It is fairly straightforward to analyse the effects of individual environmental factors on the CFT species so far as information is available. However, in determining the composition of a community in a specific location the complex interaction of physico-chemical variables must be considered - a simple presentation of this in relation to hard substrata is given in the figure below. The interactions between depth, slope and suspended matter in determining light availability are particularly important.

Environmental variables, and their interactions, important in determining community structure on hard sublittoral substrata (from Hartnoll, 1983).

Various factors are considered. Temperature is of most important on a geographical scale, whilst the others may vary widely on local scales to have major influences the distribution of CFT species and biotopes. In the previous section the significance of water movement as a determining factor was highlighted.

Temperature

Depth and light

Exposure to water movement

Substratum

Slope

Suspended matter and scour

Salinity

Grazing

References