Fouling Factors

There are many variables that affect bio-fouling in a particular environment.

The major factors are:

Season

Seasonality has a significant impact on the degree of fouling in temperate climates due to the changes to the levels of light and water temperature as we progress from summer to winter. Fouling will therefore be greater in the summer season and will have less of an impact in the winter months. In tropical regions there is continuous growth irrespective of the season as water temperatures and light levels remain fairly consistent throughout the year.

Sunlight

Plant-like organisms such as algae and seaweed require light for photosynthesis and as this reduces it limits their presence, thus depriving macro bio-foulers from a valuable source of nutrients.

Temperature

Generally, bio-fouling becomes more prevalent in areas with warmer temperatures. However there are organisms which thrive in colder waters.

Flow rates

Currents and tides assist in the dispersal of larval stages of many fouling organisms. This is a particularly important factor in determining the size and speed of spread of colonial foulers e.g. hydroids, bryozoans, polychaetes, some ascidians, bi-valves and barnacles, as these bio-foulers will spread rapidly when present in environments with several varied currents.

Salinity

The degree of salinity in most marine environments fluctuates as a result of complex seasonal and tidal variations. Although marine species can tolerate a moderately wide band, a swing to extremely low or high salinity will invariably affect the population and generally lead to reduced fouling. Low salinity conditions tend to occur in the winter months when higher rainfalls add significant amounts of fresh water. Conversely hotter weather increases evaporation resulting in a higher salt concentration.

Water Depth

Fouling organisms are present at all ocean levels although they diminish in scale as the depth increases. Photosynthetic organisms will be found in the shallower waters, which will be replaced by suspension feeders as the light decreases.

In deeper waters the environment becomes increasingly inhospitable as light does not penetrate, temperatures drop and pressure increases significantly. Organisms that can survive in these conditions tend to develop slowly and in fewer numbers than in shallower waters, although a bio-film formation does occur readily and can reach a thickness capable of obscuring substrates. In addition, the absence of natural rocky substrates in deeper waters means that any artificial surfaces will offer a particularly attractive and prominent site for marine growth.

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