Ecoregional and temporal dynamics of dugong habitat use in a complex coral reef lagoon ecosystem

Solène Derville,Claire Garrigue,Christophe Cleguer

doi:10.1038/s41598-021-04412-3

Abstract

Mobile marine species display complex and nonstationary habitat use patterns that require understanding to design effective management measures. In this study, the spatio-temporal habitat use dynamics of the vulnerable dugong (Dugong dugon) were modelled from 16 satellite-tagged individuals in the coral reef lagoonal ecosystems of New Caledonia, South Pacific. Dugong residence time was calculated along the interpolated tracks (9371 hourly positions) to estimate intensity of use in three contrasting ecoregions, previously identified through hierarchical clustering of lagoon topographic characteristics. Across ecoregions, differences were identified in dugong spatial intensity of use of shallow waters, deeper lagoon waters and the fore-reef shelf outside the barrier reef. Maps of dugong intensity of use were predicted from these ecological relationships and validated with spatial density estimates derived from aerial surveys conducted for population assessment. While high correlation was found between the two datasets, our study extended the spatial patterns of dugong distribution obtained from aerial surveys across the diel cycle, especially in shallow waters preferentially used by dugongs at night/dusk during high tide. This study has important implications for dugong conservation and illustrates the potential benefits of satellite tracking and dynamic habitat use modelling to inform spatial management of elusive and mobile marine mammals.

Highlights

Mobile marine species display complex and nonstationary habitat use patterns that require understanding to design effective management measures
Current research efforts to unravel the ecological drivers of dugong (Dugong dugon) distribution illustrate the added value of satellite telemetry to inform the conservation of this listed Vulnerable species[12]
Three ecoregions were identified over the western lagoon of New Caledonia (Fig. 1, Supplementary Fig. S1, Table 1)

Summary

Introduction

Mobile marine species display complex and nonstationary habitat use patterns that require understanding to design effective management measures. Habitat use may vary at multiple spatio-temporal scales[4], displaying complex regional geographic adaptations or following stochastic (extreme events), cyclic (diel and tidal cycles) or continuous patterns (climate change[5]) Misunderstanding of these dynamic associations of species with their environment can impair current efforts to m odel[3,6] and anticipate spatial conflicts between marine wildlife and anthropogenic activities (traffic, fishing, tourism, industries etc.). Telemetry revealed how marine mammals may respond to the fluctuations of coupled physical-biological conditions (e.g., ocean circulation and productivity) influencing the patchy distribution of their resources This ecological knowledge may provide a robust basis for designing effective management tools or spatial protection to mitigate risks for endangered marine mammal species at local[10] to global scales[11]. Understanding and incorporating these fine-scale dynamic patterns into models of dugong habitat use may help refine spatio-temporal management measures

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Discussion

Conclusion