Capturing complexity: field-testing the use of ‘structure from motion’ derived virtual models to replicate standard measures of reef physical structure

Reef structural complexity provides important refuge habitat for a range of marine organisms, and is a useful indicator of the health and resilience of reefs as a whole. Marine scientists have recently begun to use ‘Structure from Motion’ (SfM) photogrammetry in order to accurately and repeatably capture the 3D structure of physical objects underwater, including reefs. There has however been limited research on the comparability of this new method with existing analogue methods already used widely for measuring and monitoring 3D structure, such as ‘tape and chain rugosity index (RI)’ and graded visual assessments. Our findings show that analogue and SfM RI can be reliably converted over a standard 10-m reef section (SfM RI = 1.348 × chain RI—0.359, r2 = 0.82; and Chain RI = 0.606 × SfM RI + 0.465) for RI values up to 2.0; however, SfM RI values above this number become increasingly divergent from traditional tape and chain measurements. Additionally, we found SfM RI correlates well with visual assessment grades of coral reefs over a 10 × 10 m area (SfM RI = 0.1461 × visual grade + 1.117; r2 = 0.83). The SfM method is shown to be affordable and non-destructive whilst also allowing the data collected to be archival, less biased by the observer, and broader in its scope of applications than standard methods. This work allows researchers to easily transition from analogue to digital structural assessment techniques, facilitating continued long-term monitoring, whilst also improving the quality and additional research value of the data collected

Macroalgal vegetation on a north European artificial reef (Loch Linnhe, Scotland) : biodiversity, community types and role of abiotic factors

Open Access via the Springer Compact Agreement Acknowledgements: We would like to thank the dive team of the UK National Facility for Scientific Diving (NFSD), namely Elaine Azzopardi and Hugh Brown, as well as Norman Smith, skipper of the RV Seol Mara, for their diving and logistics support during the fieldwork for this study in July 2014. Funding information: This study received support from the European Community research infrastructure action under the FP7 ‘capacities’specific program ASSEMBLE (grant no. 227788). Also, the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011) supported FCK and the UK Natural Environment Research Council (NERC) funded NFSD. Funding for the construction of the artificial reefs was provided kindly by Foster Yeoman Limited.Peer reviewedPublisher PD

The Minute Alga Schizocladia ischiensis (Schizocladiophyceae, Ochrophyta) Isolated by Germling Emergence from 24 m Depth off Rhodes (Greece)

This research was funded by the UK Natural Environment Research Council in support to FCK(program Oceans 2025–WP 4.5 and grants NE/D521522/1 and NE/J023094/1) and the NERC National Facility for Scientific Diving (NFSD/14/02). We would also like to thank the TOTAL Foundation (Project “Brown algal biodiversity and ecology in the Eastern Mediterranean Sea”). This work also received support from AFP from the project IDEALG (France: ANR-10-BTBR-04) and from FCK from the Marine Alliance for Science and Technology for Scotland pooling initiative. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Peer reviewedPublisher PD

Patterns and drivers of understory macroalgal assemblage structure within subtidal kelp forests

Kelp species are found along ~ 25% of the world’s coastlines, where they provide myriad of ecological goods and services. However, compared with many other terrestrial and marine vegetated ecosystems, kelp forests have been critically understudied in many regions, leading to pressing knowledge gaps that hinder management and conservation efforts. We conducted a large-scale survey of understorey macroalgae within subtidal kelp forests dominated by Laminaria hyperborea at 12 sites, nested within 4 regions in the United Kingdom (UK). Regions spanned ~ 9° in latitude and encompassed a gradient in average sea surface temperature of ~ 2.5 °C. We employed a combination of traditional hand-harvesting of quadrat samples and a novel 3D photogrammetry technique to quantify crustose coralline algae. The structure of understorey macroalgal assemblages was highly variable but showed clear partitioning at the spatial scales of both regions and sites. At the regional-scale, we observed a general increase in richness, diversity and biomass from north to south, most likely due to biogeographical context, ocean climate and the structure and composition of overlying kelp canopies. Site level variation was most likely driven by concurrent variability in wave exposure and kelp canopy structure. Our study shows that understorey macroalgal assemblages represent a rich and abundant component of kelp forests in the northeast Atlantic, with high biodiversity value that warrant conservation measures. As these kelp forest ecosystems are structured by multiple physical and biological processes, current and predicted environmental change will likely alter the diversity and composition of understorey macroalgal assemblages

Biosecurity implications of the highly invasive carpet sea-squirt didemnum vexillum kott, 2002 for a protected area of global significance

Loch Creran on the west coast of Scotland supports the most expansive reefs of the serpulid (Serpula vermicularis) in the world. It also supports flame shell (Limaria hians) and horse mussel (Modiolus modiolus) reefs, thereby ensuring this loch received designation as a European Special Area of Conservation in 2005. In 2015, environmental DNA of the invasive, non-native colonial tunicate Didemnum vexillum, which has a worldwide distribution, was detected in Loch Creran. Didemnum vexillum was confirmed as being present at an oyster farm in the sea loch, using the cytochrome oxidase I gene (COI), following rapid intertidal and dive surveys in early September 2016. The abundance and distribution range assessment carried out at the farm indicated an early-stage D. vexillum invasion. The follow up dive surveys and wider loch intertidal surveys carried out in 2017 and 2018 confirmed that the D. vexillum presence continues to be associated exclusively with the oyster farm. This is the first time that such a highly invasive species has been found within a protected area of global significance and it has significant biosecurity and policy implications regarding how to manage such invasive species

First report of an egg nursery for the Critically Endangered flapper skate Dipturus intermedius (Rajiformes: Rajidae)

1. This study provides the first report of an egg nursery for the Critically Endangered flapper skate Dipturus intermedius and a description of the habitat, thus contributing towards our understanding of essential habitats for the species.  2. In total, 1,395 flapper skate egg cases were recorded (accounting for overlapping surveys) in two egg case collection dives (n = 67 egg cases), one photogrammetry dive (n = 10 egg cases), 509 drop-down video (DDV) camera drifts (n = 510 egg cases) and 18 remote operated vehicle (ROV) flights (n = 1,031 egg cases), carried out in the Inner Sound on the west coast of Scotland from 2018 to 2021. All of the egg cases were found on a shallow bedrock plateau between the Isle of Scalpay and a deep (>100 m) water channel between the Isle of Longay and the Crowlin Islands. Egg cases were observed on a cobble/boulder reef between 25 and 58 m depth, with a modelled annual temperature range of 9-12 °C, modelled current speeds up to 0.2 m-1, a rugosity index of 1.7 and low levels of sedimentation.  3. Flapper skate egg cases are large and the incubation period is protracted (18 months), making them potentially vulnerable to anthropogenic disturbance. A description of the habitat where egg cases were observed in this study will help inform the search for egg nurseries for this Critically Endangered species elsewhere. Targeted DDV, ROV and scuba diving surveys will support this search in areas where suitable bathymetric and hydrodynamic conditions are identified.  4. Safeguarding egg nurseries is essential for successful conservation. Protection should involve the designation of egg nurseries as Marine Protected Areas where activities that are likely to damage or alter seabed habitats are managed.Publisher PDFPeer reviewe