Stranding events of frogfishes (genus Antennarius) are rarely documented despite their ecological uniqueness as benthic ambush predators [1]. This study reports five stranded frogfish individuals representing two species, Antennarius striatus and Antennarius commersoni, recorded along the Pacific coast of central Honshu, Japan, between March 2025 and April 2026. All specimens were found during spring and exhibited no apparent external injuries or advanced decomposition, suggesting recent mortality before stranding. Species identification was based on external morphology, body coloration, and published diagnostic characters. Seasonal storms, wave action, and coastal transport processes may have contributed to the displacement and deposition of these benthic fishes [4, 5]. These observations provide new information on the occurrence of frogfish strandings and contribute to a better understanding of post-mortem transport processes affecting benthic marine fishes.
Mangrove ecosystems, between the terrestrial and marine domain, harbor a diverse and specialized microbial community, including Actinomycetia members, which produce a variety of functionally distinct bioactive metabolites. Molecular and genomic approaches have enabled the investigation of Actinomycetial diversity and identification of new strains and secondary metabolites. Mangrove-associated Actinomycetia from diverse areas have been reported in many studies. However, several habitats can still be poorly studied, hence their diversity and biosynthetic potential is lacking. This review systematically aims to highlight the study of the taxonomical diversity as well as bioactive potentials of Mangrove-associated Actinomycetia from sediments and endophytic niches from the study records published between 1988 and 2025. The integrated literature shows that these microorganisms generate diverse metabolites with antimicrobial, anticancer, antioxidant, quorum-quenching, and antibiofilm effects. Because of differences in the specific environmental conditions in mangrove ecosystems (salinity variation, tidal activities and nutrient gradients), the microbial population behaviour, adaptation and production of secondary metabolites are expected to be altered due to the particular environmental scenarios of mangrove ecosystem. Mangrove-associated Actinomycetia represent a valuable yet underexplored resource for natural product discovery. Combining established isolation methods with genetic sequencing, metabolomics and other omics based methods would be fundamental for harnessing full biosynthetic potential, allowing the discovery of new and original bioactive compounds even more quickly.
Mercury resistance is commonly associated with the mer operon, which comprises genes involved in mercury sensing, regulation, transport, and transformation. In the present study, metagenomic DNA extracted from Kongsfjorden sediments, Svalbard, was screened using a previously reported merRTΔP-targeting primer pair, followed by PCR, cloning, Sanger sequencing, and subsequent in silico analyses to characterise putative mercury-resistance-associated genetic components. A mer operon-related genetic region, designated KGmer1, comprising a regulator merR sequence, an operator-promotor (merOP) region, and two transporter merT and merP sequences, was identified. Comparative sequence analyses revealed that the identified genes shared high similarity with mer operon components reported from Pseudomonas aeruginosa. The obtained KG-merR1 gene encoded a regulator protein consisting of a DNA binding domain (DBD), dimerization helix (DH), and a metal binding domain (MBD). The transporter gene (KG-merT1) encoded a membrane protein with three transmembrane helices with dual cysteine residues associated with mercury transport. The KG-merP1 gene encoded a precursor protein with a ‘ferredoxin-like’ structural fold (βαββαβ) and a highly conserved GMTCSAC motif with two reactive cysteine residues (Cys14 and Cys17) at the metal binding site. Phylogenetic and structural analyses further demonstrated strong conservation of sequence and structural features with previously characterized mer operon components. The identified genetic region provides sequence-based evidence for the occurrence of putative mer-associated mercury-resistance components in Kongsfjorden sediments. This study provides molecular insights into the occurrence of mer operon-related genetic components in Arctic fjord sediments.
A rare, severe convective-storm impacted Shushah Island in the Northern Red Sea on 29 November 2022, producing intense rainfall exceeding 50 mm h−1 and strong winds (> 10 m s⁻1). Here, we characterize the storm event by its underwater acoustic signature and investigate potential changes in biophony caused by its passing. Initial light rain and wind elevated energy in the 2–15 kHz range, while consequent heavy rainfall introduced pronounced low-frequency energy (< 1 kHz). The rapid-onset storm masked biophony for its duration ( 15 min), especially in the low frequency range. Root-mean-square sound pressure level (SPLrms) were analyzed at two key time intervals, before and after the storm event, for both low frequency (40 Hz–800 Hz) and high frequency (2 kHz–20 kHz) bands, commonly associated with biophony of fish and snapping shrimp respectively. These levels were compared against a baseline, using recordings from the same time interval across the 10-day surrounding window (5 days before and 5 days after). SPLrms during the intervals immediately preceding and following the storm generally occupied the lower range of reference conditions, particularly in the high-frequency band, although responses were variable at the minute scale. Despite these short-term shifts, acoustic levels returned rapidly to baseline conditions, indicating high short-term resilience of the reef acoustic community following this rare extreme weather event.
The Arabian Gulf (hereafter “Gulf”) is a young ocean basin noted for its low biodiversity for many marine organisms. Natural and anthropogenic factors, such as shallow depth, high water temperatures, high salinity, and rapid urbanization and industrialization of coastal areas, are considered as stressors on biodiversity of the Gulf. It is important to investigate the broader distributional patterns of key organisms in the basin to understand how those communities might change over time. In this study, we document the diversity and summarize the distribution of marine pelagic copepods, a crucial component of marine ecosystems, throughout the basin. A comprehensive review of 82 publications covering over 110 years of zooplankton research in the Gulf was conducted to generate a taxonomic database of all known pelagic copepods from within the basin and assess taxa distributions. A total of 280 unique copepod sampling stations were identified in the Gulf, with 144 in the Western Gulf and 136 in the Eastern Gulf. A total of 107 taxa of copepods from 25 families and 43 genera were recorded from the Gulf. The most diverse copepod families included Pontellidae, Acartiidae, Paracalanidae, Coryceidae, and Oithonidae. We documented little overlap in copepod distribution across the Western and Eastern Gulf. A total of 47 taxa were exclusive to the Western Gulf, 32 were exclusive to the Eastern Gulf, and just 30 were found in both Western and Eastern regions of the Gulf. The discrepancies between copepod diversity in the Western and Eastern Gulf are discussed, and recommendations for future research on copepods in the entire Gulf are presented.
