salt marshes

how many salt marshes

world: 120

USA: 32

what are the purpose of saltmarshes

physical protection from wave energy

- found near river deltas and behind barrier islands

what percent of coastal wetlands are saltmarshes

45%

why are coastal wetlands a challenging place to live

- anoxic conditions

- build up of toxics

- large temp swings

- tides

- salinity stress

saltiness causes

physiological dryness

- saltwater results in osmotic imbalance

what are the three adaptations for salt?

- salt secretion: special glands

- salt exclusion: force water intake through specialized membrane

- sequester salts: store excess salts in vacuoles and drop em

coastal wetland productivity

1-3k

values of coastal wetlands

- shoreline stabilization

- buffer coastal waters from human waste impacts

- habitat

how do coastal wetlands stabilize

accretion (OM build up) and submergence (OM decomp)

do coastal wetlands experience submergence

yes due to sea level rise

what are the three NA salt marshes

- artic

- west coast

- atlantic coast

-- bay of fundy

-- new england

-- coastal plains

why are 90% of coastal wetlands on east and gulf coast

- pacific shorelines very steep --> coastal wetlands very narrow

what are the 4 key habitats of salt marshes

- low marsh (frequently flooded)

- high marsh (frequently exposed)

- creeks (allows tide waters to flow in/out)

- salt pans (depressions where salt accumulates)

salt marsh vegetation

- low marsh: low plant diversity

- high marsh: high plant diversity

salt marsh animals

high animal diversity

- greater than 50% commercial fish/shellfish

- lots of bird species

creeks--> salt marsh structure

- bidirectional conduits for matter and energy

- young (lost of shallow creeks) v old (deeper creeks) marshes

- flushing means decreased salinity which results in increased plant growth

- increase biomass means trapped new sediments --> increase fertility --> increase growth

pannes (salt marshes)

depressions without emergent vegetation

- salt barrens: high marsh area, trapped water-hypersaline

- mud barrens: low marsh, standing water, high salinity and sulphur

plants within salt marshes

- smooth cordgrass (low marsh and high marsh)

- salt meadow cordgrass (high marsh)

smooth cordgrass

- extreme tolerator

- tall v short rely on salinity compounds

mudflats

- low marsh zone that is mostly unvegetated (pacific coast and european)

salt marsh productivity

above ground: >1000

below ground: 1*4x AG

salt marsh microalgal productivity

- 100-350

-- most of this is 'benthic mats'

salt marsh energy flow (established view)

- most macrophyte not directly consumed

- Teal: primarily detrital based system

-- fungi, vertebrate shredders, anaerobic bacteria

salt marsh energy flow (emerging view)

- stable isotope studies confirm significant role of liable and microalgal C in higher level consumers

- high conversion efficiency from plant detritus to fungi biomass

salt marshes outwelling hypothesis

- older work: high rates of primary production

- OM exported to coastal waters (net heterotrophic)

- fisheries

salt marshes threats

- roads, cities, development

- invasive species: nutria, spartina

- decreased freshwater flows (salt marshes get saltier)