Total Dissolved Solids Ranges in Water
Although Total Dissolved Solids TDS relate to community metabolism, the quantity and quality of dissolved solids often determine the variety and abundance of plants and animals in a given aquatic situation.
In a most general sense, the limiting nature of dissolved solids is essentially two-fold.
In the first place, the chemical density of the environment of aquatic organisms is a function of the total dissolved solids. According to the laws of osmosis and diffusion, the water balance or osmoregulation of plants and animals is governed by this environmental density factor and the physiological adaptations of the various organisms to it.
The second way in which total dissolved solids influence the nature of the community relates to the supply of nutrients and otherwise important materials.
The natural range of total dissolved solids concentration for most lakes occupying open basins is between 100 and 200 mg/L. Evaporation from lakes in closed basins raises the concentration of dissolved solids in some cases to over 100,000 mg/L.
The only source of nutritionally important ions available to aquatic plants is the reservoir of matter dissolved in the water. The nature of the animal community is of course dependent upon the kinds and quantity of plants available for food. In another sense, certain animals may be directly limited by the availability of a given dissolved substance.
An example being animals carrying carbonaceous shells. In highly acid waters, some mollusks may be entirely absent, while under mildly acidic conditions, mollusks may occur, but their shells are reduced in thickness as compared to those inhabiting waters of less acidity.