Dynamics of a fish-killing dinoflagellate Karenia mikimotoi red-tide captured by composite data sources.

Bloom dynamics of K. mikimotoi during summer 2015 in the Yatsushiro Sea, Japan, which caused fish mortality was studied using field survey data and satellite data. The bloom initially formed in the western area, subsequently appeared in the southern area, and finally expanded to the central area.

Transcriptome characterization of gonadal sex differentiation in Pacific bluefin tuna, Thunnus orientalis (Temminck et Schlegel).

Tunas (genus Thunnus) are one of the most ecologically and commercially important fish worldwide. To establish a biological basis for reproduction in this globally essential species, we have recently studied crucial reproductive aspects of the Pacific bluefin tuna (T. orientalis; PBT), as a model of tuna species, based on our closed-cycle aquaculture technology.

Transcriptional responses of the marine diatom Chaetoceros tenuissimus to phosphate deficiency.

The planktonic diatom Chaetoceros tenuissimus sometimes forms blooms in coastal surface waters where dissolved inorganic phosphorus (P) is typically deficient. To understand the molecular mechanisms for survival under P-deficient conditions, we compared whole transcripts and metabolites with P-sufficient conditions using stationary growth cells. Under P-deficient conditions, cell numbers and photosynthetic activities decreased as cells entered the stationary growth phase, with downregulation of transcripts related to the Calvin cycle and glycolysis/gluconeogenesis.

Pathogenicity, genomic analysis and structure of abalone asfa-like virus: evidence for classification in the family .

This paper presents the rationale for classifying abalone asfa-like virus (AbALV) in the family based on analyses of the host, whole genome and electron microscopic observations. AbALV caused >80 % cumulative mortality in an experimentally infected mollusc, . The AbALV genome was found to be linear, approximately 281 kb in length, with a G+C content of 31.

Temperature sensitivity of the interspecific interaction strength of coastal marine fish communities.

The effects of temperature on interaction strengths are important for understanding and forecasting how global climate change impacts marine ecosystems; however, tracking and quantifying interactions of marine fish species are practically difficult especially under field conditions, and thus, how temperature influences their interaction strengths under field conditions remains poorly understood. We herein performed quantitative fish environmental DNA (eDNA) metabarcoding on 550 seawater samples that were collected twice a month from 11 coastal sites for 2 years in the Boso Peninsula, Japan, and analyzed eDNA monitoring data using nonlinear time series analytical tools. We detected fish-fish interactions as information flow between eDNA time series, reconstructed interaction networks for the top 50 frequently detected species, and quantified pairwise, fluctuating interaction strengths.

Effects of Hyphomonas Strains on the Growth of Red Algae Pyropia Species by Attaching Specifically to Their Rhizoids.

Bacteria and marine macroalgae form close associations, while various bacteria affect the morphogenesis and growth of macroalgae. Hyphomonas strains exhibit normal morphogenetic activity in protoplasts of the red alga Pyropia yezoensis (nori). However, the effects of the bacteria on the growth of Pyropia from protoplast cells to regenerated thalli remain unknown.

Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences.

Background: Zooplankton plays an important role in the marine ecosystem. A high level of taxonomic expertise is necessary for accurate species identification based on morphological characteristics. As an alternative method to morphological classification, we focused on a molecular approach using 18S and 28S ribosomal RNA (rRNA) gene sequences.

Single-Cell Level Raman Molecular Profiling Reveals the Classification of Growth Phases of .

Harmful algal blooms (HABs) are a natural phenomenon caused by outbreaks of algae, resulting in serious problems for aquatic ecosystems and the coastal environment. () is one of the diatoms responsible for HABs. The growth curve of can be observed from beginning to end of HABs: therefore, detailed analysis is necessary to characterize each growth phase of .

Growth, Toxin Content and Production of Dinophysis Norvegica in Cultured Strains Isolated from Funka Bay (Japan).

The successful cultivation of Claparède & Lachmann, 1859, isolated from Japanese coastal waters, is presented in this study, which also includes an examination of its toxin content and production for the first time. Maintaining the strains at a high abundance (>2000 cells per mL) for more than 20 months was achieved by feeding them with the ciliate Lohmann, 1908, along with the addition of the cryptophyte (W.Conrad) D.

Current environmental status of the oyster farms on Lake Kamo in Japan; viral control of the harmful bloom of .

Lake Kamo is an enclosed, low-inflow estuary connected to the open sea that is famous for oyster farming in Japan. In the fall of 2009, this lake experienced its first bloom of the dinoflagellate , which selectively kills bivalve mollusks. This species has been detected exclusively in southwestern Japan.

Eyestalk transcriptome and methyl farnesoate titers provide insight into the physiological changes in the male snow crab, Chionoecetes opilio, after its terminal molt.

The snow crab, Chionoecetes opilio, is a giant deep-sea brachyuran. While several decapod crustaceans generally continue to molt and grow throughout their lifetime, the snow crab has a fixed number of molts. Adolescent males continue to molt proportionately to their previous size until the terminal molt at which time an allometric increase in chela size occurs and an alteration of behavioral activities occurs, ensuring breeding success.

Strain, cell density, and nutrient condition affect patterns of diurnal vertical migration and superoxide production in a red-tide alga.

A red tide occurs when cell densities of autotrophic microalgae and some heterotrophic protists increase dramatically and thereby change the color of the sea. Red tides sometimes have negative impacts on human activities, such as fisheries and tourism. Most red-tide flagellates display diurnal vertical migration (DVM) in which cells normally migrate upward during the day and downward at night.

Effects of domestication and captive breeding on reaction to moving objects: implications for avoidance behaviours of masu salmon .

Domestication and captive breeding can compromise the obstacle- and predator-avoidance capabilities of animals in the wild. Whereas previous studies only examined these effects in combination, here we examine them individually by comparing the abilities of wild, F1 (offspring of wild parents) and captive-bred (approx. F15) masu salmon to avoid a falling object under experimental conditions.

Epitope mapping of the monoclonal antibody IP5B11 used for detection of viral haemorrhagic septicaemia virus facilitated by genome sequencing of carpione novirhabdovirus.

The monoclonal antibody (mAb) IP5B11, which is used worldwide for the diagnosis of viral haemorrhagic septicaemia (VHS) in fish, reacts with all genotypes of VHS virus (VHSV). The mAb exceptionally also reacts with the carpione rhabdovirus (CarRV). Following next generation genome sequencing of CarRV and N protein sequence alignment including five kinds of fish novirhabdoviruses, the epitope recognized by mAb IP5B11 was identified.

A new species of dendrochirotid holothuroid from deep water of southern Japan, with the erection of a new genus, Satsumaocnus (Echinodermata: Holothuroidea: Dendrochirotida: Cucumariidae: Colochirinae).

A new dendrochirotid sea cucumber, Satsumaocnus kaiyomarui gen. nov., sp.

Sound properties produced by white-edged rockfish (Sebastes taczanowskii) in relation to body and swim bladder size.

The sound properties produced by the white-edged rockfish (Sebastes taczanowskii Steindachner, 1880) were compared with the body size. We conducted a tank experiment to compare the sound properties with body length, which ranged from 12.4 to 19.

Phytoplankton and Microzooplankton Community Structure and Assembly Mechanisms in Northwestern Pacific Ocean Estuaries with Environmental Heterogeneity and Geographic Segregation.

Phytoplankton and microzooplankton are crucial players in marine ecosystems and first responders to environmental changes, but their community structures and how they are shaped by environmental conditions have rarely been studied simultaneously. In this study, we conducted an eDNA metabarcoding sequencing combined with multiple statistical methods to simultaneously analyze the phytoplankton and microzooplankton in Liaohe (LH) and Yalujiang (YLJ) estuaries. The major objective was to examine how plankton community structure and assembly mechanism may differ between two estuaries with similar latitudinal position and climate but geographical segregation and differential level of urbanization (more in LH).

Relationship closeness of tolerance to two neonicotinoids with their internal body burden in two estuarine resident marine crustaceans.

The estuarine resident crustacean sand shrimp, Crangon uritai, has a higher tolerance to neonicotinoid insecticides than that of the kuruma prawns, Penaeus japonicus. However, the reason for the differential sensitivities between the two marine crustaceans remains to be understood. This study explored the mechanism underlying differential sensitivities based on insecticide body residues after exposing both said crustaceans to two insecticides (acetamiprid and clothianidin) with or without oxygenase inhibitor piperonyl butoxide (PBO) for 96 h.

Chronological age-related metabolome responses in the dinoflagellate Karenia mikimotoi, can predict future bloom demise.

Karenia mikimotoi is a common harmful algal bloom (HAB)-forming dinoflagellate and has caused severe financial loss in aquaculture. There are limited metabolomic studies on dinoflagellate biology. Here, we examined alterations in metabolic profiles over the growth curve of K.

Azaspiracid accumulation in Japanese coastal bivalves and ascidians fed with Azadinium poporum producing azaspiracid-2 as the dominant toxin component.

The filter-feeding bivalves often accumulate marine toxins by feeding on toxic dinoflagellates that produce marine toxins. Azaspiracids (AZAs) are a group of lipophilic polyether toxins which have been detected in a variety of organisms in many countries. In our present study, accumulation kinetics and toxin distributions in the tissues of seven bivalve species and ascidians relevant to Japanese coastal waters were investigated by experimentally feeding a toxic dinoflagellate Azadinium poporum, which produces azaspiracid-2 (AZA2) as the dominant toxin component.

Introgressive hybridization in the west Pacific pen shells (genus Atrina): Restricted interspecies gene flow within the genome.

A compelling interest in marine biology is to elucidate how species boundaries between sympatric free-spawning marine invertebrates such as bivalve molluscs are maintained in the face of potential hybridization. Hybrid zones provide the natural resources for us to study the underlying genetic mechanisms of reproductive isolation between hybridizing species. Against this backdrop, we examined the occurrence of introgressive hybridization (introgression) between two bivalves distributed in the western Pacific margin, Atrina japonica and Atrina lischkeana, based on single-nucleotide polymorphisms (SNPs) derived from restriction site-associated DNA sequencing.

Toxicity and Environmental Risk Assessment of Polycarbamate and Its Main Components to Marine Algae and Crustaceans.

Polycarbamate is commonly used as an antifoulant coating on fishing nets in Japan. Although its toxicity to freshwater organisms has been reported, its toxicity to marine organisms is currently unknown. We conducted algal growth inhibition and crustacean immobilization tests to assess the effects of polycarbamate on marine organisms.