Lipidomic profiling reveals biosynthetic relationships between phospholipids and diacylglycerol ethers in the deep-sea soft coral Paragorgia arborea

The cold-water gorgonian coral Paragorgia arborea is considered as a foundation species of deep-sea ecosystems in the northern Atlantic and Pacific oceans. To advance lipidomic studies of deep-sea corals, molecular species compositions of diacylglycerol ethers (DAGE), which are specific storage lipids of corals, and structural glycerophospholipids (GPL) including ethanolamine, choline, inositol and serine GPL (PE, PC, PI, and PS, respectively) were analyzed in P. arborea by HPLC and tandem mass spectrometry. In DAGE molecules, alkyl groups (16:0, 14:0, and 18:1), polyunsaturated fatty acids (PUFA), and monounsaturated FA are mainly substituted the glycerol moiety at position sn-1, sn-2, and sn-3, respectively. The ether form (1-O-alkyl-2-acyl) predominates in PE and PC, while PI is comprised of the 1,2-diacyl form. Both ether and diacyl forms were observed in PS. At position sn-2, C20 PUFA are mainly attached to PC, but C24 PUFA, soft coral chemotaxonomic markers, concentrate in PS, PI, and PE. A comparison of non-polar parts of molecules has shown that DAGE, ether PE, and ether PC can originate from one set of 1-O-alkyl-2-acyl-sn-glycerols. Ether PE may be converted to ether PS by the base-exchange reaction. A diacylglycerol unit generated from phosphatidic acid can be a precursor for diacyl PS, PC, and PI. Thus, a lipidomic approach has confirmed the difference in biosynthetic origins between ether and diacyl lipids of deep-sea gorgonians.

Alcyonium bursa Linnaeus, 1758 is not a sponge

In the 10th edition of the Systema Naturae (Linnaeus, 1758), which is the starting point of the Code for Zoological Nomenclature (ICZN Art. 3), Linnaeus named three species of the genus Alcyonium, A. arboreum, A. digitatum, and A. bursa. The genus name Alcyonium was based on the 16th and 17th century pre-Linnaean use for a diversity of marine organisms, including cnidarians, sponges, bryozoans, and algae. In the first valid presentation of the genus name, Linnaeus narrowed this down to comprise two clear cnidarians (A. arboreum, currently Paragorgia arborea, and A. digitatum, still accepted under this name and subsequently assigned as type species), but the pre-Linnaean diversity perhaps explains why the third species, A. bursa, was not recognized as a cnidarian. Linnaeus defined it as ‘Alcyonium acaule pulposum subglobosum. Habitat in O. Europaea.’ (translated as: Alcyonium without stalk, fleshy, semiglobular. From the European Ocean).’ Attempts to fix its identity among contemporary authors at the end of the 18th and beginning of the 19th century followed a checkered course, with opinions varying from algae to tunicates and sponges.

An Automated Pipeline for Image Processing and Data Treatment to Track Activity Rhythms of Paragorgia arborea in Relation to Hydrographic Conditions

Imaging technologies are being deployed on cabled observatory networks worldwide. They allow for the monitoring of the biological activity of deep-sea organisms on temporal scales that were never attained before. In this paper, we customized Convolutional Neural Network image processing to track behavioral activities in an iconic conservation deep-sea species—the bubblegum coral Paragorgia arborea—in response to ambient oceanographic conditions at the Lofoten-Vesterålen observatory. Images and concomitant oceanographic data were taken hourly from February to June 2018. We considered coral activity in terms of bloated, semi-bloated and non-bloated surfaces, as proxy for polyp filtering, retraction and transient activity, respectively. A test accuracy of 90.47% was obtained. Chronobiology-oriented statistics and advanced Artificial Neural Network (ANN) multivariate regression modeling proved that a daily coral filtering rhythm occurs within one major dusk phase, being independent from tides. Polyp activity, in particular extrusion, increased from March to June, and was able to cope with an increase in chlorophyll concentration, indicating the existence of seasonality. Our study shows that it is possible to establish a model for the development of automated pipelines that are able to extract biological information from times series of images. These are helpful to obtain multidisciplinary information from cabled observatory infrastructures.

Diversity of deep-water coral-associated bacteria and comparison across depth gradients

ABSTRACTEnvironmental conditions influence species composition, including the microbial communities that associate with benthic organisms such as corals. In this study we identified and compared bacteria that associate with three common deep-water corals, Lophelia pertusa, Madrepora oculata and Paragorgia arborea, from a reef habitat on the mid-Norwegian shelf. The 16S rRNA gene amplicon sequencing data obtained revealed that >50% of sequences were represented by only five operational taxonomic units. Three were host-specific and unclassified below class level, belonging to Alphaproteobacteria with affiliation to members of the Rhizobiales order (L. pertusa), Flavobacteria affiliated with members of the Elisabethkingia genus (M. oculata) and Mollicutes sequences affiliated with the Mycoplasma genus (P. arborea). In addition, gammaproteobacterial sequences within the genera Sulfitobacter and Oleispira were found across all three deep-water coral taxa. Although highly abundant in the coral microbiomes, these sequences accounted for <0.1% of the surrounding bacterioplankton, supporting specific relationships. We combined this information with previous studies, undertaking a meta-data analysis of 165 widespread samples across coral hosts and habitats. Patterns in bacterial diversity indicated enrichment of distinct uncultured species in coral microbiomes that differed among deep (>200 m), mesophotic (30–200 m) and shallow (<30 m) reefs.

Incorporating spatial analyses into conservation and monitoring of deep-sea megafauna in Marine Protected Areas (MPAs)

Deep-sea ecosystems are being impacted by anthropogenic stressors, such as trawling and oil-gas exploration. Protection of these ecosystems is delayed by limited understanding of spatial distribution, suitable habitat, species associations, and recruitment. Imagery was analyzed from the Laurentian Channel AOI and 3 canyons (Corsair, Georges, Fiddlers Cove) on the western Scotian Slope in the Northwest Atlantic Ocean. We used two sampling designs, exploratory linear transects and a systematic-cluster transect array and will compare the information that can be extracted from each method. Megaepifaunal biodiversity, abundance, and species-species associations were identified at each site. For example, at Fiddlers Cove, different types of Gorgonian corals (e.g. Acanella, Desmophyllum, and stoloniferous coral), soft corals, and sponges occurred mainly on outcrops; sea pens and anemones, along with large colonies of Paragorgia arborea were present in Corsair Canyon; and several Gorgonian corals, anemones, lobsters, and Holothuroidea were present in Georges Canyon. We will use spatial analyses to measure spatial structure at local and regional scales, identify species-environment associations, and predict suitable habitat for deep-sea megaepifauna. Overall, the study will provide a broader understanding of deep-sea megaepifaunal ecosystems, and develop recommendations for a deep-sea MPA monitoring framework to achieve effective conservation that promotes biodiversity.

Incorporating spatial analyses into conservation and monitoring of deep-sea megafauna in Marine Protected Areas (MPAs)

Deep-sea ecosystems are being impacted by anthropogenic stressors, such as trawling and oil-gas exploration. Protection of these ecosystems is delayed by limited understanding of spatial distribution, suitable habitat, species associations, and recruitment. Imagery was analyzed from the Laurentian Channel AOI and 3 canyons (Corsair, Georges, Fiddlers Cove) on the western Scotian Slope in the Northwest Atlantic Ocean. We used two sampling designs, exploratory linear transects and a systematic-cluster transect array and will compare the information that can be extracted from each method. Megaepifaunal biodiversity, abundance, and species-species associations were identified at each site. For example, at Fiddlers Cove, different types of Gorgonian corals (e.g. Acanella, Desmophyllum, and stoloniferous coral), soft corals, and sponges occurred mainly on outcrops; sea pens and anemones, along with large colonies of Paragorgia arborea were present in Corsair Canyon; and several Gorgonian corals, anemones, lobsters, and Holothuroidea were present in Georges Canyon. We will use spatial analyses to measure spatial structure at local and regional scales, identify species-environment associations, and predict suitable habitat for deep-sea megaepifauna. Overall, the study will provide a broader understanding of deep-sea megaepifaunal ecosystems, and develop recommendations for a deep-sea MPA monitoring framework to achieve effective conservation that promotes biodiversity.