Intro to Salt Marshes

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We are here at Folgers Marsh on the island of Nantucket and

We are here at Folgers Marsh on the island of Nantucket and

we are going to talk about what a salt marsh is. Salt marshes are

communities of grass - and the animals associated with them -

that form in quiet embayments between the high tide low tide marks.

It is an interesting habitat because it is both

an aquatic habitat - flooded with salty water -

and a terrestrial habitat. When the tide comes in

- as we see here at high tide - the water moves over the surface of the grass

and is partially an aquatic habitat.

The grasses are experiencing salty-water, which is not

a great condition for them. But these grasses are

adapted to tolerate it.

Animals move onto the marsh and get some protection from predation.

Things like little shrimp and little fish can move onto the surface

of the marsh.

There is a gradation of species on the marsh -

from this edge or this low tide or low marsh mark

to the high tide mark as you move back.

At the edge we have this species called 'Spartina alterniflora'

- or salt marsh cordgrass. It can grow

pretty tall in some areas, and as you move back

onto the marsh it stuts.

It is most covered by the tide for the longest period of time

- tides come in and out on a six hour cycle

twice a day. It can tolerate being

flooded by water because it has aerial roots.

Plants take in oxygen through air not their water.

The animals that live on the marsh however, most of them are

aquatic animals. Things like mussels and fiddler crabs.

They get oxygen from the water. I am going to talk a little about the animals

in the marsh. You can see there are birds feeding.

This is [an] important habitat for feeding

- things like egrets, herons

and osprey. The water that comes in through

the marsh channels - and flows throughout the marsh -

is [an] important habitat for crabs

and smaller juvenile fish of some commercially important species such as

flounder and

bluefish. We also have smaller species that are

salt marsh creek inhabitants that provide food for the

crabs and the other larger fish. At the edge

of the marsh there is a mussel that is attached

to the substrate and to the

roots of the 'Spartina alterniflora'. This mussel called the ribbed mussel

- 'Geukensia demissa' - has a mutualistic

association with the grass. It provides

nitrogen and stabilizes the roots,

while the plant provides a place for it

to attach to - and a little bit of protection from predators.

You also find fiddler crabs. Fiddler crabs make little burrows

along the edge

- and there [are] actually three species of fiddler crab that live

in this marsh. Some live in this more sandy habitat

another species lives in more muddy habitat[s]. As you go

back through the marsh towards the road there is actually

a source of fresh water, and you get a third species that lives

in that more brackish water - or less

salty water. Fiddler crabs make burrows, and this burrow

help aerate the substrate.

One condition of a marsh is that when it is flooded you have a lot of microbial

action going on.

It depletes the water that is in the sediment of oxygen.

As you move back - if you were to dig a hole

and let it fill with water - that water would be very smelly because of the microbial

action - sulfur.

It also would have very little oxygen if any oxygen at all.

This is also a physiological stress for plants and animals.

So you can see [that] a salt marsh is a very unique

community of plants and animals that

live in this area the coast.

It is an important habitat, it is a habitat that provides a lot

of primary production. Which means the grasses take in carbon dioxide

and turn that into organic carbon.

It also is an important habitat for

the coastline behind it. It provides protection from

storm damage [as] a buffer zone between

the sea and the land.

Thirdly, it is an important habitat for

these important commercial species and juvenile fish that use the salt marshes

to grow larger - they use the food provided by the other smaller organisms

that

eat the detritus provided by the plants.

Vocabulary

Expressions / Collocations

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