Benthic Operations Assessment
There will be no adverse impacts on benthic communities during normal project operation. There
is however some potential for positive impact associated with project operation through the
artificial reef systems.
The cumulative surface area of the anticipated 68 jacket substructures between seabed and the
water surface shall be approximately 100,000m2 based on the current engineering designs of the
turbine substructures and taking account of the fact that although the surface area shall not be
solid, the faces of the metal grid sub-structure will offer a substantial cumulative surface area.
This available surface area will more than compensate for the loss of benthic infauna habitat of low
ecological value. Based on previous studies it is anticipated this artificial habitat shall enable
natural colonisation by a range of epifauna with a net positive impact at the wind farm footprint area.
Recent investigations into the rate and extent of marine growth on new marine structures in the
South China Sea recorded a biomass of almost 0.9 kg / m2 approximately 3 months after
installation, with growth recorded at all depths (Yan et al, 2006). Biodiversity was found to have
further increased at 6 and 12 months, by which time the a community of barnacles, anemones,
pearl oysters, polychaetes and bryozoans has become established at ~20m depth. The
community in more shallow waters (~3m) also supported algae, bivalves, decapods, annelids and
amphipods (ibid.).
A parallel study of communities of at least 5 years old in nearby waters to the above case study
recorded a total of 105 taxa, with molluscs (bivalves), arthropods and annelids being the most
abundant. Surveys at depths from 3 to 38 metres recorded a mean biomass of ~20 kg / m2 (ibid.).
A series of qualitative observations of benthic colonization of marine structures has also been
made by recreational divers at oil platforms in waters about ~100 metres deep in the South China
Sea. The location, some 90 km southeast of the Study Area, has regularly been visited by divers
since year 2000 (Asiatic Marine, 2007). The community age is unknown, but is assumed to be < 10
years.
An epifauna community ~15cm thick primarily comprising oysters and barnacles has been
recorded at one oil platform site, with this community forming a hard substrate for coral growth.
Coral observations of note include the dominance of the octocoral Dendronephthya spp on metal
structures at -10 to -50m. Small colonies of the black coral Carijoa sp were noted, as were
colonies of the hard coral Acropora sp. A variety of marine life has been observed associated with
the benthic community, including reef fishes, lobsters and moray eels (ibid.). Figure 5.17 indicates
the diversity and richness of the benthic community on the structure.
There will be no adverse impacts on benthic communities during normal project operation. There
is however some potential for positive impact associated with project operation through the
artificial reef systems.
The cumulative surface area of the anticipated 68 jacket substructures between seabed and the
water surface shall be approximately 100,000m2 based on the current engineering designs of the
turbine substructures and taking account of the fact that although the surface area shall not be
solid, the faces of the metal grid sub-structure will offer a substantial cumulative surface area.
This available surface area will more than compensate for the loss of benthic infauna habitat of low
ecological value. Based on previous studies it is anticipated this artificial habitat shall enable
natural colonisation by a range of epifauna with a net positive impact at the wind farm footprint area.
Recent investigations into the rate and extent of marine growth on new marine structures in the
South China Sea recorded a biomass of almost 0.9 kg / m2 approximately 3 months after
installation, with growth recorded at all depths (Yan et al, 2006). Biodiversity was found to have
further increased at 6 and 12 months, by which time the a community of barnacles, anemones,
pearl oysters, polychaetes and bryozoans has become established at ~20m depth. The
community in more shallow waters (~3m) also supported algae, bivalves, decapods, annelids and
amphipods (ibid.).
A parallel study of communities of at least 5 years old in nearby waters to the above case study
recorded a total of 105 taxa, with molluscs (bivalves), arthropods and annelids being the most
abundant. Surveys at depths from 3 to 38 metres recorded a mean biomass of ~20 kg / m2 (ibid.).
A series of qualitative observations of benthic colonization of marine structures has also been
made by recreational divers at oil platforms in waters about ~100 metres deep in the South China
Sea. The location, some 90 km southeast of the Study Area, has regularly been visited by divers
since year 2000 (Asiatic Marine, 2007). The community age is unknown, but is assumed to be < 10
years.
An epifauna community ~15cm thick primarily comprising oysters and barnacles has been
recorded at one oil platform site, with this community forming a hard substrate for coral growth.
Coral observations of note include the dominance of the octocoral Dendronephthya spp on metal
structures at -10 to -50m. Small colonies of the black coral Carijoa sp were noted, as were
colonies of the hard coral Acropora sp. A variety of marine life has been observed associated with
the benthic community, including reef fishes, lobsters and moray eels (ibid.). Figure 5.17 indicates
the diversity and richness of the benthic community on the structure.
Epifauna community at a South China
Sea Oil Rig
Source: Asiatic Marine
Sea Oil Rig
Source: Asiatic Marine
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