Depth-wise variations in biofouling community development on aquaculture cage nets in the Red Sea

This study examined the development of biofouling assemblages on cage net panels submerged at different depths in a fish farm in the Red Sea. Experimental rafts equipped with Dyneema fibre nets were submerged at depths of 5, 10 and 15  m. Results showed significant variations (P < 0.05) in fouling biomass and the composition of fouling communities among the three depths. The highest biomass accumulation (average: 71.06  g dm−2 month−1) was recorded on panels at 5  m. The fouling community that settled on the net panels included macroalgae, sponges, bryozoans, hydrozoans, mussels and ascidians. Although the results indicated a distinct pattern of successional phases during the growth of the fouling community on the cage net panels, the abundance of dominant fouling organisms varied between depths. At 5  m, ascidians and algae were most abundant, whereas panels at 10  m were primarily colonized by ascidians, bryozoans and hydrozoans. At 15  m, ascidians and bryozoans were dominant. Overall, the findings suggest that fouling abundance decreases at greater depths, with the lowest colonization observed at 15  m. These results provide valuable insights for developing effective biofouling management strategies to mitigate excessive accumulation of dominant fouling organisms in this region.