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No Thumbnail AvailableProjectSite selection for aquaculture: chemical features of water
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.As indicated already chemical features of water like the other characteristics of water are most important in deciding on the suitability of a site for aquaculture. Site selection from the major habitat point of view is obviously chemically related. The types of waters are classified for culture according to the salt content (salinity) of the medium - the common distinctions are the freshwater, brackish water and marine and then hard and soft water at the lower scale. The suitability of the me dium would be decided on the specific organisms to be cultured and the specific culture systems to be used. Thus the physical aspects of water have already been referred to. Now we shall look at the chemical aspects of water, including dissolved gases, such as oxygen carbon dioxide and ammonia, and concentrations of various ions, and their summated effects (eg. pH, dissolved solids, conductivity etc). As for some of the other major factors the chemical factor alone could rule out a site, i.e. in case proper reclamation, in view of economics) is not possible. The importance of chemical factors, is owing to their lethal and sublethal effects on culturable organisms, and also owing to their effect on biological productivity, i.e. productivity of the organism in the food chain. This aspect is discussed separately under ‘Biological Productivity’. A review through the various chemical factors as done hereunder should enable one to establish criteria to select or reject a site for aquacul ture. As this needs considerable information on the background, we have accepted to provide such information as needed. One should refer to more elaborate references as indicated at appropriate places herein if further information is required. -
No Thumbnail AvailableProjectSite selection for aquaculture: chemical features of water
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.As indicated already chemical features of water like the other characteristics of water are most important in deciding on the suitability of a site for aquaculture. Site selection from the major habitat point of view is obviously chemically related. The types of waters are classified for culture according to the salt content (salinity) of the medium - the common distinctions are the freshwater, brackish water and marine and then hard and soft water at the lower scale. The suitability of the me dium would be decided on the specific organisms to be cultured and the specific culture systems to be used. Thus the physical aspects of water have already been referred to. Now we shall look at the chemical aspects of water, including dissolved gases, such as oxygen, carbon dioxide and ammonia, and concentrations of various ions, and their summated effects (eg. pH, dissolved solids, conductivity etc). As for some of the other major factors the chemical factor alone could rule out a site, i.e. in case proper reclamation, in view of economics, is not possible. The importance of chemical factors, is owing to their lethal and sublethal effects on culturable organisms, and also owing to their effect on biological productivity, i.e. productivity of the organism in the food chain. This aspect is discussed separately under ‘Biological Productivity’. A review through the various chemical factors as done hereunder should enable one to establish criteria to select or reject a site for aquacu lture. As this needs considerable information on the background, we have attempted to provide such information as needed. One should refer to more elaborate references as indicated at appropriate places herein if further information is required. -
No Thumbnail AvailableProjectSite selection for aquaculture: biological productivity of water bodies
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.Biological productivity as an index of water quality and production potential of cultured organism needs prime consideration for site selection. Productivity in terms of qualitative and quantitative aspects of plankton and benthos are treated separately, in this manual. In the present discussion we shall look first at primary production and then show this influences secondary production in water bodies. We shall explain first certain concepts to elucidate aspects of productivity and then the ene rgy flow in an ecosystem and the importance of this information in aquaculture. Finally we shall briefly refer to the methods of measuring productivity. We have had occasion to look at the various physical and chemical and certain biological characteristics of water bodies and their influence on fish production and aquaculture in particular. I specially refer to the exercise on correlating fish production and dissolved solids (conductivity) and depth of water bodies, using Rider's (Ryder et al ., 1974) morpho-edaphic index, MEI, (Handerson & Wellcome, 1974). It is quite obvious that there is a strong correlation between fish production and the amount of dissolved solids (inversely correlated with depth of the water body), in fresh waters except generally at the extreme high level. This has to be so because fish production is based on the productivity of water which is again, correlated directly with the amount of available nutrients and minerals, most often reflected by the dissolved solid content. Before we enter into a discussion on productivity, it would be helpful to look at the concepts of the ecosystem, habitat and ecological niche, and food cycle in water bodies, including food chain and trophic structure. These terms are of specific interest to aquaculture and productivity in general and therefore deserve some consideration.
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