Multi-Year Succession of Biofouling Communities on Subsea Engineering Structures in the Aphotic Zone of the Sea of Okhotsk

The ten-year succession of the biofouling community inhabiting subsea engineering structures at a depth of 80-90 m was described on the basis of repeated video filming on the southwestern shelf of the Sea of Okhotsk. A general scheme of the stages of development of the macrofouling community in steps of 1-2 years has been compiled both for the intact community and for the sites affected by single or multiple hydrodynamic cleanups. For each stage, we visually estimated the projective cover of macrofouling and identified the typical dominant species down to the smallest possible taxon. The first two years of the intact community are characterized by low projective cover (up to 50%); in the third year and further, there is a dramatic increase in the abundance and diversity of macrofouling organisms. Barnacles Chirona evermanni, sponges Phakellia sp., bryozoans Securiflustra securifrons, and ascidians Boltenia ovifera were noted among the dominant species in the community older than two years. The early stages of the restorative succession differ from the intact succession in terms of dominant species and developmental rates.