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Marsh Plants

Marsh Plants. Objectives. Be aware of the different types of marshes Understand the stressors of a salt marsh Understand the ecological role of the marsh Understand how SAV is adapted to living in an aquatic community Have a general understanding of the role of sea grasses.

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Marsh Plants

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  1. Marsh Plants

  2. Objectives • Be aware of the different types of marshes • Understand the stressors of a salt marsh • Understand the ecological role of the marsh • Understand how SAV is adapted to living in an aquatic community • Have a general understanding of the role of sea grasses

  3. Kinds of Chesapeake marshes • Salt marshes - found closest to the ocean near the mouth of the Bay • high amount of salt water • Brackish marshes - found in the middle regions of the Bay and mid tributaries of lower Bay • mix of salt water and fresh water • Fresh water marshes - found near the headwaters of most tributaries • minimal mixing with salt water is minimal

  4. The Terrain Can Be Difficult • Water salty enough to kill most other forms of vegetation • Soft muddy bottom that doesn't offer much support • A water-logged oxygen poor substrate • The ebb and flow of tidal currents twice a day

  5. Marsh Location • This false color infrared - visible image is composed of three separate Thematic Mapper images acquired in the summer of 1993. TM bands 4,3 and 5 were used here. In general, red areas show healthy vegetation, green areas are urban. Light-blue to white areas are generally indicative of bright soil - they possibly represent agricultural areas. Marshes appear as a deeper blue. Large marsh islands, such as Bloodsworth, are visible near the center of the picture. Black areas represent open water.

  6. Plants that have adapted to these conditions have the narrow edge of land between the low and high water mark to themselves. Spartina spp.: dominant in the lower ends of the Bay Spartina alterniflora- saltmarsh cord grass in the low marsh SO…. Why Bother?

  7. Spartina patens • Spartina patens, or saltmeadow hay is in the high marsh- different from S. alterniflora in being shorter and wiry and forms "cowlicks"

  8. Adaptations: To High Salt Concentration • Xerophytic adaptations- adaptation to low water stress- salt water is very drying to tissue • Two possible ways of adapting to salt • get rid of the salt that comes in, a.) One method that Spartina spp. use is to remove the salt via salt glands - a group of cells that collect and pump salt out onto the surface of the plant. Then the rain and tides wash the salt off the plant. • deal with it once it gets into the cells. a.) Other marsh plants deal with the potentially harmful salt in their cells by taking up water to dilute the salt content. b.) seen in plants that have succulent leaves and stems

  9. Adaptation: To Soft Sediments • Most marsh plants are well anchored because marsh soils are soft and muddy, and because there is mechanical stress from the tidal currents. Many plants, like Spartina spp., are doubly anchored. • Grow by thick rhizomes just under the soil surface. • 2 types of roots along the rhizome • thin water-absorbing roots • deep stout roots that lack root hairs but act to anchor the plants.

  10. Adaptation: To Low O2 • Most marsh grasses are rooted in anaerobic soils. All cells require oxygen. Problem is how to get O2 to the roots and rhizomes. • They have lacunae in the roots and rhizomes that allow the O2 produced in the leaves to diffuse (move) down to cells that need oxygen in the roots and rhizomes.

  11. Ecological Importance of Marshes • Their massive rhizome surface and deep roots stabilize the soft sediments and reduce erosion. • They improve water quality • The marshes are habitat for many animals: • Harbor sources of nitrogen fixation • Decay of marsh plants releases vitamins and minerals • Oxygenate waters

  12. Succession • Defined as a gradual change in an ecosystem whereby species are introduced/replaced over time; usually culminating in a stable climax community. • The terrestrial/ aquatic interface is a dynamic region subject to rapid physical, chemical, and biological change.

  13. Improved Water Quality • Trap sediment, which helps water quality • Absorbing excess nutrients and pollutants- before they enter the bay • Provide food for the food chain. The marsh plants and SAV are seldom eaten directly - but rather as are eaten as detritus (plant matter after it has died-it becomes covered by bacteria which are then eaten). Estuarine ecosystems have a detrital food chain - where everyone eats detritus or eats what eats detritus.

  14. Habitat: Where Home Is • Oysters and mussels attached to the rhizomes • Periwinkles - small snails that move up and down the Spartina sp. stems with the rise and fall of the tide • Juvenile species of fish and crabs • Large wading birds like egrets and herons • Mammals like nutria and muskrat

  15. Submergent Aquatic Vegatation: SAV • Also called hydrophytes spend lives underwater • Hydrophytes have adaptations to aquatic life • SAVs evolved from terrestrial plants that re-invaded the sea • Holes or spaces (called lacunae -Latin for space) in the tissue of the seagrass. • Up to 60% of leaf volume is air space • Allows for gas exchange (O2,CO2) throughout plant • Aid in Flotation- upright leaves get more light than sunken leaves

  16. Adaptations continued • Location of Chloroplasts • in seagrasses the chloroplasts are in the periphery of the plant - intercept more light • Adaptation to constant water movement • leaves are thin, strap-like and supple. Allows them to withstand tidal currents and wave action.

  17. More still • Thick tangled mat of rhizomes that keep them attached to the soft bottom- not roots • an adaptation to soft substrate bottom of the Bay - mostly a soft muddy substrate - • allow fast vegetative growth- primary mode of reproduction • Adaptation to water pollination • Their pollen are released in gelatinous strands that are carried by water currents

  18. Role of Sea grasses • Rhizomes stabilize bottom • Leaves baffle wave energy (less destructive to shoreline) • Promote sedimentation (silt falls out), thereby improving water quality • Provide habitat/nursery/shelter for hundreds of organisms, including: sea horses, grass shrimp, small fishes. • Grass beds are a major source of detritus, and the estuarine food chain, unlike terrestrial food chains, is based on detritus - few plants eaten directly. • Grass beds are a direct food source for some animals - especially diving ducks Until recently the bay grasses were like an underwater carpet along the shallow waters of the bay

  19. Examples of SAV

  20. References • http://www.dnr.state.md.us/bay/sav/importance.html • http://www.assateague.com/marsh-cg.html • http://www.dnr.state.md.us/bay/sav/key/index.html • http://www.chesapeakebay.net/info/wetlds1.cfm

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