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The Seashore

Succession is concerned with community development over time. Find out more in our general section on succession.


Salt Marsh

Development of a Salt Marsh

Continuing Development

Our definition of a salt marsh (see above) referred to flowering plants. Other developments may occur before the flowering plant stage. The diagram above takes us to the stage of a muddy shore. On and within this shore may live a variety of organisms. During the earliest stages of development, microscopic blue-green algae (cyanobacteria) thrive on the surface layers. Their presence will help glue the particles of the mud together forming a more erosion resistant surface.

Free living (unattached to the substrate) versions of macroscopic algae like Pelvetia canaliculata (channelled wrack) and Ascophyllum nodosum (egg wrack) may also survive in the extremely sheltered conditions. In estuarine situations Fucus ceranoides (a wrack like bladderwrack and serrated wrack-see rocky shore section) which is capable of withstanding large changes in salinity can sometimes be found.

In summer fast growing ephemeral green algae like Enteromorpha spp (gut weed) or Ulva spp (sea lettuce) grow attached to small stones (or anything they can stick to) in the mud. These will also help to bind the surface of the mud together and trap particulate material against their fronds.

The height of the mud on our salt marsh increases as time goes by and consequently it experiences longer periods of emersion (being out of the water). Eventually, the height of the muddy shore reaches a point that equates roughly to the height of an average high water neap tide (5.2 metres above chart datum in Milford Haven). This is a critical point in the development of our salt marsh because at this height there are several times in the year when the shore is emersed for 2 or 3 days continuously.

If a flowering plant seed is to grow it needs sufficient undisturbed time to germinate, extend its radicle and get a grip in the ground. 2 or 3 days of emersion is just enough time for some seeds to germinate and attach. Salicornia spp (glasswort or pickle weed) is one such species.

Continuing Development of a Salt Marsh

Saltmarsh Stage 2 diagram

This section will continue by considering the next stages of salt marsh development in terms of community development with time.

<< Development: Early Stages
Succession: Start of the flowering plants stage >>


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