Johanne Vad

Natural products from marine and terrestrial organisms provide an important resource for medicinal chemistry and drug discovery. Defined as occurring at depths greater than 200 m, most of the ocean, by area and volume, is comprised of deep-sea environments. These contrasting ecosystems exhibit a wide range of temperature, pressure, and environmental chemistry conditions that harbour high phylogenetic diversity. Here we analyse the global distribution of Marine Natural Products (MNPs) from deep-sea organisms, which reveals chronic undersampling of the deep ocean as a reservoir of new and diverse chemical structures and bioactivity. The sources of 2909 compounds and extracts, compiled from published records, show a sampling bias towards benthic and shallower deep-sea habitats, with relatively few from areas beyond national jurisdictions and a concentration of records along geomorphological features that have been the focus of marine scientific interest such as seamounts and hydrothermal vents. The phylogenetic distribution of deep-sea MNPs is dominated by non-metazoan sources (76% of records) and Ascomycota fungi in particular (55%). Polyketides are the most prevalent metabolites in deep-sea MNPs, and cytotoxic and antibacterial properties are the most commonly reported bioactivities. Our analyses highlight a need for systematic sampling and consistent data reporting to explore potential relationships, if any, between, bioactivity, new chemical structures, phylogeny and deep-sea environmental conditions, which could guide targeted biodiscovery in our planet’s largest biome and enable better assessment of the benefits of protecting deep-sea biodiversity from human impacts.

Deep‐sea corals and sponges form ecologically significant habitats that support biodiversity hotspots and contribute to important ecosystem functions such as carbon and nutrient cycling as well as benthic‐pelagic coupling. However, quantifying their contributions to ecosystem functioning requires examination not only of the fine spatial distribution of community composition but also community size structure, because larger individuals are expected to contribute more to ecosystem functions than smaller ones. Here we create novel cumulative abundance profiles (CAPs) by combining body size structure with species abundance data to identify ecological drivers of sponge and coral community composition and size structure. Data were collected from 226 drop camera images captured near Saglek Bank, on the northern Labrador shelf and upper slope in the northwest Atlantic. The density of four coral and 17 sponge morphospecies were recorded from each image. The surface area covered by coral and sponge specimens was measured (1458 measurements in total) and converted to size estimates using data from live specimens collected with a rock dredge. Cumulative abundance profiles were then constructed and combined with cluster analysis to identify distinct community assemblages. In addition, distance‐based redundancy analysis was used to identify environmental drivers influencing cluster community composition and/or size structure. Finally, organic carbon turnover was calculated for each cluster using published respiration data. Three assemblages were identified with differing composition and size structures. One of these was characterized by large coral and sponge morphospecies and individuals. The spatial distribution of this cluster was controlled by interactions between substrate type, terrain position index (TPI) and orientation of the slope (eastness). When analysing composition or size structure separately, dissolved oxygen and current speed respectively were also identified as key parameters. This finding indicates that substrate type and TPI influence the presence of coral and sponges in the study area, while dissolved oxygen may constrain which morphospecies are present and bottom currents restrict the size of individuals. As predicted, high levels of carbon turnover were driven by large sponge and coral individuals, likely maintained in part by the sponge loop in which sponges recycle dissolved organic matter into particulate organic matter. This study gives the first demonstration of how CAPs can be used to analyse spatial variation in deep‐sea benthic community composition and size structure and appropriately quantify contribution to ecosystem functions such as carbon turnover.

The U.S. North Pacific harbors some of the densest and most diverse cold-water coral and sponge communities globally, yet quantitative data for depths below 900 m in the Gulf of Alaska and Aleutian Islands remain scarce. Most records originate from <300 m, despite ~80% of Alaska’s seafloor exceeding 200 m depth. Using Remotely Operated Vehicle video imagery from two NOAA Ocean Exploration expeditions in 2023 (Seascape Alaska 3 and 5), we conducted a quantitative, image-based assessment of deep-sea coral and sponge communities across 15 previously unvisited sites spanning 380-3,200 m depth. From 15,531 observations, we documented 164 distinct morphotypes - 90 Porifera and 74 Cnidaria - substantially extending known distributions for multiple taxa, including five sponge genera new to Alaska and the northernmost Pacific record of the coral genus Umbellapathes. Density and diversity peaked along the margins of the Oxygen Minimum Zone (~500-1,800 m; O₂ ≤1.43 mg L⁻¹). Additionally, eight high-density aggregations were identified meeting internationally recognized criteria, at densities up to 20.68 individuals/m⁻². Community composition was structured by a hierarchy of drivers, with oceanographic setting explaining most variation. These findings highlight the importance of oceanographic context in structuring deep-sea biodiversity and provide a baseline for future ecological, taxonomic, and conservation research in North Pacific deep-sea ecosystems. Understanding the distribution and drivers of cold-water coral and sponge communities is vital for anticipating ecosystem responses to future ocean scenarios and for designing effective management strategies to safeguard these vulnerable deep-sea habitats.

Holobionts formed by a host organism and associated symbionts are key biological units in marine ecosystems where they are responsible for fundamental ecosystem services. Therefore, understanding anthropogenic impacts on holobionts is essential. Sponges (Phylum Porifera) are ideal holobiont models. They host a complex microbial community and provide ecosystem services including nutrient cycling. At bathyal depths, sponges can accumulate forming dense sponge ground habitats supporting biodiverse associated communities. However, the impacts of spilled oil and dispersants on sponge grounds cannot be understood without considering exposures mediated through sponge filtration of marine snow particles. To examine this, we exposed the model sponge Halichondria panicea to oil, dispersant and “marine oil snow” contaminated seawater and elucidate the complex molecular response of the holobiont through metatranscriptomics. While the host response included detoxification and immune response pathways, the bacterial symbiotic response differed and was at least partially the result of a change in the host environment rather than a direct response to hydrocarbon exposure. As the sponge host reduced its pumping activity and internal tissue oxygen levels declined, the symbionts changed their metabolism from aerobic to anaerobic pathways possibly via quorum sensing. Furthermore, we found evidence of hydrocarbon degradation by sponge symbionts, but sponge mortality (even when exposed to low concentrations of hydrocarbons) implied this may not provide the holobiont with sufficient resilience against contaminants. Given the continued proposed expansion of hydrocarbon production into deep continental shelf and slope settings where sponge grounds form significant habitats it is important that dispersant use is minimised and that environmental impact assessments carefully consider the vulnerability of sponge holobionts.

Aim: We assessed the effects of regional oceanographic shifts on the macrofaunal biodiversity and biogeography of cold‐water coral reefs (CWCRs). CWCRs are often hotspots of biodiversity and ecosystem services and are in the frontline of exposure to multiple human pressures and climate change. Almost nothing is known about how large‐scale atmospheric variability affects the structure of CWCRs’ communities over ecological timescales, and this hinders their efficient conservation. This knowledge gap is especially evident for species‐rich macrofauna, a key component for ecosystem functioning.Location: The Mingulay Reef Complex, a protected biogenic ecosystem in the northeast Atlantic (120–190 m).Methods: A unique time series (2003–2011) at 79 stations was used to make the first assessment of interannual changes in CWCRs’ macrofaunal biodiversity, biogeography and functional traits. We quantified the impacts of interannual changes in North Atlantic Oscillation Index (NAOI)—the major mode of atmospheric variability in the North Atlantic, bottom temperature and salinity alongside static variables of seafloor terrain and hydrography.Results: Environmental gradients explained a significant amount of community composition ( = 26.7%, p < .01) with interannual changes in bottom temperature, salinity and NAOI explaining nearly twice as much variability than changes in terrain or hydrography. We observed significant differences in community composition, diversity and functional traits but not in species richness across interannual variability in bottom temperature. In warmer years, the biogeographic composition shifted more towards a temperate and subtropical affinity.Main Conclusions: Our findings highlight the necessity for thorough investigations of faunal communities in CWCRs as they may be sensitive to interannual changes in regional oceanography. Considering the scientific consensus on the substantial warming of North Atlantic by 2100, we recommend the establishment of programmes for the monitoring of CWCRs. This will support an advanced understanding of CWCRs’ environmental status over time and will serve their conservation for the future.

ICES Journal of Marine Science (2019), doi: 10.1093/icesjms/fsz185

Determining the scale of anthropogenic impacts is critical in order to understand ecosystem effects of human activities, within the context of changes caused by natural environmental variability. We applied spatial eigenfunction analysis to disentangle effects of anthropogenic drivers from environmental factors on species assembly in the Faroe-Shetland Channel (FSC), in the northeast Atlantic. We found that the species assembly considered here was structured at both small and large spatial scales. Specifically, substrate types, distance to oil wells and pipelines, the presence of objects and demersal fishing (both static and mobile) appeared significant in explaining large spatial scale species assembly structures. Conversely, temperature and variance in temperature shaped the species community across smaller spatial scales. Mobile scavenger species were found in areas impacted by demersal fishing. Oil and gas structures seemed to provide a habitat for a range of species including the commercially important fishes Molva sp. and Sebastes sp. These results demonstrate how the benthic ecosystem in the FSC has been shaped by multiple human activities, at both small and large spatial scales. Only by sampling datasets covering several sites, like in this study, can the effects of anthropogenic activities be separated from natural environmental controls.

Video and image data are regularly used in the field of benthic ecology to document biodiversity. However, their use is subject to a number of challenges, principally the identification of taxa within the images without associated physical specimens. The challenge of applying traditional taxonomic keys to the identification of fauna from images has led to the development of personal, group, or institution level reference image catalogues of operational taxonomic units (OTUs) or morphospecies. Lack of standardisation among these reference catalogues has led to problems with observer bias and the inability to combine datasets across studies. In addition, lack of a common reference standard is stifling efforts in the application of artificial intelligence to taxon identification. Using the North Atlantic deep sea as a case study, we propose a database structure to facilitate standardisation of morphospecies image catalogues between research groups and support future use in multiple front-end applications. We also propose a framework for coordination of international efforts to develop reference guides for the identification of marine species from images. The proposed structure follows the Darwin Core standard to allow integration with existing databases. We suggest a management framework where high-level taxonomic groups are curated by a regional team, consisting of both end users and taxonomic experts. We identify a mechanism by which overall quality of data within a common reference guide could be raised over the next decade. Finally, we discuss the role of a common reference standard in advancing marine ecology and supporting sustainable use of this ecosystem.