World Library  
Flag as Inappropriate
Email this Article

Salt pannes and pools

Article Id: WHEBN0028057388
Reproduction Date:

Title: Salt pannes and pools  
Author: World Heritage Encyclopedia
Language: English
Subject: High marsh, Wetlands, Fisheries, Coastal geography, Aquatic science
Publisher: World Heritage Encyclopedia

Salt pannes and pools

Salt marsh showing salt pannes and pools during low tide, mean low tide, high tide and very high tide (spring tide).

Salt pannes and pools are water retaining depressions located within salinity greater than that of the larger body of water. This increased salinity dictates the type of flora and fauna able to grow within the panne. Salt pools are also secondary formations, though the exact mechanism(s) of formation are not well understood; some have predicted they will increase in size and abundance in the future due to rising sea levels.

Salt pannes and pools are unique microhabitats dominated by various species of halophytes, benthic plants and varying estuarine marine life that vary considerably in composition due to a variety of factors:

  • Substrate type: affects the ability of the depression to hold water.
  • depth and diameter: affect water temperature and evaporation rate in the depression. A shallow and wide pool will evaporate at a greater rate than a pool of the same volume of water which is deeper and has a smaller surface area. Evaporation rate also affects salinity, the higher the evaporation rate the higher the salinity, with rates as high as a third greater than ocean water.
  • location within the intertidal zone, whether high marsh or low marsh and distance from the mean low tide mark which affects the length and duration of inundation until the depression is subject to evaporation as well as length of time until the rising tide replenishes the water volume.

These factors affect the types of species which can survive within the various types of salt pannes and pools.

Variants of salt pannes and pools:

Low salt marsh

Salt marsh showing smooth cordgrass Spartina alterniflora, a dominant species of halophyte in the intertidal zone, and Egrets feeding in a tidal pool.
  • Low salt marsh panne

Usually devoid of vegetation, that may be present include smooth cordgrass (Spartina alterniflora), marine algae such as knotted wrack (Ascophyllum nodosum) and rockweeds (Fucus spp.). The substrate is typically soft, silty mud.

High salt marsh

  • Arrow-grass (forb) panne

Briefly flooded, very shallow with a moderate amount of vegetation usually dominated by Arrow grass (Triglochin maritimum), with the deeper sections possibly remaining unvegetated.

  • Smooth cord-grass (short form) panne

Shallow anaerobic depressions with poor drainage, poor water quality due to low nutrient levels and high concentrations of sulfides and similar compounds which inhibit plant growth. Short form (6-12" tall)smooth cord-grass (Spartina alterniflora) is the dominant plant species. Typically found on the high salt marsh, but can occasionally be found on the upper margins of low salt marsh.

Salt marsh mosquito panne

Mummichogs, (Fundulus heteroclitus), found in deepwater pools

Minimal vegetation often found on the upper half of the high salt marsh. It is typically deeper than forb and smooth cord-grass pannes. Usually flooded by the higher of the two spring tides, retains water for 2–3 weeks later until drying out. The female eastern salt marsh mosquito (Aedes sollicitans) lays eggs on the exposed surface. The eggs lay dormant until the next time the panne floods.

Widgeon grass (Ruppia maritima) - marsh minnow deepwater pool Pools on the high salt marsh that are semi-permanently and permanently flooded. They are able to sustain populations of Sheephead minnow (Cyprinodon variegatus variegatus), Mummichogs, (Fundulus heteroclitus), and other species of small fish which may become trapped in the pools and benthic species of vegetation. Occasioanally can be found at the upper edge of the low salt marsh.

Brackish water marsh

Brackish marsh panne variants occur in brackish marshes (short graminoid variant), one of the native dominant species is spike grass (Distichlis spicata), some brackish marsh pannes are dominated by the narrow-leaved cattail (Typha angustifolia) an invasive exotic species.

Shallow depressions flooded for only for a brief time and are characterized by a variable mix of graminoids and forbs. Frequent herbs include three-square rush (Scirpus pungens), stout bulrush (S. robustus), arrow-grass, marsh creeping bent-grass (Agrostis stolonifera), salt-loving spike-rush (Eleocharis halophila). Growing with less frequency are red fescue (Festuca rubra), New York aster (Symphyotrichum novi-belgii) silverweed, saltmeadow cordgrass (Spartina patens), and salt marsh rush.

Salt marsh showing salt pannes and ponds, spartina alternifolia and invasive phragmites communis in foreground.
  • Sparsely vegetated panne

Saturated, mud dominated pannes are occasionally found in the transition zone next to forested uplands where they are shaded by overhanging tree branches thus inhibiting evaporation. This is the preferred habitat for the uncommon seaside crowfoot (Ranunculus cymbalaria), where prostrate colonies may form small patches over the soil surface. Other graminoids and forbs scattered across the mud, or more often around the panne edge, include Virginia wild rye (Elymus virginicus), chaffy salt sedge (Carex paleacea) seaside goldenrod (Solidago sempervirens), marsh creeping bent grass, New York aster and smooth cordgrass.[1][2]


  1. ^ New Hampshire Division of Forest and Lands
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.