Spill context
The prevailing weather and sea conditions (wind, swell, tides, currents,
salinity, temperature) influence the viscosity,
spread rate, dispersion and destination of the oil slicks. Thus a drastic
change in the wind direction saved the French Charente-Maritime region from
a serious threat of pollution from the Erika, but instead impacted the Pays
de la Loire region.
The time of year is also a factor which should be taken into account. The
influence of the seasons on the water temperature and biological cycles
is by no means negligible. Many species are more sensitive to oil pollution
during their reproduction, nesting and migratory periods. For annual vegetation,
the most sensitive time is the beginning of the growth period.
Other factors which directly influence the impact are the duration of exposure,
the form and concentration of hydrocarbons,
the thickness of deposits, the degree of contamination of the substrate
and the chemical evolution of the hydrocarbons. Many of these are related
to the degree of energy and water exchange in the receiving environments.
Finally, the presence of other pollutants and/or previous exposure to oil
can increase the sensitivity of certain organisms to pollution, reduce the
survival capacity of a biological community or cause the population of resistant
species to grow in relation to sensitive species.