In terms of water quality changes resulting from facilities development, these relate mainly to those facilities which require extensive in-water infrastructure, particularly in the form of artificial fixed breakwaters. Potential changes brought about by such infrastructure may include increases in water temperature, decreases in dissolved oxygen levels and increases in concentrations of certain other pollutants such as copper from antifouling paints.

The slowing in the speed of currents and mixing may promote the growth of microscopic plants and phytoplankton whilst sedimentation of suspended inorganic and organic materials may increase. The resultant increase in turbidity reduces light penetration and may smother benthic communities. It may also reduce the quantity of dissolved oxygen in the water, so causing harmful shortages when demand from various organisms is high. This is especially apparent close to the bed of the water body where there is a high demand for oxygen from the benthic communities (Bendel, 1986).

There may be a significant trade off between the desire to improve flow characteristics in a sheltered marina basin, by dredging the navigation channel, and the desire to minimise the scale and impact of dredging activities for reasons outlined above. There are, however, a number of other methods utilised for improving water flow in marina basins including the provision of culverts in the basin walls and the installation of pumping systems.

Next Section