Forçages anthropiques et environnementaux sur la dynamique interannuelle des communautés phyto- et zooplanctoniques côtières en Méditerranée Nord-Occidentale (Toulon, France)

The growing development of urbanism and anthropogenic activities is source of increasing environmental pressure on marine coastal area and especially the Mediterranean Sea. Both human activities and climate change deeply impact marine ecosystems and particularly planktonic systems, which were sensitive to environmental change. However, the combined effect of these two processes on coastal systems functioning and structure over time remains poorly understood. Therefore, planktonic time series provide powerful tools for investigating the impacts of these perturbations. The PROTEE-EBMA laboratory planktonic time series from Toulon (France) are among the oldest from the Mediterranean Sea and provide records of effects for both natural and anthropogenic pressures on planktonic communities. In the context of global change, the present work aim to determine the role of these factors on dynamic and composition of phyto- and zooplankton in NW Mediterranean (Toulon, France). The first part focused on the role of vertical mixing in the Ligurian Sea as inter annual variation driver of the spring plankton bloom in Toulon Bay. The results revealed significant shifts in precipitation regime associated with salinity change into the Large Bay (Toulon) over the period 2005-2013. Same changes were observed into 2 Ligurian basin sites (”SOFCOM” and “Point B”). According to previous hypothesis, spring blooms of phytoplankton conditioned by dry autumns and winters were on average more intense than those from wet conditions. However, differences among sites highlighted importance of local drivers affecting phytoplanktonic dynamics. The second part aimed to investigate impact of precipitation and salinity changes on plankton composition. Results showed a dramatic change in phytoplankton community composition triggering by increasing precipitations and consequently lower salinity and subsequently leading to zooplankton community shifts. In addition, these results suggested that precipitation involved in two specific processes, affecting in a different manner the plankton communities: firstly, low precipitation could contribute on the triggering of winter mixing and thus in surface water fertilization of the Ligurian Basin impacting the Toulon Bays. On the other hand, phytoplankton community shifts also suggested a developing eutrophication processes in Toulon Bay during important precipitation periods driven by increasing local river inputs. In the third part, impact of anthropogenic pressure on both phyto- and zooplankton communities was investigated based on monitoring of two neighboring coastal systems characterized by distinct levels of human activities. Zooplankton communities showed higher sensibility to anthropogenic activities than phytoplankton communities. Finally, indicators of anthropogenic pressure based on copepod families were proposed.Le développement croissant de l’urbanisme et des activités anthropiques fait peser une pression de plus en plus importante sur les zones côtières, touchant particulièrement les régions méditerranéennes. Les processus liés au changement climatique et aux activités humaines impactent en profondeur les écosystèmes marins et tout particulièrement les systèmes planctoniques qui présentent une sensibilité accrue aux perturbations du milieu. Toutefois, les effets de ces processus agissant de concert à long terme sur la structure et le fonctionnement des écosystèmes côtiers sont encore mal compris. Ainsi, les séries temporelles planctoniques représentent des outils précieux pour la compréhension des processus impactant le milieu marin. Les séries temporelles du laboratoire EBMA-PROTEE de Toulon font partie des séries les plus anciennes de Méditerranée et présentent l’intérêt de combiner l’impact des processus naturels et anthropiques sur les communautés phyto- et zooplanctoniques. C’est dans ce contexte que ce travail a pour objectif de préciser le rôle de ces facteurs sur la dynamique et la composition phyto- et zooplanctonique en Méditerranée nord-occidentale (Toulon, France). Une première partie a ainsi consisté à évaluer le rôle des mélanges verticaux se produisant au sein du bassin Ligure, comme moteur de la dynamique printanière du plancton au sein de la Rade de Toulon. Cette étude a permis d’identifier des variations significatives du régime des précipitations associées à des modifications de la salinité au sein du site de la Grande Rade de Toulon (« LaB ») sur la période 2005-2013. Variations retrouvées également sur 2 autres sites côtiers du bassin Ligure (« SOFCOM » and « Point B »). Conformément à l’hypothèse énoncée, les années conditionnées par un automne et un hiver secs ont présenté en moyenne une production phytoplanctonique printanière supérieure au sein des 3 sites, comparées aux années les plus humides. Toutefois, la présence de différences entre les sites a souligné l’impact important de mécanismes locaux sur le conditionnement de la dynamique phytoplanctonique. L’impact des changements de régime des précipitations sur la composition micro-phytoplanctonique et méso-zooplanctonique a été étudié au cours d’une seconde partie. Les résultats ont suggéré un changement profond des communautés phytoplanctoniques lié à l’augmentation des précipitations, impactant également la structure des communautés zooplanctoniques. Ainsi, ces résultats semblent indiquer que les précipitations interviennent au sein de deux processus, impactant différemment les communautés planctoniques : d’une part, une absence de précipitations participerait à la mise en place de mélanges hivernaux et à la fertilisation des eaux de surfaces au sein de bassin Ligure profitant à la rade de Toulon; d’autre part, les changements dans la composition phytoplanctonique ont évoqué la mise en place d’un processus d’eutrophisation durant les périodes pluvieuses, alimenté par les apports des rivières locales. En parallèle de cet aspect temporel, le suivi de la Petite et Grande Rade de Toulon caractérisés par un degré différent de la pression anthropique a permis, au cours d’une troisième partie, de tester le potentiel des compartiments phyto- et zooplanctoniques en tant qu’indicateur de l’augmentation de la pression anthropique. Cette étude a identifié une sensibilité accrue de la composition du zooplancton par rapport au phytoplancton. Enfin, des indicateurs de pression anthropique des zones côtières, basés sur les familles de copépodes, ont été proposés

Environmental and anthropogenic forcing on interannual dynamic of coastal phyto- and zooplankton communities in NW Mediterranean Sea (Toulon, France)

Le développement croissant de l’urbanisme et des activités anthropiques fait peser une pression de plus en plus importante sur les zones côtières, touchant particulièrement les régions méditerranéennes. Les processus liés au changement climatique et aux activités humaines impactent en profondeur les écosystèmes marins et tout particulièrement les systèmes planctoniques qui présentent une sensibilité accrue aux perturbations du milieu. Toutefois, les effets de ces processus agissant de concert à long terme sur la structure et le fonctionnement des écosystèmes côtiers sont encore mal compris. Ainsi, les séries temporelles planctoniques représentent des outils précieux pour la compréhension des processus impactant le milieu marin. Les séries temporelles du laboratoire EBMA-PROTEE de Toulon font partie des séries les plus anciennes de Méditerranée et présentent l’intérêt de combiner l’impact des processus naturels et anthropiques sur les communautés phyto- et zooplanctoniques. C’est dans ce contexte que ce travail a pour objectif de préciser le rôle de ces facteurs sur la dynamique et la composition phyto- et zooplanctonique en Méditerranée nord-occidentale (Toulon, France). Une première partie a ainsi consisté à évaluer le rôle des mélanges verticaux se produisant au sein du bassin Ligure, comme moteur de la dynamique printanière du plancton au sein de la Rade de Toulon. Cette étude a permis d’identifier des variations significatives du régime des précipitations associées à des modifications de la salinité au sein du site de la Grande Rade de Toulon (« LaB ») sur la période 2005-2013. Variations retrouvées également sur 2 autres sites côtiers du bassin Ligure (« SOFCOM » and « Point B »). Conformément à l’hypothèse énoncée, les années conditionnées par un automne et un hiver secs ont présenté en moyenne une production phytoplanctonique printanière supérieure au sein des 3 sites, comparées aux années les plus humides. Toutefois, la présence de différences entre les sites a souligné l’impact important de mécanismes locaux sur le conditionnement de la dynamique phytoplanctonique. L’impact des changements de régime des précipitations sur la composition micro-phytoplanctonique et méso-zooplanctonique a été étudié au cours d’une seconde partie. Les résultats ont suggéré un changement profond des communautés phytoplanctoniques lié à l’augmentation des précipitations, impactant également la structure des communautés zooplanctoniques. Ainsi, ces résultats semblent indiquer que les précipitations interviennent au sein de deux processus, impactant différemment les communautés planctoniques : d’une part, une absence de précipitations participerait à la mise en place de mélanges hivernaux et à la fertilisation des eaux de surfaces au sein de bassin Ligure profitant à la rade de Toulon; d’autre part, les changements dans la composition phytoplanctonique ont évoqué la mise en place d’un processus d’eutrophisation durant les périodes pluvieuses, alimenté par les apports des rivières locales. En parallèle de cet aspect temporel, le suivi de la Petite et Grande Rade de Toulon caractérisés par un degré différent de la pression anthropique a permis, au cours d’une troisième partie, de tester le potentiel des compartiments phyto- et zooplanctoniques en tant qu’indicateur de l’augmentation de la pression anthropique. Cette étude a identifié une sensibilité accrue de la composition du zooplancton par rapport au phytoplancton. Enfin, des indicateurs de pression anthropique des zones côtières, basés sur les familles de copépodes, ont été proposés.The growing development of urbanism and anthropogenic activities is source of increasing environmental pressure on marine coastal area and especially the Mediterranean Sea. Both human activities and climate change deeply impact marine ecosystems and particularly planktonic systems, which were sensitive to environmental change. However, the combined effect of these two processes on coastal systems functioning and structure over time remains poorly understood. Therefore, planktonic time series provide powerful tools for investigating the impacts of these perturbations. The PROTEE-EBMA laboratory planktonic time series from Toulon (France) are among the oldest from the Mediterranean Sea and provide records of effects for both natural and anthropogenic pressures on planktonic communities. In the context of global change, the present work aim to determine the role of these factors on dynamic and composition of phyto- and zooplankton in NW Mediterranean (Toulon, France). The first part focused on the role of vertical mixing in the Ligurian Sea as inter annual variation driver of the spring plankton bloom in Toulon Bay. The results revealed significant shifts in precipitation regime associated with salinity change into the Large Bay (Toulon) over the period 2005-2013. Same changes were observed into 2 Ligurian basin sites (”SOFCOM” and “Point B”). According to previous hypothesis, spring blooms of phytoplankton conditioned by dry autumns and winters were on average more intense than those from wet conditions. However, differences among sites highlighted importance of local drivers affecting phytoplanktonic dynamics. The second part aimed to investigate impact of precipitation and salinity changes on plankton composition. Results showed a dramatic change in phytoplankton community composition triggering by increasing precipitations and consequently lower salinity and subsequently leading to zooplankton community shifts. In addition, these results suggested that precipitation involved in two specific processes, affecting in a different manner the plankton communities: firstly, low precipitation could contribute on the triggering of winter mixing and thus in surface water fertilization of the Ligurian Basin impacting the Toulon Bays. On the other hand, phytoplankton community shifts also suggested a developing eutrophication processes in Toulon Bay during important precipitation periods driven by increasing local river inputs. In the third part, impact of anthropogenic pressure on both phyto- and zooplankton communities was investigated based on monitoring of two neighboring coastal systems characterized by distinct levels of human activities. Zooplankton communities showed higher sensibility to anthropogenic activities than phytoplankton communities. Finally, indicators of anthropogenic pressure based on copepod families were proposed

Small- and large-scale processes including anthropogenic pressures as drivers of gastropod communities in the NE Atlantic coast: A citizen science based approach

International audienceRocky-shores are among the most threatened coastal habitats, particularly under human pressures. While rocky-shore communities have been increasingly used to evaluate local anthropogenic perturbations such as water eutrophication for instance, large-scale variability in relation to both natural and anthropogenic pressures is still overlooked. Here, using citizen science-based data, we applied a Random Forest modelling approach to assess the relative impact of both small-and large-scale processes (including natural and some anthropogenic pressures) on intertidal gastropod communities as well as taxa-specific gastropod abundances over more than 1000 km of the North-East Atlantic coast. Our model results demonstrate that small-scale conditions (i.e. within shore) are determinant in shaping gastropod communities. However, community responses are mainly driven by taxon-specific effects. Among large-scale predictors, high concentrations of inorganic nutrients and total suspended matter, as found in large river plumes, are the main drivers impacting the gastropod communities by depleting both taxon abundances and richness. According to models, the decline in abundance of the yet most prevalent taxa (Steromphala umbilicalis, Patella spp., S. pennanti and Phorcus lineatus) is expected to be between 65% and 85%, while Littorina littorea was the only taxon which may be favoured by high concentrations of inorganic nutrients and total suspended matter. Such results provide relevant insights in the context of ever-increasing needs for bioindicators of coastal ecosystems. Finally, this work sheds light on the value of a citizen science program resulting from a consultation between professional and citizen volunteers as a useful and efficient tool to investigate large-scale processes

"Pico- and nanophytoplankton dynamics in two coupled but contrasting coastal bays in the NW Mediterranean Sea (France)"

International audienceDue to its ecological context, the Toulon bay represents a site of scientific interest to study temporal plankton distribution, particularly pico-and nanophytoplankton dynamics. A monthly monitoring was performed during a two-year cycle (October 2013-December 2015) at two coupled sampling sites, referred to as Little and Large bays, which had different morphometric characteristics and human pressures. Flow cytometry analyses highlighted the fact that pico-and nanophytoplankton were more abundant in the eutrophic Little bay. Furthermore, it evidenced two community structures across the Toulon bays: at times, a co-dominance of picoeukaryotes, nanoeukaryotes, Synechococcus 1-like cells and Prochlorococcus-like cells was found, and at other times, a Synechococcus 1-like dominated community existed. The alternation of one structure or the other can be explained by a combined action of temperature regime, nutrient conditions and degree of contamination. This study showed that pico-and nanophytoplankton dynamics were mainly driven by temperature in both sites, as in other temperate Mediterranean regions. Thus, the community was mainly composed of picoeukaryotes and Prochlorococcus-like cells in the winter ( 20 °C). Additionally, the multiple human stressors in the Little bay seemed to affect the increase in abundance of Synechococcus 1-like cells as they were preferentially observed in the Large bay

Search for Selection Signatures Related to Trypanosomosis Tolerance in African Goats

Livestock is heavily affected by trypanosomosis in Africa. Through strong selective pressure, several African indigenous breeds of cattle and small ruminants have acquired varying degrees of tolerance against this disease. In this study, we combined LFMM and PCAdapt for analyzing two datasets of goats from West-Central Africa and East Africa, respectively, both comprising breeds with different assumed levels of trypanotolerance. The objectives were (i) to identify molecular signatures of selection related to trypanotolerance; and (ii) to guide an optimal sampling for subsequent studies. From 33 identified signatures, 18 had been detected previously in the literature as being mainly associated with climatic adaptations. The most plausible signatures of trypanotolerance indicate the genes DIS3L2, COPS7B, PD5A, UBE2K, and UBR1. The last gene is of particular interest since previous literature has already identified E3-ubiquitin ligases as playing a decisive role in the immune response. For following-up on these findings, the West-Central African area appears particularly relevant because of (i) a clear parasitic load gradient related to a humidity gradient, and (ii) still restricted admixture levels between goat breeds. This study illustrates the importance of protecting local breeds, which have retained unique allelic combinations conferring their remarkable adaptations

Adrenal Vein Sampling in the Management of Primary Aldosteronism: The Added Value of Intraprocedural Cortisol Assessment

Introduction. Primary aldosteronism is the most common cause of secondary hypertension. Adrenal vein sampling is the gold standard for subtyping primary aldosteronism. However, this procedure is technically challenging and often has a low success rate. Our center is one of the very few performing this technique in our country with an increasing experience. Objective. The aim of this study was to evaluate the role of the cortisol intraprocedural assay in improving the performance of adrenal vein sampling. Design. We enrolled all of the patients with primary aldosteronism that underwent adrenal vein sampling from February 2016 to April 2023. The cortisol intraprocedural assay was introduced in October 2021. Methods. We enrolled a total of 50 adrenal vein samplings performed on 43 patients with the diagnosis of primary aldosteronism. In this sample, 19 patients and 24 patients underwent adrenal vein sampling before and after intraprocedural cortisol measurement, respectively. The procedure was repeated in seven patients (one before and six after intraprocedural cortisol measurement), given the unsuccess of the first exam. Selectivity of the adrenal vein sampling was assumed if the serum cortisol concentration from the adrenal vein was at least five times higher than that of the inferior vena cava. Lateralization was assumed if the aldosterone to cortisol ratio of one adrenal vein was at least four times the aldosterone to cortisol ratio of the contralateral side. Results. The mean age of the patients that underwent adrenal vein sampling (N = 43) was 55.2 ± 8.9 years, and 53.5% (n = 23) were female. The mean interval between the diagnosis of hypertension and the diagnosis of primary aldosteronism was 9.8 years (±9.9). At diagnosis, 62.8% of the patients (n = 27) had hypokalemia (mean value of 3 mmol/L (±0.34)), 88.4% (n = 38) had adrenal abnormalities on preprocedural CT scan, and 67.4% (n = 29) described as unilateral nodules. There were no statistically significant differences in the patients’ baseline characteristics between the two groups (before and after intraprocedural cortisol measurement). Before intraprocedural cortisol measurement, adrenal vein sampling selectivity was achieved in 35% (n = 7) patients. Selectivity increased to 100% (30/30) after intraprocedural cortisol measurement (p<0.001). With the exception of one patient who refused it, all patients with lateralized disease underwent unilateral adrenalectomy with normalization of the aldosterone to renin ratio postoperatively. Conclusions. The lack of effective alternatives in subtyping primary aldosteronism highlights the need to improve the success rate of adrenal vein sampling. In this study, intraprocedural cortisol measurement allowed a selectivity of 100%. Its addition to this procedure protocol should be considered, especially in centers with a low success rate

Search for Selection Signatures Related to Trypanosomosis Tolerance in African Goats

Livestock is heavily affected by trypanosomosis in Africa. Through strong selective pressure, several African indigenous breeds of cattle and small ruminants have acquired varying degrees of tolerance against this disease. In this study, we combined LFMM and PCAdapt for analyzing two datasets of goats from West-Central Africa and East Africa, respectively, both comprising breeds with different assumed levels of trypanotolerance. The objectives were (i) to identify molecular signatures of selection related to trypanotolerance; and (ii) to guide an optimal sampling for subsequent studies. From 33 identified signatures, 18 had been detected previously in the literature as being mainly associated with climatic adaptations. The most plausible signatures of trypanotolerance indicate the genes DIS3L2, COPS7B, PD5A, UBE2K, and UBR1. The last gene is of particular interest since previous literature has already identified E3-ubiquitin ligases as playing a decisive role in the immune response. For following-up on these findings, the West-Central African area appears particularly relevant because of (i) a clear parasitic load gradient related to a humidity gradient, and (ii) still restricted admixture levels between goat breeds. This study illustrates the importance of protecting local breeds, which have retained unique allelic combinations conferring their remarkable adaptations

Local adaptations of Mediterranean sheep and goats through an integrative approach

Small ruminants are suited to a wide variety of habitats and thus represent promising study models for identifying genes underlying adaptations. Here, we considered local Mediterranean breeds of goats (n = 17) and sheep (n = 25) from Italy, France and Spain. Based on historical archives, we selected the breeds potentially most linked to a territory and defined their original cradle (i.e., the geographical area in which the breed has emerged), including transhumant pastoral areas. We then used the programs PCAdapt and LFMM to identify signatures of artificial and environmental selection. Considering cradles instead of current GPS coordinates resulted in a greater number of signatures identified by the LFMM analysis. The results, combined with a systematic literature review, revealed a set of genes with potentially key adaptive roles in relation to the gradient of aridity and altitude. Some of these genes have been previously implicated in lipid metabolism (SUCLG2, BMP2), hypoxia stress/lung function (BMPR2), seasonal patterns (SOX2, DPH6) or neuronal function (TRPC4, TRPC6). Selection signatures involving the PCDH9 and KLH1 genes, as well as NBEA/NBEAL1, were identified in both species and thus could play an important adaptive role