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Acclimation of corals to light is known to rely on multiple strategies working at different timescales. Among them, photosynthetic alternative electron flows (AEFs) could act as photoprotective mechanisms under fluctuating light intensities. In this work, we first compared the use of AEFs in shallow and mesophotic colonies of the coral Stylophora pistillata by carrying out joint measurements of oxygen exchange and photosystems quantum yields. We observed similar capacities to re-route photosynthetically derived electrons toward oxygen (Mehler reaction) and to perform cyclic electron flow around photosystem I under high light intensity in both colony types. But in contrast to mesophotic colonies that hosted Cladocopium, the photosynthetic apparatus of Symbiodinium microadriaticum hosted by their shallow counterparts was notably able to drive a higher number of electrons, displayed a higher thermal dissipation of absorbed light energy. Then, a short-term light stress was applied to evaluate the plasticity of the photosynthetic apparatus. Both shallow and mesophotic colonies showed fast acclimation to the low light regime. In contrast, under the high light regime, mesophotic colonies showed a limited capacity to dissipate light energy and were strongly photoinhibited, though their PSI activity was partly preserved and likely involved cyclic electron flow. This study shows how important the photosynthetic alternative electron flows are in acclimation processes to light and how the plasticity of the photosynthetic processes in Symbiodiniaceae may shape the vertical distribution of the coral holobionts.

Marine mammals include toothed and baleen whales, as well as seals, sea lions, sea cows, sea otters and polar bears. They are adapted to an aquatic life in oceanic, coastal and riverine habitats. They range in size from sea otters to blue whales. The extreme diversity of marine mammals is related to their adaptations to different habitats and their use of different feeding strategies. The different kinds of marine mammals are not closely related but evolved from different terrestrial ancestors. Because they have been exposed to similar environmental constraints in their aquatic way of life, many evolutionary convergences can be found in different lineages. They have torpedo-shaped bodies, thick fur or fat layers to preserve heat, as well as impressive diving abilities. Here, we discuss these adaptations in their physiology and anatomy. Through hands-on exercises, students can test how their own muscle strength and heartbeat are affected by cold water.

Man-made persistent pollutants (such as PCBs, pesticides and trace metals) reach aquatic organisms through the food chains. Pollutants are ingested and assimilated by smaller organisms, and their concentration in tissues increases from prey to predators. Being at the top of the food chains, marine mammals accumulate some of the highest environmental contaminant levels of all wildlife. They are good sentinel species for monitoring long-term environmental pollution. Exposure to contaminants may have large consequences, both on an individual and a population level. The prevalence and severity of diseases of aquatic wildlife has recently increased in many species. Scientists use new methods to understand how pollutants affect the immune system of marine mammals. Learning about contaminants may also contribute to our understanding of outbreaks of infectious diseases in marine mammals.

GHaNA - The Genus Haslea, New marine resources for blue biotechnology and Aquaculture / STARE-CAPMED

Data products, based on in situ temperature and salinity observations from SeaDataNet infrastructure, have been released within the framework of SeaDataCloud (SDC) project. The data from different data providers are integrated and harmonized thanks to standardized quality assurance and quality control methodologies conducted at various stages of the data value chain. The data ingested within SeaDataNet are earlier validated by data providers who assign corresponding quality flags, but a Quality Assurance Strategy has been implemented and progressively refined to guarantee the consistency of the database content and high quality derived products. Two versions of aggregated datasets for the European marginal seas have been published and used to compute regional high resolution climatologies. External datasets, the World Ocean Database from NOAA and the CORA dataset from the Copernicus Marine Service in situ Thematic Assembly Center, have been integrated with SDC data collections to maximize data coverage and minimize the mapping error. The products are available through the SDC catalogue accompanied by Product Information Documents containing the specifications about product’s generation, characteristics and usability. Digital Object Identifiers are assigned to products and relative documentation to foster transparency of the production chain, acknowledging all actors involved from data providers to information producers.

DIVAnd (Data-Interpolating Variational Analysis, in n-dimensions) is a tool to interpolate observations on a regular grid using the variational inverse method. We have extended DIVAnd to include additional dynamic constraints relevant to surface currents, including imposing a zero normal velocity at the coastline, imposing a low horizontal divergence of the surface currents, temporal coherence and simplified dynamics based on the Coriolis force and the possibility of including a surface pressure gradient. The impact of these constraints is evaluated by cross-validation using the HF (High-Frequency) radar surface current observations in the Ibiza Channel from the Balearic Islands Coastal Ocean Observing and Forecasting System (SOCIB). A small fraction of the radial current observations are set aside to validate the velocity reconstruction. The remaining radial currents from the two radar sites are combined to derive total surface currents using DIVAnd and then compared to the cross-validation data set and to drifter observations. The benefit of the dynamic constraints is shown relative to a variational interpolation without these dynamical constraints. The best results were obtained using the Coriolis force and the surface pressure gradient as a constraint which are able to improve the reconstruction from the Open-boundary Modal Analysis, a quite commonly used method to interpolate HF radar observations, once multiple time instances are considered together. SeaDataCloud project; JERICO-S3 project

In this study, the Gulf Stream’s (GS) response to the North Atlantic oscillation (NAO) is investigated by generating an observation-based reconstruction of the GS path between 70° and 50°W since 1940. Using in situ data from WOD, SeaDataNet, ICES, Hydrobase3 and ARGO floats, a harmonized database of more than 40 million entries is created. A variational inverse method implemented in the software DIVA (Data-Interpolating Variational Analysis) allows the production of time series of monthly analyses of temperature and salinity over the North Atlantic (NA). These time series are used to derive two GS indices: the GS North Wall (GSNW) index for position and the GS Delta (GSD) index as a proxy of its transport. We find a significant correlation (0.37) between the GSNW and the NAO at a lag of 1 year (NAO preceding GS) since 1940 and significant correlations (0.50 and 0.43) between the GSD and the NAO at lags of 0 and 2 years between 1960–2014. We suggest this 2-year lag is due to Rossby waves, generated by NAO variability, that propagate westwards from the center of the NA. This is the first reconstruction of GS indices over a 75-year period based on an objective method using the largest in situ dataset so far. This enhanced tracking and quantification of the GS confirms and extends the temporal scope of this property: NAO+ phases lead to a stronger and more northward GS, and conversely for NAO− phases. The teleconnections between the NAO and the variability of the GS were extensively studied these last years, often exhibiting time delays between both phenomena. These time lags, usually ranging between 0–2 years, are sometimes explained by the hypothesis of baroclinic Rossby waves generated by the NAO in the central NA and travelling westward before interacting with the GS. In this study, we use a numerical hindcast at an eddy-resolving resolution (1/12°) from the DRAKKAR project to examine the occurrence and properties of such Rossby waves between 1970–2015, thus including a large pre-TOPEX/Poseidon period. Through the use of a two-dimensional Radon Transform (2D-RT) on Hovmöller diagrams of the Sea Surface Height (SSH), a methodology easily portable to other oceanic model outputs, we show evidence of baroclinic Rossby waves travelling at 39°N at a speed of 4.17 cm/s. This study extends the period over which Rossby waves have been found that far north to a much longer period, which reinforces the findings of previous works. These results are consistent with the time lags observed between the NAO and the GS transport while the GS latitudinal shifts might obey additional processes. The Barents Sea, located between the Norwegian Sea and the Arctic Ocean, is one of the main pathways of the Atlantic Meridional Overturning Circulation. Changes in the water mass transformations in the Barents Sea potentially affect the thermohaline circulation through the alteration of the dense water formation process. In order to investigate such changes, we present here a seasonal atlas of the Barents Sea including both temperature and salinity for the period 1965–2016. The atlas is built as a compilation of datasets from the World Ocean Database, the Polar Branch of Russian Federal Research Institute of Fisheries and Oceanography, and the Norwegian Polar Institute using the DIVA tool. DIVA allows for a minimization of the expected error variance with respect to the true field. The atlas is used to provide a volumetric analysis of water mass characteristics and an estimation of the ocean heat and freshwater contents. The results show a recent "Atlantification" of the Barents Sea, that is a general increase of both temperature and salinity, while its density remains stable. The atlas is made freely accessible as handy NetCDF files to encourage further research in the Barents Sea physics. SeaDataNet II

A new global ocean temperature and salinity climatology is proposed for two time periods: a long time mean using multiple sensor data for the 1900–2017 period and a shorter time mean using only profiling float data for the 2003–2017 period. We use the historical database of World Ocean Database 2018. The estimation approach is novel as an additional quality control procedure is implemented, along with a new mapping algorithm based on Data Interpolating Variational Analysis. The new procedure, in addition to the traditional quality control approach, resulted in low sensitivity in terms of the first guess field choice. The roughness index and the root mean square of residuals are new indices applied to the selection of the free mapping parameters along with sensitivity experiments. Overall, the new estimates were consistent with previous climatologies, but several differences were found. The cause of these discrepancies is difficult to identify due to several differences in the procedures. To minimise these uncertainties, a multi-model ensemble mean is proposed as the least uncertain estimate of the global ocean temperature and salinity climatology Refereed 14.a N/A Novel (no adoption outside originators) Method Specification of criteria