Salt Marshes Flashcards

Flashcards about salt marshes

Saltmarsh

Herbaceous vascular vegetation on sheltered particulate shores between consisting of plants of terrestrial originThese plants are adapted to saline conditions and can tolerate periodic inundation by seawater.

Saltmarshes As Coastal Defenses

Saltmarshes dissipate wave energy, reduces damage to, and overtopping of, sea walls, can allow shorter sea walls

Importance of Saltmarshes in primary productivity

Very high primary productivity, most productivity is exported as detritus to food webs in adjacent habitats, habitat to nationally rare species.

Habitat for Birds

Saltmarshes provide convenient (close to food) and relatively undisturbed roosting areas for waders (especially on neap tides from spring to august where upper marshes are not reached by the tide)

Nereis diversicolor

A polychaete that lives in Saltmarshes. Eats diatoms, seeds and seedlings, plankton and small invertebrates. This increases with high pollution levels/eutrophication and can lead to saltmarsh collapse

Carcinus maenas

Larger invertebrates tunnel into the banks of creeks in salt marshes

Fishes in Saltmarshes

Fishes use saltmarshes, especially creeks. e.g. 0 group bass feed only when in saltmarsh or mudflat habitats.

Formation of Saltmarshes

Saltmarshes are assumed to form through facilitated succession. Sand/mudflat with benthic diatoms – secrete EPS (extracellular polymeric substances) that bind and stabilise the sediment. Pioneer zone vascular plant species (e.g. Salicornia europaea) grow here where they cause further sediimentation and stabilisation allowing secondary succession etc

Saltmarsh Vertical Zonation

Plants show a vertical zonation. Lower limit is dependent on their tolerance to environmental factors (esp. salinity) and the upper by interspecific competition.

Saltmarsh Erosion

Saltmarshes are disappearing rapidly with annual losses of 1-2% worldwide.

Causes of Saltmarsh Erosion

Land claim (reclamation) and erosion suggested to be due to nutrient pollution.

Creek Erosion

Nutrient pollution leads to a decrease in root biomass, increase in above-ground biomass, and increased vulnerability of plants to herbivores. Led to collapse of creek banks; saltmarsh converted to mudflat.

Nereis increase

Nereis are more abundant, and their rates of deposit feeding higher, at the saltmarsh-mudflat interface, because of nutrient enrichment, leading to loss of saltmarsh vegetation.

Nereis exclusion

Nereis exclusion experiments demonstrate absence of pioneer zone vegetation where the sediment is high enough is due to bioturbation and herbivory (they eat seeds and seedlings).

Progradation

is the advancement of a coastline due to the accumulation of sediment, often influenced by natural processes and can impact salt marsh formation.

Parts of a salt marsh

mudflat, pioneer zone, low marsh, upper marsh, transition zone, creeks, cliffs, pans

Deposit feeding

encouraged by eutrophication, deposit feeding refers to the ingestion of sediments and organic matter from the bottom of aquatic environments by benthic organisms.