Search

Cold-water coral (CWC) reefs of the Angolan margin (SE Atlantic) are dominated by Desmophyllum pertusum and support a diverse community of associated fauna, despite hypoxic conditions. In this study, we use carbon and nitrogen stable isotope analyses (δ13C and δ15N) to decipher the trophic network of this relatively unknown CWC province. Although fresh phytodetritus is available to the reef, δ15N signatures indicate that CWCs (12.90 ± 1.00 ‰) sit two trophic levels above Suspended Particulate Organic Matter (SPOM) (4.23 ± 1.64 ‰) suggesting that CWCs are highly reliant on an intermediate food source, which may be zooplankton. Echinoderms and the polychaete Eunice norvegica occupy the same trophic guild, with high δ13C signatures (-14.00 ± 1.08 ‰) pointing to a predatory feeding behavior on CWCs and sponges, although detrital feeding on 13C enriched particles might also be important for this group. Sponges presented the highest δ15N values (20.20 ± 1.87 ‰), which could be due to the role of the sponge holobiont and bacterial food in driving intense nitrogen cycling processes in sponges’ tissue, helping to cope with the hypoxic conditions of the reef. Our study provides first insights to understand trophic interactions of CWC reefs under low-oxygen conditions.

Cold‐water coral (CWC) reefs of the Angolan margin (SE Atlantic) are dominated by Desmophyllum pertusum and support a diverse community of associated fauna, despite hypoxic conditions. In this study, we use carbon and nitrogen stable isotope analyses (δ13C and δ15N) to decipher the trophic network of this relatively unknown CWC province. Although fresh phytodetritus is available to the reef, δ15N signatures indicate that CWCs (12.90 ± 1.00 ‰) sit two trophic levels above Suspended Particulate Organic Matter (SPOM) (4.23 ± 1.64 ‰) suggesting that CWCs are highly reliant on an intermediate food source, which may be zooplankton. Echinoderms and the polychaete Eunice norvegica occupy the same trophic guild, with high δ13C signatures (‐14.00 ± 1.08 ‰) pointing to a predatory feeding behavior on CWCs and sponges, although detrital feeding on 13C enriched particles might also be important for this group. Sponges presented the highest δ15N values (20.20 ± 1.87 ‰), which could be due to the role of the sponge holobiont and bacterial food in driving intense nitrogen cycling processes in sponges’ tissue, helping to cope with the hypoxic conditions of the reef. Our study provides first insights to understand trophic interactions of CWC reefs under low‐oxygen conditions.

Sailing on scientific expeditions as an early career researcher (ECR) offers the beneficial opportunity to gain field experience and training. However, the number of available berths to achieve the scientific goals of an expedition limits the number of onboard participants. Telepresence and remote learning can be utilized to increase the number of active participants, broadening the reach of capacity development. The 2021 iMirabilis2 expedition on board the Spanish Research Vessel Sarmiento de Gamboa used telepresence to virtually involve ECRs from several countries in deep-sea science. One year post-expedition, a survey of onshore participants was conducted to assess and quantify the effectiveness of the peer-to-peer ECR ship-to-shore scheme. During the expedition, live, interactive training via WhatsApp and Zoom was utilized by onshore ECRs more than traditional static, unidirectional methods of blog posts and pre-recorded videos. All respondents either agreed or strongly agreed that the scheme provided an inclusive and accessible platform to share deep-sea science. These results suggest similar schemes could be used to supplement shorter-duration at-sea-training, used prior to a seagoing experience to better prepare ECRs, or to allow members of the science community unable to join an expedition in person to actively participate remotely, increasing inclusivity.

The characterisation of trophic nets in the deep-sea is challenging due to the remoteness and the logistic constraints to reach and sample these habitats. Stable carbon and nitrogen isotope (δ13C and δ15N) analysis has proven to be a useful tool in identifying trophic relationships. The benthic trophic network of the fauna in the recently discovered Angolan cold-water coral (CWC) mounds is being investigated through carbon and nitrogen isotopic characterization. Samples were collected in 2016 during the M122 ("ANNA") expedition on board the R/V METEOR. Organisms belonging to different functional groups of Porifera, Cnidaria, Mollusca, Annelida, Bryozoa, Arthropoda, Echinodermata, and Chordata, as well as potential food sources (suspended particulate organic matter and organic matter of sediments) were analysed. The main aims of the study are: (1) to describe the megabenthic trophic guilds of the Angolan CWC mounds, (2) to estimate the total number of trophic levels, and (3) to compare this unexplored area with previous results from other CWC dominated communities. Our first results show that particulate organic matter presented a marine signature (δ13C from -20 to -25‰ V.P.D.B.). However, the analysed CWC species seem to prefer a diet which combined a mix of detrital and resuspended organic matter (δ13C from -15 to -20‰ V.P.D.B.), similar to what has been observed for Antarctic gorgonians and other CWC habitats. Porifera presented the highest δ15N ratios (20.19±1.81‰). We hypothesise this could be due to the assimilation of bacterioplankton as a food source which has been already documented for Porifera.

VII International Symposium on Marine Sciences (ISMS 2020), 1-3 July 2020 (Barcelona).-- 2 pages, Temperature and conductivity fluctuations due to the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano, off El Hierro Island in the Canary Archipelago, may provide robust indicators for characterising and predicting the activity of the system. 21 CTD time series along a regular high-resolution grid were gathered in the VULCANO1016 cruise with the rosette sampler directly over the main seafloor crater (Santana-Casiano et al., 2016; Fraile-Nuezet al., 2018). Temperature and conductivity data compiledare analysed as manifestations of stochastic processes in terms of the Generalized Moments Method (GMM) (Bakaliset al., 2017; Bakalis et al., 2018). GMM provides the statistical momentsof the underlying processes and delivers their structure functions being their shape an indicator of the stochastic mechanism/s governing such a stochastic process. Our findings pointto an active submarine volcano, which conveys energy to the surrounding ecosystem. Yet, both temperature and conductivity fluctuations present long tails depict to strong sub-normal processes, which change very slowly in the long time limit. Temperature and conductivity fluctuations are classified as multifractal processes whose structure functions show a crossover in two distinct regimes. Multifractality suggests the multiplicative action of at least two random processes, which can be attributed to the volcano and to the aquatic environment. From the physical viewpoint the Tagoro submarine volcano can be defined as an open system given the variations over time of temperature moments, This study has been supported by funds from FEDER and the Spanish Ministry of Economy and Competitiveness through VULCANA-II (IEO2018-2020) and VULCANO-II (CTM2014-51837-R) research projects

The characterisation of trophic nets in the deep-sea is challenging due to the remoteness and the logistic constraints to reach and sample these habitats. Stable carbon and nitrogen isotope (δ13C and δ15N) analysis has proven to be a useful tool in identifying trophic relationships. The benthic trophic network of the fauna in the recently discovered Angolan cold-water coral (CWC) mounds is being investigated through carbon and nitrogen isotopic characterization. Samples were collected in 2016 during the M122 ("ANNA") expedition on board the R/V METEOR. Organisms belonging to different functional groups of Porifera, Cnidaria, Mollusca, Annelida, Bryozoa, Arthropoda, Echinodermata, and Chordata, as well as potential food sources (suspended particulate organic matter and organic matter of sediments) were analysed. The main aims of the study are: (1) to describe the megabenthic trophic guilds of the Angolan CWC mounds, (2) to estimate the total number of trophic levels, and (3) to compare this unexplored area with previous results from other CWC dominated communities. Our first results show that particulate organic matter presented a marine signature (δ13C from -20 to -25‰ V.P.D.B.). However, the analysed CWC species seem to prefer a diet which combined a mix of detrital and resuspended organic matter (δ13C from -15 to -20‰ V.P.D.B.), similar to what has been observed for Antarctic gorgonians and other CWC habitats. Porifera presented the highest δ15N ratios (20.19±1.81‰). We hypothesise this could be due to the assimilation of bacterioplankton as a food source which has been already documented for Porifera.