Ship-to-shore training for active deep-sea capacity development

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

Deep sea ecosystem exploration and ‘health check’: sampling strategy and methods applied during the iAtlantic_BR10_Petrobras cruise in the Santos Basin, Southwest Atlantic

The iAtlantic Project has established an international collaborative strategy to improve mapping andcharacterization of deep and open ocean ecosystems in understudied regions of the Atlantic and evaluatetheir health. In December 2022, the first iAtlantic expedition in the South Atlantic set off to map and exploreseafloor ecosystems in the Santos Basin slope (200-1,000 m depths) in collaboration with the Petrobras ‘SantosBasin - Regional Characterization Project.’ The 17-day ‘iAtlantic_BR10-Petrobras’ cruise was conducted onboard the research vessel NPqHOc Vital de Oliveira (Brazilian Navy) and performed (a) water column structurecharacterization, (b) seafloor morphology mapping, (c) description of benthic habitats and communities byseafloor imagery and biological/ geological sampling, and (d) ex-situ experiments to assess the functioning ofsedimentary ecosystems and their responses to climate-related environmental changes. This study describesthe rationale behind the iAtlantic_BR10-Petrobras cruise science plan, reports its sampling strategy andmethods, and summarizes its collected data and preliminary results

Database of deep-sea benthic fauna occurrences along the Brazilian Continental Margin (BCM)

The dataset contains species occurrence records of deep-sea benthic fauna distributed along the Brazilian Continental Margin (BCM). Benthic records from existing and openly published databases available online were synthesized to obtain the deep-sea benthic diversity of the Brazilian Exclusive Economic Zone (EEZ). Only records that were identified to the species level and distributed between 200 and 5000 m water depth were included in the final, standardised database

Benthic biodiversity and their biogeographic patterns on the Deep Brazilian Margin

This dataset contains species occurrences of deep-sea benthic fauna distributed along the Brazilian Continental Margin (BCM). Existing records from published databases accessible online were synthesized to derive the deep-sea benthic diversity of the Brazilian Exclusive Economic Zone (EEZ). Only records that had been identified to species level and that were found between 200 and 5000 m water depth were included in this final, standardised database. Records were mapped in ArcGIS and the here included shapefiles for each phylum are annexed. Two existing biogeographic schemes for the South Atlantic bathyal and abyssal depths (Spalding et al., 2007 and Watling et al., 2013) were tested using the distribution data of benthic species along the BCM. A third biogeographic scheme was tested to assess the relationship between benthic fauna and deep water masses within the Brazilian EEZ. Species occurrences were assigned to the biogeographical units of each biogeographical scheme from which the three occurrences databases (watling, hybrid, water masses), included here, were generated

Benthic biodiversity and biogeographic patterns on the Deep Brazilian Margin

This dataset contains species occurrences of deep-sea benthic fauna distributed along the Brazilian Continental Margin (BCM). Existing records from published databases accessible online were synthesized to derive the deep-sea benthic diversity of the Brazilian Exclusive Economic Zone (EEZ). Only records that had been identified to species level and that were found between 200 and 5000 m water depth were included in this final, standardised database. Records were mapped in ArcGIS and the here included shapefiles for each phylum are annexed. Two existing biogeographic schemes for the South Atlantic bathyal and abyssal depths (Spalding et al., 2007 and Watling et al., 2013) were tested using the distribution data of benthic species along the BCM. A third biogeographic scheme was tested to assess the relationship between benthic fauna and deep water masses within the Brazilian EEZ. Species occurrences were assigned to the biogeographical units of each biogeographical scheme from which the three occurrences databases (watling, hybrid, water masses), included here, were generated

Benthic Chamber Lander stable isotope tracer experiments with lyophilised diatoms in the Cabo Verde Abyssal Basin (14.7N, 25.2W) at 4200m during the iMirabilis2 research expedition in August 2021

A total of five deployments of a Benthic Chamber Lander (BCL) were conducted at the Cabo Verde Abyssal Plain (tropical East Atlantic, 14.7N 25.2W, ~4200 m). The deployments took place during the iMirabilis2 campaign in August 2021 from the research vessel Sarmiento de Gamboa. Each deployment carried three functional chambers, one conducting a stable isotope tracer experiment, and two collecting background data. The stable isotope tracer used was axenically cultured and lyophilised diatoms (Phaeodactylum tricornutum) labelled with 13C and 15N. The experiment had a duration of 48 hours. The chamber carried an oxygen optode (Aanderaa 4330F) for continuous oxygen concentration measurements. During the experiment seven water samples were collected at hours T0.33, T2, T10, T19, T28, T37, and T46. The water samples were processed for oxygen concentration (Micro-Winkler Titration), Dissolved Inorganic Carbon (DIC and DI13C) concentration, and nutrients (NH4, NO2, NO3, PO4, Si) concentration. The sediments were sampled after lander recovery for Total Organic Carbon (TOC and TO13C), Phospholipid-derived Fatty Acid (PLFA) biomarkers (including their 13C stable isotope signal), meiobenthos (32 µm mesh, counts, dry mass, 13C, 15N), macrobenthos (300 um mesh, counts, dry mass, 13C, 15N) incl. large foraminifera (300 µm mesh, dry mass, 13C, 15N). The data were used to calculate Sediment Community Oxygen Consumption (SCOC), nutrient fluxes, and substrate-derived respiration rates, bacterial C incorporation, meiobenthic C and N incorporation, macrofaunal C and N incorporation, and C and N incorporation by large Foraminifera

In situ benthic community response to a phytodetritus pulse in the Cabo Verde Abyssal Basin (tropical NE Atlantic)

Ecosystem functioning, i.e. the transfer of material through a system, supports the ecosystem services deep-sea sediments provide, including carbon sequestration, nutrient regeneration, and climate regulation. To date, seven studies globally have researched in situ how various benthic groups contribute to organic matter degradation in abyssal sediments through stable isotope tracer experiments, of which only one in the Atlantic (at the Porcupine Abyssal Plain or PAP). To expand the limited knowledge base on abyssal ecosystem functioning, we performed in situ stable isotope experiments in the Cabo Verde Abyssal Basin (CVAB, tropical North-East Atlantic). The Cabo Verde marine region is an oceanographically interesting region with complex currents, resulting in strong gradients of productivity and unique ecological characteristics. We conducted 2-day in situ incubations with organic substrate (lyophilised diatom culture) labelled with 13C and 15N stable isotopes through five benthic lander deployments to 4,200 m in an area presumed mesotrophic. We assessed sediment community oxygen consumption (SCOC), dissolved inorganic carbon (DI13C) production, nutrient fluxes, and label incorporation into bacteria, large Foraminifera (&gt;300 μm), meiobenthos, and macrofauna. Results were specifically compared across the Atlantic basin to the eutrophic PAP for which all the same system components were reported (Witte et al. 2003). At CVAB, bacteria and meiobenthos dominated phytodetritus processing (91% and 8%, respectively), in contrast to PAP where macrofauna dominated (98%). Phytodetritus remineralisation was two to three times lower at CVAB compared to PAP, most likely due to the low abundance of fast responding macrofauna. However, overall phytodetritus processing efficiency at CVAB was four times greater compared to PAP. Our results support a mesotrophic regime at the CVAB lander site, and provide a unique first insight into ecosystem functioning of tropical (low-latitude) abyssal systems in the Atlantic Ocean. A better understanding of abyssal ecosystem functioning in various ocean regions, to which this study contributes, provides insight into main regulators of abyssal communities and thus may have implications for our understanding of abyssal systems under future climate scenarios.</p