Abstract
The present deliverable aims to describe and explain the data pathway, from the monitoring plan specification phase to the final report, in order to better evaluate impacts of wave energy on the environment.
To obtain high quality results, each step of the data pathway requires a specific attention. Quality results are built on scientifically robust data, spatially comparable (between sites), technically comparable (between devices), manageable in the long term (comparable over the entire lifetime of a commercial project, i.e. 20-25 years), and specifically adjusted to the threshold enabling impact evaluation.
Regardless of the scale of a project (SafeWAVE project, test site management, or a commercial farm), each step of the pathway needs to be addressed with care, and even more because various different stakeholders handle data over the course of the project.
The present deliverable capitalises on the feedbacks from the SafeWAVE project, and its predecessor WESE project, to identify the most critical steps in this pathway, in the frame of environmental monitoring for the 4 topics which were addressed (electromagnetic fields – EMF, acoustics (noise), seafloor integrity, and fish communities monitoring).
The EMF monitoring plan could only be applied at one test site at the time of writing the present report. It was applied on a power cable connecting a floating wind prototype. The plan had to be adapted considering the local sea conditions and the surveyed assets. Field raw data were directly accessible using the sensor built in software. Some artefacts were dealt with by the field operator. The primary data could directly be used as inputs for WAVEC numerical model. Results from the models are in the same order of magnitude as field data. The modelled magnetic fields (for umbilical and export cable) are compared to threshold of magnetic field where behavioural or physiological effects have been observed for sensitive species, as elasmobranch. Nevertheless, the impacts of EMF on 8 Deliverable 2.1 Development of Environmental monitoring plans marine species are not well known, and individual species thresholds do not exist.
Acoustic monitoring activities within SafeWAVE followed the initial plan with little adaptations being required. Due to equipment failures (some hydrophones for some of the surveys) the expected data set is incomplete, but remains sufficient in order to evaluate impacts. Raw data required significant processing efforts, and data analysis initially focused on frequency ranges identified as noise indicators for the Marine Strategy Framework Directive (MSFD). The applicability and relevance of these indicators is questioned in the present report. Considering the impact threshold of 120 dB re 1 μPa specified by de the U.S. National Marine Fisheries Service for continuous sound (NMFS, 2018), it seems that all the WECs systems could negatively impact the cetaceans in all the studied areas since the produce sound above this threshold in all wave heights regimes and sound emission frequencies.
Regarding seafloor integrity evaluation, two different monitoring methods were deployed: remotely operated vehicles (ROV) submarine videos, and side scan sonar (SSS) coupled to an autonomous underwater vehicle (AUV). The ROV videos enabled a focused, close ranged and direct evaluation of local impacts on the seafloor. The SSS survey covered a broader area; its raw data are processed by a sensor built-in software which directly provides images. The resulting images (from the ROV and SSS) are analysed by experts in order to evaluate impacts.
The fish monitoring plan was applied only in BiMEP test site. In the absence of a wave energy device at the BIMEP site when the survey could be carried out, it was directed at the Harshlab (a floating platform with similar dimensions compared to a wave energy prototype). However, the HarsLab does not have specific elements of the WECs that can modify or affect fish behaviour, such as noise and EMF emissions, so future studies and more trials with the ITSASDRONE device are needed to further explore the association between WECs and fish aggregations. This survey enabled the validation of ITSASDRONE autonomous surface vehicle (ASV) 9 Deliverable 2.1 Development of Environmental monitoring plans equipped with an echosounder for fish monitoring. In the meantime, resources could be allocated to conduct baseline fish monitoring surveys at the Aguçadoura test site.
Regardless of the type of survey, the acquisition of auxiliary data is critical to process and analyse the field data.
Data acquired within the frame of SafeWAVE project are uploaded in the MARENDATA platform, created during previous European collaborative projects, and dedicated to environmental data and information sharing for the marine renewable energy (MRE) sector. Deliverables and data are also accessible via the SafeWAVE project website and are disseminated using social networks.
In the context of emerging marine renewable energies, impacts have to be evaluated in the long term, but knowledge is missing on the technologies themselves, and the standard monitoring protocols are not yet fully relevant nor applicable. Therefore, the authors of the present report strongly emphasise the need to address each step of the data pathway with care and as early as possible in the development of monitoring strategies and plans. Based on these considerations and on the feedbacks from SafeWAVE monitoring campaigns, specific guidelines will be developed in deliverable 2.7.