Major consequences of an intense dense shelf water cascading event on deep-sea benthic trophic condtions and meiofaunal biodiversity

Numerous submarine canyons around the world are preferential conduits for episodic dense shelf water cas- cading (DSWC), which quickly modifies physical and chem- ical ambient conditions while transporting large amounts of material towards the base of slope and basin. Observations conducted during the last 20 yr in the Lacaze-Duthiers and Cap de Creus canyons (Gulf of Lion, NW Mediterranean Sea) report several intense DSWC events. The effects of DSWC on deep-sea ecosystems are almost unknown. To in- vestigate the effects of these episodic events, we analysed changes in the meiofaunal biodiversity inside and outside the canyon. Sediment samples were collected at depths varying from ca. 1000 to >2100m in May 2004 (before a major event), April 2005 (during a major cascading event) and in October 2005, August 2006, April 2008 and April 2009 (af- ter a major event). We report here that the late winter–early spring 2005 cascading led to a reduction of the organic mat- ter contents in canyon floor sediments down to 1800 m depth, whereas surface sediments at about 2200 m depth showed an increase. Our findings suggest that the nutritional material re- moved from the shallower continental shelf, canyon floor and flanks, and also the adjacent open slope was rapidly trans- ported to the deep margin. During the cascading event the meiofaunal abundance and biodiversity in the studied deep- sea sediments were significantly lower than after the event. Benthic assemblages during the cascading were significantly different from those in all other sampling periods in both the canyon and deep margin. After only six months from the cessation of the cascading, benthic assemblages in the impacted sediments were again similar to those observed in other sampling periods, thus illustrating a quick recovery. Since the present climate change is expected to increase the intensity and frequency of these episodic events, we anticipate that they will increasingly affect benthic bathyal ecosys- tems, which may eventually challenge their resilience

Direct Discharges of Domestic Wastewater are a Major Source of Phosphorus and Nitrogen to the Mediterranean Sea

Direct discharges of treated and untreated wastewater are important sources of nutrients to coastal marine ecosystems and contribute to their eutrophication. Here, we estimate the spatially distributed annual inputs of phosphorus (P) and nitrogen (N) associated with direct domestic wastewater discharges from coastal cities to the Mediterranean Sea (MS). According to our best estimates, in 2003 these inputs amounted to 0.9 × 10⁹ mol P yr-1 and 15 × 10⁹ mol N yr-1, that is, values on the same order of magnitude as riverine inputs of P and N to the MS. By 2050, in the absence of any mitigation, population growth plus higher per capita protein intake and increased connectivity to the sewer system are projected to increase P inputs to the MS via direct wastewater discharges by 254, 163, and 32% for South, East, and North Mediterranean countries, respectively. Complete conversion to tertiary wastewater treatment would reduce the 2050 inputs to below their 2003 levels, but at an estimated additional cost of over €2 billion yr-1. Management of coastal eutrophication may be best achieved by targeting tertiary treatment upgrades to the most affected near-shore areas, while simultaneously implementing legislation limiting P in detergents and increasing wastewater reuse across the entire basin

Persistent, depth-intensified mixing during the Western Mediterranean Transition's initial stages

Piñeiro, S., González-Pola, C., Fernández-Díaz, J. M., Naveira-Garabato, A. C., Sánchez-Leal, R., Puig, P., et al. (2021). Persistent, depth-intensified mixing during the Western Mediterranean Transition's initial stages. Journal of Geophysical Research: Oceans, 126, e2020JC016535. https://doi.org/10.1029/2020JC016535. © 2020. American Geophysical Union. All Rights Reserved.© 2020. American Geophysical Union. All Rights Reserved. Major deep-convection activity in the northwestern Mediterranean during winter 2005 triggered the formation of a complex anomalous deep-water structure that substantially modified the properties of the Western Mediterranean deep layers. Since then, evolution of this thermohaline structure, the so-called Western Mediterranean Transition (WMT), has been traced through a regularly sampled hydrographic deep station located on the outer continental slope of Minorca Island. A rapid erosion of the WMT's near-bottom thermohaline signal was observed during 2005–2007. The plausible interpretation of this as local bottom-intensified mixing motivates this study. Here, the evolution of the WMT structure through 2005–2007 is reproduced by means of a one-dimensional diffusion model including double-diffusive mixing that allows vertical variation of the background mixing coefficient and includes a source term to represent the lateral advection of deep-water injections from the convection area. Using an optimization algorithm, a best guess for the depth-dependent background mixing coefficient is obtained for the study period. WMT evolution during its initial stages is satisfactorily reproduced using this simple conceptual model, indicating that strong depth-intensified mixing (K ∞ (z) ≈ 22 × 10−4 m2 s−1; z ⪆ 1,400 dbar) is a valid explanation for the observations. Extensive hydrographic and current observations gathered over the continental slope of Minorca during winter 2018, the first deep-convective winter intensively sampled in the region, provide evidence of topographically localized enhanced mixing concurrent with newly formed dense waters flowing along-slope toward the Algerian sub-basin. This transport-related boundary mixing mechanism is suggested to be a plausible source of the water-mass transformations observed during the initial stages of the WMT off Minorca.CTM2014-54374-R. BES-2015-074316.Versión del editor3,17

Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea

Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980–2013 and a detailed multi-indicator description of the period 2007–2013. Then a 1980–2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the dense water volume, increase in the bottom water density) despite an underestimation of the salinity and density trends. These deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the Gulf of Lions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. The salinity increase in the near Atlantic Ocean surface layers seems to be the external forcing that finally leads to these deep trends. In the future, our results may allow to better understand the behaviour of the DWF phenomenon in Mediterranean Sea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. The robustness of the obtained results must be however confirmed in multi-model studies

Benthic foraminiferal assemblages in the Cap de Creus canyon and adjacent open slope: Potential influence of dense shelf water cascading and open-ocean convection

The NW Mediterranean Sea is subjected to episodically intense events of dense shelf water cascading (DSWC) and open-ocean convection (OOC) that ventilate the seafloor and also have important consequences on organic matter inputs to the seabed and sediment dynamics. The influence of the massive physico-chemical disturbance driven by these events on deep-sea ecosystems is poorly known, and, to date, no information is available on the response of benthic foraminiferal assemblages. To provide insights on these gaps of knowledge, in April 2009 we investigated the foraminiferal faunas along the major axis of the Cap de Creus canyon (at 1000, 1900 and 2400 m depth) and at two additional stations located on the adjacent open slope (at 1000 and 1900 m). The area under scrutiny was hit by intense DSWC and OOC events in winters 2005 and 2006, and during winter 2009 an intense OOC event occurred, with detectable consequences observed at > 1500 m depth. We report here foraminiferal faunas characterized by low densities but relatively high levels of biodiversity at 1000-m depth stations. On the contrary, at the deeper depths, very high densities (associated with low organic matter contents) and strong dominance of the disaster species Usbekistania charoides were observed in the > 63 µm fraction. The comparison of our results – obtained immediately after an OOC event – to those previously described in spring 2004, before DSWC and OOC events, reveals the presence of largely different foraminiferal assemblages in the two periods. Based on a detailed analysis of the ecological traits of the faunas encountered in the two sampling periods, we suggest that either DSWC or OOC can have a role in shaping deep-sea foraminiferal faunas. Moreover, we contend that, at 1000 m depth, the composition of the foraminiferal assemblages in spring 2009 is suggestive of a resilient stage following the major DSWC events in 2005/2006, whereas the low evenness of faunas at ≥ 1900 m depth is, most likely, the result of the OOC event that occurred in winter 2009, a few months before our sampling

Sensor Selection and Optimization for Health Assessment of Aerospace Systems

Aerospace systems are developed similarly to other large-scale systems through a series of reviews, where designs are modified as system requirements are refined. For space-based systems few are built and placed into service. These research vehicles have limited historical experience to draw from and formidable reliability and safety requirements, due to the remote and severe environment of space. Aeronautical systems have similar reliability and safety requirements, and while these systems may have historical information to access, commercial and military systems require longevity under a range of operational conditions and applied loads. Historically, the design of aerospace systems, particularly the selection of sensors, is based on the requirements for control and performance rather than on health assessment needs. Furthermore, the safety and reliability requirements are met through sensor suite augmentation in an ad hoc, heuristic manner, rather than any systematic approach. A review of the current sensor selection practice within and outside of the aerospace community was conducted and a sensor selection architecture is proposed that will provide a justifiable, dependable sensor suite to address system health assessment requirements

Prevalence, survival analysis and multimorbidity of chronic diseases in the general veterinarian-attended horse population of the UK

he average age of the global human population is increasing, leading to increased interest in the effects of chronic disease and multimorbidity on health resources and patient welfare. It has been posited that the average age of the general veterinarian-attended horse population of the UK is also increasing, and therefore it could be assumed that chronic diseases and multimorbidity would pose an increasing risk here also. However, evidence for this trend in ageing is very limited, and the current prevalence of many chronic diseases, and of multimorbidity, is unknown. Using text mining of first-opinion electronic medical records from seven veterinary practices around the UK, Kaplan-Meier and Cox proportional hazard modelling, we were able to estimate the apparent prevalence among veterinarian-attended horses of nine chronic diseases, and to assess their relative effects on median life expectancy following diagnosis. With these methods we found evidence of increasing population age. Multimorbidity affected 1.2% of the study population, and had a significant effect upon survival times, with co-occurrence of two diseases, and three or more diseases, leading to 6.6 and 21.3 times the hazard ratio compared to no chronic disease, respectively. Laminitis was involved in 74% of cases of multimorbidity. The population of horses attended by UK veterinarians appears to be aging, and chronic diseases and their co-occurrence are common features, and as such warrant further investigation

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

Effects of temperature in juvenile seabass (Dicentrarchus labrax L.) biomarker responses and behaviour: implications for environmental monitoring

The effects of temperature on European seabass (Dicentrarchus labrax L.) juveniles were investigated using a 30-day bioassay carried out at 18 and 25 °C in laboratory conditions. A multiparameter approach was applied including fish swimming velocity and several biochemical parameters involved in important physiological functions. Fish exposed for four weeks to 25 °C showed a decreased swimming capacity, concomitant with increased oxidative stress (increased catalase and glutathione peroxidase activities) and damage (increased lipid peroxidation levels), increased activity of an enzyme involved in energy production through the aerobic pathway (isocitrate dehydrogenase) and increased activities of brain and muscle cholinesterases (neurotransmission) compared to fish kept at 18 °C. Globally, these findings indicate that basic functions, essential for juvenile seabass surviving and well performing in the wild, such as predation, predator avoidance, neurofunction and ability to face chemical stress may be compromised with increasing water temperature. This may be of particular concern if D. labrax recruitment phase in northwest European estuaries and coastal areas happens gradually inmore warm environments as a consequence of global warming. Considering that the selected endpoints are generally applied in monitoring studies with different species, these findings also highlight the need of more research, including interdisciplinary and multiparameter approaches, on the impacts of temperature on marine species, and stress the importance of considering scenarios of temperature increase in environmental monitoring and in marine ecological risk assessment