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See detailInvestigating densities of Symbiodiniaceae in two species of Antipatharians (black corals) from Madagascar
Gress, Erika; Eeckhaut, Igor; Godefroid, Mathilde et al

in Oceans (in press)

Here, we report the first methodological approach to investigate the presence and estimate density of Symbiodiniaceae cells in corals of the order Antipatharia subclass Hexacorallia, known as black corals ... [more ▼]

Here, we report the first methodological approach to investigate the presence and estimate density of Symbiodiniaceae cells in corals of the order Antipatharia subclass Hexacorallia, known as black corals. Antipatharians are understudied ecosystem engineers of shallow (<30 m depth), mesophotic (30-150 m) and deep-sea (>200 m) reefs. They provide habitat to a vast number of marine fauna, enhancing and supporting coral reefs biodiversity globally. Nonetheless, little biological and ecological information exists on antipatharians, including the extent at which global change disturbances are threatening these corals. The assumption that they were exempted from threats related to climate change was challenged by findings of high density of dinoflagellates within three antipatharian colonies. Further methodical studies were necessary to investigate the regularity of these findings. An integrated design combining microscopy and molecular techniques was used to investigate the presence and estimate density of Symbiodiniaceae cells within two antipatharians species - Cupressopathes abies and Stichopathes maldivensis - from shallow and mesophotic reefs of SW Madagascar. Symbiodiniaceae-like cells were found within the two species from both shallow and mesophotic reefs, although the overall cell density was very low (0-4 cell mm-3). These findings suggest that high abundance of Symbiodiniaceae is not characteristic of antipatharians, which has relevant implications considering climate change associated disruptions in other corals. However, the high densities of dinoflagellates found in antipatharian colonies exposed to higher light irradiance in other studies should be further examined. [less ▲]

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See detailExperimental assessment of light decrease on the biology of Posidonia oceanica
Richir, Jonathan ULiege; Luyckx, Adrien; Champenois, Willy ULiege et al

Conference (2021, May 18)

Seagrasses have a worldwide distribution and grow from the tidal zone to more than 100 m deep. They are considered ecosystem engineers, by building structurally complex meadows. Seagrass meadows are major ... [more ▼]

Seagrasses have a worldwide distribution and grow from the tidal zone to more than 100 m deep. They are considered ecosystem engineers, by building structurally complex meadows. Seagrass meadows are major coastal ecosystems, are highly productive, provide many goods and services and have considerable environmental, financial, and heritage value. Just like any autotroph, seagrass development relies on light availability. Among the many stressors that threaten seagrasses, light deprivation is consequently a major one. Light availability can decrease because of environmental (e.g., river sediment transport) or anthropogenic (e.g., eutrophication, sediment resuspension) factors, an issue expected to worsen in the future. It is in this context that we experimentally assessed the effects of environmentally relevant shading on a keystone seagrass endemic to the Mediterranean Sea, Posidonia oceanica (Linnaeus) Delile, 1813. Screens of different transparency (nominal reduction of 15, 30 and 60% compared to control) were deployed on a healthy meadow at a depth of 15 m in Corsica, France. The experiment took place between April and August 2018, i.e., during the main annual period of productivity of the plant. Seagrass pigment contents (chlorophylls and xanthophylls), photosynthesis (rapid light curves, photosynthesis/irradiance curves and quantum yield), biometry and primary production, carbohydrates (total insoluble and soluble carbohydrates) were measured monthly. Environmental parameters light, temperature and sediment porewater chemistry (methane, nitrous oxide, sulfide, nutrients) were monitored as well. Results showed the adaptability of P. oceanica to light reduction treatments. The seagrass adapted its photosynthetic activity (RLC) and efficiency (effective quantum yield) to cope with light reduction. This improvement resulted from physiological plasticity because neither the pigment contents nor the photosynthesis/irradiance curves differed between light treatments. P. oceanica shoots further maintained their growth and biomass production despite the decrease in light, but at the expense of storing carbohydrates. Finally, the chemistry of sediment porewater, in particular toxic sulfide was not altered. Results of this work underlined the high resistance and resilience of a healthy P. oceanica meadow to five months in situ light deprivation stress. However, because of the measured decrease of storage carbohydrates, seagrass meadow perennity when exposed to longer, recurrent shading is of concern. Carbohydrates and photosynthetic activity and efficiency could further be investigated as early warning indicators in seagrasses facing light reduction stress. [less ▲]

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See detailMarine Aquaculture Impacts on Marine Biota
Casadevall, Margarida; Rodríiguez-Prieto, Conxi; Torres, Jordi et al

Book published by Frontiers Media S.A. (2021)

The growing global demand for fish is resulting in a progressive increase of the aquaculture industry, which soon will surpass fisheries as main source of seafood worldwide. At present, approximately 44 ... [more ▼]

The growing global demand for fish is resulting in a progressive increase of the aquaculture industry, which soon will surpass fisheries as main source of seafood worldwide. At present, approximately 44% of the fish consumed by humans comes from aquaculture, and this percentage is predicted to reach 52% by 2025. Aquaculture provides undoubted economic benefits and diverts part of the fishing pressures exerted on wild stocks. However, it is also at the origin of many impacts on the marine environment and biota due to biological, chemical and physical effects. Production safety measures to prevent environmental contaminations from mariculture are not required yet. A number of nocive biological effects are therefore occurring such as genetic interactions between escaped and wild fishes, disease transfer or ingestion of waste by wild fishes. Aquaculture further depends on large additions of aquafeed, fertilizers and other additives leading to chemical contamination. As the industry expands, it also requires the use of more drugs, disinfectants and antifouling compounds (biocides) to eliminate microorganisms from aquaculture facilities. These chemicals are known to be harmful to the marine environment because of their toxicity. Although field evidence of, e.g. metal enrichment in sediments due to fish farming is abundant, its environmental risk is still in discussion. However, there has been increasing interest in alternative ecological approaches for improved management of aquaculture with the adoption of new, cleaner production technologies (e.g. organic aquaculture, Integrated multi-trophic aquaculture IMTA...). Mariculture farms are more or less invasive structures that physically modify and alter the marine environment. In addition, intensive fish farming causes large amounts of organic waste accumulation in the water column and sediments. Main organic waste sources are fish feces, uneaten feed and dead individuals. Their decomposition increases the biological demand in oxygen and causes the deterioration of water and sediment quality. Physical impacts of mariculture indirectly influencing the biota, they must also be taken into account in addition to biological and chemical direct stressors. The impacts and consequences of mariculture on marine organisms are complex and yet still remain unclear. They depend on a large number of parameters such as: type of organism, species, metabolism, physiological conditions, feeding mechanisms and behavior, size, age, sex, spawning status, parasites, mobility and migration, habitat and so on. Furthermore, it is now generally accepted that climate change is occurring and that this will have significant implications for the marine environment and, consequently, aquaculture. Faced with this complexity and lack of knowledge, this Frontiers Research Topic therefore aims to collect works that demonstrate the impacts of mariculture on the marine biota, in all its manifestations and in any kinds of wild organisms and that propose mitigation measures to reduce their potential negative effects. [less ▲]

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See detailEditorial: Marine Aquaculture Impacts on Marine Biota
Casadevall, Margarida; Rodríguez-Prieto, Conxi; Torres, Jordi et al

Book published by Frontiers Media S.A. (2021)

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See detailThree decades of trace element sediment contamination: The mining of governmental databases and the need to address hidden sources for clean and healthy seas
Richir, Jonathan ULiege; Bray, Simon; McAleese, Tom et al

in Environment International (2021), 149

Trace elements (TEs) frequently contaminate coastal marine sediments with many included in priority chemical lists or control legislation. These, improved waste treatment and increased recycling have ... [more ▼]

Trace elements (TEs) frequently contaminate coastal marine sediments with many included in priority chemical lists or control legislation. These, improved waste treatment and increased recycling have fostered the belief that TE pollution is declining. Nevertheless, there is a paucity of long-term robust datasets to support this confidence. By mining UK datasets (100s of sites, 31 years), we assess sediment concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) and use indices (PI [Pollution], TEPI [Trace Element Pollution] and Igeo [Geoaccumulation]) to assess TE pollution evolution. PI and TEPI show reductions of overall TE pollution in the 1980s then incremental improvements followed by a distinct increase (2010–13). Zn, As and Pb Igeo scores show low pollution, whilst Cd and Hg are moderate, but with all remaining temporally stable. Igeo scores are low for Ni, Fe and Cr, but increasing for Ni and Fe. A moderate pollution Igeo score for Cu has also steadily increased since the mid-1990s. Increasing site trends are not universal and, conversely, minimal temporal change masks some site-specific increases and decreases. To capture this variability we strongly advocate embedding sufficient sentinel sites within observation networks. Decreasing sediment pollution levels (e.g. Pb and Hg) have been achieved, but stabilizing Igeo and recently increasing TEPI and PI scores require continued global vigilance. Increasing Ni and Fe Igeo scores necessitate source identification, but this is a priority for Cu. Local, regional and world analyses indicate substantial ‘hidden’ inputs from anti-fouling paints (Cu, Zn), ship scrubbers (Cu, Zn, Ni) and sacrificial anodes (Zn) that are also predicted to increase markedly. Accurate TE input assessments and targeted legislation are, therefore, urgently required, especially in the context of rapid blue economic growth (e.g. shipping). [less ▲]

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See detailData on elemental concentrations in marine sediments from the South and South West of England
Richir, Jonathan ULiege; Bray, Simon; McAleese, Tom et al

in Data in Brief (2021)

The present Data In Brief methodological paper details the acquisition, mining and pre-processing of elemental concentration data in marine sediments (coastal and open sea) of Southern England, presented ... [more ▼]

The present Data In Brief methodological paper details the acquisition, mining and pre-processing of elemental concentration data in marine sediments (coastal and open sea) of Southern England, presented and discussed in the co-submitted Environment International paper entitled: “Three decades of trace element sediment contamination: the mining of governmental databases and the need to address hidden sources for clean and healthy seas” [1]. Elemental sediment concentration data were obtained from the two main UK environmental sources, i.e. the Environment Agency (EA) and the Marine Environment Monitoring and Assessment National database (MERMAN) managed by the British Oceanographic Data Centre (BODC). The merged database is the result of a rigorous data selection-validation process and provides spatially and temporally extensive records of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) concentrations for hundreds of sites over 31 years (1983-2013). More spatially and temporally limited records of manganese (Mn), aluminium (Al), lithium (Li), tin (Sn) [and tributyltin, TBT], barium (Ba), antimony (Sb), boron (B), calcium (Ca), molybdenum (Mo), cobalt (Co), selenium (Se), potassium (K), magnesium (Mg), beryllium (Be), vanadium (V), titanium (Ti), sodium (Na), silver (Ag), thallium (Tl) and strontium (Sr) are also included. The full secondary database is hosted in the Mendeley Data repository and the geo-spatial information to map sites is given in supplementary files to the paper. To provide end-users with the relevant context on spatial and temporal coverage, monitoring statistics are given for the nine trace elements (TEs). Site-specific statistics include: the first and last year of sediment monitoring, the number of years monitored, and minimum, maximum, mean and median numbers of years monitored. Also given are summary data on the number of sites monitored each year, from the first records from 1983 to 2013. For the nine TEs (total and strong acid digestion techniques are considered separately for Cr and Fe), monitoring statistics are presented separately for coastal and open sea sites. Data are relevant to diverse end-users to assess the local and regional contaminant loads and to contextualize anthropogenic threats to benthic systems in multiple locations from the, French/English Channel, southern North and Celtic Seas. [less ▲]

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See detailDetecting the effects of chronic metal exposure on benthic systems: Importance of biomarker and endpoint selection
Watson, Gordon J; Pini, Jennifer M; Richir, Jonathan ULiege et al

in Aquatic Toxicology (2020)

Understanding metal toxicity to benthic systems is still an ecotoxicological priority and, although numerous biomarkers exist, a multi-biomarker and endpoint approach with sediment as the delivery matrix ... [more ▼]

Understanding metal toxicity to benthic systems is still an ecotoxicological priority and, although numerous biomarkers exist, a multi-biomarker and endpoint approach with sediment as the delivery matrix combined with life-history relevant exposure timescales is missing. Here we assess potential toxicity by measuring a suite of biomarkers and endpoints after exposing the ecologically important polychaete Alitta(Nereis) virens to sediment spiked with environmentally relevant concentrations of copper and zinc (and in combination) for 3, 6 and 9 months. We compared biomarker and endpoint sensitivity providing a guide to select the appropriate endpoints for the chosen time frame (exposure period) and concentration (relevant to Sediment Quality Guidelines) needed to identify effects for benthic polychaetes such as A. virens. Target bioavailable sediment and subsequent porewater concentrations reflect the global contamination range, whilst tissue concentrations, although elevated, were comparable with other polychaetes. Survival reduced as concentrations increased, but growth was not significantly different between treatments. Metabolic changes were restricted to significant reductions in protein after 9 months exposure across all copper concentrations, and reductions in lipid at high copper concentrations (3 months). Significant changes in feeding behaviour and increases in metallothionein-like protein concentration were limited to the medium and high copper and zinc concentrations, respectively, both after 6 months exposure. Despite data highlighting A. virens′ metal tolerance, DNA damage and protein concentrations are the most sensitive biomarkers. Copper and zinc cause biomarker responses at concentrations routinely found in coastal sediments that are characterised as low contamination, suggesting a reappraisal of the current input sources (especially copper) is required. [less ▲]

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See detailStructure, Functioning and Conservation of Coastal Vegetated Wetlands
Richir, Jonathan ULiege; Bouillon, Steven; Gobert, Sylvie ULiege et al

Book published by Frontiers Media S.A. (2020)

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See detailAssessment of physico-chemical parameters of freshwater in the Sidi Abderrahmane reservoir, Safi, Morocco
Belokda, Wafae; Damsiri, Zainab; Natij, L et al

in African Journal of Aquatic Science (2020)

The purpose of the study was to assess the water quality in the Sidi Abderrahmane freshwater reservoir (Safi, Morocco). The monitoring data used in the study included physical, chemical, and biological ... [more ▼]

The purpose of the study was to assess the water quality in the Sidi Abderrahmane freshwater reservoir (Safi, Morocco). The monitoring data used in the study included physical, chemical, and biological characteristics. The spatial and temporal characteristics of these parameters was evaluated by collecting water samples fortnightly from May 2011 to December 2012 in three stations chosen to represent different parts of the reservoir. Ten parameters considered as indicators of water properties were analysed: temperature, dissolved oxygen, pH, electric conductivity, transparency, orthophosphorus, ammonium, nitrites, nitrates, and chlorophyll a. The results show that nutrient concentrations were among the highest (mean concentrations: PO43− = 0.64 mg l−1, NH4+ = 1.08 mg l−1) recorded for Moroccan freshwater reservoirs. Our data indicated that the Sidi Abderrahmane is a destratified reservoir that it is relatively warm (mean temperature: 22.42 ± 4.88 °C); a polymictic reservoir in a semi-arid climate. Fertilisers applied in the surrounding orchards affect significantly affect nutrient levels in the waterbody, particularly PO43− and NH4+ in autumn. The water column is seasonally homogeneous, as a result of wind-induced mixing, and our tests showed no anoxia throughout the study period. With suitable hydraulic conditions (short residence time, short outflow/inflow ratio, good oxygenation, and homogeneity), the Sidi Abderrahmane water body could reduce the stratification time and improve water quality. [less ▲]

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See detailThe Strange Case of Tough White Seabream (Diplodus sargus, Teleostei: Sparidae): A First Approach to the Extent of the Phenomenon in the Mediterranean
Casadevall, Margarida; Rodriguez-Prieto, Conxi; Pueyo, Josep et al

in Frontiers in Marine Science (2020)

A worrying phenomenon has been affecting the common white seabream (Diplodus sargus) for near 40 years. Professional and recreational fishers from the Mediterranean coasts and the Atlantic coasts of ... [more ▼]

A worrying phenomenon has been affecting the common white seabream (Diplodus sargus) for near 40 years. Professional and recreational fishers from the Mediterranean coasts and the Atlantic coasts of Europe and Macaronesia have reported individuals of white seabream that became “like a tire” after cooking, and consequently inedible. The phenomenon was related neither to the freshness of the fish nor to the way it had been preserved or cooked. According to recreational fishers, this Abnormally Tough Specimen (ATS) phenomenon appeared singularly in time, in different places and to different extents. This singular, scattered appearance, with no area of origin from which to spread, de facto excluded any process of contagion. In order to compensate for the lack of knowledge and understanding related to this issue, we undertook a first study that aimed at addressing the extent of the white seabream anomaly in the western Mediterranean. To reach this objective, we carried out surveys on voluntary basis among fishers (both professional and recreational) and researchers throughout the western Mediterranean. Data from the surveys (n = 270) were then analyzed to evaluate the distribution of ATS and its possible relationship with human activities. Results showed that the anomaly affected the white seabream and very occasionally some other species, mainly of the same family Sparidae. In addition, the phenomenon did not occur simultaneously in the different areas surveyed over the last years and in some places it seems to have disappeared. We highlighted a possible link between ATS occurrence and the presence of human activities in adjacent areas. We hypothesized pollution – including by copper – could be a possible driver of ATS. Results suggested a tendency of ATS to cluster around fish farms and commercial and industrial ports, although we are aware other human factors might also influence the phenomenon. To conclude, the present study gives an overview of the importance of the white seabream anomaly in the Mediterranean and encourages further research to disentangle the exact mechanisms behind this phenomenon. [less ▲]

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See detailEditorial: Structure, Functioning and Conservation of Coastal Vegetated Wetlands
Richir, Jonathan ULiege; Bouillon, Steven; Gobert, Sylvie ULiege et al

Book published by Frontiers Media S.A. (2020)

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See detailZooplankton dynamics in a changing environment: A 13-year survey in the northwestern Mediterranean Sea
Fullgrabe, Lovina ULiege; Grosjean, P.; Gobert, Sylvie ULiege et al

in Marine Environmental Research (2020), 159

Dynamics of the subsurface (2–3 m) mesozooplankton (i.e., > 200 μm) in the Bay of Calvi (Corsica, France) were explored, combining time series (2004–2016) of 14 zooplankton groups, wind gusts, water ... [more ▼]

Dynamics of the subsurface (2–3 m) mesozooplankton (i.e., > 200 μm) in the Bay of Calvi (Corsica, France) were explored, combining time series (2004–2016) of 14 zooplankton groups, wind gusts, water temperature, nitrate and chlorophyll-a. Zooplankton data was obtained through image analysis. While contrasted group-specific seasonal patterns were observed, the most productive zooplankton annual event occurred in April (spring peak), concentrating on average 25% of the total annual abundance. A “typical” year was defined based on the annual succession of different community states, highlighting particular years (2007, 2015 and 2012) mainly characterized by weak spring peak. Environmental influences on the interannual variability of zooplankton were explored and while relationship between chlorophyll-a and zooplankton abundance was unclear, the availability of nutrients (December–March), potentially mediated via the wind regime (October–January) seemed to be essential to the occurrence of the spring peak. Additionally, we observed an influence of temperature, with winter thermal thresholds (between 12.1 °C and 13.4 °C) conditioning the spring peak. Also, the occurrence of lower annual abundances after 2010 was synchronous with the sharp increase of seawater warming trend, especially regarding winter temperature (0.30 °C.year-1). Finally, winter North Atlantic Oscillation (NAO) was found to be correlated to both winter water temperature and spring peak abundance, which suggests large-scale processes to impact regional zooplankton community. [less ▲]

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See detailTrace elements and oxidative stress in the Ark shell Arca noae from a Mediterranean coastal lagoon (Bizerte lagoon, Tunisia): are there health risks associated with their consumption?
Ghribi, Feriel; Richir, Jonathan ULiege; Bejaoui, Safa et al

in Environmental Science and Pollution Research (2020)

The current study examined the concentrations of ten trace elements (TE) (nickel, chromium, cadmium, iron, zinc, manganese, aluminum, copper, selenium and lead) in the edible tissue of the Ark shell Arca ... [more ▼]

The current study examined the concentrations of ten trace elements (TE) (nickel, chromium, cadmium, iron, zinc, manganese, aluminum, copper, selenium and lead) in the edible tissue of the Ark shell Arca noae (L. 1758) from a Mediterranean coastal lagoon, the Bizerte lagoon during 2013–2014. The analysis of several redox status biomarkers, metallothioneins (MTs), malondialdehyde (MDA), glutathione peroxidase (GPx), reduced glutathione (GSH) and acetylcholinesterase (AChE), was monitored as a response to TE bioaccumulation and environmental parameters variability. Significant differences (p < 0.05) were observed between mean seasonal TE concentrations in A. noae soft tissue. The highest TE concentrations in A. noae soft tissues were recorded during summer, which coincided with the increase of body dry weight (BDW) and the gonad index (GI). During this season, biomarker responses were enhanced, revealing significant increases of MTs, MDA and GSH levels as well as GPx activity in A. noae tissues, while a decrease of AChE activity was observed. The levels of TE analyzed in A. noae and several parameters used to assess the potential human risk (estimated weekly intake, target hazard quotient and target hazard risk) were lower than the permissible limits for safe seafood consumption. Consequently, this shellfish can be considered safe for human consumption. This preliminary study presents prospects for the valorization of this seafood product in Tunisia’s food sector. It also gives basal information for future environmental assessment studies in which A. noae could be used as early warning tools in the field of biomonitoring programs and confirms the usefulness of biomarkers to monitor the health status of aquatic organisms. [less ▲]

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See detailA 15-Month Survey of Dimethylsulfoniopropionate and Dimethylsulfoxide Content in Posidonia oceanica
Richir, Jonathan ULiege; Champenois, Willy ULiege; Engels, Guyliann et al

in Frontiers in Ecology and Evolution (2020), 7(510), 1-15

Posidonia oceanica is the only reported seagrass to produce significant amount of dimethylsulfoniopropionate (DMSP). It is also the largest known producer of DMSP among coastal and inter-tidal higher ... [more ▼]

Posidonia oceanica is the only reported seagrass to produce significant amount of dimethylsulfoniopropionate (DMSP). It is also the largest known producer of DMSP among coastal and inter-tidal higher plants. Here, we studied (i) the weekly to seasonal variability and the depth variability of DMSP and its related compound dimethylsulfoxide (DMSO) in P. oceanica leaves of a non-disturbed meadow in Corsica, France, (ii) the weekly to seasonal variability and the depth variability of DMSP to DMSO concentration to assess the potential of the DMSP:DMSO ratio as indicator of stress, and (iii) the relationships between DMSP, DMSO, and the DMSP:DMSO ratio with potential explanatory variables such as light, temperature, photosynthetic activity (effective quantum yield of photosystem II), and leaf size. The overall average concentrations of organosulfured compounds in P. oceanica leaves were 130 ± 39 μmol.g−1fw for DMSP and 4.9 ± 2.1 μmol.g−1fw for DMSO. Concentrations of DMSP and DMSO in P. oceanica were overall distinctly higher and exhibited a wider range of variations than other marine primary producers such as Spartina alterniflora, phytoplankton communities, epilithic Cyanobacteria and macroalgae. Concentrations of both DMSP and DMSO in P. oceanica leaves decreased from a maximum in autumn to a minimum in summer; they changed little with depth. Potential explanatory variables except the leaf size, i.e., the leaf age were little or not related to measured concentrations. To explain the seasonal pattern of decreasing concentrations with leaf aging, we hypothesized two putative protection functions of DMSP in young leaves: antioxidant against reactive oxygen species and predator-deterrent. The similar variation of the two molecule concentrations over time and with depth suggested that DMSO content in P. oceanica leaves results from oxidation of DMSP. The DMSP:DMSO ratio remained constant around a mean value of 29.2 ± 9.0 μmol:μmol for the non-disturbed harvested meadow regardless of the time of the year, the depth or the leaf size. As suggested for the salt march plant S. alterniflora, we hypothesized the DMSP:DMSO ratio could be considered as indicator of stress in seagrasses exposed to environmental or anthropogenic stressors. More research would now be needed to confirm the functions of DMSP and DMSO in seagrasses and how the DMSP:DMSO ratio will vary under various disturbances. [less ▲]

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See detailA non-destructive method to assess the status of Posidonia oceanica meadows
Gobert, Sylvie ULiege; Lefebvre, Laurence ULiege; Boissery, P. et al

in Ecological Indicators (2020), 119

This paper presents a new non-destructive sampling technique that consists of cutting all of the leaves of a Posidonia oceanica shoot (with scissors) just above the ligula of the external leaves ... [more ▼]

This paper presents a new non-destructive sampling technique that consists of cutting all of the leaves of a Posidonia oceanica shoot (with scissors) just above the ligula of the external leaves. Developed in an undisturbed meadow in Corsica (France) at depths of 12–15 m, this sampling technique is called the Non-Destructive Shoot sampling Method (NDSM). The results of using this method indicate that most biometric parameters and relevant water quality indices can be measured and calculated from seagrasses sampled using the NDSM. It was determined that sampling shoots using the NDSM ensured a 100% survival rate. Notably, the NDSM allowed sampled shoots to grow back to lengths similar to those of an adjacent control meadow within three months. Biochemical analyses indicated that meadow portions and seagrass leaves regrown after NDSM sampling differed little in chemical composition (C, N and P and essential metal micronutrients Fe, Cu, Zn, Mn, Ni and Mo) to control seagrasses. Thus, the NDSM limits the negative effects of the sampling. Although not lethal to the plant, sampling seagrasses according to the NDSM requires exemption from the competent authority according to local, regional or national regulations for each protected species. © 2020 Elsevier Ltd [less ▲]

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See detailDeep-water Zostera marina meadows in the Mediterranean
Boutahar, Loubna; Espinosa, Free; Richir, Jonathan ULiege et al

in Aquatic Botany (2020), 166

In Morocco, Zostera marina Linnaeus has disappeared from many localities where it was historically reported. The only known remaining meadows along Mediterranean coasts of Morocco, though in North Africa ... [more ▼]

In Morocco, Zostera marina Linnaeus has disappeared from many localities where it was historically reported. The only known remaining meadows along Mediterranean coasts of Morocco, though in North Africa, are those of Belyounech bay and Oued El Mersa bay, in the marine area of ‘Jbel Moussa’. An in-depth knowledge of these meadows is required for their effective conservation purpose. The Z. marina meadows of Jbel Moussa are deep, the lower limit being 17 m depth with patches extending down to 20 m depth. Seagrass cover of Belyounech bay meadow is continuous whereas that of Oued El Mersa is fragmented. Shoot density and aboveground biomass are higher in Belyounech meadow, with 745 ± 183 shoots.m−2 and 273 ± 40 gDW. m−2 of leaf biomass. During the survey, trawling scars and the invasive algae Caulerpa cylindracea Sonder were observed. Bioavailable Ni, As, Mo, Ag, Cd, Sn, Sb and U measured in the sediment are mainly accumulated in Z. marina roots. Nitrogen level is high in seagrass leaves and low in the sediment. Conversely, sediment is more enriched in phosphorus. Carbon levels and its isotopic ratio value are respectively higher and less negative in leaves when compared to the seagrass belowground compartments. All together, data collected during this survey allows defining the overall good health status of Z. marina meadows of Jbel Moussa. These Moroccan meadows, localized within the warm temperate-southern limit of the species, are well developed compared to many places worldwide. The exceptional presence of deep Z. marina meadows in the Mediterranean requires the implementation of measures as a major priority to ensure the conservation of these ecosystems, since seagrasses are being deeply threatened worldwide. [less ▲]

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See detailPosidonia oceanica, a top producer of dimethylsulfoniopropionate and dimethylsulfoxide
Richir, Jonathan ULiege; Champenois, Willy ULiege; Engels, Guyliann et al

in CIESM WORKSHOP MONOGRAPHS (2019, October 10)

We studied the dynamic of dimethylsulfoniopropionate and its derivative dimethylsulfoxide in Posidonia oceanica. The annual average concentrations in leaves were 129 ± 39 μmol.g for DMSP and 5.0 ± 2.1 ... [more ▼]

We studied the dynamic of dimethylsulfoniopropionate and its derivative dimethylsulfoxide in Posidonia oceanica. The annual average concentrations in leaves were 129 ± 39 μmol.g for DMSP and 5.0 ± 2.1 μmol.g for DMSO. DMSP and DMSO concentrations decreased from a maximum in the fall to a minimum in the summer and were mainly correlated to the seagrass leaf size. The similar variation of the two molecule concentrations suggested that DMSO content results from oxidation of DMSP. The DMSP:DMSO ratio, considered as indicator of stress in Spartina alterniflora, remained constant around a mean value of 27.7 μmol:μmol. More research is now needed to investigate the functions of DMSP and DMSO in seagrasses, how the DMSP:DMSO ratio will vary under disturbance and whether it is useful as indicator of stress. [less ▲]

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See detailClimate Change Impact on Water Column in Corsica
Gobert, Sylvie ULiege; Fullgrabe, Lovina ULiege; Quentin, Fontaine et al

in Ozhan E (Ed.) Proceedings of the Fourteenth International Medcoast Congress on coastal and Marine Sciences, engineering, management and Conservatio, (2019, October)

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See detailReproductive cycle and follicle cleaning process of Mytilus galloprovincialis (Mollusca: Bivalvia) from a polluted coastal site in Algeria
Rouabhi, Y. L.; Grosjean, P.; Boutiba, Z. et al

in Invertebrate Reproduction and Development (2019), 63(4),

This work focused on the reproductive cycle and cleaning process of follicles in Mytilus galloprovincialis and aimed to extend knowledge of the reproductive cycles of Mytilidae. Biometric and histological ... [more ▼]

This work focused on the reproductive cycle and cleaning process of follicles in Mytilus galloprovincialis and aimed to extend knowledge of the reproductive cycles of Mytilidae. Biometric and histological measurements were taken monthly over 12 months from mussels at a polluted site, the port of Oran in Algeria. Environmental parameters were monitored concomitantly. Mytilus galloprovincialis reproduced throughout the year, with a main spawning period between November and February and a second between March and June. Several follicle cleaning processes were observed throughout the reproductive cycle. They occurred under two circumstances. First, in the absence of reserve tissues, mature gametes were degraded. This happened when spawning was about to end and corresponded to the last stage of reproduction. Second, atresia, gamete degeneration and a cessation of spawning occurred whatever the stage of the gonad development and whatever the environmental parameter values. These disturbances of reproduction may have resulted from pollution in the port of Oran and increased when temperature exceeded critical thresholds for gametogenesis. To conclude, gamete degeneration and spawning cessation because of coastal pollution and global warming could threaten M. galloprovincialis recruitment, and ultimately the shellfish economy, and could distort biomonitoring strategies using mussels. [less ▲]

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