Volume 48 (2019): Issue 1 (March 2019)

The presented research focused on macrophytes, which constitute a primary element in the assessment of the ecological status of surface waters following the guidelines of the Water Framework Directive. In Poland, such assessments are conducted using the Macrophyte Index for Rivers (MIR). The objective of this study was to characterize macrophyte species in rivers in terms of their information value in the assessment of the ecological status of rivers. The macrophyte survey was carried out at 100 river sites in the lowland area of Poland. Botanical data were used to verify the completeness of samples (the number of taxa). In the presented research, the information provided by each species was controlled. Entropy was used as the main part of information analysis. This analysis showed that the adoption of a standard approach in the studies of river macrophytes is likely to provide sample underestimation (with missing species). This may potentially lead to incorrect determination of MIR and thus result in a wrong environmental decision. On this basis, a sample completeness criterion was developed. Using this criterion, the average value of information for macrophyte species in medium-sized lowland rivers is suffcient to be considered representative.

Madagascar is an isolated island characterized by a high degree of endemism at all taxonomic levels. Diatom assemblages of the region are still poorly known and sporadic sampling events in various habitats (e.g. lagoons, mangroves) have revealed a large number of taxa that could not be identified. This study presents detailed descriptions of two new species of Luticola: L. nosybeana and L. madagascarensis, collected from mangrove roots on Nosy Be Island. Comparisons with the described congeners showed that the density of striae in Luticola nosybeana is higher than that in L. belawanensis and proximal raphe endings terminate as irregular, shallow grooves. Luticola madagascarensis differs from L. similis in the shape of proximal raphe endings, which are short and expanded in the latter, while continue with irregular, shallow, elongated L-shaped grooves in L. madagascarensis. Luticola nosybeana and L. madagascarensis can be distinguished under a light microscope by the shape of the central area (bow-tie shaped in L. madagascarensis and deltoid in L. nosybeana) and isolated pores (robust and well visible in L. madagascarensis, poorly discernible in L. nosybeana). The two new species are unique in their habitat preferences: while all known congeners are freshwater, the new species inhabit estuarine mangroves.

Over the past few decades, Ponto-Caspian gammarids Pontogammarus robustoides, Obesogammarus crassus and Dikerogammarus haemobaphes have colonized the European inland and coastal brackish waters. Previous experimental studies of P. robustoides, O. crassus and D. haemobaphes indicated that the salinity optimum for the species is about 7 PSU. We examined whether salinities below 5 PSU in the Vistula estuary – the Vistula Lagoon and the Vistula Delta, create a favorable environment and have a positive effect on Ponto-Caspian gammarids. The objective of this work was to determine the population parameters (size structure) and biological indicators (condition) of the studied gammarid species at a low salinity level. Length–weight relationships can be considered as their body condition in the environment. These relationships were calculated for each gammarid species according to the exponential equation y = axb, where: y – wet weight, x – total length, a – intercept, b – slope. The results clearly show responses of Ponto-Caspian gammarids to the low salinity habitat and indicate that such environment provides excellent conditions. The results of analysis show that the condition of gammarids is good. The optimal strategy of the examined alien gammarids may help them to maintain a strong competitive position in the environment and affect the colonization process in non-native waters with low salinity.

The objective of the present study was to document the knowledge about the biodiversity of benthic insect communities and their distribution patterns in the semi-arid bioclimatic stage in the streams of the Aurès Region (NE Algeria). The distribution patterns of communities were analyzed in relation to some environmental factors: physicochemical water parameters and global habitat characteristics, including human impact. The taxonomic biodiversity of six sampled streams (wadis) comprises 42 insect taxa, belonging to seven orders and 30 families, of which Coleoptera is the most diverse order (15 taxa), whereas Diptera, Trichoptera and Ephemeroptera dominate in terms of abundance. The human impact, flow velocity and some quality parameters of water (potential of hydrogen, nitrite, concentration of orthophosphates and conductivity) were identified as the most influential environmental variables, which allows the prediction of taxonomic diversity indicators. The classification and regression tree analysis (CART) for benthic insects shows the effect of environmental variables (habitat parameters and human impact in the arid region) on the diversity and distribution of insect orders. The RDA analysis showed that altitude, substrate type, human impact and physicochemical parameters of water (pH, flow velocity, conductivity and total dissolved solids) are the most important predictor variables that play an important role in the distribution patterns of benthic insects.

In this study, we conducted a comparative analysis of the abundance and diversity of bacteria on the surface of the submerged macrophyte Myriophyllum spicatum, as well as in the surrounding water column and sediment in the low-salinity area of Hangzhou Bay, China. Bacterial clones from three clone libraries were classified into 2089 operational taxonomic units (OTUs), most of which affiliated with bacterial divisions commonly found in marine ecosystems. Alphaproteobacteria, Cyanobacteria and Gammaproteobacteria were the most abundant groups of bacteria on the surface of plants, in the water column and sediment, respectively. Epiphytic bacterial communities were more closely related to those in the sediment than bacterioplankton, and some species of epiphytic bacteria were found only on the surface of M. spicatum. The relative abundance of epiphytic bacterial genera associated with breakdown of organic compounds and with cellulose digestion was higher in October than that in July. These results suggested that bacterial communities on the surface of M. spicatum may originate from sediment bacterial communities and their specific structure was gradually formed on the surface of M. spicatum after being cultivated in low-salinity seawater.

The round goby, Neogobius melanostomus, is a Ponto-Caspian fish species currently found in many parts of Europe, including the North Sea riverine deltas. The objective of this study was to examine the parasite community of fish caught in the lower Elbe (Süderelbe – tidal zone; Geesthacht – non-tidal) in Germany and compare it with published data from the upper Elbe (Ústí nad Labem) in the Czech Republic. Twelve parasite taxa were recorded in the lower Elbe, six in the Süderelbe and nine near the city of Geesthacht. Süderelbe fish were mainly infected with Angullicola crassus larvae, while gobies from Geesthacht – with glochidia and sporadically occurring Pomporhynchus laevis, and the opposite situation was observed at Ústí nad Labem. It appears that a large tidal weir at Geesthacht significantly contributes to the division of the round goby population, with the Geesthacht parasite community being more similar to that at Ústí nad Labem than the one from the Süderelbe, thus increasing the likelihood that shipping from Hamburg was the introduction vector to Ústí nad Labem. We also recorded Acanthocephalus rhinensis in the Elbe for the first time, and in a new host – the round goby. Thus, round gobies may represent a new vector for the introduction of this parasite along the Elbe.

Four Talitridae species have been recorded in the southern Baltic Sea, including two indigenous species – Talitrus saltator, Deshayesorchestia deshayesii, and two presumably non-indigenous ones – Cryptorchestia garbinii, Platorchestia platensis. It has been twelve years since Platorchestia platensis was recorded for the first time. The distribution and abundance of talitrids have not been studied since the 1990s. Therefore, the main objective of this research was to document the occurrence in Talitridae in the region in order to determine whether non-indigenous P. platensis has spread and whether it co-occurs with indigenous species. Talitrids were recorded at 20 out of 43 sampling sites. T. saltator occurred both along the coast of the open sea and in the Gulf of Gdańsk. The remaining species were found only around the gulf. P. platensis was more abundant than other species and its density was positively correlated with wrack biomass. Our studies have shown that the area of T. saltator occurrence has decreased during the last two decades. Non-indigenous species P. platensis co-occurred with all other Talitridae species, whereas C. garbinii co-occurred only with P. platensis.

The paper reports on the first record of Sinelobus vanhaareni, a non-native tanaid, in the Polish coastal waters (Gulf of Gdansk, southern Baltic Sea). The species was found in the port of Gdynia in 2014, while in 2015–2017 it already colonized the western part of the Gulf of Gdansk, inhabiting mainly hard substrates, including both natural (e.g. boulders) and anthropogenic ones (e.g. vertical concrete piles or walls of offshore structures and breakwaters, horizontal PVC plates and oyster shells used as filling in habitat collectors). During the survey period, S. vanhaareni was found in different seasons of the year (from winter and early spring to autumn), which, combined with the presence of ovigerous females as well as high abundance (up to tens of thousands of individuals per square meter), allows us to assume that the species has already established a population in the Gulf of Gdansk.

Unionid mussel species belong to one of the most threatened invertebrate groups on Earth. Biological invasions, especially those by filtering species, are parti cularly harmful to nati ve Unionidae species. In Poland, a significantly disturbing situati on of native Unionidae is observed in thermally polluted aquatic ecosystems. Such water bodies have favorable conditions for the settlement of alien mollusks, including Sinanodonta woodiana or Corbicula fluminea, whose shells can potenti ally be a beneficial substrate for Dreissena polymorpha. The objecti ve of the presented research was to check whether zebra mussels can hinder the invasion of alien species of bivalve mollusks in thermally polluted waters. Our results indicate that with the increase in thermal polluti on associated with the growing invasion of alien species of bivalves, D. polymorpha infestations of clams decrease considerably, which leads to the conclusion that D. polymorpha does not pose a significantnatural threat to bivalves in the lakes under study.

Arsenic (As) is a natural component of the Earth’s crust. Due to its specific properties, arsenic became e.g. the favorite poison in the 19th century in Europe, a component of an effective insecticide and herbicide in agriculture, a specific chemical weapon during World War II and a medication used to treat various diseases. The bad reputation of this element was confirmed after World War II, when arsenic-based chemical weapons were dumped on the seabed and became a potential threat to the marine ecosystem. The wide distribution of arsenic compounds in the environment necessitated the development of technologies aimed at removing arsenic from the aquatic ecosystem. This study provides a detailed overview of the occurrence, distribution and transformation of arsenic species in the aquatic environment.