3,112 research outputs found

    On the origin and processes controlling the elemental and isotopic composition of carbonates in hypersaline Andean lakes

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    H.J. and J.W.B. Rae acknowledge funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant agreement 805246).The Altiplano-Puna Plateau of the Central Andes hosts numerous lakes, playa-lakes, and salars with a great diversity and abundance of carbonates forming under extreme climatic, hydrologic, and environmental conditions. To unravel the underlying processes controlling the formation of carbonates and their geochemical signatures in hypersaline systems, we investigated coupled brine-carbonate samples in a high-altitude Andean lake using a wide suite of petrographic (SEM, XRD) and geochemical tools (δ2H, δ18O, δ13C, δ11B, major and minor ion composition, aqueous modelling). Our findings show that the inflow of hydrothermal springs in combination with strong CO2 degassing and evaporation plays an important role in creating a spatial diversity of hydro-chemical sub-environments allowing different types of microbialites (microbial mounds and mats), travertines, and fine-grained calcite minerals to form. Carbonate precipitation occurs in hot springs triggered by a shift in carbonate equilibrium by hydrothermal CO2 degassing and microbially-driven elevation of local pH at crystallisation. In lakes, carbonate precipitation is induced by evaporative supersaturation, with contributions from CO2 degassing and microbiological processes. Lake carbonates largely record the evaporitic enrichment (hence salinity) of the parent water which can be traced by Na, Li, B, and δ18O, although other factors (such as e.g., high precipitation rates, mixing with thermal waters, groundwater, or precipitation) also affect their signatures. This study is of significance to those dealing with the fractionation of oxygen, carbon, and boron isotopes and partitioning of elements in natural brine-carbonate environments. Furthermore, these findings contribute to the advancement in proxy development for these depositional environments.Peer reviewe


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    Salt production is a sustainable process based on the use of renewable resources such as wind, sun and seawater. Through fractional precipitation, induced by wind and sun, almost pure sodium chloride precipitates in crystallising basins. This process involves the use of simple technologies, modified over millennia only by the introduction of mechanical means. Thus, sea salt production can be considered a technologically mature production process. However, it is still possible to intervene by adding value through innovation in areas related to the traceability of the product and the exploitation of the enormous potential arising from the unique biodiversity present in these environments. The innovation envisaged is based on the use of DNA purification technologies, next-generation sequencing and in vitro evaluation. Using advanced molecular biology techniques, it is in fact possible to characterise the population of Bacteria and Archaeobacteria included in the salt crystals during their formation process and to define their geographical origin. Furthermore, with extraction techniques, culture characterisation and in vitro evaluation on cells, it is possible to exploit bioactive compounds extracted from halophilic microorganisms for applications in nutraceutics, pharmaceutics and cosmeceutics. Thus, despite the technological maturity of the main production process, it is possible to intervene with a high degree of innovation to help increase its overall profitability. The characterisation of the microbiome present in salt crystals is crucial for the traceability and safety of the resource. The testing of bioactive extracts, originating from saline waters, in cosmeceutical and pharmaceutical applications will enable products derived from these applications to benefit from the related traceability, safety and human health results, thus bringing significant benefits to their eco-sustainable image.The aims of this research fall within the principles of the National Strategy for Intelligent Specialisation (SNSI) approved by the European Commission, which promotes and subsidises such scientific approaches and objectives. Already in the past, the European Community has granted the Protected Geographical Indication for Trapani's sea salt, in the wake of which other European countries have applied for it. Sea salt is produced in coastal salt works, which have generally been transformed into protected environments. For this reason, the certificate of origin is associated with an incisive image of eco-sustainability, which derives from the place of production being represented by peculiar natural environments. The close relations between the various scientific themes make the aforementioned PhD project innovative, applied, connected to human activities and consumption, consistent with national strategies and in line with the European objectives.The purpose of the PhD thesis contributes to the application of current Blue Economy strategies in accordance with the "Blue Growth" and the Horizon programme, thus enabling the development of future prospects for improving the circular economy and marine production chain to obtain compounds that are useful for nutraceutical, cosmeceutical and pharmaceutical applications

    Trends and variability in methane concentrations over the Southeastern Arabian Peninsula

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    Methane (CH4) is a potent greenhouse gas with an important contribution to global warming. While national and international efforts have been put in place to reduce methane emissions, little is known about its variability, especially in hotspot regions where natural and anthropogenic emissions are compounded. In this study, the current state of CH4 concentrations and their trends over the United Arab Emirates (UAE) and surrounding region are investigated with satellite and reanalysis data. CH4 concentrations have increased over the last 5 years, with a trend in the satellite-derived column values (XCH4) of about 9 ppb/year. A clear annual cycle is detected in XCH4, with an amplitude of up to 75 ppb and peak values in the warmer months. The largest concentrations are found in coastal sites, where sabkhas and landfills are present, and along the Al Hajar mountains, where agricultural activities and microhabitats that may host CH4-producing microbes occur and where advection by the background flow is likely an important contributor. The reanalysis data shows a good agreement with the satellite-derived estimates in terms of the spatial pattern, but the magnitudes are smaller by up to 50 ppb, due to deficiencies in the data assimilated. Surface CH4 concentrations in the reanalysis data account for more than 50% of the corresponding XCH4 values, and exhibit a seasonal cycle with the opposite phase due to uncertainties in the emissions inventory. Our findings provide an overview of the state of CH4 concentration in the UAE and surrounding region, and may aid local authorities to propose the appropriate emission reduction strategies in order to meet the proposed net-zero greenhouse gas emission target by 2050. This study highlights the need for the establishment in the Arabian Peninsula region of a ground-based observational network for greenhouse gas concentrations which is still lacking to date

    Assessing the effectiveness of integrated multi-trophic aquaculture for growing west coast venus clams

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    With demand for sustainable sources of seafood on the rise, California is looking to expand aquaculture with a focus on innovative culturing methods and use of native or resident species. Therefore, this study examined the potential for culturing native North American west coast venus clams (Chione californiensis and Chione undatella) using integrated multi-trophic aquaculture (IMTA). An ITMA approach was chosen because it is a culture method that uses species from different but functionally complementary trophic levels that have been found to reduce the potential negative effects of traditional monoculture. California sea cucumber (Parastichopus californicus) and the seaweeds red ogo (Gracilaria -Gracilariopsis complex) and sea lettuce (Ulva spp.) were chosen as the detritivore and nutrient extractors for the system. Clam performance (mortality and growth) was evaluated through both a controlled aquarium (March 19- August 2, 2021) and a bay (June 25 to December 10, 2021) growout experiments. The aquarium experiment had four treatments 1) Clam Only, 2) Seaweed Only, 3) Clam and Seaweed 4) All Three Species) with four replicates each. The seaweed-only treatment was established to elucidate mechanisms underlying observed patterns in clam performance (e.g., to reveal the potential influence of seaweed on water parameters). However, the seaweed did not perform well and there were no observed differences in water parameters between treatments in the recirculating aquarium system so four slightly different treatments were tested in the bay: 1) Clam Only, 2) Clam and Seaweed, 3) Clam and Cucumber, 4) All Three Species, with each treatment represented in one of four bins in a floating aquaculture system in San Diego Bay. Clam growth did not differ between treatments in the aquarium with an average of 1-5% growth in length and weight, and low mortality (≤2 deaths/aquarium/4.5 months) across all treatments. In the bay, clams in the Clam Only treatment experienced 1.5-3x faster growth rates than the treatments in the other bins. Average mortality was similarly low across treatments in the bay (≤3 deaths/treatment-bin/6 months). While the IMTA treatments were not found to increase clam growth compared to monoculture, there were other benefits of culturing multiple species together, primarily a reduction in fouling and increased cleanliness of aquaria and treatment bins. Therefore, the results indicate that the implementation of an IMTA growout may require a tradeoff analysis, as IMTA does diversify product and has the potential to reduce cleaning and maintenance efforts but may not improve species growth. While the clams grew more when cultured alone than with other species in this study, further studies using different species, locations, growout system sizes, and/or time scales are necessary to determine a wider range of outcomes likely to be observed in experimental and production-scale aquaculture operations across the region

    A georeferenced dataset of Italian occurrence records of the phylum Rotifera

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    We report a dataset of known and published occurrence records of Italian taxa from species (and subspecies) to family rank of the phylum Rotifera; we considered only Bdelloidea, Monogononta, and Seisonacea, and did not include Acanthocephala. The dataset includes 15,525 records (12,015 of which with georeferenced coordinates) of 584 valid species and subspecies names and other taxa at family level, gathered from 332 published papers. The published literature spans the period from 1838 to 2022, with the lowest number of papers published during the first half of the twentieth century, followed by an increasing number of papers, from 20 to more than 60 in each decade. The Italian regions with the highest number of records and species are Emilia-Romagna, Lombardy, and Piedmont, whereas no records are known for Molise. The number of species known from each region mostly mirrors sampling efforts, measured as the number of publications per region. The dataset is available through the Open Science Framework (OSF), and all the georeferenced occurrence data have been uploaded to the Global Biodiversity Information Facility (GBIF)

    Invasion success of a Lessepsian symbiont-bearing foraminifera linked to high dispersal ability, preadaptation and suppression of sexual reproduction

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    Among the most successful Lessepsian invaders is the symbiont-bearing benthic foraminifera Amphistegina lobifera. In its newly conquered habitat, this prolific calcifier and ecosystem engineer is exposed to environmental conditions that exceed the range of its native habitat. To disentangle which processes facilitated the invasion success of A. lobifera into the Mediterranean Sea we analyzed a ~ 1400 bp sequence fragment covering the SSU and ITS gene markers to compare the populations from its native regions and along the invasion gradient. The genetic variability was studied at four levels: intra-genomic, population, regional and geographical. We observed that the invasion is not associated with genetic differentiation, but the invasive populations show a distinct suppression of intra-genomic variability among the multiple copies of the rRNA gene. A reduced genetic diversity compared to the Indopacific is observed already in the Red Sea populations and their high dispersal potential into the Mediterranean appears consistent with a bridgehead effect resulting from the postglacial expansion from the Indian Ocean into the Red Sea. We conclude that the genetic structure of the invasive populations reflects two processes: high dispersal ability of the Red Sea source population pre-adapted to Mediterranean conditions and a likely suppression of sexual reproduction in the invader. This discovery provides a new perspective on the cost of invasion in marine protists: The success of the invasive A. lobifera in the Mediterranean Sea comes at the cost of abandonment of sexual reproduction

    Microplastic ingestion in invertebrates within rockpool communities

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    Microplastics (<5 mm) are abundant across the world in the marine environment and so it is vital that we gain further understanding of their fate and their possible impacts on marine life. Due to their size, microplastics can interact with small marine organisms which are part of the lower trophic levels and the main interaction with these plastics is ingestion. Chemical characteristics and changes to the plastic properties, due to, for example, adsorbed chemicals and colonisation of biofilms, may affect how readily plastics are ingested. Research into the interactions of a range of organisms with microplastics enables for a better understanding of how they could be taken in, impact the organism as well as predict potential trophic transfer. This in turn could aid in predicting bigger impacts in the marine environment and on humans themselves. Rockpools are a key environment and nursery for many important marine and intertidal species, particularly those that we rely on commercially, such as crab species. This study exposed three key rockpool species of three feeding types - Beadlet anemone (Actinia equina), common prawn (Palaemon serratus), Thick top shell (Phorcus lineatus) to nylon fibres within ex-situ mesocosms. These species represent three feeding types found in a rockpool community – Suspension feeding, Filter feeding of the whole water column and deposit feeding. The organisms were exposed to either biofouled or non-biofouled, blue, black, red, or white in colour and 0.5 mm or 2 mm microfibres for six hours. This was undertaken when individuals were individually housed as single species, as well as a mixed community with a representative of all three species. Once biofouling was complete, dissection to observe the digestive tract was undertaken and then an alkaline digest was completed to obtain evidence of retention other than in the digestive tract. Beadlet anemones ingested the most microfibres and thick top shell the least. This study shows that overall, biofouled fibres are significantly more likely to be ingested than 6 that of non-biofouled (H(1)= 16.780 , p<0.001). Some ingestion and interaction colour patterns were found – black in anemones and shrimp ((H(1)= 6.224 , p=0.013 and (H(1)= 6.008 , p=0.014) and black (H(1)= 12.270 , p=0.007) and white in shrimp (H(1)= 8.143 , p=0.043). This could possibly be to do with the dye chemicals on the plastics rather than visual cues. The 0.5mm fibres were ingested and retained more than 2mm (H(1)= 20.924 , p<0.001). Thick top shells were the only organism with a difference between housing with more microfibres ingested/retained when housed individually than when housed in a mixed community. This study provides further evidence of the potential ingestion and retention of microplastics in a rockpool setting and therefore highlights the potential impact on these organisms and predator species. This may likely cause negative impacts within that rockpool as well as present a route for microfibres to expose other intertidal organisms to microfibres, particularly as the three study organisms are prey animals to many other species

    Water or mineral resource? Legal interpretations and hydrosocial configurations of lithium mining in Chile

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    This article was supported by the German Research Foundation (DFG) and the Open Access Publication Fund of Humboldt-Universität zu Berlin.The advance of electromobility has boosted global demand and interest in lithium. The consequent expansion of lithium mining puts the sustainability of Chile's Andean salt flats at risk. In these unique ecosystems, lithium is abstracted from mineralized groundwaters, referred to also as brines. This article analyses the legal treatment of brines and its implications in assessing the socioecological impacts of lithium mining projects. For our analysis, we draw from scholarship at the intersection between hydrosocial research and critical legal geography. Methodologically, our study is based on interviews and the analysis of legal texts and judicial and administrative claims, including the environmental impact assessment studies of the three single lithium mining projects approved in the country. We show that the interpretation of brines as mining resources supported by mining companies and endorsed by environmental State agencies is based on a legal loophole. We document how such interpretation is operationalized and contested in the environmental impact assessments of three mining projects and other instances. We explore how the same legal loophole could lead to alternative interpretations and relatedly regulatory proposals and discuss their implication for the assessment of socioecological impacts of mining projects. These include first an understanding of brines as hybrids minerals/waters put forward in a recent report commissioned by State agencies, and second an interpretation of brines as a type of water. The latter is in line with the position of some indigenous groups and academics. We conclude with reflections on the implications of our analysis for lithium mining in Chile and beyond.Peer Reviewe

    The influence of abiotic and biotic conditions on lifecycle stages is critical for estuarine seagrass resilience

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    Abiotic and biotic factors influence seagrass resilience, but the strength and relative importance of the effects are rarely assessed over the complete lifecycle. This study examined the effects of abiotic (salinity, temperature, water depth) and biotic (grazing by black swans) factors on Ruppia spp. over the complete lifecycle. Structures were set up in two estuaries ( – 33.637020, 115.412608) that prevented and allowed natural swan grazing of the seagrasses in May 2019, before the start of the growing season. The density of life stage(s) was measured from June 2019 when germination commenced through to January 2020 when most of the seagrass senesced. Our results showed that swans impacted some but not all life stages. Seedling densities were significantly higher in the plots that allowed natural grazing compared to the exclusion plots (e.g. 697 versus 311 seedlings per m-2), revealing an apparent benefit of swans. Swans removed ≤ 10% of seagrass vegetation but a dormant seedbank was present and new propagules were also observed. We conclude that grazing by swans provides some benefit to seagrass resilience by enhancing seedling recruitment. We further investigated the drivers of the different lifecycle stages using general additive mixed models. Higher and more variable salinity led to increased seed germination whilst temperature explained variation in seedling density and adult plant abundance. Bet-hedging strategies of R. polycarpa were revealed by our lifecycle assessment including the presence of a dormant seedbank, germinated seeds and seedlings over the 8-month study period over variable conditions (salinity 2–42 ppt; temperatures 11–28 °C). These strategies may be key determinants of resilience to emerging salinity and temperature regimes from a changing climate
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