Scottish Association For Marine Science

The planktonic marine diatom genus Pseudo-nitzschia is synonymous with the neurotoxin domoic acid (DA), which causes the syndrome amnesic shellfish poisoning (ASP). DA can bioaccumulate in shellfish during blooms of specific, toxin-producing Pseudo-nitzschia, harming wildlife and human health. Phenotypic discrimination of variants requires electron microscopic observation of the frustule, a process too time-consuming for routine monitoring, which invariably uses light microscopy. This process is less specific and has poor correlation with accumulation of DA in shellfish. The assay outlined here targets the ribosomal DNA gene, providing species resolution of Pseudo-nitzschia. It combines recombinase polymerase amplification (RPA) with nanopore sequencing and is effective on almost all known Pseudo-nitzschia species. It provides preliminary, real-time indication of environmental species composition, and further bioinformatic processing confirms results. Validation experiments correctly identified 13 reference cultures, with sufficient sensitivity (2500 cells l-1). Two environmental case studies highlighted efficacy on complex natural Pseudo-nitzschia blooms, including detection of low abundance species. The first study consisted of 37 samples collected from Scottish waters between May 2022 and August 2023, which identified 13 species. The second consisted of 10 samples from Aotearoa (New Zealand) collected February 2025, which found 17 species. Both studies identified species previously undetected in the regions. Statistical analysis of complementary toxin data from Scotland, although limited, highlighted that relative abundance of toxic species was a better predictor of toxic events than genus level cell counts. The RPA assay was also adapted to a lateral flow dipstick, providing a rapid screening tool for toxic Pseudo-nitzschia seriata and Pseudo-nitzschia australis.

ABSTRACTPeter I Island is one of the most isolated and least visited islands on earth; lying within the Antarctic Polar Front but over 420 km from continental Antarctica makes it inherently interesting to study in the context of polar biogeography. First discovered in 1821, it was only landed on in 1929 due to challenging ice conditions. Subsequent landings for scientific exploration have been rare, with the primary focus on geological studies and limited biodiversity assessments. To date, only two dedicated marine biodiversity surveys have been conducted, revealing unexpectedly high diversity but limited taxonomic coverage. We provide a comprehensive species list of the area by compiling all previous records with our own data collected in January 2022. Here, a BioBlitz was conducted on the island and surrounding waters, documenting terrestrial, avian and marine species. We identify 15 species new to the region, including benthic and pelagic fauna, as well as an expanded understanding of cetacean and pinniped presence in the area. Marine SCUBA surveys revealed diverse algal and invertebrate communities, emphasising Peter I Island's unique ecological makeup within the Antarctic marine ecosystem. This study establishes a critical biodiversity baseline for ongoing monitoring as the island faces potential ecological shifts due to global change.

<strong class="journal-contentHeaderColor">Abstract.</strong> The Rockall Trough (RT) channels an important branch of the North Atlantic Current (NAC), transporting heat from the Gulf Stream toward the Nordic Seas, and the European Slope Current (ESC) which flows northward along its eastern boundary. Variability in the NAC influences poleward heat transport and the strength of the Atlantic Meridional Overturning Circulation, while the ESC plays a key role for the oceanic conditions on the European shelf and the North Sea. Here we present observed volume, heat, and freshwater transports through the Rockall Trough from 2014 to 2022, using data from Ellett Array moorings (operational since 2014) and gliders (deployed from 2020 onward). Although gliders provide high-resolution spatial data in the ESC, their inconsistent temporal coverage complicates their integration into RT transport estimates. We develop a methodology to merge mooring and glider observations into a unified, high-resolution time series, producing&mdash;for the first time&mdash;a continuous ESC transport dataset spanning nearly a decade. This demonstrates the effectiveness of heterogeneous observing arrays and provides a transferable framework for sustained ocean transport monitoring.

<strong class="journal-contentHeaderColor">Abstract.</strong> The Rockall Trough (RT) channels an important branch of the North Atlantic Current (NAC), transporting heat from the Gulf Stream toward the Nordic Seas, and the European Slope Current (ESC) which flows northward along its eastern boundary. Variability in the NAC influences poleward heat transport and the strength of the Atlantic Meridional Overturning Circulation, while the ESC plays a key role for the oceanic conditions on the European shelf and the North Sea. Here we present observed volume, heat, and freshwater transports through the Rockall Trough from 2014 to 2022, using data from Ellett Array moorings (operational since 2014) and gliders (deployed from 2020 onward). Although gliders provide high-resolution spatial data in the ESC, their inconsistent temporal coverage complicates their integration into RT transport estimates. We develop a methodology to merge mooring and glider observations into a unified, high-resolution time series, producing&mdash;for the first time&mdash;a continuous ESC transport dataset spanning nearly a decade. This demonstrates the effectiveness of heterogeneous observing arrays and provides a transferable framework for sustained ocean transport monitoring.

ABSTRACTTo date, environmental conditions have been enough to act as an effective barrier to prevent non‐indigenous species from arriving and establishing in Arctic Canada. However, rapidly changing climatic conditions are creating more suitable habitats for non‐indigenous species to potentially establish and become invasive. Concurrently, shipping traffic in parts of Arctic Canada has increased by over 250% since 1990, providing an effective vector for transporting non‐indigenous species to the region. Arctic Canada has been historically undersampled, so Arctic biota inventories are incomplete, hampering efforts to establish if a species is new to the region (and potentially invasive) or newly discovered. In this study, we utilize environmental DNA (eDNA) metabarcoding and ships of opportunity to assess eukaryotic community composition and potential invasives along one of the busiest shipping routes, the Northwest Passage. One liter seawater samples were collected in triplicate at 27 locations, targeting touristic hotspots frequently visited by passenger vessels. Eukaryotic DNA was amplified from the 18S rRNA V9 and COI regions, resulting in 126 unique Amplicon Sequence Variants (ASVs) detected with COI and 391 ASVs with 18S, providing an important snapshot of current community composition. Copepods, dinoflagellates, and diatoms were the most abundant taxonomic groups, correlating well with previous net sampler surveys, validating the efficacy of eDNA for biodiversity surveillance. We also report the first detections of a prolific invasive species, the bay barnacle (Amphibalanus improvisus), in Arctic Canada. Further work is currently in progress to establish whether these detections represent transient barnacle larvae or sessile adults capable of recruiting and reproducing. Our study demonstrates the utility of eDNA for the detection of non‐indigenous species in a data‐poor area, which, if combined with citizen science initiatives and local communities, could provide a vital monitoring tool for the detection of new invasives in this rapidly changing area.

Background: Population persistence for organisms to survive in a world with a rapidly changing climate will require either dispersal to suitable areas, evolutionary adaptation to altered conditions and/or sufficient phenotypic plasticity to withstand it. Given the slow growth and geographically isolated populations of many tree species, there is a high likelihood of local adaption or the acclimation of functional traits in these populations across the UK. Objectives: Given the slow growth and often isolated populations of Tilia cordata (lime tree), we hypothesised that there is a high likelihood of local adaptation or the acclimation of metabolic traits in these populations across the UK. Our aim was to test if the functional metabolomic traits of Tilia cordata (lime tree), collected in situ from natural populations, varied within and between populations and to compare this to neutral allele variation in the population. Methods: We used a metabolic fingerprinting approach to obtain a snapshot of the metabolic status of leaves collected from T. cordata from six populations across the UK. Environmental metadata, longer-term functional traits (specific leaf area) and neutral allelic variation in the population were also measured to assess the plastic capacity and local adaptation of the species. Results: The metabolic fingerprints derived from leaf material collected and fixed in situ from individuals in six populations of T. cordata across its UK range were similar, despite contrasting environmental conditions during sampling. Neutral allele frequencies showed almost no significant group structure, indicating low differentiation between populations. The specific leaf area did vary between sites. Conclusions: The low metabolic variation between UK populations of T. cordata despite contrasting environmental conditions during sampling indicates high levels of phenotypic plasticity.

There is an increasing reliance on passive acoustic monitoring (PAM) as a cost-effective method for monitoring cetaceans, necessitating robust and efficient automated tools for extracting species presence. This work compares two methods, one based on the 'off-line' analysis of raw PAM data, using Convolutional Neural Networks (CNNs), and the second based on in-situ detections, implemented within the C-POD. The C-POD is a rapid, low-cost choice for monitoring of odontocetes, while CNNs, requiring large efforts to train, are gaining traction within bioacoustics as they offer performance benefits above standard detection and classification tools. This work represents the first empirical comparison of a C-POD with a system using a CNN on recorded raw acoustic data for monitoring delphinids. The comparison is based on 3000 hours of PAM data, collected off the west coast of Scotland, using a collocated C-POD and SoundTrap acoustic recorder. Results show that the system using a CNN achieves an overall accuracy of 0.82, and an effectiveness (F1-Score) of 0.78 as a click detector, whilst the C-POD achieves scores of 0.71 and 0.62, respectively. The method employing a CNN provides a lower missed detection rate, with the C-POD failing to detect > 90% delphinid positive hours at one focal site. However, the C-POD offered a lower false-positive rate across all analysis sites. This work highlights the importance of incorporating the right automated tools for long-term species monitoring, as the C-POD offers high precision rates for click detections, while the CNN based system provides a robust approach to identifying seasonal and diurnal trends in long-term dolphin occurrence.

Organic falls, hydrothermal vent fields and seeps rely primarily on chemosynthetic organic production leading to a carbon enriched habitat set against the oligotrophic deep-sea background. These habitats are typically inhabited by novel faunal assemblages with similar functional characteristics and often show harsh environmental gradients over relatively small scales with severe effects on diversity and density compared to the benthic background fauna. While the importance of particulate organic matter (POM) has been pointed out, the presence of POM as local accumulated organic deposits within hydrothermal vent fields has not been studied. Here, we present the first observations of organic deposits within active vents in the Indian Ocean including observations of giant capitellid worms inhabiting these organic mats with a length of up to 30 cm. This potential new species occurred in shrimp carcasses, the exuvia of Rimicaris kairei , on two hydrothermal vent sites from the Indian Ocean. We used imagery to build a high-resolution 3D reconstruction model of one side of a chimney complex, including the 4.8 m 2 surface area of the exuvia deposit. The capitellids occurred in dense aggregations and may contribute significantly to the food web of active hydrothermal vent fields, representing a possible overlooked food source for benthic and demersal predators. In addition, we report on observations on further organic deposit types and compare their associated epifauna along the mid-ocean ridges of the Indian Ocean. The exuvia deposits where capitellids were present appeared to be compacted and compressed implicating a potential role in stabilizing seafloor habitat. This is the first record of the family Capitellidae in organic deposits at hydrothermal vent fields, where they may serve as ecosystem engineers. • First report of organic deposits and associated megafauna at hydrothermal vents. • Potential new species of polychaetes (Capitellidae). • Capitellids may act as engineering species and increase taxonomic richness. • High frequency of capitellids may influence food-web dynamics within active vents.

Cyanobacteria oxygenated the atmosphere of early Earth and continue to be key players in global carbon and nitrogen cycles. A phylogenetically diverse subset of extant cyanobacteria can perform photosynthesis with far-red light through a process called far-red light photoacclimation, or FaRLiP. This phenotype is enabled by a cluster of ∼20 genes and involves the synthesis of red-shifted chlorophylls d and f, together with paralogs of the ubiquitous photosynthetic machinery used in visible light. The FaRLiP gene cluster is present in diverse, environmentally important cyanobacterial groups, but its origin, evolutionary history, and connection to early biotic environments have remained unclear. This study takes advantage of the recent increase in (meta)genomic data to help clarify this issue: sequence data mining, metagenomic assembly, and phylogenetic tree networks were used to recover more than 600 new FaRLiP gene sequences, corresponding to 51 new gene clusters. These data enable high-resolution phylogenetics and-by relying on multiple gene trees, together with gene arrangement conservation-support FaRLiP appearing early in cyanobacterial evolution. Sampling information shows that considerable FaRLiP diversity can be observed in microbialites to the present day, and we hypothesize that the process was associated with the formation of microbial mats and stromatolites in the early Paleoproterozoic. The ancestral FaRLiP cluster was reconstructed, revealing features that have been maintained for billions of years. Overall, far-red-light-driven oxygenic photosynthesis may have played a significant role in Earth's early history.