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When determining the most effective conservation measures for endangered species, it is critical to understand their population dynamics, the primary drivers influencing their populations, and their life history strategies. Long-term monitoring is essential to obtain this information, and a lack of adequate data exists for numerous native species experiencing substantial population declines in recent years due to various anthropogenic factors. In the present study, we investigated the population dynamics and demographic characteristics of the Japanese pond turtle, Mauremys japonica, an endemic species native to Japan. Accordingly, we conducted an eight-year mark-recapture study in a Ramsar wetland that has remained relatively unaffected by numerous primary anthropogenic disturbances in Japan. The population size estimation of this study demonstrated that the wetland was inhabited by approximately 200 individuals, comprising both males and females. Both sexes exhibited a high annual survival rate (0.87), indicating that the wetland population was stable or slightly increasing. These findings provide baseline data regarding M. japonica, a species for which information on demographic parameters and population dynamics in healthy populations is lacking. [ABSTRACT FROM AUTHOR]

Fukutoku‐Oka‐no‐Ba is a submarine volcano located at 24°17.1′ N/141°28.9′ E in the Izu–Bonin arc, and is one of the most active volcanoes in Japan. This volcano produced an explosive eruption in August 2021 that generated a large amount of volcaniclastic material, some of which drifted westward to Japan and the coastal area of East Asia as a pumice raft. The pumice clasts that drifted for >1000 km were mostly homogeneous and identical to those produced by past historical eruptions. The clasts have trachytic compositions (SiO2 = 61–63 mass% and Na2O + K2O = 8.6–10.0 mass%) and contain augite, plagioclase, olivine (Mg# ~65), and magnetite, along with a small number of mafic enclaves containing diopside and high‐Mg olivine (Mg# ~ 92). We undertook a research cruise to investigate the proximal volcaniclastic materials by dredging. The proximal materials include pumice, weakly vesiculated lapilli, and volcanic blocks, which have trachytic composition (SiO2 contents up to 64.5 mass%). The main minerals in the proximal material are similar to those in the drift pumice, although remnants of mafic magma do not occur in the SiO2‐rich samples. The petrographic and geochemical characteristics of the proximal and drift ejecta from Fukutoku‐Oka‐no‐Ba suggest the magma reservoir was stratified into two parts. The major part experienced magma mixing with a limited volume of mafic magma, whereas the other part was more differentiated. The differentiated high‐SiO2 magma accumulated in the upper part of the magma reservoir and avoided the mixing with and feed of volatile from the mafic magma, then were pushed out from the volcanic vent without extensive bubbling to sunk in the proximal area. [ABSTRACT FROM AUTHOR]

Seafloor magnetotelluric (MT) experiments were recently conducted in two areas of the northwestern Pacific to investigate the nature of the old oceanic upper mantle. The areas are far from any tectonic activity, and 'normal' mantle structure is therefore expected. The data were carefully analyzed to reduce the effects of coastlines and seafloor topographic changes, which are significant boundaries in electrical conductivity and thus distort seafloor MT data. An isotropic, one-dimensional electrical conductivity profile was estimated for each area. The profiles were compared with those obtained from two previous study areas in the northwestern Pacific. Between the four profiles, significant differences were observed in the thickness of the resistive layer beyond expectations based on cooling of homogeneous oceanic lithosphere over time. This surprising feature is now further clarified from what was suggested in a previous study. To explain the observed spatial variation, dynamic processes must be introduced, such as influence of the plume associated with the formation of the Shatsky Rise, or spatially non-uniform, small-scale convection in the asthenosphere. There is significant room of further investigation to determine a reasonable and comprehensive interpretation of the lithosphere-asthenosphere system beneath the northwestern Pacific. The present results demonstrate that electrical conductivity provides key information for such investigation. [ABSTRACT FROM AUTHOR]