Mathilde Godefroid has just published a new research paper “Higher daily temperature range at depth is linked with higher thermotolerance in antipatharians from the canary islands”, out in the Journal of Thermal Biology.
Sensitivity to ocean warming is generally expected to be lower in populations from more heterogeneous thermal environments, owing to greater phenotypic plasticity and/or genotype selection. While resilience of benthic populations from thermally fluctuating environments has been investigated at a variety of spatial scales, this has received limited attention across depths and has remained unresolved for Antipatharian corals, key habitat- forming species across a wide bathymetric range in all of the world oceans. In this study, we aimed at addressing the thermal sensitivity of Antipatharian corals across depths characterized by different levels of temperature fluctuations. We used an acute ramping experimental approach to compare the thermal sensitivity of colonies of (1) the branched Antipatharian Antipathella wollastoni (Gray, 1857) from two distinct depths (25 and 40 m) in Gran Canaria (Canary Islands, Spain); and of (2) unbranched mesophotic (80 m) Stichopathes species, from Lanzarote (Canary Islands, Spain; S. gracilis (Gray, 1857)), and Stichopathes sp. clade C from Mo’orea, French Polynesia. Results showed that the daily temperature range in Gran Canaria was larger at mesophotic depths (3.9 ◦C vs. 2.8 ◦C at 40 and 25 m, respectively) and this coincided with lower thermal sensitivity in mesophotic colonies of A. wollastoni. Second, S. gracilis from Lanzarote showed a lower thermal sensitivity than the previously studied Stichopathes sp. clade C from Mo’orea (French Polynesia) inhabiting a less variable habitat. These results are in line with the climate variability hypothesis, which states that populations under more variable thermal conditions have a lower sensitivity to warming than those from more stable environments, as they have adapted/acclimated to these higher levels of temperature fluctuations.
We have just released the TANGO1 expedition report. The report will give you an overview of the activities of the TANGO1 team in the West Antarctic Peninsula, onboard RV Australis.
The TANGO1 expedition ventured to accumulate new data on the responses of marine ecosystems to shifts in ice regimes in the West Antarctic Peninsula (WAP), taking full advantage of a nimble sampling platform, the R/V Australis, a steel hulled, fully rigged motor sailor. TANGO1 took place between February and March 2023, sampling two main locations at different spatial scales. Deploying 14 different types of gear (both traditional and modern), the TANGO1 team gathered over 4000 samples that will be brought back to Belgium for further analysis. The team focused on synchronized, transdiciplinary sampling to understand the linkages between realms (atmosphere, sea-ice, watercolumn, seafloor) and there potential responses to changes in climate-changed linked ice regime at various spatial scales. The use of R/V Australis for coastal studies deemed to be extremely efficient, in terms of environmental impact (ca. 40 times less CO2 emissions than a Polar class icebreaker) and reactivity, allowing the team to adapt the sampling efforts in function of the weather or anchoring conditions. Fully devoted to the expedition, the ship allowed the B121 team to sample in shallow areas, not accessible to icebreaker and too far away from research stations, and which have been under sampled.
The preliminary (meta)results accumulated during TANGO1 confirm the efficiency of using a nimble research platform to study fine-scale processes in the shallow areas of unchartered regions of the West Antarctic Peninsula. TANGO1 provides a first-hand experience to carry an ambitious TANGO2 expedition. Based upon Open Science approaches, the combination of B121/TANGO1 efficiency in sampling paves the way to testing the transposability of the concept to multiply similar efforts in a coordinated fashion. An overview of initial results is provided below: Fine-scale bathymetry An estimated 30 hours were spent to generate sufficient data to generate bathymetric maps All visited sampling sites were charted. The bathymetric exercise allowed reaching a very high sampling efficiency (for example for selecting preferential areas to deploy the SCUBA divers). As a side benefit, the generation charts allowed to identify and flag dangers to navigation which were immediately communicated to relevant hydrographic authorities. Aerial mapping A total of 16 drone flights were carried out during the TANGO1 expedition, generating large quantities of media fit for different purposes. Deployment of drones was found to be useful in terms of scouting when arriving in new work station, documenting their general setup as well as carrying out more sophisticated works including orthomosaic (2D) and photogrammetry (3D). Combined to other georeferenced layer gathered during the TANGO1 expedition (ROV imagery, bathymetry, etc…) the aerial imagery has a promising potential in terms of geospatial analysis at a scale matching the distribution of the sampling efforts. Oceanography In total, 15 CTD profiles were taken in different locations of Dodman Island and Blaiklock Island. Sediment trap were deployed successfully after coordinated recovery of the sample bottle and release by divers and surface recovery. One sediment trap (ST1) has been deployed at Dodman Island while another deployment (ST2) took place in Blaiklock Island. More particles were recovered at Blaiklock Island compared to Dodman Island, suggesting a significantly higher particle fluxes in Blaiklock Island. Sea-ice works We sampled two drifting ice floes: ICE-1 nearby Dodman Island, and ICE-2 at station 3 of Blaiklock island. Even though the ICE-1 floe was drifting, the overall aspect of it, the fact that we observed remaining landfast ice in person or by remote sensing in areas less than 30km away (Dimitrov Cove and Crates Bay respectivally), suggest it was landfast ice recenty detached. Ice floe ICE-2 was found at site 3 of Blaiklock island and was surrounded by floating glacial ice. The floe was thinner and less homogeneous than floe ICE-1 as the floe grew around a piece of glacial ice and was likely a remnant piece of landfast ice. Salinity of the floe was quite low for a first year sea ice, with an uncommon salinity profile. We hypothesize that the low salinity profile observed in Blaiklock, with salinity down to 0 at the surface, was due to rainfall washing down the ice. Soft sediments biodiversity and biogeochemistry The amount of samples and the storage of the samples generated for the sediment biogeochemistry part are available further in the report., In the next year the preliminary data generated during the incubations will be quality checked and the setup will be discussed with colleagues at the Ghent Marine Biology Laboratory. The samples for both the incubation measurements, the sediment environmental data, and the stable isotope analysis will be carried out. The results from the field samples will inform priorities for the upcoming campaigns and will help deciding on the feasibility of such detailed and time- consuming measurements aboard of a nimble vessel that was not originally designed to host these types of technically complex, detailed and time-consuming measurements. Benthic habitat mapping In Dodman Island, 6 different sites were sampled with a total of 20 recorded squares using a Remotely Operated Vehicle (ROV). When a squared-shaped pattern was not possible, the site was sampled by transects. In Blaiklock Island, our second sampling station, 3 contrasting sites were sampled as well as 3 sub-locations in one of the sites to characterize small scale heterogeneity. In total, 12 squares and 2 transects were sampled. Back in the Laboratory, the images will be used to create photomosaics from which we will calculate biodiversity indices ( and ), evenness/dissimilarity indices (Species Richness, Shannon-Wiener, Simpson) and functional diversity (Functional Dispersion, Rao’s Quadriatic Entropy). Then, to compare our results between sites, we will use multivariable correlative approaches (such as a Canonical Correspondence Analysis and NMDS analyses). For characterizing how benthic communities respond to environmental heterogeneities, we will perform Spatial Point Process Analyses (SPPA). To build predictive models, and investigate the drivers of ecosystem responses to their changing environment, we will use Bayesian Network Inference (BNI) analysis. Macro- and megabenthos diversity All sample collected in the different events of Rauschert Dredge and the Amphipod Trap have been partially sorted on board of Australis during the expedition. Representants of the major taxa present in the catch were isolated and counted whenever time and space were available. As agreed during the preparation of the expedition, all sorted taxa and unsorted subsamples were fixed in ethanol to be processed further thoroughly in the lab by master or PhD thesis students. Top Predators census (TOPP) Species encountered in the Magellanic area, Drake Passage, Dodman Island, Blaiklock Island and along the Antarctic Peninsula are enumerated hereunder with preliminary considerations. Overall, most species expected to be seen were observed during this voyage at the exception of the Antarctic Petrel (Thalassoica antarctica) for which not a single individual was found, which is rather unusual especially in the Bransfield Strait and South Shetland Island. Killer Whale (Orcinus orca s.l.) despite our intensive search remained equally out of sight during this expedition. Sea urchins microbiota A total of 150 urchins was processed onboard during the expedition. Due to their high abundance at all locations, there was no issue with the collection of specimens. Sizes however varied strikingly from one location to another, a variability that will be investigated into more details. Samples preserved dried and in ethanol will be analyzed upon return in Belgium for trophic niche characterization. Sexing (observation of gonad tissues) and genetic (test tissue) analyses will also be performed in Belgium as well as DNA extractions for microbiome characterization. Underwater photography This part of the project was a first approach in documenting the work and illustrating biodiversity during the expedition. Many improvements can be implemented and notably having dedicated dives to illustrate a maximum of the diversity encountered. The creation of a reference library for live specimens coupled with DNA barcoding effort is also considered. Such efforts are important and more and more valuable, especially in studies using metabarcoding/eDNA approaches. Diving A total of 30 logged dives were performed by the team of four divers collecting a total of 828 unique samples consisting of sediment cores, photo and videos and handpicking and transect collection of megafauna specimens and macroalgae. The average dive time was 30 min, the maximum dive time was 51 min. The average depth was 19 m and the maximum depth was 25 m. More details will be provided in the dedicated Scientific Diving Activity Report to be found on the Tango I website.
Three members of the BIOMAR Lab are participating in the ongoing TANGO expedition (taking place from 13 February to 19th March 2023). Lea Katz, Camille Moreau and Bruno Danis are currently in Antarctica, onboard RV Australis to contribute to our understanding of Southern Ocean ecosystem responses to environmental change. The expedition is led by Bruno Danis and Camille Moreau and Lea Katz are part of the scientific diving team, and are working on biodiversity and habitat mapping studies pertaining to the TANGO project, funded by the Belgian Science Policy Office (BELSPO).
The TANGO team sampling an ice floe in the Grandidier Channel (West Antarctic Peninsula). Photo: Camille Moreau
The TANGO team includes:
RV Australis crew: Ben Wallis , Ocean Expeditions (Skipper), Annette Bombosch (First mate), Maria Amenabar (Stewardess)
Scientific Party: Bruno Danis, Université Libre de Bruxelles (Chief Scientist), Henri Robert, Environmental Measurements – Conservation & Consciousness, Camille Moreau, Université Libre de Bruxelles, Lea Katz, Université Libre de Bruxelles, Francesca Pasotti, University of Gent (Lead Diver), Marius Buydens, University of Gent, Bruno Delille, University of Liège, Axelle Brusselman, University of Liège, Martin Dogniez, University of Liège
More information is available from the TANGO website.
You can follow the team’s progress on Facebook, Twitter and Instagram. The map below shows the progress of the expedition on Polarstep.
Three members of the BIOMAR, Lea Katz, Camille Moreau and Bruno Danis are now getting ready for a new expedition to the Southern Ocean, onboard a sailboat, the RV Australis (skipped by Ben Wallis, Ocean Expeditions). The TANGO1 expedition is funded by the Belgian Science Policy Office under the BRAIN-BE umbrella.
, The RV Australis, our research platform during the TANGO1 expedition
Lea Katz will be in charge of the ROV (Remotely Operated Vehicle) flights and is a (BSD-certified) scientific diver, Camille Moreau is also a BSD diver and will be in charge of intertidal and benthic sampling and Bruno Danis is leading the expedition. The team will also include researchers from the University of Gent, and University of Liège.
The Bluerobotics ROV we will be deploying during the expedition
A few days before departure, we are in Ushuaia, Argentina to prepare the vessel for the voyage, which will be a continuation of the Belgica 121 expedition, led by Bruno Danis in 2019. The overall objective of the expedition is to contribute to our understaning of ecosystem responses to rapid environmental change in the West Antarctic Peninsula, while using a research platform with limited environmental impact.
Zoologist Péron and artist Lesueur, both members of the scientific staff of the Baudin expedition to the Southern Lands (September 1800-March 1804), collected during their voyage 36 different species of asteroids. This is what wrote Lamarck in a report made in June 1804. This number was clearly reduced by Lamarck himself who, in his 1816 publication, listed only 15 species from the South Seas in the Paris Museum collection. However, the different asteroids collected during the expedition were drawn by Lesueur (water colours and pencil drawings) who thus realised a real pictorial register. Lesu- eur’s drawings are housed in the Le Havre Museum. Due to their realism and precision, the drawings make it easy to identify the species. Confrontation of Lamarck’s report (1804) and publication (1816) with Lesueur’s drawings (done between 1802 and 1804) gives a new, more precise idea of the impor- tance of the collection of South Seas asteroids brought back to France and allows to reliably count the number of new species that it contained. Also, this makes it possible to complete the often too brief descriptions of some Lamarckian species and to clarify their status. Eleven taxonomic changes are thus proposed here: Asterias calcar var. quinqueangula is synonymized with Parvulastra exigua (Lamarck, 1816), Asterias calcitrapa var. 1 with Bollonaster pectinatus (Sladen, 1883), Asterias calcitrapa var. 2 withAstropecten vappa Müller & Troschel, 1843, Asterias nodosa var. 3 with Protoreaster lincki (Blainville, 1830), Asterias pentagonula with Tosia australis Gray, 1840, Asterias pleyadella with Protoreaster sp., Asterias punctata with Asteropsis carinifera (Lamarck, 1816), Asterias rosacea var. lobis senis with Anse- ropoda sp., Asteriscus setaceus with Paranepanthia grandis (H. L. Clark, 1928), Astrogonium lamarckii Müller & Troschel, 1842 with Goniaster tessellatus (Lamarck, 1816) and Asterias cuspidata is moved to the genus Mediaster Stimpson, 1857 as Mediaster cuspidatus (Lamarck, 1816) n. comb.
A new article by Quentin Jossart et al. has just been published in the Zoological Journal of the Linnean Society. Our paper uses an integrative approach in discriminating species, for taxa characterized by the difficulty to identify species based on morphological characters. In this study, we combine genetics and morphology to assess the diversity of Pterasteridae, a sea star family diversified in deep-sea and polar environments. Because of their derived anatomy and the frequent loss of characters during preservation, Pterasteridae are a suitable case for an integrative study. The molecular identification of 191 specimens (mostly from the Southern Ocean) suggests 26–33 species in three genera (Diplopteraster, Hymenaster and Pteraster), which match the morphological identification in 54–62% of cases. The mismatches are either different molecular units that are morphologically indistinguishable (e.g. Pteraster stellifer units 2 and 4) or, conversely, nominal species that are genetically identical (e.g. Hymenaster coccinatus/ densus/praecoquis). Several species are shared between the Northern and Southern Hemispheres (e.g. Pteraster jordani/affinis). In conclusion, the taxonomic status of some groups is confirmed, but for others we find the need to re-evaluate the taxonomy at both genus and species levels. This work significantly increases the DNA barcode library of the Southern Ocean species and merges taxonomic information into an identification key that could become a baseline for future studies (pterasteridae-so.identificationkey.org).
In the framework of the collaborative FED-tWIN research programme between Belgian federal institutes and universities by the Belgian Federal Science Policy Office (BELSPO), the Project SO-BOMP (Southern Ocean Biodiversity Observations, Models and Policy) is recruiting a post-doctoral candidate (for a period of minimum 10 years). The position is shared between our Lab and the Royal Belgian Institute of Natural Sciences.
The Marine Biology Lab (Bruno Danis) was involved in a publication of in Nature in March 2020. Bruno Danis was a member of the data processing and analyzing team and participated in the drafting of the manuscript.
The paper is the result of a large data analysis which has direct implications for the conservation of large predators from the Southern Ocean. We assembled tracking data for 17 species to model Areas of Ecological Significance. Simultaneously, the data has been published in Open Access in the journal Scientific Data.
Abstract: Southern Ocean ecosystems are under pressure from resource exploitation and climate change. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.
A new paper on benthic ecoregionalization of the Southern Ocean has just been published in Global Change Biology, by Salomé Fabri-Ruiz et al.
The Southern Ocean (SO) is among the regions on Earth that are undergoing regionally the fastest environmental changes. The unique ecological features of its marine life make it particularly vulnerable to the multiple effects of climate change. A network of Marine Protected Areas (MPAs) has started to be implemented in the SO to protect marine ecosystems. However, considering future predictions of the Intergovernmental Panel on Climate Change (IPCC), the relevance of current, static, MPAs may be questioned under future scenarios. In this context, the ecoregionaliza- tion approach can prove promising in identifying well-delimited regions of common species composition and environmental settings. These so-called ecoregions are ex- pected to show similar biotic responses to environmental changes and can be used to define priority areas for the designation of new MPAs and the update of their current delimitation. In the present work, a benthic ecoregionalization of the entire SO is proposed for the first time based on abiotic environmental parameters and the distribution of echinoid fauna, a diversified and common member of Antarctic benthic ecosystems. A novel two-step approach was developed combining species distribution modeling with Random Forest and Gaussian Mixture modeling from spe- cies probabilities to define current ecoregions and predict future ecoregions under IPCC scenarios RCP 4.5 and 8.5. The ecological representativity of current and pro- posed MPAs of the SO is discussed with regard to the modeled benthic ecoregions. In all, 12 benthic ecoregions were determined under present conditions, they are representative of major biogeographic patterns already described. Our results show that the most dramatic changes can be expected along the Antarctic Peninsula, in East Antarctica and the sub-Antarctic islands under both IPCC scenarios. Our results advocate for a dynamic definition of MPAs, they also argue for improving the repre- sentativity of Antarctic ecoregions in proposed MPAs and support current proposals of Conservation of Antarctic Marine Living Resources for the creation of Antarctic MPAs.
You can access the paper online: https://authorservices.wiley.com/api/pdf/fullArticle/16657978
Let me ask you: what does first come to your mind when thinking about French Polynesia? Pristine white sandy beaches, luxurious island landscapes, turquoise waters, tropical fruits and fancy colourful cocktails?
The island of Moorea, French Polynesia
Well, it is! But this time, I travelled to French Polynesia to discover a completely different environment that is just starting to be explored thanks to novel technologies. This environment is called “mesophotic coral ecosystem” and has been receiving more and more attention in the recent years. Mesophotic coral ecosystems are found in tropical and subtropical regions at depths ranging from 30-40 meters and extending to over 150 meters. They are populated by a diversity of organisms such as corals, sponges, algae and fishes.
From September to December 2019, a special collaboration between the scientists from the CRIOBE (Centre de Recherches Insulaires et Observatoire de l’Environnement) and the team of technical divers and explorers of Under The Pole allowed the exploration of a specific site on the outer reef of the island of Moorea from the surface to 120 meters depth. This project, led by Dr Laetitia Hédouin, gathered scientists from different field of research and with different expertise, allowing the complete characterization of the site from the environmental conditions (light, temperature) to the organismal biodiversity and abundance.
The Under The Pole family (left) ; a diver at mesophotic depth (right)
Collecting samples and applying scientific diving techniques at such depth is challenging and requires a lot of preparation to ensure the security of the divers but also, to be able to do everything planned in the timeframe available. At 120 meters depth, the divers were able to stay for a maximum of 20 minutes, so every gesture has to be thought in advance to make the best out of that time. As part of my PhD research, I got the chance to participate in this special project and I focused on studying the antipatharians encountered by the divers on the site.
Antipatharians, also known as black corals, are anthozoans hexacorallians of distinct morphologies. They can be found from the tropics to the poles and studies have revealed their presence up to 8600 km deep. Despite this large distribution, they remain very poorly studied, mainly due to the logistical constraints associated with their study. Black corals can form dense “beds/forests” in several parts of the world and have been shown to play an important ecological role, in part due to their interactions with many organisms. In French Polynesia, the presence of black corals is known by local populations, in part because they have been fished for the jewellery industry in the past. Nonetheless, no scientific description of the assemblage of black coral species and distribution has ever been made in French Polynesia, and this represented one of my objective during this field trip (Results coming soon …).
A black coral in Tahiti (left) ; Map of the distribution of black corals in the world (right)
Another main aspect of my mission in the CRIOBE implied the maintenance of mesophotic antipatharians in aquaria to get a first insight into the metabolism of these organisms. We submitted them to different temperature treatments and evaluated their responses to heat stress through a combination of approaches, from a physiological to a subcellular biological organization level. Our preliminary results are already quite exciting… but this shall be for a latter post!
I would like to thank the Fonds Léopold III pour l’Exploration de la Nature for their financial support in this project. I also thank all the team from Under The Pole, all my colleagues and friends from the CRIOBE and all the wonderful persons I had the chance to meet and share moments with during this mission: Laetitia, Gonzalo, Yann, Alex, Caro, Anne, Fred, Benoit, Frank, Yannick, Françoise, Fabio, Lorenzo and his pastas, Kim, Ian, José, Alex and their cute baby black tips, Adeline, Julien, Camille, Will, Rohan, Zara (the Australian team), Elénonore and Aude, Pascal, Gilles, Cécile, Elina, Annaïg, Minouche & Minette. I hope to see you all very soon, either sharing a cold beer with fries in Belgium, or a pineapple juice with “poisson cru au lait de coco” in Moorea…
