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Low energy shoreline habitats

I. Salt marsh

A. Characteristics

1. Estuarine, intertidal

2. Protected/low energy

3. Width depends on slope - thin zone or mile wide, depending on how rapidly land rises

4. High productivity
   a. marsh grasses (Spartina)
   b. macro algae (Ulva)
   c. nutrients come down river and in with tide (detritus)
   d. rapid recycling of in-house and in-coming nutrients
   e. wrack – seasonal death and recycling of cord grass

B. Zonation

1. Low marsh – flooded twice a day by incoming tides
   a. Salt marsh cord grass – Spartina alterniflora
   b. Ribbed mussels - Gukensia (east coast)
   c. Marsh periwinkle - Littorina

2. High marsh – only flooded by high winds or high spring tides, soil still contains a lot of salts
   a. Salt marsh hay – Spartina patens
   b. salt resistant and succulent plants – e.g. pickle weed, seaside lavender
   c. fiddler crabs – Uca sp.
   d. marsh snails – Melampus

3. Transition zone/maritime forest – above the highest tide
   a. soils forming, getting deeper, trapping fresh water
   b. plants resistant to salt spray; bayberry, loblolly pine, wax myrtle, Phragmities

4. Tidal creeks – carry brackish water further into the salt marsh, edges of creeks often resemble the low marsh, even if well away from the waterline

II. Mud flat

A. Characteristics

1. In well protected areas, or fine mud would never settle out

2. Gradual slope

3. Below the low tide, extending away into the sub-tidal zone

4. Anaerobic below the first few millimeters (bacteria)

5. Tides carry lots of detritus to this area

B. Algae

1. Microalgae – on mud, in aerobic layer; diatoms, dinoflagellates, blue-greens, filamentous greens

2. Macroalgae – grow on the surface of the mud flat, most often attached to a firm substrate, such as annelid burrows, or dead clams, whelks, etc.
   Primarily greens: Ulva, Enteromorpha, Cladophora

C. Animals

1. Roamers – on the surface
   a. Crabs –Fiddler – Uca, Hermit crabs
   b. Shrimp – Palaemonetes, Crangon
   c. Snails – mud snail – Ilyanassa
   - whelks – Busycon

2. Burrowers – in the mud, all must reach to surface for oxygen (& most for food)
   a. Annelids – leave mounds of excavated soil and castings on the mud flat surface
   – raptorial, deposit
   - burrowing and tube building
   b. Molluscs – hard clam (Mercenaria) soft clam (Mya – squirt water by retracting their long siphons), razor clam, jacknife clam

III. Sea grass beds

A. Characteristics

1. Less well protected, nearly flat

2. Soft sandy/mud bottom, more well oxygenated due to more coarse grain size, larger interstitial spaces

3. Grasses roots help to stabilize the bottom

4. Long leaves help to slow the tidal currents, reducing sediment movement

B. Plants/algae

1. Zostera marina - eel grass, true plant, most common in high salinity waters

2. Ruppia maritima – widgeon grass also common in CB

3. Sea grasses add to primary productivity & decomposition adds greatly to detritus (washing up on beaches = strand line).
   Few organisms eat the grasses directly

4. Very important to water fowl in the bay

5. Ulva and other algae

C. Animals –

1. Grass provides a habitat for benthic organisms: sponges bryozoans, sm worms, tunicates

2. Detritovores – grass shrimp, sm inverts, sand dollars

3. Predators -sea slugs (bryozoan) snails, crabs, fishes (sea horse, pipefish, visitors)

4. Refuge and nursery – for larvae, moliting crabs, small inverts – some must leave safety to feed

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