SALT MARSHES GEOGRAPHICAL DISTRIBUTION. - areas vegetated by herbs, grasses or low shrubs bordering saline water bodies

GEOGRAPHICAL DISTRIBUTION SALT MARSHES - areas vegetated by herbs, grasses or low shrubs bordering saline water bodies - interface between terrestria...
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GEOGRAPHICAL DISTRIBUTION

SALT MARSHES - areas vegetated by herbs, grasses or low shrubs bordering saline water bodies - interface between terrestrial and marine habitats Arctic marshes

- tidal submergence

Boreal marshes Temperate marshes Tropical marshes Inland salt marshes

ARCTIC MARSHES- Spitzbergen, Greenland, Canadian Arctic, Alaskan marshes, - ice action, patchy distribution grasses, sedges, bryophytes, very few annuals (Carex subspathacea; Puccinellia phryganodes)

BOREAL MARSHES - ecotone between arctic and temperate - Hudson Bay, British Columbia, Northern Baltic, Southern Norway and Sweden - more plant species (arrow weed, Triglochin maritima, pickleweed Salicornia europea) -low salinities – (melt water)

TEMPERATE MARSHES - East and West coast of the U.S., Europe, Japan, China, Korea, A ustralia, South Africa “Dry coast type – Mediterranean marshes”

- greater floristic differentiation, graminoids, halophytes, less mosses

TROPICAL MARSHES - adjacent to mangroves, - secondary communities in disturbed mangroves - species poor

INLAND SALT MARSHES -white alkali soils ("solontschak"), semi-arid areas (Caspian Sea, Middle east, Utah) - black alkali soils ("solonetz") - no tidal influence

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TROPICAL MARSHES GEOMORPHOLOGY - marsh development determined by tides, shoreline structure,

freshwater input, sedimentation, primary production - shoreline features allowing for marsh development, barrier islands -marsh stability - determined by relative rates of sedimentation Sesuvium portulacastrum

salt marshes young (~ 3000-4000 y) -coastal submergence (cold periods global lowering of sea level by 100-150 m; 15000-6000 y ago rapid sea level rise; last ~ 5000 y relatively stable rise of about 1m/century) Gulf Coast: 1.2 cm/y submergence,only 0.7cm/y accretion; West coast about equal Booby, Sula sp.

HYDROLOGY - lower and upper limits of the marsh - tidal range

CHEMISTRY

- upper marsh (high marsh) flooded irregularly, higher differences in salinity

- water and soil salinity influenced by: frequency of tidal inundation , rainfall; network of tidal creeks

- lower marsh (intertidal marsh) flooded almost daily

- nutrients - often N-limited, usually not P-limited -high sulfur concentrations, sulfide toxicity

-tidal creeks - conduits for material and energy ( 1s t, 2nd, 3rd , order –shift, 4th , 5 th order

Salinity dominated by NaCl

stable )

Average sea water composition:

role of vegetation in trapping the sediments progression x retrogression

mg/l Cl SO4

- tidal pools (ponds) and pans - elevated salinity

Sum = 35 g/l = 35 ppt

pool origin: patchy distribution of vegetation, accretion

mg/l

19.4

Na

10.8

2.7

Mg

1.3

Ca

0.4

K

0.4

Salinity data can be expressed as specific conductivity (conductance). Conductivity [mS/cm] = 1.5 * Salinity [ppt]

remaining open parts of retrogressing creeks

STRESS - tidal submergence

VEGETATION STRUCTURE

- salinity

- perennial grasses (cordgrass)

- anoxia

- Spartina anglica (England)

- temperature

- Spartina alterniflora(East Coast)

- litter accumulation ( “wrack”)

- Spartina foliosa (West Coast)

- human activities

- Distichlis spicata – salt grass - succulent species

tidal submergence

-Salicorniaspp., Jaumea, Batis - algae, seaweeds - shrubs Grindelia -

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Spartina foliosa

Distichlis spicata – salt grass

Salicornia virginica

Plant zonation

Parasitic plant – dodder Cuscuta salina

algae, seaweeds

Grindelia sp.

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Spartina stories

Spartina stories

(1) 1829 – S. alterniflora ( native of the East Coast) introduced to England Native S. maritima x S. alterniflora 2n = 60

(2) 1960’s – S. alterniflora introduced to the West coast Native S. foliosa x S. alterniflora

2n = 62 S. townsendii (~ 1870) sterile hybrid 2n = 62

hybrid Hybrids are more aggressive, they are altering the ecology of the West coast marshes

S. anglica 2n = 120, 122, 124 ( fertile allopolyploid) S. anglica completely altered the saltmarsh ecology of N-European marshes

(3) S. anglica introduced to China and New Zealand – extremely invasive

Spartina has not been a successful colonizer in the tropical regions – requires cold periods for seed germination C4 plant Growth of Spartina alterniflorais strongly regulated by sediment oxidation status – tall plants (~ 3 m!) near the water edge and along the tidal creeks; in low redox zones very short individuals (~ 20 cm), low AEC Hybrid swarms

Spartina alterniflora - initial invasion HALOPHYTES (plants which complete their life cycle in saline environment) non-halophytes ( glycophytes) facultative and obligate (??) halophytes The relative biomass increase can be just caused by salt uptake

+ 0

salinity

The effects of salinity: 1) direct toxic effect of Na, Cl 2) interference with uptake of essential nutrients 3) lowered external water potential

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WATER POTENTIAL ( ? )

WATER POTENTIAL ( ? )

? i = internal potential

-halophytes attain internal water potential below that of external solution to generate turgor pressure permitting growth - ( water potential is the thermodynamic parameter – energy (work) involved in

moving 1 mole of water from some point in the system into a pool of pure water)

-increase in salt concentration = decrease in ?

?

:

high

? ? = osmotic potential

? e = external water potential; freshwater ~ 0 MPa ? ? in the range of –0.5 to –1.0 MPa (salts in cytoplasm) => ? p has to be +0.5 to +1.0 MPa (for turgor pressure to stay positive)

high

Sea water: ? e = about –2.5 MPa

low

? i = internal potential Plants: ? i = ? p + ? ?

? p = turgor pressure ? ? = osmotic potential

WATER POTENTIAL ( ? ) -

halophytes attain internal water potential below that of external solution to generate turgor pressure permitting growth

? i has to stay below ? e; ? p has to stay positive => ? ? ~ -3.5 MPa (? ? ~ -3.5 MPa corresponds to ~ 40 ppt NaCl !)

REGULATION OF SALT UPTAKE - exclusion - succulence ( Salicornia spp., Batis,

HOW ??

Jaumea, Sesuvium)

1)

Uptake of inorganic salts ( salts are already there; transport

- extrusion (secretion) requires

mechanism – transpiration – is there)

energy (Distichlis, Frankenia, Limonium)

2) 3)

? p = turgor pressure

(MPa)

H2O salt concentration: low

Plants: ? i = ? p + ? ?

Production of organic osmolytica ( drain on carbohydrates and N; examples: glycinbetain, prolin, sugars

- leaf loss ( Sessuvium)

Dehydration

- reduced transpiration, high WUE

(C4)

------Regulation of salt uptake:

Limonium californicum – sea lavender

Examples: Salicornia spp., Batis, Jaumea, Sesuvium

ALGAL MATS Positive plant interactions

Cyanobacteria– N2 fixation

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FAUNA - permanent x visitors x seasonal (migrating birds) - invertebrates: lugworms, crabs, many insects, spiders - vertebrates: not many reptiles and amphibians, fish - birds - mammals: rabbits and hares, mice, muskrats, nutria

Lugworm – Arenicola marina, large annelid worm - feeds on bacterial particles and DOM - has to pump in water with oxygen for respiration - can switch to anaerobic respiration, changes in AEC - deals w. high concentrations of H2S by oxidizing it during aerobic conditions - deals w. high salinity by having high concnetrations of salts in body cavity + some organic osmolytica

IMPACT OF GEESE ON ARCTIC AND BOREAL MARSHES

IMPACT OF GEESE ON ARCTIC AND BOREAL MARSHES

La Pérouse Bay (part of Hudson Bay)

B

Breeding grounds of Lesser snow geese (Chen caerulescens caerulescens) – keystone species ~ 1.2 mil. 1970’s

> 2 mil. 1990’s

> 3 mil. 2000’s

– after geese increased over carrying capacity:

Geese need more biomass, grubbing activities – digging for rhizomes => increase plant damage => bare areas => exposure of marine sediments => increased evapotranspiration => increased salinity

end May- mid August

(hypersalinity)

A

Larger bare areas => faster snow melt => more geese => more

– before geese increased over carrying capacity:

Geese removed about 80% of NPP (100 -200 g.m2 ~ 1-2g N/m2)

grubbing

Positive feedback – more grazing => more biomass production

Larger bare areas - problems with revegetation, grass, Puccinelia phryganodes, is not able to colonize large bare patches, Salicornia

Input of N from droppings

borealis

After geese leave in August, plants have time to recover; open spaces dominated by cyanobacteria that contribute ~ 1g/m2 of N before the season is over)

ECOSYSTEM FUNCTIONS

Marshes of New England (from Mark Bertness web page)

Primary production - high (but not in all marshes) Spartina alterniflora East Coast NPP 2500g/m2/year - West Coast marshes lower production - streamside effect - algal production important - epibenthic algal mats Southern California marshes: algal production about equal to vascular plant production

Decomposition - detritus broken down mostly by bacteria - export to adjacent estuaries

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POSITIVE INTERACTIONS – prevalent under harsh physical or limiting nutrient conditions; (Mark Bertness et al)

HYPERSALINITY

ANOXIA

+

+

+

-

-

+

+ : feces from mussel beds increase production and stabilize the marsh edge; fiddler crabs aerate; dense vegetation aerates; dense vegetation prevents hypersalinization

- : intraspecific competition – displacing subordinates by stronger competitors

PNAS 99:1395, 2002

Marshes on Sapelo Island, Georgia

Control of plant growth: BOTTOM UP

X

TOP DOWN

Resource availability

Consumers

( nutrients)

( predators herbivores primary producers)

-------------------------------------------------------------------------------------Bottom-up forces have been regarded as primary determinants of plant production in Spartina alterniflora dominated salt marshes on the Atlantic coast (Odum, Mitsch & Gosselink) Never tested experimentally !!

Periwinkle story

TROPHIC CASCADE

(Silliman & Bertness 2002, PNAS 99: 10500)

- prosobranch periwinkle snails (Littoraria irrorata) are common inhabitants of the East coast salt marshes - these snails are consumed by predators such as the blue crab (Calinectes sapidus)

I

SPARTINA

- it has been assumed that periwinkle snails feed only on dead and dying Spartina plant materials - Silliman and Bertness found that once periwinkles are released from the predation by crabs, they will readily eat living cordgrass . - also, the greater the nitrogen content of the grass the more attractive the grass became to the periwinkles - nitrogen is the prime nutrient in mainland run-off

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-the results indicate that a simple trophic cascade regulates the structure and functions of the salt marshes

Low periwinkle density plot

- the discovery of this simple trophic cascade implies that over -harvesting of snail predators, such as blue crabs, may be an important factor contributing to the massive die- off of salt marshes across the southeastern United States - densities of blue crabs dropped 4080% in the Gulf estuaries over last 10 years

High periwinkle density plot

- predator depletion can result in in conversion of salt marshes to mud flats.

tissue scarring - radulation

Human impact – restoration projects

TIDAL FRESHWATER MARSHES (TFM) - historically ignored - marshes that are close enough to coast to experience significant tides, but above the reach of salt water

Geographical Distribution - distributed worldwide, usually in association with large river systems, deltas, “sloughs”

Geomorphology - recent in origin, in river valleys created during the Pleistocene period of low sea levels

Salinity - TFM occur where the average annual salinity is below 0.5 ppt - salinity may rise periodically during droughts; inflow of salt water during hurricanes

Tidal range - sometimes the tidal range of TFM can exceed that of tidal salt marsh due to the constricting of the tidal mass as it moves upstream in a narrowing river channel

Sediment composition and bank morphology - usually fine inorganic and organic sediments, sometimes more erodable than salt marsh sediments

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Vegetation structure

Chemistry

- plant species restricted to freshwater or low salinities

- not too high sulfur concentrations - more dissolved and particular organic carbon than salt marshes, more C input of terrestrial origin - lot of nitrogen bound in organic form

- usually complex assemblages of perennial and annual species - large proportion of broadleaved emergent macrophytes (Pontederia, Sagittaria) - many submersed species (Potamogeton spp., Myriophyllum spp., Elodea spp.) in ponds and creeks

- variable phosphorus

- communities of annuals (Bidens spp., Polygonum spp. ) - often extensive stands of Typha spp., Zizannia aquatica, Panicum hemitomon “floating marshes” - large seed banks, germination dependent on flooding - no distinct zonation because of habitat overlap - benthic algae, usually during the fall and winter when the vascular flora is reduced

Fauna - relatively low species diversity of invertebrates - much higher diversity of reptiles and amphibians than in salt marshes -largest and most diverse populations of birds of any wetland type - mammals: otter, mink, muskrat, nutria, raccoon, marsh rice rat

Ecosystem function - Primary production - higher than in salt marshes (range of 1000 to 3000 g/m2/y) -Decomposition - generally proceeds at a rapid rate - much higher methane emissions in TFM than in salt marshes -Nutrient flux - nutrient transformers

Human impact – ex. Danube delta

DANUBE DELTA – concept of hydrologic connectivity Water mediated transfer of matter, energy, and/or organisms Alterations of HC are threatening biological reserves

DANUBE DELTA (Pringle et al. 1993 Amer. Sci., Vol. 81) -the largest European wetland (Romania & Ukraine) - consists of rivers, lakes,marshes, meadows, sand dunes and forests - the delta receives drainage from70% of the area of central Europe => major environmental problems - rich economic resource of fish, timber and reed and is home to about 80 000 people -Important migrating bird habitat Die-offs of reeds

Pringle 2001, Ecol. Appl . 11: 981

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- as a centre of wetland biodiversity, the Danube delta ranks among the top sites in Europe.

Danube Delta

-up to 75 different species of fish can be found in the delta and several globally threatened bird species, including the red -breasted goose, the Dalmatian pelican and the pygmy cormorant, either breed in the delta or use the delta as a winter quarter.

- changes in hydrology - elimination of natural water flow

-impacts: hydrology changes upstream AND in the delta; pollution (Hg)

- aquaculture – reduced local fisheries

- pollution – high nutrient loads in the Danube river from upstream - floodplain elimination; coastal erosion (17 m/y!) - attempts to drain for agriculture failed

-creation of a canal network in the delta - the reduction of the wetland area by the construction of agricultural polders and fishponds.

reed

-As a result, biodiversity has been reduced and the fundamentally important natural water and sediment transport system has been altered, diminishing the ability of the delta to retain nutrients. corn

- diked polders for Phragmites cultivation

- decline in emergent macrophytes

- decline in reed growth, replacement with cattails - overall decrease in species diversity - contamination with pesticides and heavy metals

- algal blooms (Cyanobacteria ) - Black sea = one of the largest anoxic marine basins in the world

Failed aquaculture operation

Danube delta

- 1990’s – political changes in Romania - August 1990 – Biospheric reserve & World Heritage Site (about 7000 sq. km – not ALL is damaged!) -needs integrated watershed management and international cooperation !! - specifically water quality improvement and restoration of the natural flow – hydrologic connectivity - Danube Delta Biodiversity project - Partners for Wetlands Ukraine is now developing wetland restoration sites in the Danube Delta floodplain

Polder restoration sites

- WWF project - Black Sea Action Plan

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Danube Delta - >300 lakes of various types (reference sites):

Other threatened deltas: Colorado River, Yellow & Huang Rivers, Ganges River Nile, Mississippi, Niger, erosion because of the elimination of sediment input

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