Multi-year renewal of green tides: 18 years of algal mat monitoring (2003-2020) on French coastline (Brittany region).

To better understand the green tide phenomenon impacting French coastline and give guidance to stakeholders to elaborate effective mitigation plan, an extensive survey has been deployed on Brittany hot spots. Based on 18 years monitoring database, the objectives of this work were to investigate the inter-and-intra annual evolutions of Ulva beaching, and to assess the parameters driving green tide annual renewal. The yearly cumulated area of Ulva mat on the Brittany coast averaged 2,42 ± 0,84 ha, of which 55 ± 12 % % was reported within Saint Brieuc-Binic Bay, with a maximal beaching generally observed in July. The renewal of green tide at spring time seems to be correlated with the Ulva bloom from the previous autumn period, particularly in bays with low exposure to swell. The residual stock, defined as Ulva fragments maintained in healthy conditions during the winter season, appears as highly dependent on nitrogen summer flows.

Assessment of fitness and vector competence of a New Caledonia wMel Aedes aegypti strain before field-release.

BACKGROUND: Biological control programs involving Wolbachia-infected Aedes aegypti are currently deployed in different epidemiological settings. New Caledonia (NC) is an ideal location for the implementation and evaluation of such a strategy as the only proven vector for dengue virus (DENV) is Ae. aegypti and dengue outbreaks frequency and severity are increasing. We report the generation of a NC Wolbachia-infected Ae. aegypti strain and the results of experiments to assess the vector competence and fitness of this strain for future implementation as a disease control strategy in Noumea, NC. METHODS/PRINCIPAL FINDINGS: The NC Wolbachia strain (NC-wMel) was obtained by backcrossing Australian AUS-wMel females with New Caledonian Wild-Type (NC-WT) males. Blocking of DENV, chikungunya (CHIKV), and Zika (ZIKV) viruses were evaluated via mosquito oral feeding experiments and intrathoracic DENV challenge. Significant reduction in infection rates were observed for NC-wMel Ae. aegypti compared to WT Ae. aegypti. No transmission was observed for NC-wMel Ae. aegypti. Maternal transmission, cytoplasmic incompatibility, fertility, fecundity, wing length, and insecticide resistance were also assessed in laboratory experiments. Ae. aegypti NC-wMel showed complete cytoplasmic incompatibility and a strong maternal transmission. Ae. aegypti NC-wMel fitness seemed to be reduced compared to NC-WT Ae. aegypti and AUS-wMel Ae. aegypti regarding fertility and fecundity. However further experiments are required to assess it accurately. CONCLUSIONS/SIGNIFICANCE: Our results demonstrated that the NC-wMel Ae. aegypti strain is a strong inhibitor of DENV, CHIKV, and ZIKV infection and prevents transmission of infectious viral particles in mosquito saliva. Furthermore, our NC-wMel Ae. aegypti strain induces reproductive cytoplasmic incompatibility with minimal apparent fitness costs and high maternal transmission, supporting field-releases in Noumea, NC.

In situ heavy metals (copper, lead and cadmium) in different plankton compartments and suspended particulate matter in two coupled Mediterranean coastal ecosystems (Toulon Bay, France).

We monitored the concentrations of copper, lead and cadmium in seawater, in suspended particulate matter (SPM) and in bacteria, phyto- and zooplankton communities separated from abiogenic particles, over a one year cycle in two coupled Mediterranean coastal ecosystems (Little Bay (LiB) and Large Bay (LaB)). Metals were present in seawater in the order Cu>Pb>Cd in both bays and showed important variations within the same month than among months. In LiB, their concentrations were between 0.62 and 2.82 microg Cu l(-1), 0.16 and 19 microg Pb l(-1) and 0.007 and 0.14 microg Cd l(-1), respectively, whereas in LaB, they were between 0.23 and 2.11 microg Cu l(-1), 0.09 and 0.76 microg Pb l(-1) and not detected and 0.65 microg Cd l(-1). SPM play an important role on metal adsorption, especially for copper. Bioaccumulation factors showed that bacteria and phytoplankton accumulate metals whereas zooplankton tends to biodiminish them in the plankton food web.