A novel use of Stereo Baited Remote Underwater Video and Drop-Down Video for biodiversity and marine landscape mapping and prediction

PLOS ONE | https://doi.org/10.1371/journal.pone.0319355 April 3, 2025 5 / 23 PLOS ONE Marine landscape and biodiversity mapping using SBRUVs and DDV is permitted (DTDC); and a full no take zone where all activities including scallop diving and prohibited (NTZ) (Table 1). SBRUV surveys were carried out within the South Arran Marine Protected Area in 2013, 2014, 2018 and 2019, using a 6.5 m RIB, 10.8 m research vessel (RV Actinia), and 10.0 m creel boat (Table 2). The study area was divided into 5 zones differing in exposure level and topog- raphy [4], stations were generated within each zone via random points stratified by depth using Quantum Geographic Information System [53], and identified using combinations of alphanumeric identifiers including year and date. The three SBRUV camera set ups each consisted of a pair of Canon HF G25 video cameras encased in waterproof camera housings with an inward angle of ~ 8o and a basal separation of 58 cm [4,54], mounted on a steel frame 57 cm in height, with two LED W38VR Archon lights providing illumination (Fig 3). All cameras were set to automatic exposure, with focus set to infinity. Frames were freshly baited with locally caught mackerel (Scomber scombrus) for each station [4]. The camera systems remained on the seabed and recording for 60 minutes per deployment. In order, to prevent bait odour plumes from affecting neighbouring deployments on the same day camera systems were positioned more than 500 metres apart, depths for SBRUV deployments ranged from 4.1 m to 47.2 m. Our sampling for diversity may have been affected

Fig 2. Locations of all Stereo baited remote underwater video and drop-down video (DDV) surveys. (A) University of Glasgow SBRUV survey sites for all years 2013-2019. (B) NatureScot drop-down video (DDV) survey locations for 2013-2018. fishing management limitations are as follows outlined in Table 1. https://doi.org/10.1371/journal.pone.0319355.g002 Table 1. Fishing restrictions implemented in the South Arran MPA as per marine conservation order 2015. TND) Trawl and Dredge - Limitations throughout MPA: no demersal trawling and scallop dredging. BT) Beam Trawl - As with TND but with restrictions on beam trawling and limited demersal trawling allowed. DTDC) Demersal Trawl Dredge and Creel - As with TND but with additional bans on passive gear such as creels. NTZ) No fishing activities whatsoever – (No Take Zone). Schedule (ordered least- most restrictive) Gear prohibited Scallop dredge Demersal trawl Otter trawl, “specified vessels” Passive gear (e.g., creeling) Scallop diving 1 (trawl derogation - BT) x x 0 (core - TND) x x x 2 (maerl boxes - DTDC) x x x x 3 (NTZ) x x x x x https://doi.org/10.1371/journal.pone.0319355.t001