Cumulative reproduction model to quantify the production of the invasive species Arctodiaptomus dorsalis (Calanoida, Copepoda)2023 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Ecological Modelling Arctodiaptomus dorsalis is an invasive calanoid copepod originally from America and has recently established a population in Lake Taal in the Philippines. It has been proposed that eutrophication due to aquaculture contributes to the establishment and success of this species. This study aimed to clarify this hypothesis by quantifying the effect of increasing food concentration on the reproduction of A. dorsalis using an Individual-Based Model. We parameterized food concentration-dependent equations to simulate the effect of different food concentration on the reproductive traits (latency time, embryonic development time, clutch size, and hatching success) of this species using data from the literature and simulated the reproduction of 1000 independent females for 20 days at different food concentration, taking into account the variability among individuals. The simulation results showed that the cumulative production of eggs and offspring increased continuously with time when the food concentration was above 3.2 × 104 cells mL−1, suggesting that this value was the threshold concentration required for stable reproduction of A. dorsalis. This value is not particularly low compared to other copepods. Hence, our result revealed that the food use efficiency of A. dorsalis is not particularly outstanding and urge the need of a comparison with native species to confirm a possible superiority. We suggest that A. dorsalis has filled the ecological niche left vacant by the disappearance of the original species due to the deterioration of water quality caused by the eutrophication of the lake. The reproductive cycle model developed in this study constitutes a necessary step in the development of a complete population dynamics model, which can help clarify the invasive abilities of A. dorsalis. DOI： 10.1016/j.ecolmodel.2023.110398 Scopus その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85154021346&origin=inward
Sedimentary DNA can reveal the past population dynamics of a pelagic copepod2023 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Freshwater Biology Copepods play a key trophic role as secondary producers, transferring primary production to higher trophic levels such as fish. Copepod production contributes significantly to successful fish recruitment. Despite their importance, knowledge of copepod dynamics over several decades remains limited due to the lack of long-term data series with adequate sampling and analysis. However, an understanding of long-term copepod dynamics is urgently required to strive toward better management for sustainable aquatic ecosystems and fish recruitment. Sedimentary DNA (sedDNA) has been developing as a useful tool for reconstructing past plankton dynamics. This study evaluates whether sedDNA targeting the pelagic copepod, Eodiaptomus japonicus, in Lake Biwa (Japan) can be an effective tool for elucidating its past population dynamics. We applied a quantitative polymerase chain reaction method targeting the mitochondrial cytochrome c oxidase subunit I gene on two sediment cores and compared the detected sedDNA concentrations with the unique long-term dataset of demographic traits, biomass, specific growth rate, production, subitaneous eggs, and resting eggs of E. japonicus. The sedDNA concentration of E. japonicus recovered from sediment layers correlated significantly with in situ production, biomass, and production of immediately hatching eggs but not with resting eggs or specific growth rate. Our study provides evidence for the effective use of sedDNA as a tracking tool for assessing past copepod production dynamics. DOI： 10.1111/fwb.14096 Scopus その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85153617187&origin=inward
Causal networks of phytoplankton diversity and biomass are modulated by environmental context2022 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Nature Communications Untangling causal links and feedbacks among biodiversity, ecosystem functioning, and environmental factors is challenging due to their complex and context-dependent interactions (e.g., a nutrient-dependent relationship between diversity and biomass). Consequently, studies that only consider separable, unidirectional effects can produce divergent conclusions and equivocal ecological implications. To address this complexity, we use empirical dynamic modeling to assemble causal networks for 19 natural aquatic ecosystems (N24◦~N58◦) and quantified strengths of feedbacks among phytoplankton diversity, phytoplankton biomass, and environmental factors. Through a cross-system comparison, we identify macroecological patterns; in more diverse, oligotrophic ecosystems, biodiversity effects are more important than environmental effects (nutrients and temperature) as drivers of biomass. Furthermore, feedback strengths vary with productivity. In warm, productive systems, strong nitrate-mediated feedbacks usually prevail, whereas there are strong, phosphate-mediated feedbacks in cold, less productive systems. Our findings, based on recovered feedbacks, highlight the importance of a network view in future ecosystem management. DOI： 10.1038/s41467-022-28761-3 Scopus その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85125688612&origin=inward
