TY - RPRT
TI - Understanding the potential effects of wave energy devices on kelp biotopes
AU - Macleod, A
AU - Orr, K
AU - Greenhill, L
AU - Burrows, M
AB - Background:Scottish Natural Heritage (SNH) has identified a research need to improve understanding of the changes to kelp habitats as a result of the development of wave energy projects around Scotland. Notable development is planned in The Crown Estate’s current leasing round with further zones being identified by Scottish Government in the latest draft plan options for the sector. Some of these developments have the potential to occur within the subtidal zone, where kelp habitats are prevalent.Activities associated with wave projects such as installation, operation, maintenance and decommissioning may impact kelp communities in a number of ways, including kelp removal to permit installation of devices and associated infrastructure (cables and pipelines).Main findings:Areas designated for the deployment of shallow-water and shore-based wave energy converters (WECs) in Scotland coincide with important kelp habitats (dominated by Laminaria hyperborea).Kelp covers approximately 3600 km2 of Scotland's coast and the estimated 10 million tonnes of kelp biomass supports more than 1800 different species of flora and fauna including other seaweeds, invertebrates, fish, diving birds and otters.Existing wave lease areas coincide with 1.2% of Scotland’s kelp habitats where kelp has a 50% likelihood of being rare or more abundant on the SACFOR scale.The expected area of impact on kelp habitats will be much lower, given that the footprint of individual WECs will be far smaller than the wave lease areas.Environmental impacts associated with wave energy projects may occur during construction, operation, maintenance and decommissioning project phases. Activities with potential impacts on kelp include: site preparation; installation of mooring anchors, cabling, mono-piling and / or construction of breakwaters; introduction of new substrates such as rock mattressing, metal or plastic piping; routine maintenance and decommissioning. These activities may result in direct loss of kelp habitats and / or temporary disturbances from which kelp can recover.WECs may indirectly impact kelp habitats and wider nearshore ecosystems by inducing changes in hydrodynamics, sedimentation and wave energy, which favour the establishment of less diverse seaweed communities. The introduction of non-native species also poses a risk to kelp communities. However, the degree of this threat is largely uncertain.Kelp habitats are subject to a high level of natural disturbance (for example loss of biomass during storms) and have an inherent capacity to recover rapidly.After clearing, the kelp canopy can return to virgin biomass within 2-5 years and associated flora and fauna may take 1 to >6 years to return to their original density, dependent on species. Kelps are also able to colonise a variety of artificial substrates such as concrete blocks and rock mattressing. Repeat clearing of kelp at intervals of less than 2 years will prevent recovery of kelp habitat.Recovery of kelp habitats after disturbance can be facilitated by: - Introducing new substrates that best match the natural environment. - Not sterilising new surfaces unless essential for device operation. - Leaving kelp holdfasts intact when clearing and thereby retaining refuges for associated fauna. - Allowing kelp canopy to mature (>5 years age) between successive clearings. - Avoiding sites that are adjacent to extensive areas of fine sediments.The findings of the objective risk assessment are that kelp habitats have a medium to very high sensitivity to site-specific disturbances that may be induced by wave energy projects. However, given the extent of kelp habitat in Scotland and the level of natural disturbance tolerated by these habitats, the magnitude of the predicted impact is generally minor or negligible on a regional and national scale.
DA - 2014/01//
PY - 2014
SP - 60
PB - Scottish Natural Heritage
SN - Report No. 783
UR - https://www.nature.scot/snh-commissioned-report-783-understanding-potential-effects-wave-energy-devices-kelp-biotopes
LA - English
KW - Wave
KW - Habitat Change
KW - Ecosystem Processes
ER -