Search Results (139)

The blue crab Callinectes sapidus Rathbun, 1896 is native to the western coast of the Atlantic Ocean. Although its arrival to the Mediterranean was probably due to ballast water, this species has several characteristics that have enabled it to successfully invade countless localities in the Mediterranean and the Black Sea. Little is known about its feeding habits and ecosystem impacts in the Mediterranean basin. This study aimed to provide information on the natural diet of C. sapidus by comparing the stomach contents of specimens caught in different seasons and habitats of the SE Iberian Peninsula (hypersaline waters in Mar Menor Lagoon and brackish waters in Guardamar Bay). This study also tested whether gender influences prey selection and if ovigerous females exhibit limited feeding activity. Regarding the frequency of occurrence, the results indicated that in Mar Menor Lagoon the most frequently consumed prey were Crustacea (60%), followed by fish (57%) and Mollusca (29%), whilst in Guardamar Bay, Mollusca (40%), sediment (32%), algae (24%) and Crustacea (24%) were dominant. It has been determined that this species predates heavily on Mediterranean shrimp Penaeus kerathurus, an economically important shrimp species in the lagoon area. Analysis using a generalised linear model indicated that sex, season and size class were factors that significantly influenced the stomach content weight. Furthermore, non-ovigerous females had significantly fuller stomachs than ovigerous individuals. Since the population of Callinectes sapidus tends to increase in the Mediterranean basin, monitoring of its feeding ecology is recommended to determine its impact on the ecosystem. Full article

The agricultural sector plays one of the pivotal roles in fulfilling the objectives set forth by the EU Green Deal. However, the extensive use of synthetic fertilizers has contributed to nutrient over-enrichment in aquatic ecosystems, promoting eutrophication due to excess nitrogen inputs from fertilizers. This phenomenon is a key driver of rapid and excessive algal blooms in rivers, lakes, and seas. In this study, three globally cultivated crop species—oilseed rape (Brassica napus L.), common wheat (Triticum aestivum L.), and pea (Pisum sativum L.)—were selected for experimental analysis, including the assessment of biochemical parameters such as proline content, lipid peroxidation levels, hydrogen peroxide production, total phenol content, and antioxidant activity, which were evaluated to determine the potential of phytoplankton biomass as a substitute for synthetic fertilizers. Various quantities of lyophilized phytoplankton biomass, collected from the Curonian Lagoon, a biologically productive and ecologically sensitive brackish water body in the southeastern Baltic region, were incorporated into the growth substrates of the studied plants. The findings indicate that utilizing excess phytoplankton biomass can serve not only as a plant growth biostimulant but also as a sustainable alternative to synthetic fertilizers, thereby contributing to improved water quality and more environmentally responsible agricultural practices. Full article

In this study, we investigate the diversity and spatiotemporal distribution of gelatinous zooplankton (GZ) in the central Baltic Sea (coastal waters of Gotland and adjacent Eastern and Western Gotland Basins), a region characterised by low salinity and ecological sensitivity. Despite the Baltic Sea being the largest brackish water body globally, knowledge about its GZ, specifically, medusae and ctenophores, is limited. Our research synthesises the existing literature, open-access data, and local reports. Three to five GZ species occur within the studied area, with the common jellyfish Aurelia aurita dominating. Peak sightings of A. aurita happen between July and October, whereas the ctenophore Mertensia ovum and scyphozoan Cyanea capillata display sporadic occurrences. We identify notable gaps in understanding GZ phenology and food web impacts due to historical neglect and insufficient monitoring, particularly under low-salinity conditions (between 5 and 8), which restricts species richness. Jellyfish and ctenophores fall under the Essential Ocean Variable (EOV) “Zooplankton Biomass and Diversity” governed by the Global Ocean Observing System, UNESCO-IOC. EOVs are an approach for globally usable data and adhere to Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. Including EOVs in routine collection and reporting would significantly enhance regional and global understanding, contributing to a holistic ecosystem view. Thus, we advocate for global ocean observation frameworks to comprehensively monitor GZ populations and their ecological, biogeochemical, and socioeconomic roles. Our findings serve as a crucial step towards understanding the implications of climate change for GZ assemblages in the Baltic Sea, promoting a holistic approach to marine ecosystem management. Full article

The Baltic Sea is an intra-continental marginal sea that is vertically stratified with a strong halocline isolating the saline bottom layer from the brackish surface layer. The surface layer is eutrophic, and abiotic zones lacking oxygen are common in the deeper regions. While freshwater is constantly flowing into the North Sea, oxygen-rich bottom waters can only occasionally enter the Baltic Sea following a special sequence of transient weather conditions. These so-called Major Baltic Inflow events can be monitored via the sea level gradients between the Kattegat and the Western Baltic Sea. Innovative interferometric altimetry from the Surface Water and Ocean Topography (SWOT) mission gave us the first opportunity to directly observe the sea level signal associated with the inflow event in December 2023. Recent high-rate multi-mission nadir altimetry observations support the SWOT findings for scales larger than 50 km. The SWOT observations are compared to the simulations with the regional 3D HBMnoku ocean circulation model operated by the German Federal Maritime and Hydrographic Agency (BSH). The model explains more than 80% of the variance observed by SWOT and up to 90% of the variance observed by the nadir altimeters. However, the north–south gradients of the two datasets differ by about 10% of the overall gradient. Comparisons with tide gauges suggest possible model deficiencies on daily to sub-daily time scales. In addition, the SWOT data have many fine scale structures, such as eddies and fronts, which cannot be adequately modeled. Full article

The largescale blackfish, Girella punctata Gray, 1835, is important in the fishing industry and recreational fishing, and it is also cultured in East Asia. Cymothoidae (Crustacea: Isopoda) is a group of parasites that infest fish in marine, brackish, and freshwater environments. In this study, we report, for the first time, Ceratothoa arimae (Nunomura, 2001) (Cymothoidae) from the buccal cavity of G. punctata in the Seto Inland Sea, Japan. Ceratothoa arimae showed a prevalence of 29.4–66.7% in G. punctata. The morphology of the mancae of this species was also described in comparison with that of the adult female (ovigerous), transitional stage, and adult male. The manca of Ceratothoa arimae has more chromatophores than those of other Ceratothoa species from Japan, and is a candidate for a future taxonomic trait. This species may have a negative impact on cultured G. punctata, which would be important to determine in future studies. Currently, it is difficult to identify cymothoid mancae species based on their morphology, but the information provided in this study could be useful when combined with other methods developed in the future, such as molecular analysis. Full article

The study of river backwater points (bpts) is pivotal for understanding the interactions between riverine and coastal systems, including brackish water dynamics, coastal flooding, and ecosystem processes. Despite extensive research, the global spatio-temporal dynamics of bpts, particularly in rivers with minimal human intervention, remains underexplored. This study investigates backwater lengths and shifts in 18 major global rivers (discharge > 5000 m³/s) from 2000 to 2020, uncovering significant hydrological and geographical patterns. In 2000, backwater lengths ranged from 113.16 km (Salween) to 828.75 km (Amur), with bpts consistently positioned upstream of apex points. By 2020, all rivers exhibited upstream retreats of their bpts, ranging from 10.43 km (Salween) to 132.51 km (Amazon), and retreat ratios typically falling between 0% and 20%. The Salween, Niger (60%), and Irrawaddy (38%) demonstrated the most significant proportional shifts. Geographical transitions of bpts varied widely: rivers such as the Ganges and Amur shifted toward urbanized areas, while the Amazon and Orinoco remained in remote regions, reflecting the differential impact of human activity and natural processes. There was a general correlation between backwater length and river discharge, with exceptions like the Amur indicating the influence of other factors such as geomorphic settings and sediment dynamics. While sea-level rise (0.019–0.115 m) affected estuarine conditions, it showed no consistent relationship with bpt retreat at the global scale, but a regional-scale analysis indicates that sea-level rise can lead to the retreat of bpts for those rivers with macro-tidal environments and high sediment yields with less human intervention, suggesting localized interactions dominate backwater dynamics. These findings highlight the complex interplay of environmental and anthropogenic pressures on global river systems. They provide a critical foundation for advancing hydrological modeling, improving river management strategies, and understanding the broader implications of spatio-temporal bpt dynamics under changing climatic and human influences. Full article

The Baltic Sea blue mussel (Mytilus trossulus) plays a crucial role in this brackish water ecosystem, filtering water and accumulating pollutants. This study investigated how exposure to crude oil and dispersants affects the microbiome of M. trossulus at two salinities (5.6 and 15) over 21 days. Results showed that dispersant use significantly increased the accumulation of polycyclic aromatic hydrocarbons (PAHs) in mussel tissues, particularly at lower salinity. The microbial communities in gills and digestive glands were notably affected, with shifts towards hydrocarbon-degrading bacteria like Shewanella and Acinetobacter in samples exposed to chemically enhanced water accommodated fraction of crude oil (CEWAF). Salinity was a key factor in determining both PAH accumulation and microbial diversity, with lower salinity leading to reduced bacterial diversity in dispersant treatments. This study highlights the need for a cautious use of dispersants in sensitive environments like the Baltic Sea, emphasizing the ecological implications of altered microbial communities. Full article

An accelerated sea-level rise (SLR) may threaten the future livability of the Netherlands. Three perspectives to anticipate this SLR are elaborated here regarding technical, physical, and spatial aspects: Protect, Advance, and Accommodate. The overall objective was to explore the tools and measures that are available for adaptation, assess their spatial impacts, and identify dos and don’ts in current spatial issues like housing, climate adaptation, infrastructure, and the energy transition. Each elaboration was performed by a consortium consisting of representatives from private parties (engineering consultancy, project contractors, (landscape) architects, economists), knowledge institutes (including universities), and government, using an iterative process of model computations and design workshops. The elaborations made clear that a realistic and livable future perspective for the Dutch Delta continues to exist, even with a maximum analyzed SLR of 5 m, and will consist of a combination of elements from all three perspectives. This will require large investments and space for new and upgraded water infrastructure and will have large impacts on land use, water availability, agriculture, nature, residential buildings, shipping, and regional water systems. There is still a significant degree of uncertainty regarding future SLR; therefore, it is not advisable to make major investment decisions at this time. Nevertheless, some no-regret measures are already clear: continuation of the protection of the Randstad agglomeration (Amsterdam, The Hague, Rotterdam, and Utrecht) and its economic earning potential for future generations, adaptation of agriculture to more brackish and saline conditions, designation of space for additional future flood protection, extra storage capacity (for river discharge and increased precipitation), river discharge, and sand extraction (for future coastal maintenance). The research identified concrete actions for today’s decision-making processes, even though the time horizon of the analysis captures centuries. Including the perspectives in long term, policy planning is already necessary because the transition processes will take decades, if not more than a century, to be implemented. Full article

This study focuses on the analysis of sediment core retrieved from the deepest part (25 m) of Pirovac Bay. A long sedimentary sequence (7.45 m) supplemented by a shorter sediment core (1.45 m) from a shallower part of the bay was analyzed for sedimentological, mineralogical, geochemical, and micropaleontological (ostracod) parameters. The sediment thickness above the underlying karst paleorelief (karstic bedrock) is up to 12 m. Sediments recorded a transition from a freshwater to a marine environment starting from post-Neapolitan Yellow Tuff tephra sedimentation. First, the floodplain developed in Pirovac Bay, with intermittent pools and ponds, followed by wetland environment. The formation of a shallow freshwater paleolake during the Middle Holocene at 10 cal kyr BP was enabled by the rising sea level and high freshwater input from the karstified underground from the adjacent Lake Vrana (Biograd na Moru). The onset of marine intrusions through the karstified underground is evident with formation of a brackish lake in the Pirovac Bay basin. Marine transgression and flooding of the bay occurred at 7.3 cal kyr BP, evidenced by the geochemical and ostracod parameters, providing crucial insights into the dynamics of coastal inundation under past climate change. Intriguingly, freshwater ostracod species were still present in the marine sediments, brought into the bay from Lake Vrana through surficial canal Prosika and groundwater discharge (numerous estavelles) along the northeastern shores of the bay, proving their mutual influence. This submerged Holocene freshwater paleolake, reported here for the first time, underlines the sensitivity of coastal karst systems to the rise in sea level and serves to stress how important understanding of these processes is for effective management in coastal zone and climate change adaptation strategies. The findings provided evidence supporting the existence of coastal marine basins as freshwater lakes prior to being flooded by seawater as a consequence of the Holocene post-glacial sea level rise. Full article

Treatment of extremely saline water such as the brine rejected from reverse osmosis water desalination plants, and produced water from shale oil and non-conventional gas extraction, is considered a global problem. Consequently, in this work, hollow fiber membrane distillation (HFMD) is experimentally evaluated for desalinating extremely saline water of a salinity ranging from 40,000 to 130,000 ppm. For the purpose of comparison, the HFMD is also tested for desalinating brackish (3000–12,000 ppm) and sea (25,000–40,000 ppm) water. Firstly, the HFMD is tested at two values of feed water temperature (65 and 76 °C) and flow rate (600 and 850 L/h). The experimental results showed that the HFMD productivity significantly increases when the temperature of feed water increases. Increasing the feed water flow rate also has a positive effect on the productivity of HFMD. It is also concluded that the productivity of the HFMD is not significantly affected by increasing the salt concentration when brackish and sea water are used. The productivity also slightly decreases with increasing the salt concentration when extremely saline water is used. The decrement in the productivity reaches 27%, when the salt concentration increases from 40,000 to 130,000 ppm. Based on the conducted economic analysis, the HFMD shows a good potential for desalinating extremely saline water especially when the solar collector is used as a heat source. In this case, the cost per liter of freshwater is reduced by 21.7–23.1% when the evacuated tube solar collectors are used compared to the system using electrical heaters. More reduction in the cost per liter of freshwater is expected when a high capacity solar-powered HFMD plant is installed. Full article

Aquaculture is a rapidly growing industry that contributes to the growing global demand for food. Numerous studies have investigated the necessity of increasing food production while reducing its negative effects on the environment. Aquaculture involves the cultivation of aquatic animals such as fish, shrimp, and mollusks that require water for their growth and maintenance in various types of aquaculture operations, such as recirculated aquaculture systems (RASs), ponds, and sea cages. This study investigates mainly life cycle assessment (LCA) in relation to water consumption, the water footprint (WF) and water budgeting approaches in aquaculture. In addition, it contributes to the expansion of knowledge and understanding of the different methodologies used, production practices, types of water (freshwater, marine or brackish) and direct or indirect water consumption in intensive, semi-intensive and extensive types of aquaculture. Notably, this study focuses on water consumption and does not include water indices that account for all the water used in a system, regardless of whether it is returned to the sourced watershed and is therefore available for other uses. Approximately 15% of the reviewed studies focus on the fish processing stage of the production chain, which emphasizes the need for more research on this stage. The species of carp, tilapia, shrimp, and catfish are the most frequently studied aquatic animals in relation to water consumption in aquaculture. Research on water consumption patterns can contribute to the development of a more water-efficient aquaculture system that is essential for promoting sustainable practices. Full article

The Amuyo Ponds (APs) are a group of three brackish hydrothermal lagoons located at 3700 m above sea level in a pre-Andean setting in the Atacama Desert. Each pond shows a conspicuous green (GP), red (RP), or yellow (YP) coloration, and discharges water rich in arsenic and boron into the Caritaya River (Camarones Basin, northern Chile). Microorganisms are subjected to harsh environmental conditions in these ponds, and the microbial composition and diversity in the Amuyo Ponds’ sediments are unknown. The microbial life colonizing AP sediments was explored by metagenomics analyses, showing a diverse microbial life dominated by members of the bacterial domain, with nearly 800 bacterial genome sequences, and sequences associated with Archaea, Eukarya, and viruses. The genus Pseudomonas was more abundant in GP and YP sediments, while the genera Pseudomonas, Aeromonas, and Shewanella were enriched in RP sediments. Archaeal composition was similar in all sediments, and enriched with methanogens sequences from the Archaeoglobi and Halobacteria classes. Abundant fungi sequences were detected in all sediments from the phyla Blastocladiomycota and Ascomycota. We also report putative functional capabilities related to virulence and defense genes, the biosynthesis of secondary metabolites, and tolerance to arsenic. Thirteen bacterial and fourteen viral metagenome-assembled genomes were reconstructed and informed here. This work expands our knowledge on the richness of the microorganisms in the APs and open further studies on the ecology and genomics of this striking Andean geosite. Full article

Various biological traits support the invasive success of different organisms. The osmoregulatory capacity and food preferences of the signal crayfish Pacifastacus leniusculus were experimentally tested to determine if they contribute to its invasive success. The osmotic concentrations of haemolymph were determined after acclimation of the crustaceans to seven salinities from 0 to 20 PSU. Food preferences were tested using Canadian pondweed Elodea canadensis, and rainbow trout Oncorhynchus mykiss. The results showed that the signal crayfish exhibits a hyper-hypoosmotic regulation pattern in the salinity range from 0 to 20 PSU, enabling them to inhabit both freshwater and brackish environments. Furthermore, the study found signal crayfish to have non-specific food preferences, although fish muscle tissue is more beneficial as a source of energy. Both features, osmoregulatory ability and food preferences, can increase the invasive success of this species as it expands into new areas. The ability to survive in higher salinities compared to the coastal waters of the Baltic Sea along the Polish coastline should be considered in targeted management strategies to control the spread of this invasive species. Full article

Coastal backwater effects on low-gradient coastal plain rivers extend well upstream of the head of the estuary and propagate upstream as sea-level rises. Hydrological, geomorphological, and ecological indicators can serve as sentinels of the upriver encroachment. Analyzing the along-river spatial distribution of these indicators as a space-for-time substitution allows the prediction of sequential changes. Interpretation of results from 20 rivers in Virginia and the Carolinas shows that backwater effects at the leading edge result in higher river stages, increasing floodplain inundation, and raising water tables. Lower slopes and flow velocities reduce sediment transport, reducing river sediment input and floodplain deposition. This inhibits natural levee development, reducing bank heights. These factors combine to increase the frequency and duration of inundation, resulting in semi-permanently flooded wetlands. Anaerobic conditions limit organic decomposition, and ponding allows transported and suspended organic matter to settle, leading to organic muck and peat floodplain soils. This accumulation, coupled with general valley-filling, buries alluvial terrace remnants. Finally, vegetation changes driven by salinity increases occur, resulting in swamp conversions to brackish marsh. Backwater encroachment is strongly controlled by channel bed slope, with relatively steeper channels experiencing slower rates of tidal extension. With accelerating sea-level rise (SLR), the lowest-sloping channels could experience encroachment rates of >1 km yr⁻¹. Hydrological changes associated with SLR are most rapid at the leading, upriver end—averaging 71 km upstream of the head of the estuary in the study rivers at present—and at the lowermost, downstream end of the fluvial-estuarine transition zone. Full article

The genus Eurytemora is a diverse group of copepods found in coastal, estuarine, brackish, and freshwater environments. The main research has focused on Eurytemora affinis (Poppe, 1880) and revealed it to be a species complex. Eurytemora velox (Liljeborg, 1853) has only recently been characterized in the Scheldt estuary but never within a global phylogenetic context. This study integrated nearly all European Eurytemora species sequences available, along with original ones from the Scheldt. A total of 351 sequences were analyzed using one mitochondrial gene (CO1) and one nuclear gene (nITS), with sequencing performed specifically on the CO1 gene. Phylogenetic reconstructions were performed using the Maximum Likelihood method, along with haplowebs and genetic diversity indices. A significant subdivision between six European species was observed. The monophyletic clade status of the E. affinis complex was confirmed alongside the existence of three geographically isolated lineages of the E. affinis species, the East Atlantic, the North Sea/English Channel, and the Baltic lineages, each exhibiting pronounced genetic differentiation. The population of E. velox from the Urals differs significantly from the European ones. These results provide both an overview of the genetic structure of the genus in geographic Europe as well as new insights on E. velox. Full article