Biology

Deep-sea hydrothermal vent fauna is often regarded as highly endemic, although exceptions have been reported. We examined genetic connectivity across broad spatial scales within the alvinocaridid genus Rimicaris, which has undergone substantial adaptive radiation worldwide. We analyzed six Rimicaris species using three genetic markers, cytochrome c oxidase subunit I (COI), 16S ribosomal rRNA gene (16S), and histone h3 (H3), and complete mitogenomes, employing newly generated sequences combined with publicly available sequence data. A genetic tree and haplotype networks were constructed, and divergence analyses were performed. Three clades of paired Rimicaris species were identified, each made up of taxa from different oceanic regions but showing relatively low COI divergence (0.35–1.90%). In Clade I, Rimicaris chacei and Rimicaris hybisae are morphologically similar and exhibit bidirectional gene flow, implying a dispersal route between the Mid-Atlantic Ridge (MAR) and the Mid-Cayman Spreading Center (MCSC). In Clade II, Rimicaris exoculata and Rimicaris kairei are morphologically, genetically, and ecologically distinct, reflecting restricted connectivity between the MAR and the Carlsberg Ridge (CR)–Central Indian Ridge (CIR). In Clade III, Rimicaris variabilis and Rimicaris cf. variabilis differ in nutritional strategies, showing a unidirectional dispersal route from the CIR to the southwestern Pacific (SWP), but morphological data to distinguish them are currently lacking. Some Rimicaris lineages maintain connectivity across distinct oceanic regions while others still form unique regional populations. This finding highlights the need for conservation strategies that incorporate both global-scale connectivity and regional endemism, rather than treating individual vent ecosystems as a single homogeneous management unit.

Quick Quantitative (QQ) immunoassays have been increasingly applied for the measurement of enrofloxacin (ENR) and ciprofloxacin (CIP) residues in aquaculture due to their speed and convenience. However, their quantitative reliability remains limited because measurement uncertainty (MU) is rarely considered during field testing. To enhance the metrological reliability of QQ-based residue analysis, we developed AquaUncertainty Pal, a mobile application that embeds real-time MU computation into the QQ workflow. The software automatically evaluates uncertainty sources during sampling and pipetting, visualizes the uncertainty budget, and guides users through optimized operations. The framework was validated against ISO/IEC 17025–accredited LC–MS/MS and assessed through a user study involving 20 frontline technicians. With the integrated software, pipetting precision (RSD) at 100 μL improved from 4.1% to 1.79%, the inter-operator variability (CV) decreased by 52%, and conformity assessment accuracy for samples near the maximum residue limit (MRL) increased from 25% to 70%. This suggests that real-time MU visualization effectively guided technicians toward consistent pipetting and interpretation behavior. These results demonstrate that integrating MU into the QQ workflow is both feasible and effective, substantially improving reliability and providing a replicable digital framework for uncertainty-informed residue monitoring in aquaculture.

This study investigates the growth performance, gut content composition, and biochemical profiles of the fairy shrimp Streptocephalus sirindhornae cultured with natural diets under low and high stocking densities (20 and 40 ind. L⁻¹). Fairy shrimp were reared for 15 days in 1 m³ floating cages placed in earthen ponds. On day 15, individuals in the low-density treatment exhibited significantly greater body weight (0.074 ± 0.013 g) and total length (20.97 ± 0.90 mm) than those in the high-density group. A total of 54 food taxa were identified in the gut contents, with phytoplankton comprising the dominant fraction (91%). In contrast, 105 food taxa were recorded in the culture ponds, including 54 phytoplankton and 51 zooplankton taxa; chlorophytes (27 taxa, 50%) and rotifers (33 species, 63.46%) were the most diverse groups. Fairy shrimp feeding on natural pond foods exhibited high levels of essential amino acids, with monounsaturated fatty acids dominating and linoleic acid (C18:2n6c) representing the principal polyunsaturated fatty acid. Overall, the results indicate that low-density rearing enhances fairy shrimp growth, while the high diversity of natural food organisms contributes to the favorable nutritional composition of S. sirindhornae.