Unit Three: Mangroves/ Marshes

Salt marshes are

coastal grasslands that are flooded and drained by the tides

What conditions foster the development of salt marshes?

1. protection from waves

2. gradual slope thru intertidal region (passive margin)

3. temperate. subpolar latitudes

Where are the most extensive salt marshes found?

southeastern US, GA

Latitude's affect on primary production

high latitude = low PP

low latitude = high PP

Tidal drainage network

-tidal creeks

-brings water/ organisms into marsh

Coastal wetlands provide

storm protection, C sequestration, habitat, tourism, and more

What effects do salt marshes have on marine environments?

-reduced flooding (accretion)

-protection from erosion (trapping sediments)

-improved water quality (biological filters)

Three common plants found in salt marshes

1. Spartina (cord grass)

2. Juncus (black needle brush)

3. Salicornia

Challenge: osmotic uptake at roots

-Solution 1: maintain water vis osmolytes, waxy leaf coating, inc. SA, water storage tissues

-Solution 2: salt export via salt crystals, salt excretion

Challenge: O2 availability in sediments

Solution: roots grow close to surface, air passages in aerenchyma tissue that can also inc. in volume

Zonation in salt marshes

-Tall-form cordgrass: more frequent inundation, well drained sediment, lower salinity, higher O2, lower H2S

-Short-form cordgrass: less frequent inundation, poorly drained sediments, higher salinity (evaporation), lower O2, higher H2S

Physical factors effecting zonation

tolerance

Biological factors effecting zonation

-competition

-juncus is bad competitor once water is salty

-salicornia is bad competitor in less inundation

How is primary production processes through the food web?

-salty, high lignin content --> not great food

-detritus-based food web

What conditions foster the development of mangrove forests?

1. protection from waves

2. gradual slope thru intertidal regions

3. tropical latitudes/ no freezing temps

Salt marshes and mangroves are found in ___ environments but different ___.

environments; latitudes

Both salt marshes and mangroves act as

biological filters

Common Trees in mangrove forests

-Rhizophora (red mangrove): most inundated, aerial propogation, roots for stability/ O2

-Avicennia (black mangrove): horizontal roots for O2

-Laguncularia (white mangrove): least inundated, highest elevations

What are the challenges for plants living in a mangrove environment?

1. osmotic uptake

2. O2 availability in sediments

How does Rhizophora adapt to the challenges?

-tolerates 60-65 psu

-organic osmolytes

-aerial propogation roots

-lenticels (pore for gas exchange)

How does Avicennia adapt to the challenges?

-tolerates >90 psu

-salt-secreting glands on leaves

-lenticels

0pneumatophores (above ground roots for O2)

-organic osmolytes

Zonation in mangrove forests is affected by

physical tolerance and competitive ability

How is primary production process through the food web of a mangrove forest?

-very few herbivores bc trees hard to eat

-detritus-based food web

Blue Carbon

organic C stored as plants/ sediments in marine ecosystems

Why are salt marshes, mangroves, and seagrass meadows important?

-they are major pools of carbon storage

-sequesters CO2 from atmosphere

Loss of Blue Carbon does what?

releases CO2 into atmosphere