St Kilda Survey COR0924 (Blog #2): Post-survey update
By Lucy Hirschle
Following a successful offshore survey to the seas off St Kilda, as part of the Defra-funded mNCEA (marine Natural Capital and Ecosystem Assessment) Programme, in this blog post our offshore survey team provide us with a post-survey update.
In our previous blog post, we delved into the fascinating world beneath the waves surrounding St Kilda, sharing insights from the multidisciplinary mNCEA survey. This ambitious project aimed to assess the marine natural capital and ecosystem (mNCEA) of this remote archipelago.
The 2024 offshore survey set sail from Belfast to the seas south of St Kilda on 27 September. After eventually setting eyes on the remote islands after almost 24 hours transit time and successfully getting stuck into our survey sampling, we received notice of the closure of our survey area for Ministry of Defence (MOD) operations. Disappointed but not disheartened our team successfully adapted, and the survey plan adjusted to visit contingency sites at Stanton Banks and South Rigg MPAs. Despite this challenge, we were still able to use these contingency sites to deliver the meet the majority of our survey aims, including sampling mud habitats exposed to a variety of fishing pressures using different techniques, and testing novel and innovative approaches to monitoring.
Figure 1. The uninhabited rocky outcrops of St Kilda, viewed on a clear day during grab sampling operations (image: Jolyon Chesworth).
One of the highlights of the 2024 survey was the successful trial of novel techniques. After some adjustments to our methodology, we were able to collect high-quality video footage of both benthic and pelagic mobile species from our Baited Remote Underwater Video (BRUV) cameras. This innovative approach allowed us to observe many species that are typically missed by traditional underwater imagery techniques like camera sleds and drop cameras.
Figure 2. JNCC Survey scientist, checking the cameras and lights on the BRUV camera, a crucial step in preparing for underwater surveys. This non-invasive method allows us to study marine life without taking physical samples. (image: Lucy Hirschle).
Figure 3. This series of images, captured by a benthic BRUV, showcase the incredible diversity of marine life in the deep sea. Mobile species drawn by the scent of mackerel bait, approach the camera, offering a glimpse into it the species present at the survey site.
Another exciting novel technique was the deployment of eDNA meta-probes at three sites. By collecting genetic material shed by marine organisms into their environment, we can detect and identify species without the need for physical sampling. This non-invasive method holds immense potential for marine biodiversity assessments. However, we are still working to optimize eDNA collection techniques, and the results from this survey will help us refine our approach.
Figure 4. Two eDNA meta probes ready for deployment. The yellow probe has a mesh treatment, while the red probe is without mesh looking into the effectiveness of collecting environmental DNA in muddy sediments. (image: Jolyon Chesworth).
Figure 5. Meta probes were deployed by attaching them to the frame of the camera sledge which were submerged for roughly 30 minutes taking video and capturing images of the seabed (image: Jolyon Chesworth).
While the 2024 survey presented some unexpected challenges, it also yielded valuable insights and demonstrated the adaptability of our research team. The data collected from this survey will contribute to our understanding of marine ecosystems in the region and inform future conservation efforts.
We would like to extend our sincere thanks to the staff and crew of the RV Corystes and the AFBI scientific staff for their invaluable support and hard work during this survey. Their dedication and expertise were instrumental in the success of this project.
Figure 6. Goodbye from the Corystes and the mNCEA data collection survey (image: Lucy Hirschle).