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Map portfolio of Octopus vulgaris off Mauritania


This study aims to identify the octopus's main recurrent spatial patterns, a cornerstone stock of the Mauritanian ecosystem, during each spawning season. Furthermore, it coins the map portfolio concept and shows how it can be developed in real case studies. Location: Mauritania Taxon: Octopus vulgaris Methods: The principal spatial maps are a subset of the empirical orthogonal maps of the full dataset. Maps are first selected so as to recover 60% of the input variability. Amongst them, maps whose amplitude through time were significantly correlated with abundance are subselected. Results: During the hot season, one single principal map explains half (48%) of the overall variability of the initial data. Its amplitude is strongly correlated with the abundance of octopus. During the cold season, the biogeography of octopus is more composite. Ten spatial patterns are needed to explain 62% of the initial variability. Five of these are correlated with abundance and have strong spatial structures. One map shows a significant correlation with the upwelling index six months before and represents the part of the spatial patterns connected with this key environmental factor. Main conclusions: Based on octopus case study, the concept of a map portfolio is put forward. In the present case, its size represents the number of spatial patterns from which the octopus mainly composed its distribution over the past three decades. Assuming that specific but hidden processes explain each biomass distributions of the portfolio, its size could be a proxy for the systems' resilience. For a large portfolio, a process could decrease without damaging the overall system if compensated by an other process. Small portfolio could be symptomatic of more fragile systems. One perspective of this work could be to quantify the sizes of many portfolios and connect them to knowledge about the resilience of the system they characterize.
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Dates and versions

hal-03649730 , version 1 (22-04-2022)
hal-03649730 , version 2 (10-04-2023)


  • HAL Id : hal-03649730 , version 1


Dedah Ahmed-Babou, Hervé Demarcq, Beyah Meissa, Nicolas Bez. Map portfolio of Octopus vulgaris off Mauritania. 2022. ⟨hal-03649730v1⟩
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