[MARMAM] New publication - Combining multiple visual surveys to model the habitat of,deep‐diving cetaceans at the basin scale
Dear Colleagues, On behalf of all co-authors, I am pleased to announce the publication of our article "Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale". Virgili A, Authier M, Boisseau O, et al. Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale. Global Ecol Biogeogr. 2018;00:1–15. https://doi.org/10./geb.12850 *Abstract* *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 linetransect 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. For any questions or pdf requests, please feel free to email me at auriane.virg...@univ-lr.fr. Best regards, Auriane Virgili -- Dr Auriane VIRGILI Ingénieure de recherche Observatoire Pelagis UMS 3462 CNRS/Université de La Rochelle 5 Allées de l'Océan 17000 La Rochelle E-mail : auriane.virg...@univ-lr.fr ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Towards a better characterisation of deep-diving whales’ distributions by using prey distribution model outputs?
My co-authors and I are pleased to announce the publication of a new manuscript in PLoS ONE: Virgili, A., Hedon, L., Authier, M., Calmettes, B., Claridge, D., Cole, T., ... & Ridoux, V. (2021). Towards a better characterisation of deep-diving whales’ distributions by using prey distribution model outputs?. PloS one, 16(8), e0255667. https://doi.org/10.1371/journal.pone.0255667 Abstract: 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. This publication is open-access and can be found at this link: https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0255667&fbclid=IwAR3F7LprXYeHAvTOPndlaSnOsxUenhiSrcIgFeZs78NT08rCyxy7Wy6wO44 Enjoy your day! -- Dr Auriane VIRGILI Ingénieure de recherche Observatoire Pelagis UMS 3462 CNRS/La Rochelle Université 5 Allées de l'Océan, 17000 La Rochelle Tél : 05 16 49 67 20 Standard: 05 46 44 99 10 E-mail : auriane.virg...@univ-lr.fr http://observatoire-pelagis.cnrs.fr/ ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Deep ocean drivers better explain habitat preferences of sperm whales Physeter macrocephalus than beaked whales in the Bay of Biscay
Dear MARMAM community, My co-authors and I are pleased to announce the publication of our article in Scientific Reports: Virgili, A., Teillard, V., Dorémus, G. et al. Deep ocean drivers better explain habitat preferences of sperm whales Physeter macrocephalus than beaked whales in the Bay of Biscay. Sci Rep 12, 9620 (2022). https://doi.org/10.1038/s41598-022-13546-x The article is open-access and available at: https://doi.org/10.1038/s41598-022-13546-x Abstract Species Distribution Models are commonly used with surface dynamic environmental variables as proxies for prey distribution to characterise marine top predator habitats. For oceanic species that spend lot of time at depth, surface variables might not be relevant to predict deep-dwelling prey distributions. We hypothesised that descriptors of deep-water layers would better predict the deep-diving cetacean distributions than surface variables. We combined static variables and dynamic variables integrated over different depth classes of the water column into Generalised Additive Models to predict the distribution of sperm whales Physeter macrocephalus and beaked whales Ziphiidae in the Bay of Biscay, eastern North Atlantic. We identified which variables best predicted their distribution. Although the highest densities of both taxa were predicted near the continental slope and canyons, the most important variables for beaked whales appeared to be static variables and surface to subsurface dynamic variables, while for sperm whales only surface and deep-water variables were selected. This could suggest differences in foraging strategies and in the prey targeted between the two taxa. Increasing the use of variables describing the deep-water layers would provide a better understanding of the oceanic species distribution and better assist in the planning of human activities in these habitats. Best regards, Auriane Virgili -- Dr Auriane Virgili Ingénieure de recherche / Research engineer Tél : +(33) 5 16 49 67 20 Standard: +(33) 5 46 44 99 10 https://www.observatoire-pelagis.cnrs.fr/auriane-virgili/ Télétravaille le jeudi et vendredi / Remote working on Thursday and Friday Observatoire PELAGIS *La Rochelle Université* Centre commun d'analyse 5 allée de l'océan 17000 La Rochelle www.observatoire-pelagis.cnrs.fr <http://www.observatoire-pelagis.cnrs.fr> univ-larochelle.fr <http://www.univ-larochelle.fr> Facebook <https://www.facebook.com/LaRochelleUniversite/> | Twitter <https://twitter.com/UnivLaRochelle> | Instagram <https://www.instagram.com/univlarochelle/> | Linkedin <https://www.linkedin.com/school/university-of-la-rochelle/> | YouTube <https://www.youtube.com/channel/UC-Cf7Z00cbodH9qC8i7SHXA> ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Summer distribution of the Mediterranean sperm whale: insights from the acoustic Accobams survey initiative.
Dear colleagues, On behalf of my co-authors, we are pleased to share with you our recent publication published in Frontiers in Marine science: "Summer distribution of the Mediterranean sperm whale: insights from the acoustic Accobams survey initiative." Lerebourg, C., Boisseau, O., Ridoux, V., & Virgili, A. Frontiers in Marine Science, 10, 1229682. https://doi.org/10.3389/fmars.2023.1229682 Abstract: The Mediterranean sperm whale population, Physeter macrocephalus, is listed as endangered due to population decline caused by human activities. To mitigate the impact of these activities, accurate knowledge of their distribution and abundance is crucial. During their long dives, sperm whales are not available to visual observation, but since they produce sounds when they dive, they are available to acoustic detection. Therefore, we aimed to use towed acoustic data to model their habitat and fill the knowledge gap on Mediterranean sperm whale distribution. Generalised additive models were used to link the number of sperm whales detected acoustically during the ACCOBAMS Survey Initiative in 2018 with different environmental variables integrated over different depth classes, encompassing the depth range used by the species for foraging. Sperm whale distribution was influenced by water temperature at the bottom, eddy kinetic energy between 200 and 600 m, as well as gradients of sea surface temperature and chlorophyll-a concentrations. The abundance of sperm whales was estimated at 2,959 individuals [2,077 - 4,265] in the sampled areas of the Mediterranean Sea. We predicted that sperm whales were mainly distributed in summer along the continental slope of the north-western Mediterranean basin from the Balearic Islands to the Ligurian Sea and off the Algerian coast. They were present throughout the western Mediterranean Sea and in the northern Ionian Sea. In contrast, predicted densities were low in the eastern part of the Mediterranean Sea. The use of acoustic data compensated for the main difficulty in studying sperm whales, the unavailability of animals at the surface during visual observation and the paucity of visual data. We thus encourage more systematic use of passive acoustics to study sperm whale distribution. The model highlighted a higher concentration of sperm whales in the western Mediterranean basin than in the eastern basin in summer, opening up avenues to improve the conservation of this endangered Mediterranean sub-population. Best regards, Auriane -- Dr Auriane VIRGILI Ingénieure de recherche / Research engineer Share the Ocean consortium, 14 place de l'Eglise, 56870 Larmor Baden, France E-mail : auriane@sharetheocean.earth ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Prospective modelling of operational offshore wind farms on the distribution of marine megafauna in the southern North Sea
Dear MARMAM colleagues, On behalf of my co-authors, I am pleased to share our new publication in the open access journal Frontiers in Marine Science, Vol. 11: Virgili, A. / Laran, S. / Authier, M. / Dorémus, G. / Van Canneyt, O. / Spitz, J. Prospective modelling of operational offshore wind farms on the distribution of marine megafauna in the southern North Sea. In this publication, we carried out a series of 6 aerial surveys in the English Channel to monitor marine megafauna in 2017-2018, covering all seasons. The monitored area has been commissioned to host an offshore wind farm (OWF) off the town of Dunkirk. France has been lagging compared to northern European countries with respect to the harnessing of wind power for energy consumption. The surveys took place to establish baselines. Taking stock of the fact that neighbouring countries (Belgium and the UK) already have operating OWFs in the neighbourhood of the studied area, we carried out a prospective modelling exercise to predict, using a Before-After Gradient (BAG) design, the potential effect of the *operating* Dunkirk OWF. In effect, distance to the nearest OWF was included in models and the distribution of seabirds and harbour porpoises predicted under the assumption that the Dunkirk OWF were already in operation to assess potential changes. We found a negative effect of distance to the nearest OWF on harbour porpoise, black-legged kittiwakes, cormorants and northern gannets: the highest densities of these megafauna were found at distances larger than 40 km from operating OWFs. Our prospective study highlighted potential impacts on these species of the Dunkirk OWF when it will start operating. The paper is available in open access here : https://doi.org/10.3389/fmars.2024.1344013. If you have any questions about our work, please reach out. Cheers, Auriane -- Dr Auriane VIRGILI Ingénieure de recherche / Research engineer Share the Ocean consortium, 14 place de l'Eglise, 56870 Larmor Baden, France E-mail : auriane@sharetheocean.earth ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Seasonal distribution of cetaceans in the European Atlantic and Mediterranean waters
Dear colleagues, My co-authors and I are pleased to share our new publication: Virgili, A., Araújo, H., Diaz, A. A., Doremus, G., Garcıa-Baron, I., Eira, C., ... & Ridoux, V. (2024). Seasonal distribution of cetaceans in the European Atlantic and Mediterranean waters. Frontiers in Marine Science, 11, 1319791. The article is available here (open access): https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1319791/full. Abstract: As apex predators, cetaceans play an essential ecological role in marine ecosystems. Fluctuations in the abundance of these top predators linked to human activities can have detrimental consequences for the entire ecosystem. Cetaceans face numerous anthropogenic threats that can have both short and long-term effects. To ensure their conservation, it is necessary to identify changes in seasonal distributions at small and large scales. We aimed to model the seasonal distribution of the most abundant cetacean species in the European Atlantic waters and the Mediterranean Sea by assembling datasets collected over 16 years of surveys using a standardised line-transect protocol. Data were homogenised, detection functions fitted and effective strip widths estimated. We extracted environmental variables integrated over the water column, which we transformed using a principal component analysis (PCA). The dimensions of the PCA were then integrated as explanatory variables in a generalised additive model, taking seasonal and spatial effects into account to predict the seasonal cetacean distribution. We were able to highlight changes in the spatial distribution and/or density of cetaceans throughout the year at a large scale, considering environmental extrapolation areas to predict where environmental variables were sampled during the surveys. For minke (Balaenoptera acutorostrata) and fin (B. physalus) whales, densities varied over the seasons but not the distribution, suggesting a seasonal migration outside the survey areas. For common dolphins (Delphinus delphis), bottlenose dolphins (Tursiops truncatus) and harbour porpoises (Phocoena phocoena), densities varied little but distributions did over the seasons. Finally, pilot whales (Globicephala spp), Risso’s (Grampus griseus) and striped (Stenella coeruleoalba) dolphins showed little seasonal variation in their distribution. Using monthly dynamic environmental variables at depth and PCA dimensions in habitat models, we produced maps of the seasonal distribution of cetaceans in the Mediterranean Sea and the European Atlantic waters to help fill gaps in our knowledge of cetacean distribution. If you have any questions, please feel free to contact me at auriane@sharetheocean.earth. Best wishes, Auriane -- Dr Auriane VIRGILI Ingénieure de recherche / Research engineer Share the Ocean consortium, 14 place de l'Eglise, 56870 Larmor-Baden, France E-mail : auriane@sharetheocean.earth ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
