http://scholars.ntou.edu.tw/handle/123456789/5 2026-08-29T10:24:19Z http://scholars.ntou.edu.tw/handle/123456789/26809 標題: Preferential impairment of later mating stages and sex-dependent metabolic shifts in Japanese medaka exposed to acute acidification 作者: Chung, Chih-Ching; Liu, Sian-Tai; Horng, Jiun-Lin; Chou, Ming-Yi 摘要: Environmental acidification poses a significant threat to aquatic organisms, yet the underlying mechanisms of how acid stress disrupts complex social and reproductive behaviors remain incompletely understood. In the present study, we investigated the behavioral and physiological responses of adult Japanese medaka (Oryzias latipes) under acute acid exposure (pH 4.5, 24 h). Our results showed that acute acid stress reduced mating success, with a stronger impairment observed in the transition to the crossing stage and subsequent spawning, while the earlier, male-driven stages of following and courtship were relatively less affected under the present experimental conditions. This reproductive impairment did not coincide with detectable changes in generalized emotional-like behavior. Fish showed normal performance in the novel tank test and maintained territorial aggression. Physiologically, we observed a clear sexual dimorphism. Under acid stress, males maintained relatively stable MOB and JAmm, whereas females showed elevated MOB and JAmm. These findings suggest that reproductive impairment may be more pronounced in energetically demanding mating stages and may be associated with sex-dependent physiological strain. We further propose that the increased metabolic cost of acidbase regulation in females could shift energy allocation, and that high-cost coordination behaviors may be reduced in order to maintain short-term survival. This study provides evidence linking bioenergetics, acid-base regulation, and reproductive behavior in a teleost model under acidification. 2026-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26805 標題: Robust Nonlinear GNSS Navigation Under Heavy-Tailed Measurement Noise Using a Cauchy-Kernel Correntropy Extended Kalman Filter 作者: Jwo, Dah-Jing; Abdi, Abdirisak Daud; Chang, Yi 摘要: In urban canyon environments, the performance of global navigation satellite systems (GNSS) is severely degraded by multipath propagation, signal occlusion, and non-Gaussian measurement noise. These effects reduce positioning accuracy and service reliability. Kalman filtering and its nonlinear extensions are widely used for GNSS positioning. However, these filters rely on Gaussian noise assumptions and are formulated using the minimum mean square error (MMSE) criterion. Consequently, their performance degrades in non-Gaussian environments. Recently, filtering methods based on the maximum correntropy criterion (MCC) have been investigated as robust alternatives to MMSE-based approaches. The performance of MCC filters is strongly influenced by the choice of the kernel function. In particular, Gaussian kernel-based MCC algorithms may suffer from numerical instability under large measurement noise and strong sensitivity to kernel bandwidth selection. These limitations compromise estimation robustness and convergence stability. To address these limitations, this study proposes a Cauchy kernel-based maximum correntropy extended Kalman filter (CKMCEKF). The effectiveness of the proposed filter was validated using both simulation and real GNSS datasets. The results confirm the superior accuracy, stability, and reduced sensitivity to kernel bandwidth selection of the proposed method. 2026-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26796 標題: Regional exploitation signals inferred from a data-limited per-recruit assessment of Trichiurus japonicus in Taiwanese waters 作者: Lin, Chih-Yu; Lu, Yu-Heng; Xu, Wen-Qi; Wang, Sheng-Ping; Kitakado, Toshihide 摘要: Trichiurus japonicus is a heavily exploited coastal fishery species in the Northwest Pacific Ocean. Although Taiwan contributes less than 2% of regional landings, localized assessment is important because exploitation pressure reflects cumulative fishing mortality across jurisdictions and biological parameters may vary geographically. The lack of species-specific catch data and long-term abundance indices has prevented formal stock assessment in Taiwanese waters. To evaluate relative exploitation status under severe data constraints, agestructured and length-structured per-recruit analyses were conducted using length-frequency data collected from Taiwanese coastal fisheries between 2019 and 2023. Natural mortality was estimated using six empirical methods, and total mortality was estimated using seven catch-curve approaches, yielding forty-two fishing mortality scenarios. Length compositions were consistently dominated by small to medium individuals, and reconstructed age compositions were strongly truncated, with age-0 and age-1 fish comprising most of the catch. Current fishing mortality ranged from 0.749 to 1.483 year(-1) and exceeded conservative biological reference points, including F0.1 (0.203-0.731 year(-1)), in most scenarios. It also frequently approached or exceeded FMAX (0.385-1.887 year(-1)) and spawning potential ratio (SPR)-based thresholds. Current SPR ranged from 0.128 to 0.456 and was generally below the 40% target threshold and often near or below the 25% limit threshold. Although available data preclude a complete stock assessment, consistent signals across model structures and selectivity assumptions indicate elevated exploitation that reduces survival to older ages and limits reproductive output. These findings demonstrate that per-recruit analyses can provide useful indicators of relative exploitation under data-limited conditions and highlight the importance of incorporating localized biological indicators into future regional assessments of this transboundary resource. 2026-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26798 標題: Using geochemical signatures to identify subsurface flow pathways in the intermittent reach of the Yusheng Creek in Taiwan 作者: Lee, Tsung-Yu; Yeh, Hsiu-Hao; Pan, Yen-Wei; Hsu, Shao-Yu; Chiu, Yung-Chia; Huang, Jr-Chuan 摘要: Study region: Yusheng Creek is a mountain stream in central Taiwan where the critically endangered Formosan landlocked salmon (Oncorhynchus masou formosanus) has been reintroduced but remains vulnerable to intermittent streamflow. Study focus: Subsurface flow pathways and groundwater-stream interactions were investigated using end-member mixing analysis (EMMA). Monthly water samples were collected from four observation wells, stream water, and tributaries during two monitoring periods (January-November 2017; October 2021-August 2022). Geochemical parameters and stable isotopes (delta 18O and delta 2H) were analyzed to trace water sources. New hydrological insights: Results reveal contrasting hydrological connectivity between dry and wet years. During dry years, the hyporheic zone persisted within the streambed but remained disconnected from groundwater, while upstream stream water infiltrated and migrated downstream through subsurface pathways. In wet years, the hyporheic zone and groundwater formed a hydraulically connected system, as indicated by similar geochemical signatures. These results highlight the critical role of the hyporheic zone in maintaining longitudinal connectivity in intermittent mountain streams, providing new insights into subsurface flow dynamics in humid subtropical regions. 2026-01-01T00:00:00Z