Seasonal Variability of Biofouling Assemblages in the Largest International Port in Indonesia

Biofouling assemblages may pose negative effects on navigation activities and marine environment in international ports. Investigating the settlement of these assemblages is important to help in the mitigation of their impacts. Tanjung Priok Port, Jakarta, is the largest and busiest international port in Indonesia, yet the assessment of biofouling assemblages in this port is limited. We analysed differences in the settlement of those assemblages between wet (November 2011 to January 2012) and dry (May to July 2012) seasons over different submersion durations (one, two, and three months). Non-toxic polyvinyl chloride panels of 0.1 m x 0.2 m were submerged vertically at a depth of 1 m as biofouling collectors. Physico-chemical parameters (temperature, salinity, pH, dissolved oxygen, nitrate, nitrite, phosphate, and total suspended solid) and biological parameters (phytoplankton and zooplankton) of the water column were also recorded. The composition of biofouling assemblages significantly differed between wet and dry seasons (p < 0.05), but the assemblage dissimilarity between seasons was smaller after three months of submersion. Tunicates dominated biofouling assemblages during the wet season across all submersion durations. In the dry season, macroalgae were the most dominant group after one month of submersion but replaced by calcareous polychaetes after two and three months of submersion. The seasonal variability of biofouling assemblages was associated with zooplankton diversity and richness, phytoplankton diversity, dissolved oxygen, and nitrate in the water column.