World Library  
Flag as Inappropriate
Email this Article

Euryhaline

Article Id: WHEBN0004432401
Reproduction Date:

Title: Euryhaline  
Author: World Heritage Encyclopedia
Language: English
Subject: Coastal fish, Diversity of fish, Brachionus plicatilis, Freshwater crab, Strongylocentrotus droebachiensis
Collection: Aquatic Ecology
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Euryhaline

Atlantic sturgeon under six years of age stay in the brackish water where they were born. They then move into the ocean where, after seven to twenty-three years, they become sexually mature. When mature, they travel up a fresh water river to spawn. The females spawn every two to six years, returning to the ocean after laying their eggs. Males can remain upstream for longer periods.

Euryhaline organisms are able to adapt to a wide range of life cycle involves migration between freshwater and marine environments, as is the case with salmon and eels.

The opposite of euryhaline organisms are stenohaline ones, which can only survive within a narrow range of salinities. Most freshwater organisms are stenohaline, and will die in seawater, and similarly most marine organisms are stenohaline, and cannot live in fresh water.

Contents

  • Osmoregulation 1
  • Euryhaline fish 2
  • Other euryhaline organisms 3
  • See also 4
  • See also 5

Osmoregulation

Osmoregulation
Movement of water and ions in a saltwater fish
(yellow jack)
Movement of water and ions in a freshwater fish
(brown trout)

Osmoconformers match their body osmolarity to their environment actively or passively. Most marine invertebrates are osmoconformers, although their ionic composition may be different from that of seawater.

Osmoregulators tightly regulate their body osmolarity, which always stays constant, and are more common in the animal kingdom. Osmoregulators actively control salt concentrations despite the salt concentrations in the environment. An example is freshwater fish. The gills actively uptake salt from the environment by the use of mitochondria-rich cells. Water will diffuse into the fish, so it excretes a very hypotonic (dilute) urine to expel all the excess water. A marine fish has an internal osmotic concentration lower than that of the surrounding seawater, so it tends to lose water (to the more negative surroundings) and gain salt. It actively excretes salt out from the gills. Most fish are stenohaline, which means they are restricted to either salt or fresh water and cannot survive in water with a different salt concentration than they are adapted to. However, some fish show a tremendous ability to effectively osmoregulate across a broad range of salinities; fish with this ability are known as euryhaline species, e.g., salmon. Salmon has been observed to inhabit two utterly disparate environments — marine and fresh water — and it is inherent to adapt to both by bringing in behavioral and physiological modifications.

Some marine fish, like sharks, have adopted a different, efficient mechanism to conserve water, i.e., osmoregulation. They retain urea in their blood in relatively higher concentration. Urea is damaging to living tissue so, to cope with this problem, some fish retain trimethylamine oxide. This provides a better solution to urea's toxicity. Sharks, having slightly higher solute concentration (i.e., above 1000 mOsm which is sea solute concentration), do not drink water like fresh water fish.

Euryhaline fish

The level of salinity in intertidal zones can also be quite variable. Low salinities can be caused by rainwater or river inputs of freshwater. Estuarine species must be especially euryhaline, or able to tolerate a wide range of salinities. High salinities occur in locations with high evaporation rates, such as in salt marshes and high intertidal pools. Shading by plants, especially in the salt marsh, can slow evaporation and thus ameliorate salinity stress. In addition, salt marsh plants tolerate high salinities by several physiological mechanisms, including excreting salt through salt glands and preventing salt uptake into the roots.

Despite having a regular freshwater presence, the Atlantic stingray is physiologically euryhaline and no population has evolved the specialized osmoregulatory mechanisms found in the river stingrays of the family Potamotrygonidae. This may be due to the relatively recent date of freshwater colonization (under one million years), and/or possibly incomplete genetic isolation of the freshwater populations, as they remain capable of surviving in salt water. Freshwater Atlantic stingrays have only 30-50% the concentration of urea and other osmolytes in their blood compared to marine populations. However, the osmotic pressure between their internal fluids and external environment still causes water to diffuse into their bodies, and they must produce large quantities of dilute urine (at 10 times the rate of marine individuals) to compensate.[2]

Partial list

Other euryhaline organisms

See also

See also

  1. ^ Thorson, T.B. (1983). "Observations on the morphology, ecology and life history of the euryhaline stingray, Dasyatis guttata (Bloch and Schneider) 1801". Acta Biologica Venezuelica 11 (4): 95–126. 
  2. ^ Piermarini, P.M. and Evans, D.H. (1998). "Osmoregulation of the Atlantic Stingray (Dasyatis sabina) from the Freshwater Lake Jesup of the St. Johns River, Florida". Physiological and Biochemical Zoology 71 (5): 553–560.  
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 USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov 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 Project Gutenberg 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.