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Seagrass beds provide habitat for a wide array of organisms. Among these, macrobenthos constitute a major group in seagrass bed communities. The effects of seagrass meadows on macrobenthic community structure have been studied in many areas, and have revealed contradictory results regarding the meadow’s effects. In this study, sediment environment and macrobenthic community structure and diversity were investigated in an eelgrass bed and an adjacent unvegetated area in Swan Lake, northern China, from November 2011 to October 2012. Sediment grain size and organic matter did not differ significantly between the two areas. Polychaeta were the most abundant taxon, and herbivores, detritivores, and deposit feeders were the main functional feeding groups. Carnivores were slightly more abundant in the eelgrass bed than in the unvegetated area. Permutational multivariate analysis of variance (PERMANOVA) indicated that the macrobenthic assemblage differed between the two habitats, but analysis of similarities (ANOSIM) did not validate this result. Analysis of similarity percentages (SIMPER) demonstrated that Polychaeta was the largest contributor to dissimilarity between the macrobenthic assemblages; however, diversity was similar throughout the year, and theoretical species richness was equivalent (80 species) between the two areas. Thus, the presence of eelgrass did not affect macrobenthic community structure or diversity in the Swan Lake ecosystem. [ABSTRACT FROM AUTHOR]

Because of its high nutritional value and health benefits, aquaculture production of Apostichopus japonicus in China is the largest of any single species. Therefore, the development of new farming methods is of considerable significance. In this study, discarded oyster shells have been used to create an artificial reef for the culture of this species. The results have shown that from 6th March 2009 to 26th November 2009, the wet weight of sea cucumber increased from 49.57 ± 1.16 to 79.87 ± 1.46 g ind−1. Between 16th July and 18th October, the specific growth rate and daily weight gain of A. japonicus differed significantly from other periods. Population density was higher within the reef compared with outside the reef area, and the difference was significant ( P < 0.01). The maximum distance between A. japonicus individuals within the reef area on 3rd March and 16th July was 65.0 ± 3.3 and 62.9 ± 4.4 cm, respectively, but the difference was not significant ( P > 0.05). The diatom species attached to the oyster shells were similar to those found in the stomach content of A. japonicus. In conclusion, the oyster-shell reef provides a suitable habitat and shelter for the culture of the sea cucumber, A. japonicus. [ABSTRACT FROM AUTHOR]

Prokaryotes play a crucial role in marine ecosystem health and drive biogeochemical processes. The northern Ninety East Ridge (NER) of the Indian Ocean, a pivotal yet understudied area for these cycles, has been the focus of our study. We employed high-throughput 16S rRNA gene sequencing to analyze 35 water samples from five stations along the ridge, categorized into three depth- and dissolved oxygen-level-based groups. Our approach uncovered a clear stratification of microbial communities, with key bioindicators such as Prochlorococcus MIT9313, Sva0996 marine group, and Candidatus Actinomarina in the upper layer; Ketobacter , Pseudophaeobacter , Nitrospina , and SAR324 clade in the middle layer; and Methylobacterium-Methylorubrum , Sphingomonas , Sphingobium , and Erythrobacter in the deep layer. Methylobacterium-Methylorubrum emerged as the most abundant bacterial genus, while Nitrosopumilaceae predominated among archaeal communities. The spatial and depth-wise distribution patterns revealed that Ketobacter was unique to the northern NER, whereas Methylobacterium-Methylorubrum , UBA10353, SAR324 clade, SAR406, Sva0996&#95;marine&#95;group, Candidatus Actinomarina were ubiquitous across various marine regions, exhibiting niche differentiation at the OTU level. Environmental factors, especially dissolved oxygen (DO), silicate, nitrate, and salinity, significantly influence community structure. These findings not only reveal the novelty and adaptability of the microbial ecosystem in the northern NER but also contribute to the broader understanding of marine microbial diversity and its response to environmental heterogeneity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Li, Wang, Jiang, Zeng, Xu, Zhang, Zheng and Shao.)

The soft-shell clam Mya japonica (Jay, 1857) is a commercially important fishery resource. In this study, we identified the complete mitochondrial genome of M. japonica and performed a phylogenetic analysis to explore its genetic relationship with Mya arenaria . The genome is 21,396 bp in length and contains 13 protein-coding genes (PCGs), 23 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and 5 D-Loop control regions. The atp8 gene was annotated in Myidae for the first time. Notably, the genome contains an additional trnM , consistent with M. arenaria . The length of the cox2 gene is 1,947 bp, which is 513 bp longer than that in M. arenaria . Its base composition is 29.14% A, 37.26% T, 10.89% C, and 22.71% G. Phylogenetic analysis based on 12 PCGs and 2 rRNAs indicates that M. japonica and M. arenaria form a sister group. In this study, the identification and phylogenetic analysis of the complete mitochondrial genome of M. japonica provide significant information for future taxonomic and evolutionary research of the genus Mya ., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)