Salt Marshes and Mangels

Spartina dominates salt marshes

  • Salt marsh plants are ecosystem engineers. They trap fine particles

  • Common in mid-high latitude regions

  • Spartina plants spread by means of a rhizome system - formation of organic peat, colonized by other species at higher levels

  • Importance: High carbon fixation rates, refuge and rich nursery grounds for many invertebrates and fish, prevent sediment erosion

Aerenchymal tissue: Allows Spartina to exchange gases even to plant extremities in sediment

  • Important in salt marshes because oxygen is low in the sediment ^

Vertical Zonation

  • Salt marshes exhibit intertidal vertical zonation

  • From low to high intertidal, border between zones is often quite sharp

Benthic algae attract many invertebrate grazers - mollusk, mud snail

Halophytes - eg pickleweed, common in salt marshes and mangrove systems

Grazing on Spartina

  • Invertebrate grazing is light

  • Tough leaves, rich in cellulose, lignin and embedded silica (glass)

  • Grazing on flowers can be high, causing seeding failures

  • Fiddler crab burrows enhances spartina growth, aerates the soil

  • Marsh mussels also enhance growth, recycling of nutrients within system

Losses in marsh ecosystems

  • Land-use change

  • Dredging and coastal development

  • Severe weather

  • Nutrient pollution

  • Introduction of invasive seagrasses

  • Sea-level Change

Mangels

Mangrove forests

  • Different species can dominate mangels

  • Common in subtropical and tropical protected shores around the world

  • Broadly rooted but only shallow depths in quite anoxic (no oxygen) soils

  • Underground roots have projections into air that facilitate oxygen use

Very Salt Tolerant - leaves have a salt gland that can excrete salt from cell cytosol to the leaf surface

Important features:

  • High primary productivity and supply organic matter

  • Falling leaves support rich communities of detritivoress and deposit feeders

  • Zonation of mangrove species with mudflats and creeks (from land to sea: White, Black, and Red mangrove - salt tolerance vs reproduction strategies)

  • Roots support sessile marine invertebrates (oyster, barnacle) and fish nurseries

  • Habitat for terrestrial organisms

  • Planet has lost 35% of mangels in the last 20 years ☹

  • Land use change, dredging and coastal development, severe weather, nutrient pollution, excavation and shrimp farming, sea level change

  • - Farming shrimp - how valuable is the industry?? very! 68 billion dollars

Podcast: Mangroves: Nature’s Best Tree? ← HOMEWORK