1 / 25

Freshwater ecosystems

Freshwater ecosystems. Kinds Characteristics Threats. Aquatic ecosystems. Key distinction: salinity = salt content of the water Measured in parts per thousand (ppt) 1 gm of salt in 1000 gms water = 1 ppt FRESH usually < 0.5 ppt OCEANS average 35 ppt 0.5 to 17 ppt is called BRACKISH.

lazar
Download Presentation

Freshwater ecosystems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Freshwater ecosystems Kinds Characteristics Threats

  2. Aquatic ecosystems • Key distinction: salinity = salt content of the water • Measured in parts per thousand (ppt) • 1 gm of salt in 1000 gms water = 1 ppt • FRESH usually < 0.5 ppt • OCEANS average 35 ppt • 0.5 to 17 ppt is called BRACKISH

  3. Kinds of freshwater habitats • Rivers, streams • Flowing freshwater • Source: where it starts • Mouth: where it ends • Lakes, ponds • Wetlands

  4. All freshwater ecosystems • Just a fraction of the Earth’s water • .01% = one one-hundredth of one percent • Occupy less than 1 percent of the Earth’s surface

  5. www.noaa.gov/str-plan/images/river.gif Rivers and streams • More than 3.5 million miles of rivers and streams (including intermittent streams) • Just the U.S.! More than 140 times around the Earth.

  6. Source = Headwaters Can be: Snowmelt Spring Even a lake Water is colder, clearer, more highly oxygenated Organisms include trout, mayflies Mouth: where the river ends Usually the ocean or another river, or lake River widens and slows, getting warmer, siltier. Middle is most diverse, lots of plants Near mouth, increased sediment limits light and plants, water is warmest Rivers from start to finish

  7. What are some of the differences? • Trout stream, NW NJ Mississippi R. Greenville, MS

  8. Mouth • Mississippi River delta

  9. Lakes and ponds • What’s the difference? • Ponds typically smaller • May be seasonal—that is, dry up part of the year • Lakes exist hundreds or thousands of years • But, even lakes can fill in or dry up

  10. Parts of a lake

  11. Parts of a lake • Littoral zone: near shore • Nutrient rich, lots of plant and animal life • Warm • Limnetic zone: near surface, open water • Lots of light • Lots of plankton • Profundal zone: deeper, little light • Benthic zone: the bottom, little light, low oxygen

  12. If nutrients increase too much in a lake, pond, or ocean, excessive plant growth results Phosphorus Nitrogen NOT GOOD: why? As plants decay, decomposing bacteria use oxygen dissolved in the lake to do their jobs. Dissolved oxygen goes down Eutrophication

  13. Wetlands • CA OR AK

  14. Wetlands: what are they? • For regulatory purposes under the Clean Water Act, the term wetlands means "those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas."

  15. Wetlands • May be fresh or brackish • Freshwater types include: • Marsh • Swamp • Bog • Fen

  16. Marsh • Most common freshwater wetland in U.S. • Occur along streams or in depressions • Characterized by organic, wet soils and non-woody (i.e., no trees) vegetation.

  17. Swamp • Wetland dominated by woody plants • Common in SE U.S.

  18. New Jersey wetlands • About 916,000 acres, or 19% of New Jersey, is wetlands, which seems like a lot; but the bad news is that about 40% of the original 1,500,000 acres has been lost to dredging and filling, dams, farming, development and highways.

  19. NJ wetlands

  20. What good are wetlands? • Reduce flooding by acting like sponges

  21. What good are wetlands? • Help clean water by acting like a filter • The plants and slow water flow in a wetland help remove pollutants, leaving water cleaner downstream in a lake or river. • Too much pollution can leave a wetland toxic to visiting animals, such as many birds.

  22. What good are wetlands? • Protect shorelines from erosion • Erosion in this case came from grazing animals

More Related