BIOL1110L-Salt Marsh Review

Salt Marsh Review - BIOL1110L

Salt Marsh History

  • Historical Significance: Salt marshes have supported human populations for millennia due to their high productivity.
    • The Mi'kmaq people utilized these marshes for food resources such as clams, mussels, and waterfowl.
    • Their legends, particularly the Glooscap legends, reference local macrofauna and the historical expansion of the Minas Basin, stemming from long-term observations of this environment.
  • European Settlement:
    • When Europeans settled, salt marshes were among the first areas utilized for agriculture due to their treeless landscape and fertile soils.
    • The fertility of these soils is enhanced by mineral-rich sediments from surrounding uplands due to erosion.
    • Early agricultural practices included
      • Hay production
      • Grazing
      • Crop cultivation
    • To farm these marshes, dykes had to be constructed to block saltwater intrusions.
      • Dykes were made by excavating soil from the marsh base.
      • The Acadians initiated dyke construction in the Grand Pré area in the 1680s.
      • Post the Acadian expulsion in 1755, these lands were occupied by New England Planters, Irish, and German settlers.
      • Currently, dykes are owned by farmers but maintained by the Department of Agriculture.
  • Contemporary Concerns:
    • Salt marshes are among Nova Scotia's most endangered habitats.
    • The town of Wolfville borders the Minas Basin, recognized for having the world’s highest tidal range.
    • Loss of Marshlands: Approximately 75% to 85% of the original marshland in the Bay of Fundy has been lost to agriculture.
    • Ecological and Socioeconomic Value: Salt marshes provide numerous services, including:
      • Pollinator support
      • Shoreline stabilization via imported sediments
      • Storm buffering through protective vegetation
      • Carbon sequestration, aiding in climate change mitigation.

Salt Marsh Vegetation

  • Ecosystem Services: Salt marsh vegetation is crucial for ecosystem health, especially regarding carbon capture and storage.
    • Considered one of the most effective blue carbon ecosystems, they capture carbon in two primary ways:
      • Through plant biomass
      • Through sedimentary carbon.
    • Mechanisms of Carbon Capture: Tidal sediments rich in carbon are trapped by marsh plants, while carbon is additionally fixed through photosynthesis and root growth.
    • Role of Mycorrhizae:
      • Root-associated mycorrhizal fungi depend on captured carbon, bolstering biomass through structures called hyphae.
      • Mycorrhizae coexist with most salt marsh plant roots.

Specific Plant Species Characteristics

  • Blackgrass Rush (Juncus gerardii):
    • Description: Clumps of erect stems reaching up to 70 cm; stems are cylindrical and hollow; flowers are located near the top side of the stem.
  • Saltmeadow Cordgrass (Sporobolus pumilus, formerly Spartina patens):
    • Description: Fine grass growing up to 60 cm; found at mid to high elevations; utilized for hay to feed livestock.
  • Smooth Cordgrass (Sporobolus alterniflorus, formerly Spartina alterniflora):
    • Description: Coarse grass up to 2 m tall; dominant in lower elevations; capable of tolerating regular flooding.
  • Saltgrass (Distichlis spicata):
    • Description: Fine grass reaching up to 1.2 m; often grows alongside saltmeadow cordgrass in mid-elevations; tolerates high salinity, often situated where pond evaporation has increased salinity levels.

Mud Flats

  • Definition: Mud flats are formed in sheltered bays, harbors, or estuaries, consisting of accumulated fine silt and clay sediments.
  • Role in Salt Marsh Formation:
    • The growth of salt marsh plants converts exposed mud flats into salt marshes as sediment accumulates beyond water surface levels.
  • Organisms:
    • Mud flats provide habitat for diverse organisms, many of which are abundant and play critical roles in the ecosystem.
    • At low tide, the surface of the mud is often coated with tiny, single-celled algae (photosynthetic protists) known as diatoms, which exhibit vertical migration patterns to avoid predation and the tidal currents.
  • Inhabitants:
    • Corophium: An amphipod crustacean that can number as high as 50,000 per square meter, serving as a primary food source for shorebirds.
      • Features sexual dimorphism.
      • Feeds by creating currents with their legs to filter particles through their U-shaped tubes.
      • Characterized by audible sounds produced when they open and close their tubes.
    • Other tube-dwelling inhabitants include:
      • Annelid Worms: Emerge from their tubes to catch prey or forage at night.
      • Macoma Clams: Exhibit star patterns around burrows when utilizing siphons for feeding.

Additional Plant Species

  • Seaside Plantain (Plantago maritima):
    • Description: Features succulent, narrow, basal leaves, found in high elevations; flowers clustered on erect spikes.
  • Marsh Elder (Iva frutescens):
    • Unique shrub species in Nova Scotia salt marshes; vulnerable to frequent flooding; forms narrow belts at high elevations; important for reducing wave energy on coastal areas.
  • Salt marsh plants may exhibit two strategies to deal with salinity:
    • Succulence: Storage of water to dilute salt concentrations, leading to increased succulent characteristics from spring to fall.
    • Salt Excretion:
    • Examples include the shedding of leaves by Blackgrass Rush when salt concentrations rise, and salt glands in Spear Saltbush and Smooth Cordgrass that excrete excess salt onto leaf surfaces.

Species Diversity in Salt Marshes

  • Environmental Complexity: Species diversity within salt marshes can be attributed to several factors, one being the partitioning of environments among specialists.
    • This suggests that species adapted to specific conditions will outcompete generalist species, hence affecting overall diversity.
    • The complexity of the salt marsh environment supports a wide variety of species, dictated by factors such as elevation and tidal influences.

Example Plant Species of Interest

  • Glasswort (Salicornia maritima):
    • Jointed, fleshy branches; leaves reduced to scales; annual plant; seeds can germinate in salt water, historically used in glassmaking.
  • Spear Saltbush (Atriplex patula):
    • Broadleaf plant up to 50 cm; distinctive triangular leaves; annual with two seed types.
  • Herbaceous Seepweed (Suaeda maritima):
    • Stature of up to 20 cm; light green leaves with a distinctive appearance.
  • Carolina Sea Lavender (Limonium carolinianum):
    • Characterized by bluish flowers and fleshy basal leaves; often used ornamentally.
  • Seaside Goldenrod (Solidago sempervirens):
    • Features arching branches with yellow flowers; reaches up to 2 m in height; thrives in high elevation areas.