Four PhDs of the ECOMERS laboratory presented their work on 28 of January 2019. You will find hereafter a summary and a PDF of their presentation.

Alexandre Schickele: Climate induced distribution shifts: the case of European small pelagic fishes

Predicting future climate induced shifts on marine species distribution has become an important challenge for sustainable resource and ecosystem management. Our study aims to investigate the potential distribution changes of the most harvested small pelagic fish (SPF) species in the Mediterranean Sea. Species distribution models have been extensively used to over last years to investigate potential future distribution shifts. However, no consistent framework to calibrate and evaluate these models exists. Therefore we developed a comprehensive numerical procedure based on recent scientific advances, allowing a better consideration of sampling biases and improving the modelled distribution. Both temperature mean and variability appear as the major factors driving SPF’s distribution. Regardless of the emission scenario, the models converge toward a decrease in climate suitability in the Mediterranean Sea for SPF, leaving the Adriatic Sea and the Gulf of Lion as the last suitable areas in case of a pessimistic scenario such as RCP8.5. Link to presentation

Eugenio Di Franco: Impact of noise pollution on the development and settlement of coastal fish juveniles

The undersea environment has long been depicted as a silent world. Research carried out in the last decades, however, has raised a growing awareness about sounds and noises as important components of the marine environment. The raise of global industrialization and trading has resulted in a dramatic increase in anthropogenic noises at sea. Coastal areas, in particular, are experiencing an unprecedented increase in human population, urbanisation, industrial and touristic settlements. Most of these activities generate or contribute to the so- called “noise pollution”. There is increasing evidence that anthropogenic noise may impact a large variety of marine animal species. The effects of anthropogenic noise on marine organisms can range from very weak effects to immediate death. The aim of this thesis will be to test whether behavioural, morphological and physiological variables of juvenile sparid fish are affected by different levels of anthropogenic noise, with the objectives of better understand its biological impact on marine organisms to ecosystems. Link to presentation

Elena Desidera: Characterization of the spawning aggregations of the Dusky grouper, Epinephelus marginatus (Lowe, 1834) in the Marine Protected Area of “Tavolara - Punta Cavallo” (Sardinia, NW Mediterranean)

The Dusky grouper, Epinephelus marginatus, is an ecologically and economically valuable fish, highly vulnerable to overfishing due to slow growth rates, late sexual maturity, protogynous hermaphroditism and reproduction via spawning aggregations. Fishing caused dramatic declines in density and size of this fish in many areas of the Mediterranean Sea. Nowadays, this species is abundant only in Marine Protected Areas (MPAs), where its spawning aggregations are mostly documented. This multi-disciplinary project aims at investigating the effect of protection measures on Dusky groupers’ spawning aggregations in the MPA of “Tavolara-Punta Cavallo” (Sardinia). These spawning aggregations are characterized by collecting and analyzing data about i) the historical local ecological knowledge of the species, ii) abundance, iii) reproductive-related behaviours, and iv) courtship-related sound production patterns of Dusky groupers at the study sites. The project will help support monitoring and management programs to protect this endangered species during a vital phase of its life cycle. Link to presentation

Elisabeth Riera: An easy method to assess 3D underwater habitat complexity

It is a common theme in ecology that 3D habitat complexity begets faunal diversity and abundance. However, complexity is a parameter that still remains difficult to assess in the field, especially underwater. Most studies employ qualitative or semi-quantitative measures, which limits comparison between them. Recently, we have developed a method to quantitatively assess the complexity; we computed an index providing a quantitative measure of the abiotic complexity of habitats. First, based on the rugosity and the surface–volume ratios of the structure, which define the structure refolding degree important for the settlement of sessile species. Secondly, based on Shannon diversity computed on the habitat cavities that define shelter for mobile species. Those parameters can be measured directly underwater and can also be computed on a digital model representing the 3D structure of the habitat. First results on fictive 3D models and artificial reefs 3D models give promising perspectives. Link to presentation

Since several years, ECOMERS collaborates with IUCN within several specialist groups. Several contributions to the Red List have been produced (see the complete list in the "Read more" section). In November 2018, the IUCN Red List of Threatened Species published the new global assessments on Groupers. ECOMERS contributed to the status evaluation 6 of these species: the White Grouper (Epinephelus aeneus), the Dogtooth Grouper (E. caninus), the Goldblotch Grouper (E. costae), the Dusky Grouper (E. marginatus), the Haifa Grouper (Hyporthodus haifensis) and the Mottled Grouper (Mycteroperca rubra).

Two species are considered as Data Deficient, E. caninus, E. costae, two as Least Concern, H. haifensis, M. rubra, one as Near Threatened, E. aeneus, and one as Vulnerable, E. marginatus. The previous status of E. marginatus, the most important species within the Mediterranean basin, was Endangered. This change from EN to VU status does not prove that there are some improvements of the status of the dusky grouper. The population trend is clearly decreasing on its whole geographic distribution. However, the change in status from the previous assessment reflects an improved application of the IUCN Red List Categories and Criteria, as well as a better understanding of available data. It means that further research is needed on its population status, especially in the southwestern Indian Ocean, the southwestern Atlantic and West Africa, and actions that reduce fishing effort are greatly needed. Similarly in the Mediterranean, more research efforts have to be deployed to assess the current fishing effort on this species.

It is also important to highlight that these 2018 status evaluations for the Grouper species are global, i.e. considering their whole geographical distribution. At a regional scale, the Mediterranean, the present status of the Dusky Grouper is still Endangered.

CREOCEAN and GEOLAB companies are developing a methodology and know-how in underwater photogrammetry. The objective is to reconstruct in 3D as accurately as possible objects immersed from series of underwater photos. A modelling of the 3D printed artificial reefs immersed in Larvotto Marine Protected Area has been recently conducted in collaboration with AMPN and ECOMERS. The main objective is to compare the theoretical model used for 3D printing with the model reconstructed by photogrammetry. This modelling could be integrated into the work conducted by Elisabeth Riera as part of her doctoral thesis on the evaluation of the tridimensional complexity of all types of artificial reefs. Ultimately, this technique can also be applied in other areas of research.

Photo P. Francour: underwater photography of a 3D printed artificial reef. Several hundred of photos are necessary to reconstruct by photogrammetry a tridimensional object.

Photo CREOCEAN: the first reconstruction by photogrammetry of a Larvotto 3D artificial reef.

Monitoring of marine benthos with an hyperspectral camera: a first in the Mediterranean

Habitat destruction is one of the main causes of the decline of marine biodiversity and fisheries resources. An artificial reef can be considered as a tool to protect or restore these habitats and their declining biodiversity. The Barcelona Convention defines artificial reefs as "structures specifically built to protect, regenerate, concentrate and / or increase the production of biological marine resources, whether for fishing or nature conservation, which includes the protection and protection of the environment. regeneration of habitats ". In response to these problems, nearly 88,000 m3 of artificial reefs, mostly made of concrete, have been deployed on the Mediterranean coast of France for some thirty years. To date, the assessment of reef performance has focussed primarily on fish communities and has almost completely ignored the development of epibiosis (biofilm and macrofouling). Historically in the Mediterranean, the first published works in the 70s deal with the species of macrofouling. Thereafter, during the last decades, most of the works focussed on the fish assemblages. However, the biofilm (mainly bacteria and unicellular micro-algae) and macrofouling (mostly algae and fixed invertebrates) are the first elements of the food web that will allow the installation and development of the fauna of large invertebrates (crustaceans) and fish on or around artificial reefs.

In November 2017, 6 large 3D printed artificial reefs were immersed in the Larvotto marine protected area (Monaco). ECOMERS and BOREA (Museum of Natural History of Paris), in collaboration with AMPN, launched a long-term monitoring of these reefs, including an analysis of biofilm and macrofouling.

To answer this, an innovative technique is being tested with the use of an immersible hyperspectral camera. This camera is developed by PlanBlue, a start-up from the Max Planck Institute (Germany). Briefly, hyperspectral imaging is a technique combining imaging and spectroscopy where each image is taken for a narrow band of the electromagnetic spectrum. For example, the human eye sees light in three bands (red, green, and blue) while hyperspectral imaging can 'see' in a very large number of bands typically ranging from visible to near infrared. Each species has a particular signature (hyperspectral image) that can be used to identify it. The development of a submergible camera allows to acquire underwater scuba images of different substrates colonized and thus to quickly have a precise identification (species or genus) of the species present. This speed and ease of identification are the main highlights of this camera. Once the validation is done (association between a light spectrum and a species or group of species), it will then be easy to determine the composition of the macrofouling species. Moreover, this promising technology go further than the simple identification of species. This camera can also give information about the physiological activities of photosynthetic species growing over the time.

This innovative technique has never been used in the Mediterranean. Its development in Monaco by ECOMERS and AMPN in partnership with CREOCEAN and its validation as a method of monitoring the macrofouling will be a first. This technique could subsequently be used in the monitoring of the benthos, whether on artificial or natural substrate. The prospects of application far exceed the only artificial reefs.

Photos P. Francour: Test and calibration of the hyperspectral camera in shallow habitats