Brackish Research Articles

Physicochemical Characteristics and Plankton Diversity of Lagos Lagoon and its Adjoining Abule-Agege and Abule-Eledu Tidal Creeks, Lagos State, Nigeria

Plankton have great ecological importance as they fix carbon dioxide, produce oxygen, and serve as autotrophs at the base of various food chains in the different aquatic environments worldwide. Hence, the objective of this paper was to investigate the physicochemical characteristics and plankton diversity of Lagos Lagoon and its adjoining Abule-Agege and Abule-Eledu Tidal Creeks, Lagos State, Nigeria using appropriate standard techniques. Result of the physicochemical conditions varied from fresh through low to high brackish water conditions at the study locations. Thirty-five (35) taxa belonging to 21 genera were observed for the phytoplankton. The blue-green algae recorded 2 species from 2 Orders (5.71 %), while the diatoms are the more abundant group with a total of 33 taxa from 2 Orders (94.29 %). Zooplankton forms recorded a total of 17 taxa belonging to 14 genera from three main groups. Arthropods were the most abundant group with 13 taxa from 3 classes (52 %), while the Rotifers made up 4 species from 4 genera (16 %) and 5 Juvenile stages (32 %) respectively. Notable phytoplankton species reported were Microcystis aeruginosa, Oscillatoria sp., Synedra crystallina, and the zooplankton species were Paracalanus parvus, Enterpina acutifrons, Cyclops strenus, Daphnia magma, Keratella cochlearis, Baranacle nauplii, Gastropod and Polychaetes larva. Importantly as salinity increased, the diversity of plankton form groups increased in these ecosystems.

Mining rhizobacteria from indigenous halophytes to enhance alfalfa (Medicago sativa L.) growth and soil reclamation in saline soils of Northwest China

Enhancing the growth of alfalfa (Medicago sativa L.) through inoculation with rhizobacteria represents a sustainable strategy for reclaiming saline soils. However, the lack of suitable strains and practical application guidelines poses significant challenges to the utilization of Plant Growth-Promoting Rhizobacteria (PGPR) in salt-affected soils of Northwest China. In this study, we selected four PGPR strains derived from indigenous halophytes based on their growth-promoting characteristics. These strains underwent further selection via a petri dish assay. Subsequently, the effects of the selected PGPR strains on alfalfa growth and soil fertility were rigorously examined through pot trials. The results demonstrated that Bacillus filamentosus HL3, B. filamentosus HL6, Bacillus subtilis subsp. stercoris HG12, and Paenibacillus peoriae HG24 significantly produced indole-3-acetic acid (IAA), solubilized phosphorus, and fixed nitrogen (except for B. filamentosus HL6, which did not significantly fix nitrogen). Compared to non-inoculated plants, B. filamentosus HL6 and B. subtilis subsp. stercoris HG12 significantly enhanced seed germination, root elongation, and seedling biomass in a 150 mM NaCl saline solution. In saline-alkaline soils, PGPR inoculation under brackish water irrigation did not restore alfalfa growth to the levels observed under freshwater irrigation. Principal Component Analysis (PCA) condensed ten indicators into two indices, explaining 86.85% of the variance. Using these two indices as weights, an evaluation model for the PGPR-alfalfa symbiosis indicated that B. subtilis subsp. stercoris HG12 had the most substantial effect under freshwater irrigation, while co-inoculation with B. subtilis subsp. stercoris HG12 and B. filamentosus HL6 had the most significant impact on alfalfa growth and soil improvement under brackish water irrigation. Available phosphorus was identified as the primary factor influencing alfalfa growth, contributing 82.3% to the growth variation. These findings provide suitable microbial strains for the utilization of saline-alkali land and underscore the potential of applying indigenous PGPR-alfalfa symbiotic techniques to improve soil fertility and crop yield in the arid regions of Northwest China.

Optimal Exploitation Strategies of Sustainable Utilization of Egypt's Fossil Groundwater Reserves

Groundwater-dependent areas in Egypt are being reclaimed as a result of the impending food crisis. Thus, the national project for land reclamation aims to turn vast tracts of desert land into productive agricultural land. Even while this kind of rural development is desperately needed, relying solely on fossil groundwater sources is a dangerous course of action. Therefore, it is crucial to use these groundwater resources quite carefully. Selecting a safe pumping schedule to prevent aquifer depletion and/or seawater intrusion is just one of the goals. However, using groundwater simulation models based on optimal approaches would introduce exploitation plans that, at the same time, guarantee the aquifers' sufficiency for continued development and maximize the agricultural investment. Thus, a groundwater flow model was generated using the FEFLOW software to explore the Moghra aquifer’s potential for extensive rural development. The maximum pumping regime that coincides with the regulation rule that was set by the MWRI for the next 100 years has been concluded. There is a potential for sustainable exploitation of this water resource to irrigate a total area of 85,715 acres (34,687 ha). The resulting drawdown is expected to reach 95.4 m. Furthermore, a few mitigating techniques are suggested as efficient ways to stop or impede the saltwater intrusion, such as the installation of subterranean barriers and brackish water scavenger wells. Without a doubt, the intended findings would serve as the foundation for wise local water management choices that might strike a balance between the socioeconomic welfare of our nation and environmental preservation. The outcomes of the project can be used by decision making and stakeholder to achieve sustainable water resources management in the new lands for reclamation projects in the northwestern of Nile Delta, Egypt.

Assessing RO and NF Desalination Technologies for Irrigation-Grade Water

In this work, the performance of a Reverse Osmosis (RO) process using different types of reverse osmosis (RO) and nanofiltration (NF) membranes is evaluated for brackish water desalination for producing irrigation-grade water. The proposed desalination system is a single-stage system, where three types of RO and two NF membranes were examined. The different desalination systems were simulated using ROSA72 software. In order to validate the theoretical model, the results obtained from the simulation were compared to those obtained from the experiment conducted in this work. The El-Moghra aquifer of Egypt is considered the test bed due to a considerable amount of data being available for this aquifer. The El-Moghra aquifer has 79 wells, and the available water data, when checked against several quality parameters, show that none of the investigated wells are suitable for direct irrigation without treatment due to problems of salinity, the sodium adsorption ratio, and low water quality according to the irrigation water quality index values. The obtained results show that nanofiltration membranes exhibited superior energy efficiency compared to reverse osmosis membranes. However, what sets the nanofiltration membranes apart is their ability to elevate water quality in 89.9% of the total investigated wells to an acceptable level for agricultural purposes. This underscores the nanofiltration membranes as a highly effective alternative to reverse osmosis membranes, demonstrating the capability to produce water suitable for irrigation while concurrently reducing operational costs due to the lower energy consumption in nanofiltration-based systems.

Long term operation of a continuous submerged photocatalytic membrane reactor utilizing membrane distillation: Membrane performance and treatment efficiency

Long term (200 h) continuous operation of a submerged photocatalytic membrane reactor utilizing direct contact membrane distillation (SPMR-DCMD) is presented. Various types of feed contaminated with ketoprofen were treated: brackish water (BW), seawater (SeaW), and secondary wastewater effluent (SE). Ketoprofen decomposition after 24 h exceeded 99.5 %, regardless of feed type. The distillate showed no toxicity to Aliivibrio fischeri. A significant decrease in flux after 100–124 h of BW and SeaW treatment occurred due to scaling, while for SE the flux remained almost constant for 200 h. This indicates that a shorter study would not allow a proper analysis of the process. A scaling layer was formed regardless of feed type, and the formation of CaSO4⋅2H2O, CaCO3 or (Ca,Mg)CO3 was proved. The porous structure of the deposit during SE treatment prevented significant flux deterioration. The formed TiO2 layer protected the membrane from damage by the growing salt crystals.

Wrinkled hierarchical porous carbon spheres with interconnected multi-cavity for ultrahigh capacitive deionization

As one of the most promising electrode materials for capacitive deionization (CDI), the development of carbon materials with controllable pore structure and continuous mass production is essential for their practical application. Herein, a facile ultrasonic spray pyrolysis method was developed to synthesize surface-functionalized wrinkled hierarchical porous carbon spheres (HCS) with unique interconnected multi-cavity structures. The wrinkled and interconnected multi-cavity hierarchical pores of the HCS play a crucial role in providing accessible ion adsorption sites and promoting ion diffusion and storage in the “multi-cavity warehouse”. The carboxyl groups on the surface of HCS generate a negative charge that promotes the adsorption of cations. The optimized HCS possesses outstanding desalination capacity (114.25 mg g−1), fast adsorption rate (6.57 mg g−1 min−1), and superior cycling stability (95%). Meanwhile, the HCS exhibited impressive desalination capacities in brackish water. Furthermore, the density functional theory calculation results confirmed that the synergistic effect of carboxyl groups and defects significantly enhanced the Na+ adsorption capacity and facilitated ion diffusion. This study extends the synthesis method of surface-functionalized hierarchical porous carbon, which is expected to facilitate the development of CDI electrode materials.

Impacts of distinct residual aluminum on gypsum scaling in nanofiltration: Identification of key species

Membrane scaling severely hinders practical application of nanofiltration (NF) for brackish water treatment. However, the contributions of residual aluminum (Al), especially various species with differing polymerization degrees and sizes, to gypsum scaling remain unclear. Herein, the complex interactions between three Al species (AlCl3, Al13 and Al30) and gypsum scaling were investigated, including surface and bulk crystallization processes. Results demonstrated that Al species adhering to the membrane surface promoted surface crystallization and altered crystal morphology. Notably, the Al13 species induced the formation of dense, complete rosette crystals causing the most severe flux decline. For bulk crystallization, Al30 was the primary species to promote nucleation. This promotion resulted from two factors: a lower nucleation energy barrier and the promoted aggregation of small crystals. Furthermore, molecular dynamics (MD) simulations revealed that the inhibition of nucleation due to the competition between Al species and calcium ions at nucleation sites was negligible compared to the strong promotion effect. These findings demonstrated that PACl exhibit higher scaling potential during NF than monomeric Al coagulants. Ultimately, the competition between surface and bulk crystallization determined the final membrane flux decline. This study offers valuable insights into the mechanisms of NF scaling caused by residual Al and guides mitigation strategies.

Simulation of Maize Growth Under the Applications of Brackish Water in Northwest China

The objective of this study is to assess the suitability of the AquaCrop model for growing maize using brackish water irrigation in Northwest China. Additionally, this study aims to examine how maize utilizes water in various soil layers when irrigated with varying water qualities. The AquaCrop model was calibrated and verified using experimental data from the years 2022 and 2023 in this research. (1) The findings indicated that the AquaCrop model effectively simulated the canopy cover, biomass, and yield of maize when irrigated with brackish water. The validation year’s R2, MAPE, and RMSE values for canopy cover, biomass, and yield of maize were 0.95, 5.36%, and 4.77%, respectively. For biomass, the R2, MAPE, and RMSE values were 0.91, 16.61%, and 2.12 t·hm−2, respectively. For yield, the R2, MAPE, and RMSE values were 0.84, 3.62%, and 0.42 t·hm−2, respectively. (2) Irrigation with water of high mineral content, measured at 1.6 ds/m, as well as with fresh water over the whole reproductive period, resulted in an increased reliance on groundwater for maize cultivation. There was no notable disparity in the usage of various soil layers between the irrigation with alternating freshwater and brackish water. (3) The AquaCrop model simulated the effects of seven different irrigation water quality treatments. It was shown that using water with mineralization levels of 0.5 and 0.8 ds/m resulted in decreased freshwater use without causing a substantial decrease in maize yield and biomass.

Elucidating the use of pressure-recovery diagrams for analyzing energy consumption in reverse osmosis desalination

The pressure-recovery (PY) diagram used in reverse osmosis (RO) literature to compare energy consumptions in different RO configurations has a flaw of not holding the design flux constant. In this work, the PY diagrams are constructed with the aid of transport models. It is shown that the area underneath the PY curve represents the specific energy consumption (SEC) imposed by design flux and thermodynamics, which may be reduced by improving spatial uniformity in flux. The trend generally observes the equipartition of entropy production theorem. For seawater RO (SWRO) in which pressure drop relative to feed osmotic pressure is small and operation is near the thermodynamic limit, staged designs with interstage booster pumps enable a more uniform flux, thus reducing the SEC. However, for low-salinity brackish water RO (BWRO), improving flux uniformity may lead to a higher SEC as the increased friction loss often outweighs the reduced energy requirement imposed by system flux.

Detection and mitigation of soil salinization risk from saline/brackish water aquaculture in coastal areas: an application of remote sensing and managed aquifer recharge

This study focuses on detecting and mitigating soil salinization in four coastal areas of the Mekong Delta (Vietnam). Salinity patterns in the soils of the Mekong River Delta are not random but linked to land use practices and distance to the sea. We examine two quick yet reliable remote sensing-based techniques to detect the coastal aquaculture area and separate it from the inland freshwater farmland. These techniques can eventually be used to identify locations with an elevated risk of salinization in other coastal regions. Finally, we investigate a salinization mitigation solution based on creating a managed aquifer recharge system along the buffer zone that separates the coastal aquaculture area from the inland freshwater agriculture area. The implementation of an infiltration pond system is technically feasible in the Mekong Delta provided that hydrogeological characteristics, the fresh-saline interface position, and freshwater demands are considered. The transitional zone between freshwater agriculture and brackish water aquaculture in Bac Lieu, Soc Trang, Tra Vinh and Ben Tre provinces is optimal for implementing an aquifer recharge/freshwater barrier scheme.

Seafloor alkalinity enhancement as a carbon dioxide removal strategy in the Baltic Sea

Carbon dioxide removal from the atmosphere and storage over long times scales in terrestrial and marine reservoirs is urgently needed to limit global warming and for sustainable management of the global carbon cycle. Ocean alkalinity enhancement by the artificial addition of carbonate minerals to the seafloor has been proposed as a method to sequester atmospheric CO2 and store it in the ocean as dissolved bicarbonate. Here, a reaction-transport model is used to scrutinize the efficacy of calcite addition and dissolution at a well-studied site in the southwestern Baltic Sea – a brackish coastal water body in northern Europe. We find that most calcite is simply buried without dissolution under moderate addition rates. Applying the model to other sites in the Baltic Sea suggests that dissolution rates and efficiencies are higher in areas with low salinity and undersaturated bottom waters. A simple box model predicts a tentative net CO2 uptake rate from the atmosphere of 3.2 megatonnes of carbon dioxide per year for the wider Baltic Sea after continually adding calcite to muddy sediments for 10 years. More robust estimates now require validation by field studies.

Habitat for Coilia nasus in southern Zhejiang Province, China, based on a maximum entropy model

As an important fishery resource and endangered species, studying the habitat of Coilia nasus (C. nasus) is highly significant. This study used fishery survey data from southern Zhejiang coastal waters from 2016 to 2020, employing a maximum entropy model (MaxEnt) to map the habitat distribution of C. nasus. Model performance was evaluated using two metrics: the area under the curve (AUC) of the receiver operating characteristic curve for the training and test sets and true skill statistics (TSS). This study aimed to predict the habitat distribution of C. nasus and explore how environmental variables influence habitat suitability. The results indicated that the models for each season had strong predictive performance, with AUC values above 0.8 and TSS values exceeding 0.6, indicating that they could accurately predict the presence of C. nasus. In the study area, C. nasus was primarily found in brackish or marine waters near bays and coastal islands. Among all environmental factors, salinity (S) and bottom temperature (BOT) had the highest correlations with habitat distribution, although these correlations varied across seasons. The findings of this study provide empirical evidence and a reference for the conservation and management of C. nasus and for the designation of its protected areas.

Ecological filtering drives rapid spatiotemporal dynamics in fish skin microbiomes.

Skin microbiomes provide vital functions, yet knowledge about the drivers and processes structuring their species assemblages is limited-especially for non-model organisms. In this study, fish skin microbiome was assessed by high throughput sequencing of amplicon sequence variants from metabarcoding of V3-V4 regions in the 16S rRNA gene on fish hosts subjected to the following experimental manipulations: (i) translocation between fresh and brackish water habitats to investigate the role of environment; (ii) treatment with an antibacterial disinfectant to reboot the microbiome and investigate community assembly and priority effects; and (iii) maintained alone or in pairs to study the role of social environment and inter-host dispersal of microbes. The results revealed that fish skin microbiomes harbour a highly dynamic microbial composition that was distinct from bacterioplankton communities in the ambient water. Microbiome composition first diverged as an effect of translocation to either the brackish or freshwater habitat. When the freshwater individuals were translocated back to brackish water, their microbiome composition converged towards the fish microbiomes in the brackish habitat. In summary, external environmental conditions and individual-specific factors jointly determined the community composition dynamics, whereas inter-host dispersal had negligible effects. The dynamics of the microbiome composition was seemingly non-affected by reboot treatment, pointing towards high resilience to disturbance. The results emphasised the role of inter-individual variability for the unexplained variation found in many host-microbiome systems, although the mechanistic underpinnings remain to be identified.

Thin-film composite (TFC) membranes incorporated with hydrophilic additives and layered double hydroxides (LDHs) for effective brackish water (BW) desalination

To overcome the limited water permeability of thin-film nanocomposite (TFN) membranes for brackish water reverse osmosis (BWRO) processes, we have incorporated a few amine or hydroxyl group terminated hydrophilic additives during interfacial polymerization when fabricating RO membranes and found that the membrane comprising 1 wt% 2-(2-hydroxyethyl)pyridine (2-(2-pyridyl)ethylahydroxide, PEH) has the best BWRO performance. The membrane was subsequently infiltrated with layered double hydroxide (LDH) nanoparticles by a post ethanol activation and could deliver a water permeability of 4.18 LMH bar−1 which is 100 % more than the control membrane without much compromising the salt rejection. The newly developed process not only incorporates nanofillers with the advantages of simplicity and decoupling from the interfacial polymerization process, but also endows the TFN membranes with enhanced separation performance. The study may provide useful insights to incorporate nanofillers by the solvent activation approach for the fabrication of TFN membranes.

Vapor Pressure and Evaporation Studies of Saline Solutions on Natural and Synthetic Fabrics for Industrial Water Treatment.

In the present paper, we have conducted a comprehensive analysis of vapor pressures of both saturated and unsaturated solutions, alongside a study of evaporation using synthetic and natural fabrics for industrial applications in brackish water treatment under zero liquid discharge (ZLD) philosophy. By determining the vapor pressures of saturated solutions, we obtained results consistent with those of other researchers, extending the range of tested temperatures from 1 to 50 °C and successfully fitting the parameters of an Antoine-type equation. Similarly, positive results were achieved for unsaturated solutions, where various parameters of different equations accounting for the salt concentration were estimated, simplifying the fitting procedure. Natural evaporation tests from water surfaces using saturated solutions revealed that salts with higher associated vapor pressures exhibit higher evaporation rates. On the other hand, hydrated salts retain water in their structure and are significantly affected by ambient humidity. Evaporation studies on natural and synthetic fabrics with saturated NaCl and CuSO4·5H2O solutions showed distinct behaviors. NaCl increased both the evaporation rate and salt deposition with each cycle. In contrast, CuSO4·5H2O reduced the absorption capacity by blocking the fabric's structure, decreasing the evaporation efficiency over successive cycles.

Effects of manganese and copper ions on fouling formation in agricultural irrigation pipelines fed with brackish water

Brackish water utilization has emerged as a promising solution to address water scarcity issues. However, fouling poses significant technical and economic challenges to brackish water distribution systems (BWDS). Manganese (Mn2+) and copper (Cu2+) ions are common in brackish water, yet their impacts on BWDS fouling remain largely unknown. This study investigated the effects of four concentrations of Mn2+ (0.05, 0.5, 1.5, and 3.0 mg L−1) and four concentrations of Cu2+ (0.02, 0.2, 0.6, and 1.2 mg L−1) on fouling dynamics in BWDS. The results indicate that BWDS fouling significantly increased at higher concentrations of Mn2+ and Cu2+. Compared to a concentration of 0.05 mg L−1 of Mn2+, concentrations ranging from 0.5 to 3.0 mg L−1 increased fouling total weight by 29.9 % to 63.0 %. Similarly, compared to a concentration of 0.02 mg L−1 of Cu2+, concentrations ranging from 0.2 to 1.2 mg L−1 increased fouling weight by 16.9 % to 59.1 %. Although Mn2+ and Cu2+ aggravated BWDS fouling, no Mn2+ or Cu2+ chemical precipitations were detected in the fouling components. It is likely that Mn2+ and Cu2+ cations act as a “bridge” between water particles, facilitating flocculation and particle deposition, thereby increasing particulate fouling (e.g., quartz and silicates) in BWDS. Additionally, increased particulate fouling provided more nucleation sites for calcium carbonate precipitation, which significantly raised the content of calcium carbonate fouling. Therefore, it is recommended that the concentrations of Mn2+ and Cu2+ be maintained below 1.5 mg L−1 and 0.6 mg L−1, respectively, to mitigate BWDS fouling. This study elucidates the underlying mechanisms of Mn2+ and Cu2+ influence on BWDS fouling, offering valuable insights for the utilization of brackish water in efforts to mitigate global water scarcity.

Salmonirosea aquatica gen. nov., sp. nov., a Novel Genus within the Family Spirosomaceae, Was Isolated from Brackish Water in the Republic of Korea.

A Gram-stain-negative, obligately aerobic, non-motile, rod-shaped bacterial strain designated SJW1-29T was isolated from brackish water samples collected from the Seomjin River, Republic of Korea. The purpose of this study was to characterize strain SJW1-29T and determine its taxonomic position as a potential new genus within the family Spirosomaceae. The strain grew within the range of 10-30 °C (optimum, 25 °C), pH 5.0-10.0 (optimum, 7.0), and 1-4% NaCl (optimum, 3%). Phylogenetic analysis based on the 16S rRNA gene revealed that strain SJW1-29T belongs to the family Spirosomaceae and is closely related to Persicitalea jodogahamensis Shu-9-SY12-35CT (91.3% similarity), Rhabdobacter roseus R491T (90.6%), and Arundinibacter roseus DMA-K-7aT (90.0%), while the similarities to strains within the order Cytophagales were lower than 90.0%. The genome is 7.1 Mbp with a G+C content of 50.7 mol%. The use of genome-relatedness indices confirmed that this strain belongs to a new genus. The major polar lipid profile consisted of phosphatidylethanolamine, and MK-7 was the predominant menaquinone. The predominant fatty acids were summed feature 3 (C16:1ω7c and/or C16:1ω6c), iso-C15:0, iso-C17:0 3-OH, and C16:0, representing more than 80% of the total fatty acids. The phenotypic, chemotaxonomic, genetic, and phylogenetic properties suggest that strain SJW1-29T represents a novel species within a new genus in the family Spirosomaceae, for which the name Salmonirosea aquatica gen. nov., sp. nov., is proposed. The type strain of Salmonirosea aquatica is SJW1-29T (=KCTC 72493T = NBRC 114061T = FBCC-B16924T).

Water Lily-Inspired CNT@cotton towel solar evaporator with Marangoni effect and optimal water supply for achieving zero liquid discharge desalination and irrigation

Solar-driven interfacial evaporation is an environmentally friendly technology to address the global water scarcity crisis by efficiently purifying unavailable water resources (seawater, brackish water, high salinity wastewater and various water resources). However, the inevitable contradiction between salt deposition and highly efficient water evaporation during long-term desalination remains a major challenge. In this work, we report a self-floating bionic water lily evaporator with zero liquid discharge, consisting of CNT@cotton towel with the uneven-gap structure as the photothermal material and the square groove insulation foam with controllable water supply as edge-preferred crystallization support. The formed four-building-in ramp structure generates different surface tensions along the whole ramp and brings Marangoni flow. With the combination of Marangoni flow and optimal water supply volume, salt is spatially isolated from the CNT@CT surface, the biomimetic design can achieve continuous water evaporation and salt collection (79 g m-2h−1) for 84 h in 10 wt% NaCl under edge-preferred crystallization. The purified water meets drinking water standards and is applied to growing crops. This distinctive solar evaporator provides new insights for designing a low-cost and zero-liquid-discharge evaporator, advancing its application in high-saline brines, various water resources, and irrigation.

Impact of the traffic on a population of European pond turtles (Emys orbicularis) inhabiting heavily urbanized area at the city of Burgas

We report on the impact of vehicle traffic on a local population of European pond turtles (Emys orbicularis) inhabiting the city of Burgas (Bulgaria). We performed a six-year monitoring program to collect data on the presence of turtles on road E 87 in the south region of the city. The road section splits a Natura 2000 site and crosses through an artificial water basin with fresh to brackish water. We visited the road section in irregular intervals from 3 to over 20 days in the period March to October from 2016 to 2021. For the period of the monitoring, we were able to detect a total of over 300 specimens from all ontogenetic stages (33 juveniles, 74 subadults and 224 adults). During our field surveys in 2016, we detected a total of 47 live and 23 dead adults. In the next years, we found more dead adult turtles than live ones. Similar results were recorded for subadults. In the juveniles, the dead specimens were almost equal to those which were detected alive. Our results indicate an impact of the traffic on the local population of E. orbicularis. We discuss the design and position of constructions, which can mitigate the conflict and reduce the potential for Wildlife-vehicle collisions (WVC).

The Impact of Artificial Barriers on the Varuna litterata Migration Route in the Lower Serayu River, Central Java and Its Molecular Identification

The Serayu River is one of the longest rivers in Central Java. Dams built in the lower reaches of the Serayu River are thought to block the migration paths of fish and aquatic macrocrustaceans. This study aimed to determine the effect of dam on Varuna litterata migration and its molecular identification. This research was conducted using the observation method. Migration observations were made on vertical paths while molecular identification of V. litterata in the lower reaches of the Serayu River was compared with existing data in GenBank. The study covered the freshwater area above the Serayu Dam, the open area with freshwater below the Serayu Dam, and the open area with brackish water at the estuary of the Serayu River, with a study length of 33.37 km. The results showed that the presence of dams in the lower reaches of the Serayu River inhibited the migration pattern of V. litterata. The vertical shape of the dam causes only a few V. litterata to migrate to the top of the dam. The dam in the lower reaches of the Serayu River resulted in not many V. litterata being able to migrate to the top of the dam, so there were very few V. litterata found in the population upstream of the dam (115 ind). The results of molecular identification of V. litratata using the cytochrome C oxidase subunit I (COI) gene show that this crab is 100% the same as the data in GenBank and is closely related to Varuna yui and other Varunidae crab species.Keywords: Dams, Molecular, Migration, Serayu River, Varuna litterata