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 13 / 23 PLOS ONE Marine landscape and biodiversity mapping using SBRUVs and DDV showed that biodiversity was statistically significant between the different substratum types (Mud – Algae, z = -2.9, P = 0.03; Mud – Sand, z = 3.24, P = 0.001) (Fig 10). When diversity is compared between fishing measures limitations areas within the South Arran MPA, there is a statistically significant difference between the core area of the MPA which has restrictions on trawling and dredging (TND), and the areas closed to trawling, dredging and creeling (DTDC). Kruskal-Wallis chi-squared test were significant (H = 0.008, df = 2, P = 0.046), and a pairwise post-hoc Dunn’s test with a Bonferroni adjustment (DTDC – TND, z = -2.42, P = 0.04) (Fig 11). As no SBRUV drops were conducted in the bottom trawl derogation (BT) areas there is no comparison between BT and other areas. Predicted proportional coverage of each substratum and biodiversity throughout the MPA calculated by mean per 500 x 500m grid square (Fig S2) is shown in Fig 12. Areas closed to all bottom trawling but still open to static gear such as creeling (TND, Fig 2, Table 1), had the highest mean biodiversity. Areas closed only to demersal and beam trawling had lower biodiversity, but as these covered larger areas had move overall variation (Fig 12). The area closed to all fishing activities had the lowest biodiversity, but as this only encompasses 2.67 km2 it will not possess as much variation in substrata and overall surface area. Having only

been closed to all fishing activities in 2008 it will be interesting to see how this develops in the future. Fig 9. Patch characteristics per substratum Characteristics of substrata patches for area (m2), Perimeter (m), Perimeter to area ratio, and fractal dimension index. Blue crosses denote the median and bars indicted the mean, boxplot width denotes number of data points. https://doi.org/10.1371/journal.pone.0319355.g009