153 research outputs found
New species of bone-eating worm Osedax from the abyssal South Atlantic Ocean (Annelida, Siboglinidae)
A new species of bone-eating annelid, Osedax braziliensis sp. n., found in a sunken whale carcass at a depth of 4,204 m at the base of the São Paulo Ridge in the South Atlantic Ocean off the Brazilian coast is described. The organism was retrieved using the human-occupied vehicle Shinkai 6500 during the QUELLE 2013 expedition. This is the 26th species of the genus and the first discovery from the South Atlantic Ocean, representing the deepest record of Osedax worldwide to date. This species morphologically resembles Osedax frankpressi but is distinguished by the presence of a yellow bump or patch behind the prostomium and its trunk length. Molecular phylogenetic analysis using three genetic markers (COI, 16S, and 18S) showed that O. braziliensis sp. n. is distinct from all other Osedax worms reported and is a sister species of O. frankpressi
Optimization of environmental DNA analysis using pumped deep-sea water for the monitoring of fish biodiversity
Deep-sea ecosystems present difficulties in surveying and continuous monitoring of the biodiversity of deep-sea ecosystems because of the logistical constraints, high cost, and limited opportunities for sampling. Environmental DNA (eDNA) metabarcoding analysis provides a useful method for estimating the biodiversity in aquatic ecosystems but has rarely been applied to the study of deep-sea fish communities. In this study, we utilized pumped deep-sea water for the continuous monitoring of deep-sea fish communities by eDNA metabarcoding. In order to develop an optimum method for continuous monitoring of deep-sea fish biodiversity by eDNA metabarcoding, we determined the appropriate amount of pumped deep-sea water to be filtered and the practical number of filtered sample replicates required for biodiversity monitoring of deep-sea fish communities. Pumped deep-sea water samples were filtered in various volumes (5–53 L) at two sites (Akazawa: pumping depth 800 m, and Yaizu: pumping depth 400 m, Shizuoka, Japan) of deep-sea water pumping facilities. Based on the result of evaluations of filtration time, efficiency of PCR amplification, and number of detected fish reads, the filtration of 20 L of pumped deep-sea water from Akazawa and filtration of 10 L from Yaizu were demonstrated to be suitable filtration volumes for the present study. Fish biodiversity obtained by the eDNA metabarcoding analyses showed a clear difference between the Akazawa and Yaizu samples. We also evaluated the effect of the number of filter replicates on the species richness detected by eDNA metabarcoding from the pumped deep-sea water. At both sites, more than 10 sample replicates were required for the detection of commonly occurring fish species. Our optimized method using pumped deep-sea water and eDNA metabarcoding can be applied to eDNA-based continuous biodiversity monitoring of deep-sea fish to better understand the effects of climate change on deep-sea ecosystems
Association of Thioautotrophic Bacteria with Deep-Sea Sponges
We investigated microorganisms associated with a deep-sea sponge, Characella sp. (Pachastrellidae) collected at a hydrothermal vent site (686 m depth) in the Sumisu Caldera, Ogasawara Island chain, Japan, and with two sponges, Pachastrella sp. (Pachastrellidae) and an unidentified Poecilosclerida sponge, collected at an oil seep (572 m depth) in the Gulf of Mexico, using polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) directed at bacterial 16S rRNA gene sequences. In the PCR-DGGE profiles, we detected a single clearly dominant band in each of the Characella sp. and the unidentified Poecilosclerida sponge. BLAST search of their sequences showed that they were most similar (>99% identity) to those of the gammaproteobacterial thioautotrophic symbionts of deep-sea bivalves from hydrothermal vents, Bathymodiolus spp. Phylogenetic analysis of the near-full length sequences of the 16S rRNA genes cloned from the unidentified Poecilosclerida sponge and Characella sp. confirmed that they were closely related to thioautotrophic symbionts. Although associations between sponges and methanotrophic bacteria have been reported previously, this is the first report of a possible stable association between sponges and thioautotrophic bacteria
Algivore or phototroph?: Plakobranchus ocellatus (Gastropoda) continuously acquires kleptoplasts and nutrition from multiple algal species in nature
The sea slug Plakobranchus ocellatus (Sacoglossa, Gastropoda) retains photosynthetically active chloroplasts from ingested algae (functional kleptoplasts) in the epithelial cells of its digestive gland for up to 10 months. While its feeding behavior has not been observed in natural habitats, two hypotheses have been proposed: 1) adult P. ocellatus uses kleptoplasts to obtain photosynthates and nutritionally behaves as a photoautotroph without replenishing the kleptoplasts; or 2) it behaves as a mixotroph (photoautotroph and herbivorous consumer) and replenishes kleptoplasts continually or periodically. To address the question of which hypothesis is more likely, we examined the source algae for kleptoplasts and temporal changes in kleptoplast composition and nutritional contribution. By characterizing the temporal diversity of P. ocellatus kleptoplasts using rbcL sequences, we found that P. ocellatus harvests kleptoplasts from at least 8 different siphonous green algal species, that kleptoplasts from more than one species are present in each individual sea slug, and that the kleptoplast composition differs temporally. These results suggest that wild P. ocellatus often feed on multiple species of siphonous algae from which they continually obtain fresh chloroplasts. By estimating the trophic position of wild and starved P. ocellatus using the stable nitrogen isotopic composition of amino acids, we showed that despite the abundance of kleptoplasts, their photosynthates do not contribute greatly to the nutrition of wild P. ocellatus, but that kleptoplast photosynthates form a significant source of nutrition for starved sea slugs. The herbivorous nature of wild P. ocellatus is consistent with insights from molecular analyses indicating that kleptoplasts are frequently replenished from ingested algae, leading to the conclusion that natural populations of P. ocellatus do not rely on photosynthesis but mainly on the digestion of ingested algae
Extracellular and Mixotrophic Symbiosis in the Whale-Fall Mussel Adipicola pacifica: A Trend in Evolution from Extra- to Intracellular Symbiosis
http://www.godac.jamstec.go.jp/darwin/cruise/natsushima/nt05-12/
Rapid, contamination-less, and efficient environmental DNA filtration system
Due to the sporadic distribution and trace amount of environmental DNA (eDNA) in deep-sea water, in the context of biodiversity monitoring, large volumes of filtration and multiple filtration replicates are required for eDNA metabarcoding. To address issues tied to the use of multiple filtration devices and large filtration volumes (e.g., contamination, time consumption, etc.), we have developed two systems for simple, rapid, and contamination-less filtration simultaneously that allow for the processing of multiple sample replicates from large volumes of water. First, the water from a Niskin bottle was filtered directly using a solenoid pump. Second, the pumped deep-sea water, using the siphon effect, was directly filtered by a filtration device driven by water pressure. This system can process 24 replicates simultaneously without the need for expensive equipment and active driving force. Compared with conventional filtering methods, e.g., peristaltic pumps, the proposed systems reduce filtration time, minimizing contamination, and enabling the simultaneous acquisition of multiple replicates. Overall, the systems presented here provide an effective approach for eDNA metabarcoding analysis, particularly for the filtration of large volumes of water containing small amounts of eDNA, such as deep-sea water. • The present systems reduce filtration time and contamination without water having to be transferred. • Simultaneous multiple replicates improve the efficiency and reliability of biodiversity assessments
Figure 5 from: Fujiwara Y, Jimi N, Sumida PYG, Kawato M, Kitazato H (2019) New species of bone-eating worm Osedax from the abyssal South Atlantic Ocean (Annelida, Siboglinidae). ZooKeys 814: 53-69. https://doi.org/10.3897/zookeys.814.28869
A New Species of Osedax (Annelida: Siboglinidae) Associated with Whale Carcasses off Kyushu, Japan
鯨骨生物群集と二つの「飛び石」仮説
http://www.godac.jamstec.go.jp/darwin/cruise/natsushima/nt03-08_leg1/ehttp://www.godac.jamstec.go.jp/darwin/cruise/natsushima/nt04-08_leg1/
Amphritea japonica sp. nov. and Amphritea balenae sp. nov., isolated from the sediment adjacent to sperm whale carcasses off Kagoshima, Japan
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