How many sightings to model rare marine species distributions

Virgili, Auriane; Authier, Matthieu; Monestiez, Pascal; Ridoux, Vincent

doi:10.1371/journal.pone.0193231

Cited by 15 publications

(20 citation statements)

References 38 publications

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“…We took care in using appropriate statistical tools for modelling the habitat of species with few sightings (Virgili, Authier, Monestiez, & Ridoux, 2018). Indeed, Virgili et al (2018) showed that GAMs with a Tweedie distribution generated reliable habitat modelling predictions for rarely sighted marine predators. Here, the habitat models we selected had moderate to high levels of explained deviances (from 20.6% to 55.7%), suggestive of a good fit to the data.…”

Section: Methodological Considerationsmentioning

confidence: 99%

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Virgili

Authier

Boisseau³

et al. 2018

Global Ecol Biogeogr

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Aim Deep‐diving cetaceans are oceanic species exposed to multiple anthropogenic pressures including high intensity underwater noise, and knowledge of their distribution is crucial to manage their conservation. Due to intrinsic low densities, wide distribution ranges and limited presence at the sea surface, these species are rarely sighted. Pooling data from multiple visual surveys sharing a common line‐transect methodology can increase sightings but requires accounting for heterogeneity in protocols and platforms. Location North Atlantic Ocean and Mediterranean Sea. Time period 1998 to 2015. Major taxa Ziphiidae; Physeteriidae; Kogiidae. Methods About 1,240,000 km of pooled effort provided 630 sightings of ziphiids, 836 of physeteriids and 106 of kogiids. For each taxon, we built a hierarchical model to estimate the effective strip width depending on observation conditions and survey types. We then modelled relative densities in a generalized additive modelling framework. Geographical predictions were limited to interpolations identified with a gap analysis of environmental space coverage. Results Deeper areas of the North Atlantic gyre were mostly environmental extrapolation in the predictions, thereby highlighting gaps in sampling across the different surveys. For the three species groups, the highest relative densities were predicted along continental slopes, particularly in the western North Atlantic Ocean where the Gulf Stream creates dynamic frontal zones and eddies. Main conclusions Pooling a large number of surveys provided the first basin‐wide models of distribution for deep‐diving cetaceans, including several data‐deficient taxa, across the North Atlantic Ocean and the Mediterranean Sea. These models can help the conservation of elusive and poorly known marine megafauna.

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Section: Methodological Considerationsmentioning

confidence: 99%

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Virgili

Authier

Boisseau³

et al. 2018

Global Ecol Biogeogr

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“…Given we had no estimation of the proportions of adult and immature gannets within mixed groups, they were not included in habitat modelling. In addition, the number of segments with presence of mixed groups was too low in winter to perform habitat modelling (Virgili et al ; Table 2).…”

Section: Resultsmentioning

confidence: 99%

Spatial segregation between immatures and adults in a pelagic seabird suggests age‐related competition

Pettex

Lambert

Fort

et al. 2019

Journal of Avian Biology

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Individual competitiveness conditions access to resources when they are limited. Immature individuals that are less skilled than adults have to adapt their foraging strategies to survive. Among strategies to reduce competition, spatial segregation has been widely demonstrated. However, the use of spatial segregation by immatures to limit intra‐specific competition with adults has rarely been tested. In this study, we investigated and compared habitat preferences and distributions of free‐ranging immature and breeding adult northern gannets Morus bassanus in order to determine whether they compete for similar habitats during the year, and if this results in a spatial segregation between birds of different age groups. Based on > 66 000 km of aerial surveys conducted in the North‐East Atlantic Ocean during winter and summer 2012, habitats selected by immatures and adult birds were modelled independently, linking gannet density to a set of oceanographic and physiographic predictors. Their large‐scale seasonal distribution was then predicted. We found that gannets displayed a strong season‐dependent competition between immatures and adults, as a consequence of immatures and adults using similar habitats in both summer and winter. During summer, when adults are constrained by reproduction, both groups were spatially highly segregated despite similar habitat preferences (thermal fronts), with youngest individuals selecting habitats out of range of central‐place foragers, highlighting intra‐specific competition. Contrastingly during winter, when reproductive constraints disappear, immature and adult distributions largely overlapped. Our study provides new insights into the role played by age, foraging experience and reproductive constraints on the distribution of marine predators. More specifically, these results highlight in seabirds how the youngest fraction mitigates, through spatial segregation, the competition with experienced adults, and suggest a progressive strategy along the maturation process.

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“…We took care in using appropriate statistical tools for modelling the habitat of species with few sightings [ 71 ]. Virgili et al [ 71 ] showed that GAMs with a Tweedie distribution generated reliable habitat modelling predictions for rarely sighted marine predators.…”

Section: Discussionmentioning

confidence: 99%

Towards a better characterisation of deep-diving whales’ distributions by using prey distribution model outputs?

et al. 2021

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In habitat modelling, environmental variables are assumed to be proxies of lower trophic levels distribution and by extension, of marine top predator distributions. More proximal variables, such as potential prey fields, could refine relationships between top predator distributions and their environment. In situ data on prey distributions are not available over large spatial scales but, a numerical model, the Spatial Ecosystem And POpulation DYnamics Model (SEAPODYM), provides simulations of the biomass and production of zooplankton and six functional groups of micronekton at the global scale. Here, we explored whether generalised additive models fitted to simulated prey distribution data better predicted deep-diver densities (here beaked whales Ziphiidae and sperm whales Physeter macrocephalus) than models fitted to environmental variables. We assessed whether the combination of environmental and prey distribution data would further improve model fit by comparing their explanatory power. For both taxa, results were suggestive of a preference for habitats associated with topographic features and thermal fronts but also for habitats with an extended euphotic zone and with large prey of the lower mesopelagic layer. For beaked whales, no SEAPODYM variable was selected in the best model that combined the two types of variables, possibly because SEAPODYM does not accurately simulate the organisms on which beaked whales feed on. For sperm whales, the increase model performance was only marginal. SEAPODYM outputs were at best weakly correlated with sightings of deep-diving cetaceans, suggesting SEAPODYM may not accurately predict the prey fields of these taxa. This study was a first investigation and mostly highlighted the importance of the physiographic variables to understand mechanisms that influence the distribution of deep-diving cetaceans. A more systematic use of SEAPODYM could allow to better define the limits of its use and a development of the model that would simulate larger prey beyond 1,000 m would probably better characterise the prey of deep-diving cetaceans.

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How many sightings to model rare marine species distributions

Cited by 15 publications

References 38 publications

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Spatial segregation between immatures and adults in a pelagic seabird suggests age‐related competition

Towards a better characterisation of deep-diving whales’ distributions by using prey distribution model outputs?

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