The Ross Worm (Sabellaria spinulosa) can, when found in sufficiently high densities, form a biogenic reef attracts other fauna to the same vicinity. Such reef are now protected as an Annex 1 habitat under the European Union Habitats Directive. As a result, companies proposing to lay infrastructure such as pipelines and cables, or place structures, such as rigs, anchors or piles, on the seabed are obliged to move their proposed structure's location if a sabellaria reef is found within the survey area.
The only way of conclusively confirming the presence or otherwise of sabellaria is through direct sampling, such as video and camera work or grab sample, but because they are all limited spatially it is prohibitively expensive to conduct such a survey. Additionally, grab sample destroys the very habitat that should be protected.
A habitat survey in the Southern North Sea (SNS) used remote sensing by side-scan sonar to identify reef as characterised by the seabed's ‘hummocky’ nature. This included patches of potential colonization within areas of gravels and coarse sands which required further investigation to confirm the presence or otherwise of sabellaria using remotely operated vehicles (ROVs) and cameras.
This information can be presented using a geographical information system (GIS) package to communicate to stakeholders the findings of the survey. It is suggested that a multistage approach should be adopted, with a side-scan sonar to identify reefs and areas of colonisation, followed by camera work to ground truth the data and combined with GIS to communicate the information to stakeholders and regulators, this approach can be improved on for similar projects and further works should be done on the use of remote sensing for classifying habitats within similar sedimentological areas. It is further suggested that GIS can be used to illustrate the level of confidence in the interpretation.
The Ross Worms (Sabellaria spinulosa) are widespread and have been identified in the seas around the UK. These filter-feeding polychaete worms construct hard tubes from sand grains found on a seabed, typically comprising sandy gravels with shells and boulders, in areas of high tidal flow. They can occur as small colonies and thin mats, which can be the precursor to the final but most important type of colony-biogenic reefs. The worms themselves are not rare; small colonies and thin mats are common and can be established rapidly, but they can often be short lived. The more permanent reefs attract other fauna and therefore increase the density and richness of animals in the immediate vicinity, where they support a rich diversity of organisms and can become a focus of biodiversity. These reefs are rare and have been reported to stand up to 60cm proud of the seabed and persist over time1, which is why they are accorded protection under European Union Habitats Directive and included in Annex 1. The lack of knowledge relating to their sensitivity means that traditional intrusive benthic sampling method, such as box and grab corers, can destroy the very habitat that should be protected.