Data_Sheet_1_SubCAS: A Portable, Submersible Hyperbaric Chamber to Collect Living Mesophotic Fishes.docx

<p>Accompanying the recent technological innovations in remotely operated vehicles (ROVs), submersibles, technical SCUBA, and closed-circuit rebreather diving gear, new discoveries are being made on mesophotic coral ecosystems around the world. However, collecting live fishes from mesophotic depths (60–150 m) is challenging, given the difficulty of accessing the habitat, catching the fishes, and the barotrauma that can result from rapid decompression during their transport to the surface. Here, we designed and tested the performance of a portable, submersible hyperbaric chamber, the SubCAS, which we used to safely surface reef fishes from mesophotic depths. During six expeditions between 2014 and 2017 to the Philippines, Vanuatu, Palau and Pohnpei, we assessed the survival of 174 fishes caught between 60 and 150 m depth and decompressed using this chamber. A total of 155 (89.1%) fishes survived decompression, and 143 of 148 specimens shipped (96.6%) survived air cargo transport from remote field sites to the Steinhart Aquarium at the California Academy of Sciences. Survival was significantly related to taxonomic family, with Pomacentridae and Apogonidae showing the highest mortality. Collection depth, fish body size, and length of decompression had no relation to survivorship. Significant interactions between individual decompression events and both fish body size and taxonomic family indicate that low survival was associated with specific SubCAS trials. The SubCAS has allowed us to reliably surface charismatic fishes previously unknown to science and maintain them in aquaria for research and public engagement purposes. This opportunity facilitates a direct connection between our more than one million annual visitors and the wonders of exploration and the science of mesophotic coral ecosystems.</p

Baseline Assessment of Mesophotic Reefs of the Vitória-Trindade Seamount Chain Based on Water Quality, Microbial Diversity, Benthic Cover and Fish Biomass Data

<div><p>Seamounts are considered important sources of biodiversity and minerals. However, their biodiversity and health status are not well understood; therefore, potential conservation problems are unknown. The mesophotic reefs of the Vitória-Trindade Seamount Chain (VTC) were investigated via benthic community and fish surveys, metagenomic and water chemistry analyses, and water microbial abundance estimations. The VTC is a mosaic of reef systems and includes fleshy algae dominated rhodolith beds, crustose coralline algae (CCA) reefs, and turf algae dominated rocky reefs of varying health levels. Macro-carnivores and larger fish presented higher biomass at the CCA reefs (4.4 kg per frame) than in the rhodolith beds and rocky reefs (0.0 to 0.1 kg per frame). A larger number of metagenomic sequences identified as primary producers (e.g., Chlorophyta and Streptophyta) were found at the CCA reefs. However, the rocky reefs contained more diseased corals (>90%) than the CCA reefs (~40%) and rhodolith beds (~10%). Metagenomic analyses indicated a heterotrophic and fast-growing microbiome in rocky reef corals that may possibly lead to unhealthy conditions possibly enhanced by environmental features (e.g. light stress and high loads of labile dissolved organic carbon). VTC mounts represent important hotspots of biodiversity that deserve further conservation actions.</p></div

Hypothetical schematic representation of VTC macro-habitats and processes.

<p>CCA reefs (Group 1), fleshy algae dominated rhodolith beds (Group 2) and turf algae dominated rocky reefs (Group 3) are represented. In pink, CCA reefs and fleshy algae (dark green) dominated rhodolith beds. In light green, high turf algae cover at rocky reefs. The highly complex habitat of CCA reefs harbors high biomass of carnivorous fishes. Input of nutrients and upwelling/downwelling generating microbial productivity. During downwelling periods, regenerated and/or excreted nutrients (e.g., ammonia and phosphorus) may be provided to the system by the benthic organisms/microorganisms. At Group 3 Euphotic reefs microbial growth stimulated by DOC released by turf algae may have toxic effects and cause coral disease. At Group 1 and 2 mesophotic environments probably fleshly algae is the major DOC producer, having no toxic effects on coral health. During upwelling periods, new nutrients (nitrate) from deeper water masses may become available to the systems. Microbial communities are connected between the seamounts (Karlin signature). Not to scale. Grouper and black durgon pictures from <a href="http://www.fishbase.org" target="_blank">www.fishbase.org</a> [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130084#pone.0130084.ref029" target="_blank">29</a>].</p

Fish Biodiversity of the Vitória-Trindade Seamount Chain, Southwestern Atlantic: An Updated Database

<div><p>Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management.</p></div

Principal component analysis of water chemical and biological inventories.

<p>Abbreviations: Bac Counts–Bacterial counts; DOC–Dissolved Organic Carbon, Org N–Organic Nitrogen, Ortho P–Orthophosphate, Org P–Organic Phosphorous, Richness–Number of bacterial families, Shannon–Shannon entropy index, Evenness–Shannon evenness index (Hill’s Ratio).</p

Relative abundance of fish size classes (a) and trophic guilds (b) and biomass of fish size classes (c) and trophic guilds (d).

<p>Data are presented as the mean±SE.</p

Relative abundance of the major benthic categories for each sampled system.

<p>Data presented as the mean±SE.</p

Study area.

<p>Data on benthic fish, microbes and nutrients were collected for the Vitoria-Trindade Chain and Trindade Island. Detailed information on the samples and sites can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130084#pone.0130084.t001" target="_blank">Table 1</a>. (a) Main currents and location of VTC along the Brazilian coast; (b) sampling sites location along the VTC; (c) details of Vitoria, Eclaireur, Jaseur, Columbia Bank and Almirante Saldanha seamounts; (d) details of Davis Seamount sampling site; (e) details of Trindade Island sampling sites; (f) Davis Seamount (CCA reef, Group 1); (g) Jaseur Seamount (fleshy algae dominated rhodolith beds, Group 2); (h) Trindade Island (turf algae dominated rocky reef, Group 3); corals from (i) CCA reef, (j) rhodolith bed and (l) rocky reef. The maps were generated using Qgis software [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130084#pone.0130084.ref068" target="_blank">68</a>]. Photo credit: Ronaldo Francini-Filho.</p

Nonmetric multidimensional scaling of dinucleotide signatures of water (a) and coral (b) metagenomes.

<p>There was no clear distinction between the samples, indicating that there is a genetic connectivity between the reef environments.</p

Taxonomic diversity of the metagenomes.

<p>Bacterial and proteobacterial phyla relative abundance in corals (a) and water (b). Eukaryotic phyla relative abundance in corals (c) and water (d). Asterisks show significant differences between the different macro-habitats (groups). Data are presented as the mean±SE.</p