An assessment of maintenance works and their impact on macroinvertebrate communities and long-term recolonization to small lowland watercourses.

Due to their small size and high anthropogenic pressure, small watercourses are particularly prone to severe siltation and are densely overgrown with macrophytes. Many of these watercourses are subject to regular maintenance works (RMW), consisting of seasonal desilting and vegetation clearance, in order to ensure unobstructed water flow. The aim of the study was to assess the impact of three types of maintenance works: dredging and mud removal (DMR), river channel vegetation removal (RCVR) and river bank vegetation removal (RBVR) on taxa species richness, macroinvertebrate density and the Shannon-Wiener diversity index, as well as their changes and long-term benthic recolonization one and two years after completion of the works. The study was carried out in 21 habitats on eight rivers in the European Central Plains Ecoregion. A total of 107 zoobenthic taxa were found at all sites, and their species composition was characteristic of highly hydrophytic waters with low hydrological and hydrochemical quality parameters. A significant decrease in macroinvertebrate taxa richness was observed one year after the works, as the average number of taxa had dropped from thirteen to eight, with a further fall to seven taxa two years after the RMW. The same was true for density, which had decreased from an average of 2496 to 786 individuals per square meter one year after the RMW, while, a gradual recolonization was recorded two years after the RMW, with an average density of 1295 individuals per square meter. The Shannon-Wiener index, which had averaged 2.528 before the RMW, also decreased, falling to 1.982 and 1.832 one and two years after. BACI statistical analyses showed that of the three types of maintenance work, desilting and bottom sediment removal had the largest negative impact, significantly reducing taxonomic composition (by an average of 53%), density (by an average of 43%), and ecological index values (by an average of 40%). Over-frequent maintenance can prevent macroinvertebrate populations from recovering, thus depleting the environment of valuable taxa, including those that provide food for fish and other vertebrates.

Invasive Round Goby (Neogobius melanostomus) Fish from the Southern Baltic as a Source of Arsenic and Selenium-Food Safety Aspects.

Minimizing human exposure to arsenic (As) and ensuring an adequate dietary intake of selenium (Se) are significant issues in research on food sources. This study measured the content of As and Se in the muscles, gills, liver, and gonads of the fish round goby (Neogobius melanostomus) to assess the benefits and risks associated with their consumption. This was achieved by using dietary reference intake (DRI), estimated daily intake (EDI), target hazard quotient (THQ), and carcinogenic risk (CR). The elements were analyzed by atomic absorption spectrometry. The mean concentrations of As and Se (in µg kg-1 wet weight) were 25.1 and 161.4 in muscle, 58.8 and 367.4 in liver, 47.4 and 635.3 in gonads, and 16.4 and 228.5 in gills, respectively. Arsenic in the muscle portion of fish accounted for up to 0.5% of the DRI, while Se constituted approximately 30% of the DRI. The EDI values were below the reference oral dose (RfD). The THQ were much below the permissible levels (THQ < 1), and the CR were at least within the permissible limit (CR < 10-4). With regard to the As content, round goby muscles can be deemed safe for consumers. They may also be a valuable source of Se in the human diet. However, round goby consumption should be monitored for the proper and safe intake of these elements.

Nutritional Quality and Fatty Acids Composition of Invasive Chinese Mitten Crab from Odra Estuary (Baltic Basin).

The Chinese mitten crab (Eriocheir sinensis) is recognized as an invasive species in Europe but increasing fishing efforts may hold economic benefits and yield positive ecological and nutritional outcomes. The objective of this study was to determine the yield of edible parts and the compositional and nutritional characteristics of this crab, especially as a source of n-3 PUFA. The overall yield of edible parts amounted to 38.09%, with males (27.72%) exhibiting a higher meat content compared to females (25.30%). The gonads displayed the highest protein content (24.12%), while the hepatopancreas (11.67%) showcased the highest fat content. Furthermore, the fatty acid composition varied depending on the distribution within different crab segments and gender and individual size. Notably, the gonad lipids contained the most nutritionally valuable n-3 fatty acids, followed by muscle and hepatopancreas lipids. The determined index of atherogenicity (IA) from 0.2 for gonadal lipids to 0.42 for hepatopancreas lipids, index of thrombogenicity (IT) in the range of 0.10 for gonads to 0.41 for hepatopancreas, and flesh lipid quality (FLQ) from 6.9 for hepatopancreas to 23 for muscle lipids indicate their pro-health properties. The ratio of n-3 to n-6 fatty acids showed Chinese mitten crab as an excellent source of oil that can be used for food fortification and dietary supplement production.

An Analysis of Hydromorphological Index for Rivers (HIR) Model Components, Based on a Hydromorphological Assessment of Watercourses in the Central European Plain.

Assessing the hydromorphological conditions of watercourses is a requirement of the Water Framework Directive (WFD) and national river status monitors (e.g., in Poland,the State Environmental Monitoring, and Water Monitoring coordinated by Chief Inspectorate of Environmental Protection). This paper evaluates the hydromorphological status of 10 watercourses (30 measurement sections) in Poland based on the multimetric Hydromorphological Index for Rivers (HIR). A new approach to the delineation of the river valley (small watercourses) is proposed. An analysis of the influence of river valley management on the value of HIR and its components was carried out using statistical methods (basic statistics, Mann-Whitney U Test and Ward's cluster analysis). In addition, the relationship between the components of the HDS (Hydromorphological Diversity Score) and HMS (Hydromorphological Modification Score) was analyzed (Spearman's Rank Correlation Coefficient). HIR values for the watercourse sections ranged from 0.553 to 0.825. HDS values ranged from 27.5 to 75.5 and HMS from 2.0 to 17.5. The results of the basic statistical analyses showed slight differences between the two river valley delineation methods. The Mann-Whitney U Test showed a significant difference in the test significance level of the HDS, HMS and HIR for the river valley delineation methods. Spearman's rank correlation analysis showed that most of the HDS and HMS parameters components had a low degree of correlation. The juxtaposition of the two methods for delineating a river valley and its influence on the HIR allows for a better understanding of the interdependence between its parameters.

Habitat Conditions of the Microbiota in Ballast Water of Ships Entering the Oder Estuary.

Ballast water is a vector for the transfer of microorganisms between ecospheres that can subsequently have a negative impact on native species of aquatic fauna. In this study, we determined the microbiota and selected physicochemical properties of ballast water from long- and short-range ships entering a southern Baltic port within a large estuary in autumn and winter (Police, Poland). Microbiological tests of the ballast water samples were carried out according to ISO 6887-1, and physicochemical tests were performed according to standard methods. Low amounts of oxygen (1.6-3.10 mg/dm3 in autumn and 0.60-2.10 mg/dm3 in winter) were recorded in all ship ballast water samples, with pH (above 7.90) and PSU (above 1.20) were higher than in the port waters. Yeast, mold, Pseudomonas bacteria (including Pseudomonas fluorescens), and halophilic bacteria as well as lipolytic, amylolytic, and proteolytic bacteria were found in the ballast water samples. Heterotrophic bacteria and mold fungi (log. 2.45-3.26) dominated in the autumn period, while Pseudomonas bacteria (log. 3.32-4.40) dominated in the winter period. In addition, the ballast water samples taken during the autumn period were characterized by a statistically significantly higher (p < 0.1) abundance of microorganisms (log 1.97-2.55) than in the winter period (log 1.39-2.27).

Characterisation of Benthic Macroinvertebrate Communities in Small Watercourses of the European Central Plains Ecoregion and the Effect of Different Environmental Factors.

Most publications on the influence of environmental factors on macroinvertebrate communities focus on large rivers, whereas relatively few examine small watercourses in agricultural areas, which, due to their size and pressure from intensive agricultural production, are much more susceptible to the effects of unfavourable environmental conditions or anthropopressure. The aim of our study was to compare the biodiversity of macrozoobenthos assemblages and to determine the effects of physicochemical and hydrological conditions on their abundance and density in 10 small rivers in agricultural areas located in northwest (53°23' N 15°14' E) and central (52°11' N 20°48' E) Poland. In total, 105 taxa were recorded, with the majority being euryoecious. Among the assessed physicochemical parameters, oxygenation was found to affect the density and number of taxa; another important factor was the content of nitrate nitrogen. Sensitivity to changes in water temperature was observed in some macrozoobenthos taxa (especially Decapoda). Of the examined hydrological parameters, the greatest effects were exerted by speed, flow, and depth.

Impact of polyaluminum chloride on the bioaccumulation of selected elements in the tissues of invasive spiny-cheek crayfish (Faxonius limosus) - Potential risks to consumers.

The effect of coagulants used in lake reclamation on crayfish is poorly understood. Therefore, the aim of this study was to evaluate changes in the bioaccumulation of Al, Ca, Cu, Fe, K, Mg, Na and Zn in the gills, exoskeleton, muscle and hepatopancreas of spiny-cheek crayfish (Faxonius limosus) as a result of exposure to PAX®18 coagulant, containing polyaluminum chloride. The study also evaluated the risk to human health from the consumption of crayfish muscle. Metal levels, determined using atomic absorption spectrometry, differed between metals (the highest concentrations for Ca, K, Na, Mg) and the body part. Calcium was most abundant in the exoskeleton, K in the muscles, while Cu and Al in the hepatopancreas. The bioaccumulation of metals was affected by exposure to the coagulant, with a statistically significant (p < 0.05) increase in muscle concentration of Al and Na and a decrease in Ca and Fe. The concentrations of elements (in µg g-1) in the muscle of the control group crayfish and those in contact with the coagulant were, respectively: K (2150; 2090), Na (1540; 2020), Ca (749; 602), Mg (207; 174), Al (103; 164), Zn (21.1; 19.1), Fe (7.6; 3.8) and Cu (8.4; 7.6). Most elements were below 12% of the Dietary Reference Values (DRV). The Al concentration in the muscle exceeded the tolerable weekly intake (TWI) (maximum 164% TWI for muscle of crayfish exposed to polyaluminum chloride). In conclusion, the studied F. limosus had typical elemental bioaccumulation for a crayfish, but the contact with the coagulant increased Al concentration and decreased Fe, Ca, Mg, Zn and Cu concentrations. The muscle of crayfish can be used as a supplementary source of essential elements in the human diet, but it seems necessary to introduce obligatory control of Al levels due to the use of polyaluminum chloride in lake restoration.

Reproductive Potential of Stone Moroko (Pseudorasbora parva, Temminck et Schlegel, 1846) (Teleostei: Cypriniformes: Gobionidae) Inhabiting Central Europe.

Similar to other invasive species, stone moroko is extending its global distribution. The present study aimed to assess the reproductive potential of stone moroko fish in a new habitat in Poland based on analysing the sexual cycle and fecundity. Fish morphometric data, age, and gonadal structures were analysed. Fish age ranged from 0+ to 5+ years. Most females and males (93% and 60%, respectively) had reached sexual maturity in the first year of their life, with the smallest length of 25 mm and 28 mm, respectively. The mean, standard length of the body was 50 mm. The spawning season was spread over four months from late-April to mid-August. Females laid eggs in portions, and the absolute and relative fecundity was 1372 and 1691, respectively. Stone moroko males were ready to spawn for a longer time period than females. The present study shows greater reproductive potential of stone moroko population in the central Europe than the native population, suggesting its successful colonisation in the new habitat.

A comparison of the concentrations of heavy metals in modern and medieval shells of swollen river mussels (Unio tumidus) from the Szczecin Lagoon, SW Baltic basin.

The shells of mussels, live-collected bivalves or during archaeological excavations, can be used as bioindicators of current and historical levels of heavy metal contamination. In this study, we examined the shells of Unio tumidus, commonly found in the Baltic Sea region, and determined the concentrations of Zn, Cu, Fe, Pb, Ni, and Cd in samples from the 10th, 11th, and 21st century from the area of the Szczecin Lagoon. The average levels of heavy metals (in µg g-1 dry weight) in the shells from the Middle Ages were: 137.5 (Fe), 3.87 (Zn), 0.789 (Cu), 0.012 (Pb), 0.047 (Ni), and 0.0009 (Cd). Shells from the 21st century were significantly (P<0.05) more abundant in Fe, Cu, Ni, Pb, and Cd (rates of increase: 1.96×, 3.54×, 2.71×, 2.08×, and 3.55×, respectively) than shells from the Middle Ages. These results reflect contemporary anthropogenic pollution of the environment with heavy metals and confirm the possibility of using U. tumidus shells in the assessment of heavy metal pollution levels.

Effect of Artificial Regime Shifts and Biotic Factors on the Intensity of Foraging of Planktivorous Fish.

It is still to be confirmed whether global warming with its predicted elevated water temperature will cause an increase in predation and alter phenological and physiological processes leading to changes in the size of aquatic organisms. In an experimental system of water column stratification simulating a natural combination of field conditions, we created artificial abiotic factors that mimicked the natural environment, i.e., light intensity, oxygen conditions, and thermal stratification. Subsequently, we added biotic factors such as algae, Daphnia, and planktivorous fish. We studied the intensity of foraging of planktivorous fish on individuals of Daphnia per min in different conditions of biotic and abiotic gradients. We demonstrated a possible scenario involving the risk of elimination of large prey within macrocladocera communities by predatory pressure as a result of climate change. A higher intensity of foraging of planktivorous fish caused or increased the occurrence of larger groups of planktonic animals with a smaller body size. The mechanisms of a future scenario were discovered at a higher trophic level in the aquatic environment.

Macroelements and Trace Elements in Invasive Signal Crayfish (Pacifastacus leniusculus) from the Wieprza River (Southern Baltic): Human Health Implications.

Signal crayfish (Pacifastacus leniusculus) is an invasive species displacing native European crayfish from their natural habitats. The elemental composition of the population from the southern Baltic coastal river and the potential health hazards are not known. The aim of the conducted research was to assess the quantitative content of Al, As, Ca, Cd, Cu, Fe, K, Mg, Na, Ni, Pb, Se, and Zn in meat, hepatopancreas, and exoskeleton in a population from Wieprza River (Poland) and compare the results with the recommendations of daily human consumption. Analysis also involved the composition of water and sediments. The concentrations of elements were analyzed using an Atomic Absorption Spectrometer. The bioconcentration factor (BCF) of elements in the signal crayfish was much higher from water than from sediments. Bioaccumulation of elements differed between the particular parts of the body of crayfish, e.g., Ca showed extreme predominance in the exoskeleton, while in meat exhibited a predominance of K, Na, Ca, and Mg. Among trace elements, crayfish meat was the richest in Zn, Cu, and Fe. The concentrations of non-essential Cd, Pb, and As were low compared to other determined elements. The highest concentrations of As, Cd, Cu, Fe, Ni, and Se were found in the hepatopancreas, while the highest levels of Al and Pb were found in the exoskeleton. Generally, it was found that the meat of P. leniusculus can be a perfect supplement to the human diet, and the consumption of 100 g of meat per day did not exceed the dietary reference values for essential elements and also for Al, As, Cd, Ni, and Pb.

Microelements and macroelements in the body of the invasive Harris mud crab (Rhithropanopeus harrisii, Maitland, 1874) from the central coast of the South Baltic Sea.

In this study, we determined the levels of essential and non-essential elements in the Harris mud crab (Rhithropanopeus harrisii, Maitland, 1874) from the southern Baltic Sea. Results revealed high levels of Ca (246,000 ppm), Mg (11,000 ppm), Na (8160 ppm), K (3,780 ppm), and Fe (1830 ppm). The concentrations of essential metals such as Zn (62.5 ppm) and Cu (25 ppm) were similar to those recorded in other crab species. The concentrations of non-essential metals such as Pb (0.140 ppm), Cd (0.0017 ppm), and As (0.288 ppm) were well below the International Standards for Maximum Levels for Food. In view of the above, the Harris mud crab from the southern Baltic is safe to be used as a component of well-balanced feeds for terrestrial and aquatic animals.

Molecular connectedness between self and none self-sustainable populations of Chinese mitten crab (Eriocheir sinensis, H. Milne Edwards, 1853) with focus to the Swedish Lake Vänern and the Oder and Vistula River in Poland.

The highly invasive Chinese mitten crabs (Eriocheir sinensis) was studied to reveal the genetic relationship between three none self-sustainable population within the Polish Oder and Vistula River and Lake Vänern in Sweden. Crabs from self-sustainable populations were collected from the Elbe River (Germany), San Francisco Bay (USA) and five Asian river estuaries. Both parsimony and maximum likelihood analysis of the nuclear ITS 1 and ITS 2 regions reveal a similar topological pattern. The mitochondrial cytochrome c oxidase subunit I (COI) sequence had too low resolution to be informative. The Oder River haplotypes showed high sequence similarities to both the Elbe population and/or the native spawning areas in China. The Vistula River showed haplotypic similarity to specimens from the Oder River in Poland or the Elbe River. Also high sequence similarities were observed to the specimens from the Swedish Lake Vänern indicating to an origin from the River Elbe. Minor changes in evolutionary interpretation exist depending on how gaps are treated and the analytic method. There is a complex movement involving back and forth transoceanic colonization of the Chinese mitten crab haplotypes. Invasion routes are discussed in relation to ship transfer routes and canal waterways.