Evaluating Three Modelling Frameworks for Assessing Changes in Fin Whale Distribution in the Mediterranean Sea.

Understanding the habitat of highly migratory species is aided by using species distribution models to identify species-habitat relationships and to inform conservation and management plans. While Generalized Additive Models (GAMs) are commonly used in ecology, and particularly the habitat modeling of marine mammals, there remains a debate between modeling habitat (presence/absence) versus density (# individuals). Our study assesses the performance and predictive capabilities of GAMs compared to boosted regression trees (BRTs) for modeling both fin whale density and habitat suitability alongside Hurdle Models treating presence/absence and density as a two-stage process to address the challenge of zero-inflated data.

Investigating the presence of different bottlenose dolphin ecotypes in the Mediterranean Sea.

The common bottlenose dolphin is a cosmopolitan species that can be found worldwide in all oceans except polar and sub-polar waters. This wide distribution is associated with a certain level of morphological variation, which seems consistent with the presence of a globally distributed pelagic/offshore ecotype and several coastal/inshore ecotypes distributed along the continental shelf. In the Mediterranean Sea, the common bottlenose dolphin is a regularly occurring species and the second most sighted cetacean after the striped dolphin.

Trends in summer presence of fin whales in the Western Mediterranean Sea Region: new insights from a long-term monitoring program.

Background: The Mediterranean subpopulation of fin whale (Linnaeus, 1758) has recently been listed as Vulnerable by the IUCN Red List of threatened species. The species is also listed as species in need of strict protection under the Habitat Directive and is one of the indicators for the assessment of Good Environmental Status under the MSFD. Reference values on population abundance and trends are needed in order to set the threshold values and to assess the conservation status of the population.

Floating marine macro litter: Density reference values and monitoring protocol settings from coast to offshore. Results from the MEDSEALITTER project.

Monitoring Floating Marine Macro Litter (FMML) is a global priority, stressed within international programs, and regulated for the European Seas by the Marine Strategy Framework Directive. Although some well-defined common protocols exist for the assessment of beach litter and ingested litter, methodologies for FMML monitoring still vary, leading to some inconsistent results and hampering the global assessment of this threat. Within the MEDSEALITTER project (2016-2019), field experiments were implemented to define optimal monitoring parameters for FMML visual monitoring at different spatial scales, by assessing the influence of platform speed, strip width, observers experience, weather conditions, and litter size on its detectability.

Assessing cetacean surveys throughout the Mediterranean Sea: a gap analysis in environmental space.

Heterogeneous data collection in the marine environment has led to large gaps in our knowledge of marine species distributions. To fill these gaps, models calibrated on existing data may be used to predict species distributions in unsampled areas, given that available data are sufficiently representative. Our objective was to evaluate the feasibility of mapping cetacean densities across the entire Mediterranean Sea using models calibrated on available survey data and various environmental covariates.

Floating macro-litter along the Mediterranean French coast: Composition, density, distribution and overlap with cetacean range.

This study investigated the composition, density and distribution of floating macro-litter along the Liguro-Provençal basin with respect to cetaceans presence. Survey transects were performed in summer between 2006 and 2015 from sailing vessels with simultaneous cetaceans observations. During 5171km travelled, 1993 floating items were recorded, widespread in the whole study area.