Brackish-water classification, its development and problems
In: Hydrobiological Bulletin. Netherlands Hydrobiological Society: Amsterdam. ISSN 0165-1404; e-ISSN 2214-708X, meer
Ook verschenen in:(1974). Proceedings of the International Symposium on Ecology and Physiology of the Brackish Environment, Amsterdam, September 4-7, 1973. Organized by the Netherlands Hydrobiological Society in honour of the Dutch hydrobiologist Dr. H.C. Redeke (1873-1945). Hydrobiological Bulletin, 8(1-2). Netherlands Hydrobiological Society: Amsterdam. 252 pp., meer
|  |
| Trefwoorden |
Water > Brackish water
Brak water |
| Abstract |
(1) A survey is given of the main developments of brackish-water classification since Redeke (1922) published his system. Brackish-water classification is primarily a classification of biocoenoses in the border area between the sea and the fresh water. (2) The concept "brackish water" is discussed. It is conclude that term "brackish water" does not denote a homogeneous environment but is rather a collective term for a number of different well-characterized habitats in the border area between the sea and fresh water. (3) The original brackish-water classifications by Redeke (1922) and Valikangas (1926) are discussed against the background of their time. It is shown that these classifications were based on local conditions in the Netherlands and in Finland respectively. (4) The difficulties met by applying the Redeke-Valikangas system in areas other than for which it was designed can be largely ascribed to (a) over-estimation of the significance of the average salinity figures. (b) the inability of the biologists of that time, to improve the "static system" by incorporating the salinity fluctuations in it. (c) the fact that it was not realized that in open systems benthos and plankton have different salinity characteristics. (5) The Venice system was defined in 1958 for universal application. It has been criticized on the lack of a biological basis and on its compromise characters. (6) Some incorrect applications of brackish-water classification are discussed. e.g. the use of biologically defined border lines in hydrography. (7) A number of recent developments in brackish-water classification are discussed, viz.: (a) the subdivision of the hyperhalinicum, and its biological delimitation from the continental salt waters. (b) the typology of brackish habitats which is based on continuity or discontinuity of the transition between the sea and the fresh water and the pattern of the salinity fluctuations. (c) the significance of the "species minimum in the brackish water" for the classification. (8) A new, multifactorial approach is recommended in order to come to a more satisfying classification of brackish biota. |
|
