Ecology and conservation of North-Atlantic shads in a global changing context : inputs from a mechanistic species distribution model
Two emblematic anadromous species of the Northern Atlantic coasts, allis shad and the American shad, have undergone a drastic decline of their populations over the last century. On that, a better understanding of the remaining “knowledge gaps” related to their ecology and population dynamics, especi...
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| Other Authors: | , , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | French |
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HAL CCSD
2022
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| Subjects: | |
| Online Access: | https://theses.hal.science/tel-03875846 https://theses.hal.science/tel-03875846/document https://theses.hal.science/tel-03875846/file/POULET_CAMILLE_2022.pdf |
| Summary: | Two emblematic anadromous species of the Northern Atlantic coasts, allis shad and the American shad, have undergone a drastic decline of their populations over the last century. On that, a better understanding of the remaining “knowledge gaps” related to their ecology and population dynamics, especially at sea, is required to implement appropriate conservation policies and ensure the recovery and sustainability of both species and the ecosystem services they provide to human societies. Mechanistic species distribution models are useful tools to tackle these remaining knowledge gaps, since they enable the exploration of the population dynamics at a large spatio- temporal scale and allow modelers to test different scenarios and/or ecological hypotheses that cannot be addressed otherwise by field monitoring or lab experiments. In this study, the mechanistic species distribution model, GR3D (Global Repositioning Dynamics for Diadromous fish Distribution), which was first developed for allis shad in Western Europe, was adapted to fit the American shad ecology across the Eastern U.S. coast. The model application to this new species implied a reconfiguration of the marine environment implemented into GR3D, by including trophic migrations of individuals at sea. In addition, the exploration of the GR3DUS model through a sensitivity analysis has underlined the role of dispersal and depensatory forces in the spatial structure of American shad populations. In the same way, the integration of a new nutrient calculator within GR3DEU primarily required the distinction between males and females into the model and then, provided a first quantification of the regulation service (i.e. nutrient fluxes) operated by allis shad at the scale of its distribution range. Finally, a comparative ecology approach, simulating the population dynamics of the two species on both Atlantic coasts, allowed deepened investigation of the role played by temperature and dispersal in the dynamics behind their distribution and their metapopulation ... |
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