Imagery has become one of the main data sources for investigating seascape spatial patterns. This is particularly true in deep-sea environments, which are only accessible with underwater vehicles. On the one hand, using collaborative web-based tools and machine learning algorithms, biological and geological features can now be massively annotated on 2D images with the support of experts. On the other hand, geomorphometrics such as slope or rugosity derived from 3D models built with structure from motion (sfm) methodology can then be used to answer spatial distribution questions. However, precise georeferencing of 2D annotations on 3D models has proven challenging for deep-sea images, due to a large mismatch between navigation obtained from underwater vehicles and the reprojected navigation computed in the process of building 3D models. In addition, although 3D models can be directly annotated, the process becomes challenging due to the low resolution of textures and the large size of the models. In this article, we propose a streamlined, open-access processing pipeline to reproject 2D image annotations onto 3D models using ray tracing. Using four underwater image datasets, we assessed the accuracy of annotation reprojection on 3D models and achieved successful georeferencing to centimetric accuracy. The combination of photogrammetric 3D models and accurate 2D annotations would allow the construction of a 3D representation of the landscape and could provide new insights into understanding species microdistribution and biotic interactions.

Climate change is known to affect the distribution and composition of species, but concomitant alterations to functionally important aspects of behaviour and species-environment relations are poorly constrained. Here, we examine the ecosystem ramifications of changes in sediment-dwelling invertebrate bioturbation behaviour-a key process mediating nutrient cycling-associated with near-future environmental conditions (+ 1.5 °C, 550 ppm [pCO2]) for species from polar regions experiencing rapid rates of climate change. We find that responses to warming and acidification vary between species and lead to a reduction in intra-specific variability in behavioural trait expression that adjusts the magnitude and direction of nutrient concentrations. Our analyses also indicate that species behaviour is not predetermined, but can be dependent on local variations in environmental history that set population capacities for phenotypic plasticity. We provide evidence that certain, but subtle, aspects of inter- and intra-specific variation in behavioural trait expression, rather than the presence or proportional representation of species per se, is an important and under-appreciated determinant of benthic biogeochemical responses to climate change. Such changes in species behaviour may act as an early warning for impending ecological transitions associated with progressive climate forcing.

The impact of ocean warming on fish and fisheries is vigorously debated. Leading theories project limited adaptive capacity of tropical fishes and 14-39% size reductions by 2050 due to mass-scaling limitations of oxygen supply in larger individuals. Using the world\'s hottest coral reefs in the Persian/Arabian Gulf as a natural laboratory for ocean warming - where species have survived >35.0 °C summer temperatures for over 6000 years and are 14-40% smaller at maximum size compared to cooler locations - we identified two adaptive pathways that enhance survival at elevated temperatures across 10 metabolic and swimming performance metrics. Comparing Lutjanus ehrenbergii and Scolopsis ghanam from reefs both inside and outside the Persian/Arabian Gulf across temperatures of 27.0 °C, 31.5 °C and 35.5 °C, we reveal that these species show a lower-than-expected rise in basal metabolic demands and a right-shifted thermal window, which aids in maintaining oxygen supply and aerobic performance to 35.5 °C. Importantly, our findings challenge traditional oxygen-limitation theories, suggesting a mismatch in energy acquisition and demand as the primary driver of size reductions. Our data support a modified resource-acquisition theory to explain how ocean warming leads to species-specific size reductions and why smaller individuals are evolutionarily favored under elevated temperatures.

The Cosmonaut Sea is one of the least accessed regions in the Southern Ocean, and our knowledge about the fish biodiversity in the region is sparse. In this study, we provided a description of demersal fish diversity in the Cosmonaut Sea by analysing cytochrome oxidase I (COI) barcodes of 98 fish samples that were hauled by trawling during the 37th and 38th Chinese National Antarctic Research Expedition (CHINARE) cruises. Twenty-four species representing 19 genera and 11 families, namely, Artedidraconidae, Bathydraconidae, Bathylagidae, Channichthyidae, Liparidae, Macrouridae, Muraenolepididae, Myctophidae, Nototheniidae, Paralepididae and Zoarcidae, were discriminated and identified, which were largely identical to local fish occurrence records and the general pattern of demersal fish communities at high Antarctic shelf areas. The validity of a barcoding gap failed to be detected and confirmed across all species due to the indicative signals of two potential cryptic species. Nevertheless, DNA barcoding still demonstrated to be a very efficient and sound method for the discrimination and classification of Antarctic fishes. In the future, various sampling strategies that cover all geographic sections and depth strata of the Cosmonaut Sea are encouraged to enhance our understanding of local fish communities, within which DNA barcoding can play an important role in either molecular taxonomy or the establishment of a dedicated local reference database for eDNA metabarcoding analyses.

A novel fibrinolytic enzyme, BSFE1, was isolated from the marine bacterium Bacillus sp. S-3685 (GenBank No.: KJ023685) found in the South China Sea. This enzyme, with a molecular weight of approximately 42 kDa and a specific activity of 736.4 U/mg, exhibited its highest activity at 37 °C in a phosphate buffer at pH 8.0. The fibrinolytic enzyme remained stable over a pH range of 7.5 to 10.0 and retained about 76% of its activity after being incubated at 37 °C for 2 h. The Km and Vmax values of the enzyme at 37 °C were determined to be 2.1 μM and 49.0 μmol min-1 mg-1, respectively. The fibrinolytic activity of BSFE1 was enhanced by Na+, Ba2+, K+, Co2+, Mn2+, Al3+, and Cu2+, while it was inhibited by Fe3+, Ca2+, Mg2+, Zn2+, and Fe2+. These findings indicate that the fibrinolytic enzyme isolated in this study exhibits a strong affinity for fibrin. Moreover, the enzyme we have purified demonstrates thrombolytic enzymatic activity. These characteristics make BSFE1 a promising candidate for thrombolytic therapy. In conclusion, the results obtained from this study suggest that our work holds potential in the development of agents for thrombolytic treatment.

BACKGROUND: The nervous system is central to coordinating behavioural responses to environmental change, likely including ocean acidification (OA). However, a clear understanding of neurobiological responses to OA is lacking, especially for marine invertebrates.
RESULTS: We evaluated the transcriptomic response of the central nervous system (CNS) and eyes of the two-toned pygmy squid (Idiosepius pygmaeus) to OA conditions, using a de novo transcriptome assembly created with long read PacBio ISO-sequencing data. We then correlated patterns of gene expression with CO2 treatment levels and OA-affected behaviours in the same individuals. OA induced transcriptomic responses within the nervous system related to various different types of neurotransmission, neuroplasticity, immune function and oxidative stress. These molecular changes may contribute to OA-induced behavioural changes, as suggested by correlations among gene expression profiles, CO2 treatment and OA-affected behaviours.
CONCLUSIONS: This study provides the first molecular insights into the neurobiological effects of OA on a cephalopod and correlates molecular changes with whole animal behavioural responses, helping to bridge the gaps in our knowledge between environmental change and animal responses.

Record mean sea surface temperatures (SST) during the past decades and marine heatwaves have been identified as responsible for severe impacts on marine ecosystems, but the role of changes in the patterns of temporal variability under global warming has been much less studied. We compare descriptors of two time series of SST, encompassing extirpations (i.e. local extinctions) of six cold-temperate macroalgae species at their trailing range edge. We decompose the effects of gradual warming, extreme events and intrinsic variability (e.g. seasonality). We also relate the main factors determining macroalgae range shifts with their life cycles characteristics and thermal tolerance. We found extirpations of macroalgae were related to stretches of coast where autumn SST underwent warming, increased temperature seasonality, and decreased skewness over time. Regardless of the species, the persisting populations shared a common environmental domain, which was clearly differentiated from those experiencing local extinction. However, macroalgae species responded to temperature components in different ways, showing dissimilar resilience. Consideration of multiple thermal manifestations of climate change is needed to better understand local extinctions of habitat-forming species. Our study provides a framework for the incorporation of unused measures of environmental variability while analyzing the distributions of coastal species.

Animal-borne tags are effective instruments for collecting ocean data and can be used to fill spatial gaps in the observing network. We deployed the first conductivity, temperature, and depth (CTD) satellite tags on the dorsal fin of salmon sharks (Lamna ditropis) to demonstrate the potential of sharks to monitor essential ocean variables and oceanographic features in the Gulf of Alaska. Over 1360 km and 36 days in the summer of 2015, the salmon shark collected 56 geolocated, temperature-salinity profiles. The shark swam through a plume of anomalously salty water that originated from the \"Blob\" and encountered several mesoscale eddies, whose subsurface properties were altered by the marine heatwave. We demonstrate that salmon sharks have the potential to serve as submesoscale-resolving oceanographic platforms and substantially increase the spatial coverage of observations in the Gulf of Alaska.

BACKGROUND: The deep (> 200 m) ocean floor is often considered to be a refugium of biodiversity; many benthic marine animals appear to share ancient common ancestry with nearshore and terrestrial relatives. Whether this pattern holds for vertebrates is obscured by a poor understanding of the evolutionary history of the oldest marine vertebrate clades. Hagfishes are jawless vertebrates that are either the living sister to all vertebrates or form a clade with lampreys, the only other surviving jawless fishes.
RESULTS: We use the hagfish fossil record and molecular data for all recognized genera to construct a novel hypothesis for hagfish relationships and diversification. We find that crown hagfishes persisted through three mass extinctions after appearing in the Permian ~ 275 Ma, making them one of the oldest living vertebrate lineages. In contrast to most other deep marine vertebrates, we consistently infer a deep origin of continental slope occupation by hagfishes that dates to the Paleozoic. Yet, we show that hagfishes have experienced marked body size diversification over the last hundred million years, contrasting with a view of this clade as morphologically stagnant.
CONCLUSIONS: Our results establish hagfishes as ancient members of demersal continental slope faunas and suggest a prolonged accumulation of deep sea jawless vertebrate biodiversity.

Fluorescence is a widespread phenomenon found in animals, bacteria, fungi, and plants. In marine environments fluorescence has been proposed to play a role in physiological and behavioral responses. Many fluorescent proteins and other molecules have been described in jellyfish, corals, and fish. Here we describe fluorescence in marine species, which we observed and photographed during night dives in the Banda Sea, Indonesia, and in the Red Sea, Egypt. Among various phyla we found fluorescence in sponges, molluscs, tunicates, and fish. Our study extends the knowledge on how many different organisms fluoresce in marine environments. We describe the occurrence of fluorescence in 27 species, in which fluorescence has not been described yet in peer-reviewed literature. It especially extends the knowledge beyond Scleractinia, the so far best described taxon regarding diversity in fluorescent proteins.