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  1. Article ; Online: Detecting shifts in nonlinear dynamics using Empirical Dynamic Modeling with Nested-Library Analysis.

    Yong-Jin Huang / Chun-Wei Chang / Chih-Hao Hsieh

    PLoS Computational Biology, Vol 20, Iss 1, p e

    2024  Volume 1011759

    Abstract: Abrupt changes in system states and dynamical behaviors are often observed in natural systems; such phenomena, named regime shifts, are explained as transitions between alternative steady states (more generally, attractors). Various methods have been ... ...

    Abstract Abrupt changes in system states and dynamical behaviors are often observed in natural systems; such phenomena, named regime shifts, are explained as transitions between alternative steady states (more generally, attractors). Various methods have been proposed to detect regime shifts from time series data, but a generic detection method with theoretical linkage to underlying dynamics is lacking. Here, we provide a novel method named Nested-Library Analysis (NLA) to retrospectively detect regime shifts using empirical dynamic modeling (EDM) rooted in theory of attractor reconstruction. Specifically, NLA determines the time of regime shift as the cutting point at which sequential reduction of the library set (i.e., the time series data used to reconstruct the attractor for forecasting) optimizes the forecast skill of EDM. We illustrate this method on a chaotic model of which changing parameters present a critical transition. Our analysis shows that NLA detects the change point in the model system and outperforms existing approaches based on statistical characteristics. In addition, NLA empirically detected a real-world regime shift event revealing an abrupt change of Pacific Decadal Oscillation index around the mid-1970s. Importantly, our method can be easily generalized to various systems because NLA is equation-free and requires only a single time series.
    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2024-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Comments on identifying causal relationships in nonlinear dynamical systems via empirical mode decomposition

    Chun-Wei Chang / Stephan B. Munch / Chih-hao Hsieh

    Nature Communications, Vol 13, Iss 1, Pp 1-

    2022  Volume 4

    Keywords Science ; Q
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Using Geographical Overlaps to Track Temporal Changes in Species Interactions and Community Coexistence Instability

    Yin-Zheng Lai / Chih-Wei Tu / Chih-hao Hsieh / Chia-Ying Ko

    Frontiers in Marine Science, Vol

    2022  Volume 9

    Abstract: Environmental and climatic changes are expected to redistribute species, altering the strengths of species interaction networks; however, long-term and large-scale evaluations remain elusive. One way to infer species interaction networks is by analyzing ... ...

    Abstract Environmental and climatic changes are expected to redistribute species, altering the strengths of species interaction networks; however, long-term and large-scale evaluations remain elusive. One way to infer species interaction networks is by analyzing their geographical overlaps, which provides indices of species interdependence, such as mean spatial robustness (MSR), which represents the geographical impact of a species on other species, and mean spatial sensitivity (MSS), which indicates how a species is influenced by other species. Integrating MSR and MSS further allows us to assess community coexistence stability and structure, with a stronger negative relationship between MSR and MSS (i.e., species are unequally dependent on each other) within a community at a given time suggesting a more stable community. Here, we assessed multidecadal changes in adult marine fish communities using bottom trawl datasets across latitudes from 1982 to 2011 in the Eastern US Continental Shelf, North Sea, and Eastern Bering Sea. Consistent, significant long-term increasing temporal trends of MSR and MSS were found in all three large marine communities. MSR exhibited strong correlations with species’ range sizes, especially in high-latitude communities, while MSS was strongly positively correlated with species’ median proportion of overlap with interacting species. The relationships between MSR and MSS were generally negative, indicating stably coexisting fish communities. However, the negative relationships weakened over time, implying that the coexisting fish communities gradually became unstable. Our findings provide an assessment of changes in spatially geographical aspects of multiple species, for decades and at mid- to high latitudes, to allow the detection of global ecological changes in marine systems by alternative estimation of geographic overlaps of species interaction networks. Such species co-occurrence estimation can help stay vigilant of strategies for accelerating climate change mitigation particularly at coarser spatial scales.
    Keywords adult marine fish ; geographical overlap ; species interaction network ; community coexistence ; species distribution ; Climate change ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Language English
    Publishing date 2022-02-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Effects of the Coastal Uplift on the Kuroshio Ecosystem, Eastern Taiwan, the Western Boundary Current of the North Pacific Ocean

    Chung-Chi Chen / Chun-Yi Lu / Sen Jan / Chih-hao Hsieh / Chih-Ching Chung

    Frontiers in Marine Science, Vol

    2022  Volume 9

    Abstract: The Kuroshio is the western boundary current of the North Pacific Ocean. In the subtropical region of eastern Taiwan, a coastal uplift of the isotherms has occurred. To explore its impact on this oligotrophic ecosystem, hydrographic data along the ... ...

    Abstract The Kuroshio is the western boundary current of the North Pacific Ocean. In the subtropical region of eastern Taiwan, a coastal uplift of the isotherms has occurred. To explore its impact on this oligotrophic ecosystem, hydrographic data along the transect line at 23.75°N were measured between September 2012 and September 2014. Results show that the intensity of coastal uplift was positively correlated to the flow volume transport of the Kuroshio. Significant dissolved inorganic nutrients were uplifted to the sunlit zone, especially in the onshore. For example, compared to the offshore, nitrate concentration increased 0.49 μM (or ∼178%) in the upper 100 m of the onshore. The increased nutrients thereafter enhanced the growth of phytoplankton; for instance, the Chl a concentration increased 88.3%, compared to offshore, in the upper 100 m of the onshore. Phytoplankton community was mostly composed of picophytoplankton (<2 μm in size), which were dominated, in terms of relative abundance, by Prochlorococcus (83.6%), followed by Synechococcus (13.8%) and picoeukaryotes (2.7%). The relative abundance of Prochlorococcus increased from onshore toward offshore, but the trend was reversed for Synechococcus and picoeukaryotes, which may be affected by the coastal uplift. The results also suggest that the coastal uplift may support more energy transferred to higher tropical levels in this oligotrophic Kuroshio ecosystem.
    Keywords coastal uplift ; dissolved inorganic nutrients ; picoeukaryotes ; picoplankton ; Prochlorococcus ; Synechococcus ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Subject code 551
    Language English
    Publishing date 2022-02-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Causal effects of population dynamics and environmental changes on spatial variability of marine fishes

    Jheng-Yu Wang / Ting-Chun Kuo / Chih-hao Hsieh

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 10

    Abstract: Extracting causality from time series on natural populations is challenging. Here the authors apply empirical dynamical modeling to 25 years of fish survey data from North Sea fisheries to quantify causal effects of age structure, abundance, and ... ...

    Abstract Extracting causality from time series on natural populations is challenging. Here the authors apply empirical dynamical modeling to 25 years of fish survey data from North Sea fisheries to quantify causal effects of age structure, abundance, and environment on population spatial variability, finding both common and species-specific patterns.
    Keywords Science ; Q
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Causal effects of population dynamics and environmental changes on spatial variability of marine fishes

    Jheng-Yu Wang / Ting-Chun Kuo / Chih-hao Hsieh

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 10

    Abstract: Extracting causality from time series on natural populations is challenging. Here the authors apply empirical dynamical modeling to 25 years of fish survey data from North Sea fisheries to quantify causal effects of age structure, abundance, and ... ...

    Abstract Extracting causality from time series on natural populations is challenging. Here the authors apply empirical dynamical modeling to 25 years of fish survey data from North Sea fisheries to quantify causal effects of age structure, abundance, and environment on population spatial variability, finding both common and species-specific patterns.
    Keywords Science ; Q
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Importance of prey size on investigating prey availability of larval fishes.

    Yu-Hsuan Huang / Hsiao-Hang Tao / Gwo-Ching Gong / Chih-Hao Hsieh

    PLoS ONE, Vol 16, Iss 5, p e

    2021  Volume 0251344

    Abstract: Prey availability plays an important role in determining larval fish survival. Numerous studies have found close relationships between the density of mesozooplankton and larval fishes; however, emerging studies suggest that small-size zooplankton are ... ...

    Abstract Prey availability plays an important role in determining larval fish survival. Numerous studies have found close relationships between the density of mesozooplankton and larval fishes; however, emerging studies suggest that small-size zooplankton are more important prey for some larval fish species. One arising question is whether the size of zooplankton determines the relationship between zooplankton and larval fish community in natural environments. To address this question, we collected small-size (50-200 μm) zooplankton, mesozooplankton (> 330 μm), and larval fish using three different mesh-size (50, 330, 1000 μm, respectively) nets in the East China Sea, and examined their relationships in density. Both meso- and small-size zooplankton densities showed positive relationships with larval fish density, while the relationship is much stronger for the small-size zooplankton. Specifically, the smallest size classes (50-75 and 75-100 μm) of small-size zooplankton showed the highest positive relationships with larval fish density. Temperature, salinity, and chlorophyll-a concentration did not significantly explain larval fish density. Based on these findings, we demonstrate the importance of considering prey size when investigating prey availability for larval fishes.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Age‐specific habitat preference, carrying capacity, and landscape structure determine the response of population spatial variability to fishing‐driven age truncation

    Hsiao‐Hang Tao / Gaël Dur / Po‐Ju Ke / Sami Souissi / Chih‐hao Hsieh

    Ecology and Evolution, Vol 11, Iss 11, Pp 6358-

    2021  Volume 6370

    Abstract: Abstract Understanding the mechanisms underlying spatial variability of exploited fish is critical for the sustainable management of fish stocks. Empirical studies suggest that size‐selective fishing can elevate fish population spatial variability (i.e., ...

    Abstract Abstract Understanding the mechanisms underlying spatial variability of exploited fish is critical for the sustainable management of fish stocks. Empirical studies suggest that size‐selective fishing can elevate fish population spatial variability (i.e., more heterogeneous distribution) through age truncation, making the population less resilient to changing environment. However, species differ in how their spatial variability responds to age truncation and the underlying mechanisms remain unclear. We hypothesize that age‐specific habitat preference, together with environmental carrying capacity and landscape structure, determines the response of population spatial variability to fishing‐induced age truncation. To test these hypotheses, we design an individual‐based model of an age‐structured fish population on a two‐dimensional landscape under size‐selective fishing. Individual fish reproduces and survives, and moves between habitats according to age‐specific habitat preference and density‐dependent habitat selection. Population spatial variability elevates with increasing age truncation, and the response is stronger for populations with stronger age‐specific habitat preference. On a gradient landscape, reducing carrying capacity elevates the relative importance of density dependence in habitat selection, which weakens the response of spatial variability to age truncation for populations with strong age‐specific habitat preference. On a fragmented landscape, both populations with strong and weak age‐specific habitat preferences are restricted at local optimal habitats, and reducing carrying capacity weakens the responses of spatial variability to age truncation for both populations. Synthesis and applications. We demonstrate that to track and predict the changes in population spatial variability under exploitation, it is essential to consider the interactive effects of age‐specific habitat preference, carrying capacity, and landscape structure. To improve spatial management in fisheries, it is crucial to ...
    Keywords age truncation ; age‐specific habitat preference ; individual‐based model ; size‐selective fishing ; spatial variability ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Empirical Dynamic Modelling Identifies different Responses of Aedes Polynesiensis Subpopulations to Natural Environmental Variables

    Florian Grziwotz / Jakob Friedrich Strauß / Chih-hao Hsieh / Arndt Telschow

    Scientific Reports, Vol 8, Iss 1, Pp 1-

    2018  Volume 10

    Abstract: Abstract To control mosquito populations for managing vector-borne diseases, a critical need is to identify and predict their response to causal environmental variables. However, most existing attempts rely on linear approaches based on correlation, ... ...

    Abstract Abstract To control mosquito populations for managing vector-borne diseases, a critical need is to identify and predict their response to causal environmental variables. However, most existing attempts rely on linear approaches based on correlation, which cannot apply in complex, nonlinear natural systems, because correlation is neither a necessary nor sufficient condition for causation. Applying empirical dynamic modelling that acknowledges nonlinear dynamics on nine subpopulations of tiger mosquitos from three neighbouring reef islets of the Raiatea atoll, we identified temperature, precipitation, dew point, air pressure, and mean tide level as causal environmental variables. Interestingly, responses of subpopulations in close proximity (100–500 m) differed with respect to their causal environmental variables and the time delay of effect, highlighting complexity in mosquito-environment causality network. Moreover, we demonstrated how to explore the effects of changing environmental variables on number and strength of mosquito outbreaks, providing a new framework for pest control and disease vector ecology.
    Keywords Medicine ; R ; Science ; Q
    Subject code 333
    Language English
    Publishing date 2018-11-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Fishing and temperature effects on the size structure of exploited fish stocks

    Chen-Yi Tu / Kuan-Ting Chen / Chih-hao Hsieh

    Scientific Reports, Vol 8, Iss 1, Pp 1-

    2018  Volume 10

    Abstract: Abstract Size structure of fish stock plays an important role in maintaining sustainability of the population. Size distribution of an exploited stock is predicted to shift toward small individuals caused by size-selective fishing and/or warming; however, ...

    Abstract Abstract Size structure of fish stock plays an important role in maintaining sustainability of the population. Size distribution of an exploited stock is predicted to shift toward small individuals caused by size-selective fishing and/or warming; however, their relative contribution remains relatively unexplored. In addition, existing analyses on size structure have focused on univariate size-based indicators (SBIs), such as mean length, evenness of size classes, or the upper 95-percentile of the length frequency distribution; these approaches may not capture full information of size structure. To bridge the gap, we used the variation partitioning approach to examine how the size structure (composition of size classes) responded to fishing, warming and the interaction. We analyzed 28 exploited stocks in the West US, Alaska and North Sea. Our result shows fishing has the most prominent effect on the size structure of the exploited stocks. In addition, the fish stocks experienced higher variability in fishing is more responsive to the temperature effect in their size structure, suggesting that fishing may elevate the sensitivity of exploited stocks in responding to environmental effects. The variation partitioning approach provides complementary information to univariate SBIs in analyzing size structure.
    Keywords Medicine ; R ; Science ; Q
    Subject code 310
    Language English
    Publishing date 2018-05-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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