Genetic diversity and population structure of Capitulum mitella (Linnaeus, 1767) in Fujian (China) revealed by mtDNA COI sequences.

Background: Capitulum mitella is a widely distributed and ecologically important stalked barnacle that settles extensively on rocky shores. This species contributes to the structural complexity of intertidal habitats and plays a critical role in the marine ecosystem. This study aimed to reveal the genetic diversity and population structure of C. mitella by analyzing the mitochondrial cytochrome oxidase I (COI) gene. Methods: A 683bp fragment of the COI gene was sequenced from 390 individuals sampled from six localities in Fujian, China. Results: A total of 84 distinct haplotypes were identified through the analysis of 82 polymorphic sites, resulting in an average haplotype diversity (h) of 0.660 and nucleotide diversity (π) of 0.00182. Analysis of molecular variance (AMOVA) and pairwise F ST statistics showed no significant population structure. Neutrality tests and mismatch distributions provided evidence of recent population expansion for the species. Conclusions: We suggest that the species' high dispersal ability, and ocean currents coupled with limited physical barriers in the region, contribute to its current phylogeographic structure. These findings enhance our comprehension of the genetic diversity and population structure of C. mitella, providing valuable insights for future conservation efforts.

Copepods as Indicators of Different Water Masses during the Northeast Monsoon Prevailing Period in the Northeast Taiwan.

During this research, the average surface temperature, salinity, dissolved oxygen, and pH were 24.65 ± 1.53 (°C), 34.21 ± 0.07 (PSU), 6.85 ± 0.18 (mg/L), and 8.36 ± 0.03, respectively. Based on these environmental parameters, stations were arranged into three groups. Group A represents stations located around Keelung Island with the relative highest average dissolved oxygen, lowest average temperature, and pH values. Instead, the lowest average dissolved oxygen and highest average temperature, salinity, and pH values were recorded at the offshore stations. Keelung Island area was charged by cold water masses, which were driven by the Northeast monsoon, and stations in group C were affected by the Kuroshio Current. Kueishan Island area was mainly affected by mixed water masses resulting from the Kuroshio intrusion and monsoon-derived cold water. In this study, a total of 108 copepod species were identified, with an average abundance of 774.24 ± 289.42 (inds. m-3). Most species belong to the orders Calanoida and Poecilostomatoida, with an average relative abundance (RA) of 62.96% and 30.56%, respectively. Calanoid copepodites were the most dominant group, with a RA of 28.06%. This was followed by Paracalanus aculeatus, with a RA of 18.44%. The RA of Clausocalanus furcatus and Canthocalanus pauper was 4.80% and 3.59%, respectively. The dominant species P. aculeatus, C. pauper, Paracalanus parvus, and Temora turbinata were positively correlated with dissolved oxygen and negatively correlated with temperature in the surface waters. pH showed a negative correlation with P. parvus and T. turbinata, while the temperature was negatively correlated with these two dominant species. Indicator species were selected by an indicator value higher than 50%. Temora turbinata, Calanopia elliptica, C. pauper, Euchaeta concinna, Temora discaudata, Acartia pacifica, Macrosetella gracilis, Corycaeus speciosus, and P. parvus were considered as monsoonal cold water indicator species in Group A. Indicator copepod species for the Kuroshio Current were Farranula concinna, Copilia mirabilis, Candacia aethiopica, Corycaeus agilis, Farranula gibbula and Acrocalanus monachus in the study area. Paracandacia truncata, Oncaea clevei, P. aculeatus, and Centropages furcatus were considered suitable indicators for mixed water masses.

Molecular phylogeny suggests synonymy of Sandaliabridgesi Lorenz, 2009 with S.triticea (Lamarck, 1810) (Gastropoda, Ovulidae).

The Ovulidae (Gastropoda, Cypraeoidea) is a family of small to medium Mollusca in the order Littorinimorpha, and Sandalia is a very small genus containing only three extant species. In the present study, 132 specimens of Ovulidae were collected, belonging to seven genera and nine species, including 54 Sandaliabridgesi and three Sandaliatriticea individuals. The cytochrome c oxidase I gene, 16S rRNA, and ITS1-5.8S-ITS2 sequences were obtained from all specimens and compared with sequences downloaded from GenBank to calculate genetic distances and construct phylogenetic trees. The sequences of S.bridgesi and S.triticea exhibited a high degree of similarity, and S.bridgesi does not form a separate clade, supporting the proposal that S.bridgesi should be synonymised with S.triticea.