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Sea Lettuce

Ulva lactuca

Sea lettuce grows in the Chesapeake Bay's shallow, brackish and salty waters. (N Sloth/Biopix)
Sea lettuce grows in the Chesapeake Bay's shallow, brackish and salty waters. (N Sloth/Biopix)

Sea lettuce is a type of algae that grows in thin, green, wavy-edged sheets. It can be found in shallow waters throughout most of the Chesapeake Bay.

Appearance:

  • Thin, green sheets with wavy, ruffled edges
  • Looks similar to wilted lettuce
  • Usually grows in large masses
  • Grows 6-24 inches

Habitat:

  • Grows in shallow, brackish and salty waters
  • Especially common in nutrient-rich areas
  • Can be free-floating in the water or attached to rocks, pilings and other hard surfaces also be free-floating
  • Often found washed up on the shore

Range:

  • Found throughout most of the Chesapeake Bay, except in the extreme upper Bay

Reproduction and Life Cycle:

  • Goes through two reproductive phases
  • During the first phase, adults produce spores by meiosis. The spores settle and grow to form male and female plants.
  • During the second phase, the male and female plants produce gametes by mitosis. The gametes unite and develop into adult plants.
  • When sea lettuce dies, it sinks to the Bay’s bottom, where it is decomposed by bacteria. During this process, bacteria consume oxygen until there is little or none left in these bottom waters.

Other Facts:

  • Commonly referred to as seaweed
  • When abundant, sea lettuce can smother bay grasses growing in the shallows
  • Large masses of sea lettuce are often an indicator of nutrient pollution in the water
  • In some parts of the world, people eat sea lettuce in soups and salads

Sources and Additional Information:

  • Underwater Grasses in Chesapeake Bay & Mid-Atlantic Coastal Watersby Peter W. Bergstrom, Robert F. Murphy, Michael D. Naylor, Ryan C. Davis and Justin T. Reel
  • Chesapeake Bay: Nature of the Estuary, A Field Guideby Christopher P. White
  • Sea Lettuce (Ulva lactuca) – University of Rhode Island

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