamander and amphibian breeding habitat

7. Water Pollution and Plant Growth Point sources - chemicals that affect the growth of aquatic plants may enter an aquatic ecosystem when there is an industrial accident or daily operations at an industrial plant or sewage treatment plant ▫From a specific place Nonpoint sources – herbicides and fertilizers enter aquatic ecosystems in storm water runoff from lawns, farms, etc. ▫From non-specific place

8. Many aquatic ecosystems are polluted w/ chemical s that stimulate plant growth ▫Fertilizers containing nitrates and phosphates Major sources of nutrients are sewage treatment plants, developments w/ individual home septic systems, food processing plants, animal wastes, etc.

9. Water Use and Plant Growth Must control plant growth sometimes Interfere w/ operations at fish hatcheries Slows flow of water in irrigation systems Plants steal water intended for farm crops Intake pipes for factories and water treatment plants may become clogged w/ floating plants

10. Controlling Plant Growth Physical removal ▫Time-consuming Animals ▫Usually not very helpful Chemicals ▫Must identify plants causing problem, select correct herbicide, time the application, and calculate correct amount ▫Many herbicides are toxic to fish Decay of dead plants may lower DO