Estuary Water Research Articles

Do spatial differences account for the variation in abundance of human pathogenic bacteria in waters and fishes of the monsoonal estuary?

Spatiotemporal variation of human pathogenic bacteria was observed in the surface waters of a monsoonal estuary and these bacteria were also found to be associated with the native fish of two monsoonal estuaries. The temporal variation was in accordance with any monsoonal estuary. Also, the spatial variation in physicochemical parameters and bacterial counts was very evident at any given time. For instance, one sampling location in the estuary consistently had 103 fold higher bacterial counts than the rest of the locations within the same estuary. Coliforms, Salmonella-like (SmLO) organisms, Shigella-like (SLO) organisms, Vibrio parahaemolyticus-like (VPLO) organisms and Vibrio cholerae-like (VCLO) organisms occurred at many locations, but the abundance of each group varied differently with time at different locations in the estuary. Coliforms, unlike others, showed an increase in abundance from post-monsoon to pre-monsoon season. VCLO were the most abundant amongst all. Not all the pathogenic bacteria were widespread throughout the channel indicative of dominance in spatial variation over seasonal in this estuary. Most of the fish samples showed similar trend of bacterial numbers as that in surrounding waters, except a few. Presence of sewage pollution indicator bacteria in the fish indicated that fish served as reservoirs of these bacteria. Thermal death time of randomly picked fish-associated isolates was 30 min at 80 °C and these could survive freezing temperature for 24 h and produce siderophore which can account for their pathogenic nature. The monsoonal estuaries thus render survival ground of such bacteria.

Denitrification rates in tidal marsh soils: The roles of soil texture, salinity and nitrogen enrichment

AbstractThe denitrification rates of freshwater and oligohaline tidal marsh soils with different textures (loam and sandy soils) in a subtropical estuary, and their responses to nitrogen (N) loading, were investigated. In both marshes, the denitrification rates varied significantly with the season only in loam soil. The denitrification rates were highest in oligohaline marsh loam soil and lowest in freshwater marsh sandy soil. NH4NO3 addition significantly increased the denitrification rates of all the marsh soils. Our findings suggest that soil texture, soil organic matter (OM) content and low‐level increases in salinity all had large effects on denitrification, indicating that the dynamics of denitrification rates in estuarine marshes with low‐level salinity were controlled by the interaction of salinity and soil texture but mainly depended on OM content. We propose that denitrification in tidal marshes plays an important role in regulating current and future N loading into estuary and inshore coastal waters, especially for tidal freshwater marshes, which introduces great uncertainty into the N dynamics of estuaries under global changes.Highlights Denitrification rates were higher in loam than sandy soil, independent of salinity. Denitrification rates were higher in oligohaline marsh loam than freshwater marsh loam. Exogenous N input enhanced denitrification in estuarine marsh soil. Loam with high N enhanced N removal, especially in freshwater environments.

Influence of environmental variability on the body condition of the mangrove horseshoe crab Carcinoscorpius rotundicauda from Banyuasin Estuarine, South Sumatra, Indonesia

The body conditions indices were useful to determine an individual's well-being, and favorable food availability indicating a good environmental condition. The conditions of the mangrove horseshoe crab (Carcinoscorpius rotundicauda) might be related to several environmental parameters. The study's aim was to analyze the key environmental parameters affecting the body condition of C. rotundicauda found in Banyuasin Estuary Waters. The sampling was conducted in July 2019 in Banyuasin Estuary Waters. The data of weight and prosomal width for C. rotundicauda were used to estimate the body conditions indices (relative condition factor). While the environmental parameters data were recorded for each sampling site. The backward stepwise regression was used to determine the key environmental parameters affecting the body condition indices. The best-fitted model (adjusted R2 = 91.9%; F = 60.102; p < 0.05) indicated several environmental parameters (salinity, pH, seafloor temperature, clay and silt contents) significantly affecting the body condition indices. Changes in the key environmental parameters could generate changes in the availability of favorable food for C. rotundicauda. The result also can be used as baseline data for determining the marine conservation areas as well as horseshoe crab management plan.

Behavior of tetracycline and polystyrene nanoparticles in estuaries and their joint toxicity on marine microalgae Skeletonema costatum

Polystyrene nanoplastics (PS NPs), which are newly emerging as particulate pollutants, are one of the most abundant plastic types in marine debris. Although there has been extensive research on microplastics, the sorption behavior of PS NPs in surface waters remains unknown. In addition, in the previous joint toxicity studies, the concentration of organic pollutant in the joint system was based on the EC50 of this pollutant, rather than the actually amount of this pollutant adsorbed on nanoplastics (NPs). In this study, the sorption behavior of PS NPs with different surface charges in the surface water of estuaries and joint toxicity of that absorbed tetracycline antibiotic in equilibrium were investigated for the first time. Because of the electrostatic repulsion, salting-out effect, and partition function, the sorption capacity of tetracycline antibiotic by differently charged PS NPs was enhanced with increasing salinity. The biological effects of exposure to tetracycline-saturated PS NPs were complicated, which can be attributed to the surface characteristics of mixtures such as hydrophobicity and charges. Thus, the role of NPs in the natural environment as a carrier of antibiotics may provide an alternative for antibiotic inputs from inland water to coastal marine water, which would not only change the environmental fate and ecotoxicology of antibiotics and NPs, but also pose challenges to the safety of coastal aquaculture and marine ecosystem.

Seasonal and spatial controls on N2O concentrations and emissions in low-nitrogen estuaries: Evidence from three tropical systems

Nitrous oxide (N2O) production and emissions are observed in estuary waters, yet little is known about estuary N2O fluxes under low dissolved inorganic nitrogen (DIN) conditions. We present high-resolution spatial surveys of N2O concentrations in three low-DIN (NO3− < 30 μmol L−1) tropical estuaries in Queensland, Australia (Johnstone River, Fitzroy River, Constant Creek), during consecutive wet and dry seasons. Constant Creek had the lowest concentrations of dissolved inorganic nitrogen (DIN; 0.01 to 5.4 μmol L−1 of NO3− and 0.09 to 13.6 μmol L−1 of NH4+) and N2O (93–132% saturation), and associated low mean N2O emissions (0.02–3 μmol m−2 d−1). The Johnstone River Estuary had the highest N2O concentrations (97–245% saturation), with mean emissions of 4 to 6 μmol m−2 d−1, driven by upstream groundwater and riverine sources. In the Fitzroy River Estuary, N2O concentrations (100–204% saturation) and emissions (1–2 μmol m−2 d−1) were associated with wastewater inputs, which had a larger effect during the dry season. Estuary freshwater flushing time was an important factor: when freshwater was relatively stagnant, in-situ N2O emissions were larger than riverine N2O inputs. Conversely, fast freshwater flushing times diminished the role of in-situ emissions, and dissolved N2O largely flushed through the estuary directly to the ocean. Overall N2O emissions from the three tropical estuaries were low compared to previous studies, but were reasonably predicted by DIN concentrations: at low water column NO3− concentrations (i.e. <5 μmol L−1) estuaries can exhibit negative water-air N2O fluxes.

Insights on aquatic microbiome of the Indian Sundarbans mangrove areas.

Anthropogenic perturbations have strong impact on water quality and ecological health of mangrove areas of Indian Sundarbans. Diversity in microbial community composition is important causes for maintaining the health of the mangrove ecosystem. However, microbial communities of estuarine water in Indian Sundarbans mangrove areas and environmental determinants that contribute to those communities were seldom studied. Nevertheless, this study attempted first to report bacterial and archaeal communities simultaneously in the water from Matla River and Thakuran River of Maipith coastal areas more accurately using 16S rRNA gene-based amplicon approaches. Attempt also been made to assess the capability of the environmental parameters for explaining the variation in microbial community composition. Our investigation indicates the dominancy of halophilic marine bacteria from families Flavobacteriaceae and OM1 clade in the water with lower nutrient load collected from costal regions of a small Island of Sundarban Mangroves (ISM). At higher eutrophic conditions, changes in bacterial communities in Open Marine Water (OMW) were detected, where some of the marine hydrocarbons degrading bacteria under families Oceanospirillaceae and Spongiibacteraceae were dominated. While most abundant bacterial family Rhodobacteracea almost equally (18% of the total community) dominated in both sites. Minor variation in the composition of archaeal community was also observed between OMW and ISM. Redundancy analysis indicates a combination of total nitrogen and dissolved inorganic nutrients for OMW and for ISM, salinity and total nitrogen was responsible for explaining the changes in their respective microbial community composition. Our study contributes the first conclusive overview on how do multiple environmental/anthropogenic stressors (salinity, pollution, eutrophication, land-use) affect the Sundarban estuary water and consequently the microbial communities in concert. However, systematic approaches with more samples for evaluating the effect of environmental pollutions on mangrove microbial communities are recommended.

Fast-start escape performance across temperature and salinity gradients in mummichog Fundulus heteroclitus.

Fast-start predator-escape performance of mummichogs Fundulus heteroclitus was tested across field-informed variation in temperature (24, 30 and 36°C) and salinity (2, 12 and 32 ppt). Performance was similar across temperatures and salinities when fish were allowed to acclimate to these conditions. However, when mummichogs experienced acute temperature changes, performance exhibited thermal dependence in two contrasting ways. Fast-start turning rates and linear speeds varied directly with the temperature at which the manoeuvre was executed, but these aspects of performance varied inversely with acclimation temperature, with cool-acclimated fish exhibiting faster starts across test temperatures. Temperature effects were consistent across salinities. These results suggest that while mummichogs increase performance with acute temperature increases, long-term rises in sea temperature may cause these fish to become more susceptible to predation during abrupt cooling events, such as when storm events flood shallow water estuaries with cool rainwater.

Simulation Of Bod And Cod Pollutants Distribution In Tello River Makassar City

Water quality management and water pollution are one of the natural resources that have a very important function for human life that must be managed and secured from the conditions of pollution, therefore efforts are needed to monitor and monitor river water quality. In connection with that, a study was conducted aimed at assessing changes in water quality in the Tallo River through the distribution of pollutant concentrations of BOD (Biological Oxygen Demand), DO (Dissolved Oxygen) and COD (Chemical Oxygen Demand) by analyzing the mathematical model approach in the form of Surface Software Water Modeling System (SMS 8.1) integrated with RMA2 and RMA4. The research method carried explanation was a field survey in the form of data collection of water as many as 5 points in the drainage along the Tallo River. Simulation results show that based on water content requirements in the Republic of Indonesia Government Regulation No. 82/2001 regarding water quality standards it is known that for existing conditions and simulation results it is known that the classification of estuary river water conditions based on Dissolved Oxygen (DO) content is classified as Class 4 and the content of Biochemical Oxygen Demand (BOD) is classified as class I and the content of Chemical Oxygen Demand (COD) is categorized as class IV.

Взаємодія в паразито-хазяїнних відносинах на прикладі криптокотильозу риб родини Gobiidae в лиманних водах та акваторії Чорного моря півдня України

Наведено результати аналізу формування та функціонування системи «паразит – хазяїн», а також її складових елементів, на прикладі бичкових риб (Gobiidae) і трематод родини Heterophyidae. Подано дані щодо поширення збудника криптокотильозу серед бичкових риб природної водойми, клінічних ознак за даного паразитарного захворювання; результатів експериментального інвазування дослідних каченят із метою визначення патогенного впливу на організм птаха та з’ясування особливостей морфології статевозрілого паразита. Викладено основні моменти життєвого циклу збудника криптокотильозу. Встановлено поширення зазначеного паразита в акваторії Дніпро-Бузького лиману та частини Чорного моря Миколаївської та Одеської областей. Зазначено, що паразитична стратегія трематоди та сумісна коеволюція зумовили виникнення, в процесі еволюції, пристосувань, що збалансовують динамічну взаємодію між паразитом та хазяїном: анатомо-морфологічні характеристики, антигенна мімікрія, фізіологічні та трофічні особливості паразитичного способу існування тощо. Адаптативні здатності паразитів трематод проявляють себе ще на ранніх етапах життєвого циклу. За результатами експериментального інвазування дослідних каченят установлено патогенний вплив збудника криптокотильозу на організм дефінітивного хазяїна – птаха. Визначаючи особливості патологічного впливу паразитів на організм дослідних каченят, реєстрували запальні процеси кишкової трубки птахів: ентерити різного ступеня важкості, вторинні ураження гепатобіліарної системи. Вплив паразита на організм хазяїна не обмежується змінами на органному рівні. Неспецифічний захист проявляється, в основному, шляхом розвитку запальних реакцій на клітинному і гуморальному рівнях. Проведено ретроспективний аналіз літературних джерел щодо основних принципів взаємодії у паразито-хязяїнній системі.

Web evaluation of maceration length period on antioxidant potency of Sonneratia caseolaris leaf

Diabetic and cancer, as an examples of degenerative diseases in human may arise as consequences of free radicals, i.e. highly reactive molecules. The reactiveness of free radicals can be constrained by a substance, known as antioxidant. Mangroves that inhabitant of highly dynamic waters of estuary is likely have defend activity by produce some substances those known as bioactive compounds that may have potency of antioxidant. The quality and quantity of bioactive compounds may affected by extraction method. This study aims to evaluate antioxidant potency of Sonneratia caseolaris leaf with three diferent length time (24, 48 and 72 hours) of maceration by applying of DPPD (1,1-diphenyl-β-picryl hydrazyl) method. Result based on 50% of inhibition concentration (IC50) value suggest that the best maceration time is 24 hours (IC50 was 6.35 ppm), following by 72 and 48 hours (IC50 were 11.5 and 17.4 ppm, respectively). In addition, overall of different maceration time show IC value lowe than 50 ppm, indicate that Sonneatia caseolaris leaf have very strong potential of antioxidant activity.

Water regime formation of river basins in the delta zone on the example of the Azov region

Ignoring the specific soil and climatic conditions of the Lower Kuban against the background of irrevocable water use and constant increase in production intensification using new, little-studied pesticides and herbicides without studying the mechanism of its environmental impact, has led to serious environmental and economic problems. In this regard, there was needed to study and analyze environmental problems, establish mechanism for its origin and develop a concept and recommendations for overcoming the environmental crisis in which the Lower Kuban, including Azov and Black Seas ecosystems. The article has processed perennial data and our own research results into dynamics of the qualitative and quantitative indicators of the Lower Kuban delta zone basin for more than 70 years. The results of the ionic composition research of estuary water and collector-drainage water were obtained and analyzed. The causal relationships of catastrophic changes in the water ecosystem of the river delta are established and specific recommendations are developed to improve the ecological environment in line with modern standards. The estuaries ichthyofauna composition is analyzed and the reasons for the reduction in fish productivity are identified, ways to solve this are proposed.

George Eliot's Estuarial Form

This essay recasts the central locale of The Mill on the Floss in order to show how the geography and society of George Eliot's novel function together as a conjoined ecological system. I show that the port at St. Ogg's is set on an estuary, and from this observation, I claim that the entanglement of multiple estuarial waters provides a formal model for the overall ecology of the novel. Referring to this system as “ecological form,” the essay shows how the characters’ misunderstanding of the estuarial nature of the St. Ogg's hydrography is the primary source of the communal divisions with which the novel is so famously riven. In so doing, this essay makes two methodological interventions, one local, and one slightly more global. In the first, I show how unsticking the progression of our criticism from that of a novel's plot—especially one with such a catastrophically strong telos as Mill’s—can allow us to view form and, particularly, geography as newly vital to literary history. This leads to the second intervention, in which I suggest that reading practices in an age of environmental collapse should look beyond disaster itself and toward affected communities’ systemic ties to those extraneous systems—economic, legal, imperial—that aid and abet disasters elsewhere and even ignore the potential for catastrophic reoccurrence in the near future. In other words, reading for water readily yields a wide-ranging map of global capitalism perhaps unexpectedly centered on a small town in Lincolnshire.

Fish diversity of the Utlytsky estuary

Article deals with characteristic of the Utlytsky estuary’s ichthyocenosis. Utlytsky estuary is one of the biggest estuaries of the Sea of Azov, which located in the north-west part of the sea. In modern conditions 48 species of fish from 22 families was observed. Nowadays, such species as longsnouted seahorse, thick-snouted pipefish, narrow-snouted pipefish, river burbot, common vimba, common bream aren’t registered. Their absence is related to the low numbers or their total absence in the Azov Sea in recent years. The enrichment of the estuary fish fauna was due to new invasive species, such as soiyu mullet, sunfish, prussian carp and by extending the range of Black Sea species – atlantic bonito, mediterranean horse mackerel, sand sole etc. The basis of the estuary ichthyocenosis by the number of individuals is the european anchovy, the round goby and the Black Sea sand smelt. These species account for more than half of the catch by number of individuals in catches of gill nets and fry trawls. Secondary species are golden gray mullet and soiyu mullet, prussian carp, round goby, monkey goby, tubenose goby, grass goby, greater pipefish and others. Changes in the salinity of the estuary waters, which influenced the structure of the aquatic fauna of the reservoir, were noted. Thus, the catches have a high number of silver carp, gossip ordinary and not even typical of marine waters freshwater species – northern pike, sunfish, common rudd and others, in the conditions of relatively low salinity. On the other hand, catches of marine fish species are increasing in the estuary in the salinity rise conditions. So, the numbers in the catch of european anchovy, golden gray mullet, flathead mullet, grass goby and others increased from 1–2 % to 10–12 % of the total number of individuals caught.

Сучасні знахідки головня європейського Squalius cephalus (Linnaeus, 1758), карася звичайного Carassius carassius (Linnaeus, 1758) та хроміста плітки звичайної Rutilus rutilus (Linnaeus, 1758) в пониззі Дніпра

The article presents the materials on the detection of two very rare species of fish: the European chub Squalius cephalus (Linnaeus, 1758) and the crucian carp (the golden carp) Carassius carassius (Linnaeus, 1758) in the waters of the lower estuary of the Dnipro river in recent years. C. carassius is listed in the Red Book of Ukraine (2009). The article also describes the first encounter in these waters with the khromist of the common roach Rutilus rutilus (Linnaeus, 1758), which has a yellow-golden colour of the whole body. The basin of the Lower Dnipro includes the Kakhovske reservoir, the Ingulets river, several small tributaries and the lower unregulated part of the Dnipro riverbed along with the straits. Over the entire period of observation, up to 72 species of the round-mouthed fish and the fish from 59 genera and 19 families have been spotted in the fish fauna of the Lower Dnipro basin. According to some data, it is stated that within the migratory and freshwater species of the round-mouthed fish and the fish of the Lower Dnipro's ichthyocenosis only 21 out of 47 species of the native fish fauna have survived here. In general, the current fish fauna of the unregulated part of the Lower Dnipro amounts to 51 species of fish. The habitat of 28 species of fish in the lower estuary of the Dnipro river was confirmed in 2019.

Change of spatial distribution in the ichiotocenosis of the shabolat estuary in the process of its anthropogenic transformation

Consequences of Shabolat estuary natural ecosystems transformation under the influence of anthropogenic factors are reflected in the composition of ichthyocenosis, changes in the basic population characteristics of the most mass species.The purpose of the work was to find out the spatial distribution of the Shabolat estuary most massive representatives of the ichthyocenosis in terms of its anthropogenic transformation.Material and methods. The material for the study was selected from industrial fishing gear in the spring, summer and autumn periods of 2009-2012. A complete biological analysis of fish (goby round, goby grass, flounder, flounder, mullet pilengas, etc.) was carried out according to the conventional method.Result. The regularities of formation of ichthyocenosis largest masses populations were studied depending on: water salinity, connection with adjacent water areas, fish acclimatization and introduction, anthropogenic loading and peculiarities of spatial distribution of ichthyocenosis largest masses populations in aquatics.The most important Shabolat estuary ichthyocomplex components include representatives of the Gobiidae family, the Platichthys luscus population and the mullet family representatives.Of particular interest to the members of the goby family are the mass species of gobies: the round goby Neogobius melanostomus and the grass goby Zosterisessor ophiocephalus, which are able to hibernate and reproduce in the estuary. This is an important link in the food chains of the reservoir. By entering into competition with other representatives of ichthyocenosis, they significantly affect the state of the forage base and production capacity of the estuary.Representatives of the mullet family and gloss flounder are distributed in the estuary deep water areas and in areas with maximum salinity.Conclusions. It has been established, that in the conditions of anthropogenic transformation of the estuary, in the last 35-40 years, the round goby and grass goby numbers and distribution range have decreased. In bulk, they have survived only in reservoir small, local areas, due to the deterioration of reproduction conditions and the degradation of the zoster and reddest associations. The main reasons for the decline in the size and distribution range of gobies in the Shabolatsky estuary was their mass death as a result of a large-scale environmental catastrophe and reproduction conditions deterioration. The reason for the significant decrease in the flounder and mullet number and distribution range was the mass death in 1992, as well as changes in the salinity of the Shabolat estuary

The Tagus Estuary as a Numerical Modeling Test Bed: A Review

The Tagus Estuary is the largest estuarine system in the Iberian Peninsula. Located in a heavily populated metropolitan area (Lisbon), the estuary-coastal continuum is subject to significant natural variability (e.g., tidal variations, winds, river inflow, etc.) and human pressures (e.g., sewage outflow, infrastructures, coastal reclamation, dredging, etc.). Since the 1980s, the estuary has been a natural laboratory for a great number of multidisciplinary studies, but also a numerical laboratory to test models and to develop new ideas and numerical methodologies. Hydrodynamic and biogeochemical models have been used ever since to ascertain the main spatial and temporal features of the Tagus system, connecting its dynamic to its biogeochemical cycles, providing numerical tools used to increase knowledge and to manage the estuary and nearby coastal waters. The main objective of this paper is to present a synopsis of the scientific output related to numerical studies in the Tagus system, by reviewing more than fifty papers published over the past four decades. Our work provides a historical background and description of the numerical models implemented to address estuarine hydrodynamics, nutrient uptake, primary production, light availability, seasonal and annual cycles and the link between physical, biological and chemical estuarine oceanography.

The influence of the biotic and abiotic factors on the state of the parasitic fauna of the hydrobionts in natural waters of the Southern Ukraine

The article observes the results of the scientifi c researches conducted in 2018–2019. 198 samples of the Gobiidae fi shes (Neogobius fl uviatialis Pallas, 1814, Mesogobius batrachocephalus Pallas, 1814, Neogobius melanostomum Pallas, 1814,), as well as 78 samples of other predatory fi shes (Perca fl uviatilis Linnaeus, 1758, Sander lucioperca Linnaeus, 1758, Esox lucius Linnaeus) were subjected to the ihtyopathological analysis with such an aim. The samples were caught in the waters of the Dnipro-Buh estuary near the Dniprovske village and near the Agigol Cape in the Mykolayiv Region. The average index of the invasion extensiveness among the Gobiidae fi shes of the Dnipro-Buh estuary in June counted 26.6%, and the highest level of the invasion intensiveness counted – 94 – 157 metacecaria – the cryptocotyle agents. Following the fi sh-kill in July 2018 it was possible to notice the 114.2 % – decrease of the Gobiidae fi shes population. The level; of the cryptocotyle invasion of these fi shes reached its peak in August, counting 60.3%, and the amplitude of the invasion intensiveness waved between 102 and 211 samples. In June the level of invasion of the predatory fi shes (perch, pike, sander) with eustrongylides counted 63.8%, and the invasion intensiveness reached the highest point among Esox lucius Linnaeus – from 1 to 8 nematoda larvae. The 47.8 % – decrease of the amount of the predatory fi shes caught in the waters of the DniproBuh estuary was noticed after the fi sh-kill. In August the eustrongylide invasion extensiveness counted 84.3%, and the index of the invasion intensiveness was 2–12 parasites. The impact of the fi sh-eating birds on forming the natural focuses of the cryptocotyle and eustrongylide invasions among the main commercial fi shes of the Dnipro-Buh estuary was determined. Hydrochemical analysis of the waters of the Dnipro-Buh estuary was held separately to determine the reason of the mass fi sh-kill in July 2018. The hydrochemical analysis of the waters of the DniproBuh estuary in July showed contradictions of such points as pH, oxygen, free ammonia, and total hardness to the actual normative legal documents. The inappropriate hydrochemical condition was the reason of the fi sh-kill in the aquatic biological recourses. The infl uence of biotic and abiotic factors on the condition of the parasitic fauna in the researched fi shes of the natural waters of the Southern Ukraine was determined. Key words: gobiidae fi shes, predatory fi shes, abiotioc and biotic factors, cryptocotilosis, eustrongylidosis.

The association of cryptocotylosis with other types of parasitic invasions of gobiidae fishes in the natural waters of southern Ukraine

The article gives the result of the research of such fishes of the Gobiidae bloodline as Neogobius fluviatialis Pallas, 1814, Neogobius melanostomum Pallas, 1814, and Mesogobius batrachocephalus Pallas, 1814, in the waters of the Dnipro-Buh estuary and the Black Sea near Mykolayiv and Odessa regions. It established the possible associations of cryptocotylosis with other types of parasitic invasions of Gobiidae fishes. It has been set up that the researched fishes have been the most invaded by such agents of parasitic diseases as trematodes and nematodes – 52.2% and 37.3% respectively. The smallest parasitic group affecting commercial fishes is cestodiasis – 0.37%. Neogobius fluviatialis Pallas, 1814, has been noticed as invaded by Asymphylodora pontica Chernyshenko, 1949. The prevelence (P) counted 2.58%, and the invasion intensiveness (II) counted 4–12 samples. Cryptocotyle concavum Creplin, 1825 (P – 30.4%, ІІ – 9–124 samples); Cryptocotyle jejuna Nicoll, 19 07 (P – 15.9%, ІІ – 12–103 metacecaria); Ligula pavlovski Dubinina, 1959 (P – 0.21%, ІІ – 1sample); Cucullanellus minutus Rudolphi, 1819 (P – 9.05%, ІІ – 1–3 nematodes); Eustrongylides excisus, Jägerskiöld, 1909 (P – 23.06%, ІІ – 1 – 4 larvae); Raphidascaris sp. (P – 2.8%, ІІ – 1 nematode); Telosentis exiguus (Linstow, 1901) (P – 1.07%, ІІ – 1–2 samples.); Ergasilus nanus (Beneden, 1870) (ІE – 8.18%, ІІ – 1–31 maxillopods).The parasitic fauna of Neogobius melanostomum Pallas, 1814 was characterized by such agents as Asymphylodora pontica Chernyshenko,1949 (P – 10.2%, ІІ – 5–36 samples); Cryptocotyle concavum Creplin, 1825 (P – 59.2%, ІІ – 94–211 samples); Cryptocotyle jejuna Nicoll, 1907 (P – 44.8%, ІІ – 4–87 metacercaria); Stephanostomum bicoronatum (Stossich, 1883) Fuhrmann, 1928 (P – 26.5%, ІІ – 6 – 69 larvae); Ligula pavlovski Dubinina,1959 (P – 2.04%, ІІ – 1sample); Cucullanellus minutus Rudolphi, 1819 (P – 16.3%, ІІ – 1–6 nematodes); Eustrongylides excisus, Jägerskiöld, 1909 (P – 22.4%, ІІ – 1–4 larvae); Raphidascaris sp. (P – 4.08%, ІІ – 1–2 nematodes); Telosentis exiguus (Linstow, 1901) (P – 8.16%, ІІ – 1–2 samples); Ergasilus nanus Beneden, 1870 (P – 14.2%, ІІ – 2–8 maxillopods). Parasitic invasions of Mesogobius batrachocephalus Pallas, 1814, also took place. For example, there were registered the cases of invasion with such agents as Cryptocotyle concavum Creplin, 1825 (P – 17%, ІІ – 18–89 samples); Cryptocotyle jejuna Nicoll, 1907 (P – 13.5%, ІІ – 7–21 metacecaria); Stephanostomum bicoronatum (Stossich, 1883) Fuhrmann, 1928 (P – 6.77%, ІІ – 5–11 larvae); Cucullanellus minutus Rudolphi, 1819 (P – 35.6%, ІІ – 1–3 nematodes); Eustrongylides excisus, Jägerskiöld, 1909 (P – 32.2%, ІІ – 1–3 larvae); Сontracaecum sp. (P – 5.08%, ІІ – 1 nematode); Ergasilus nanus Beneden, 1870 (P – 8.74%, ІІ – 1–15 parasites).

Estimation of vessel collision frequency in the Yangtze River estuary considering dynamic ship domains

With the Automatic Identification System (AIS) data collected from Donghai Navigation Safety Administration, this study aims to estimate vessel collision frequency in the Yangtze River estuary water areas considering dynamic ship domain sizes. To take into account the possible impacts of ship type, time of the day, and ship relative speed, ship domain size is further modeled as linear functions of these influencing factors based on our questionnaire survey data. Ship results reveal that the calculated vessel collision frequency in the Yangtze River estuary water areas is about 4.29 × 10−3 per ship-year, in which cargo ships have the highest vessel collision frequency, while fishing ships have the lowest frequency. Moreover, head-on collision is the collision type that has the largest collision frequency, followed by overtaking collision and crossing collision in the Yangtze River estuary. Big-sized vessels (e.g., Container ship and Cargo ship) are more likely to encounter head-on collisions, while the majority of small vessels (e.g., Fishing ship and Passenger ship) involved in overtaking collisions. Because of higher vessel traffic flow and density, the daytime period is associated with a larger vessel collision frequency, as compared with the nighttime period.

Distribution of dissolved matter in the Yenisei river estuary and adjacent water area of the Kara sea and its interannual variability

The distribution of dissolved matter (major ions, nutrients, and trace elements) in the Yenisei River estuary and adjacent water area was studied according to the natural observations data from 20092016. These results were compared to the literature data of hydrochemical researches of this region. It was shown that transport of major ions (Na, K, Mg, Ca, SO4) and some trace elements (Li, Rb, Cs, Sr, B, F, Cr, Ge, As, Mo, U) is described by the stable in the long-term period equations of conservative mixing between riverine and seawater masses. Alkalinity also belongs to conservative components; however this parameter exhibits substantial spatiotemporal variability of the distribution caused by complex hydrological structure of the Yenisei Bay and adjoining part of the Kara Sea. Concentrations of Pmin, Si, and V in the desalinized waters of photic layer decreases seaward during vegetation period owing to uptake by phytoplankton. The losses of these elements reach 3057, 30, and 9% of their supply by river runoff, respectively. The content of dissolved Pmin and V in the intermediate and near-bottom layers of the Yenisei River estuary strongly increases with increase of salinity due to regeneration of precipitated organic matter, whereas silica remineralization is much less pronounced. Barium in the all estuary is intensively desorbed from river suspended matter in the quantity reaching 20100% of its dissolved forms input with river runoff depending on seasonal variations of chemical composition of the last. The transport of dissolved forms of heavy metals (Mn, Fe, Pb) and elements-hydrolyzates (Al, Ti, Y, La, Ce, Pr) in the mixing zone between the riverine and seawater masses is probably controlled by the coagulation and flocculation of organic and organomineral colloids, which is indicated by decrease in the concentrations of these elements at the beginning of salinization (for 2061%) with subsequent approximation to the seawater mass characteristics.