This work aims to review the major marine fouling organisms found worldwide with a primary focus on those found in European waters. These organisms have been categorised as microfoulers (eg. bacteria and phytoplankton) and macrofoulers (eg. barnacles and algae). Biofouling is the unwanted attachment of organisms on surfaces which can negatively affect the hydrodynamic performance of ship hulls, for example increasing a vessel’s drag resulting in increased fuel consumption. Additionally, the environmental issue of alien species translocation, between the world’s harbours due to shipping, can affect local marine biodiversity. A better understanding of the fouling communities is required for the development of modern antifouling coatings and future legislation.

The seasonal and bio-geographical variance of shipping paths means that antifouling performance which is effective in temperate waters may be ineffective in tropical waters due to the variety of species present. It is, therefore, important to test the antifouling efficacy against a broad spectrum of organisms and marine environments. There are many environmental factors that affect settlement and growth which include temperature, salinity, nutrient availability, turbidity, dissolved oxygen, light penetration, current flow and ultraviolet intensities. As such, it is important to identify the geographical distribution of fouling organisms and their population dynamics. A review of key antifouling bioassay organisms has also been included. A key objective of this review is to establish the most relevant and/or likely ship hull foulers for use as bioassays with reference to their geographical distribution. The major hull macrofoulers have been identified as barnacles, algae, bryozoans, cnidarians, ascidians and annelids, with the first group being described as the most important, economically, for ship hulls.