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The dissolved organic and inorganic contaminants in rivers, lakes and seas are distributed among the aquatic phase, biota, sediments and biofilms formed on different artificial and natural substrata. Since the biofilms play an important role in the food web of aquatic ecosystems, it is necessary to clarify what kind of contaminants are bounded to these biological surfaces. In this study the concentration of eight pharmaceuticals (carbamazepine, ciprofloxacin, clarithromycin, diclofenac, metoprolol, sitagliptin, sulfamethoxazole and tetracycline) was determined in the Danube water at Budapest (Hungary) and in the biofilms formed on glass and polycarbonate substrata during a six weeks long growing period at the same sampling site. The target compounds were extracted from the dried biofilms by microwave (MW) assisted hot water treatment, however, the recovery of tetracycline was extremely low, indicating damage and loss of this constituent caused by MW treatment. The concentrations of the other seven pharmaceuticals were determined by LC-MS following the solid phase extraction of analytes. Clarithromycin, ciprofloxacin, diclofenac, metoprolol and sitagliptin were detectable in the biofilms due to biological uptake and electrostatic-mediated adsorption on the negatively charged biofilms, however, carbamazepine and sulfamethoxazole with neutral charge were not detected. The bioaccumulation factors of biofilms grown on glass or polycarbonate substrata changed between 175 and 614 and 148–314 L/kg, respectively, and increased in order of diclofenac

Diatoms are widely applied in the ecological status assessment of aquatic ecosystems using indices calculated from pollution sensitivity and indicator values of species. Traditional, morphology-based identification of species requires in-depth taxonomic knowledge and expertise. Identifying taxa according to their barcode sequences obtained with high-throughput sequencing (metabarcoding) would be a promising alternative. In this pilot study, we tested the applicability of metabarcoding of benthic diatom assemblages for the ecological status assessment of Hungarian water bodies, comparing its performance to that of morphology-based identification of species. The barcode region of the rbcL gene was investigated in samples from running waters with various trophic states and unique lentic habitats, namely soda pans. For running waters, the Specific Pollution Sensitivity Index (IPS) and for soda pans the H index and the Indice Biologique Diatomées (IBD) were calculated from the morphology- and sequence-based abundances. The ecological quality ratio was determined for running waters. Overall, more infrageneric taxa were found with microscopy than with metabarcoding in the lotic and lentic samples. The correspondence between taxon lists detected by the two methods was relatively low but increased considerably in the case of morphologically dominant taxa. Community composition based on microscopy and DNA sequence analysis showed a significant correlation and was determined by the same main environmental drivers. Morphology-based indices strongly correlated with sequence-based indices. Both aspects indicated the same ecological status class for more than half of the lotic samples. In other cases, a status shift from good to moderate was frequent, a phenomenon that could prove problematic because the Water Framework Directive prescribes intervention for waters with a moderate or worse status. Considering discrepancies between the results obtained with microscopy and metabarcoding, using both methods in parallel could be proposed until the reference database has been suitably updated.

The chemical ecology of rotifers has been little studied. A yet unknown property is presented within some monogonant rotifers, namely the ability to produce an exogenic filamentous biopolymer, named ‘Rotimer’. This rotifer-specific viscoelastic fiber was observed in six different freshwater monogonants (Euchlanis dilatata, Lecane bulla, Lepadella patella, Itura aurita, Colurella adriatica and Trichocerca iernis) in exception of four species. Induction of Rotimer secretion can only be achieved by mechanically irritating rotifer ciliate with administering different types (yeast cell skeleton, denatured BSA, epoxy, Carmine or urea crystals and micro-cellulose) and sizes (approx. from 2.5 to 50 µm diameter) of inert particles, as inductors or visualization by adhering particles. The thickness of this Rotimer is 33 ± 3 nm, detected by scanning electron microscope. This material has two structural formations (fiber or gluelike) in nano dimension. The existence of the novel adherent natural product becomes visible by forming a ‘Rotimer-Inductor Conglomerate’ (RIC) web structure within a few minutes. The RIC-producing capacity of animals, depends on viability, is significantly modified according to physiological- (depletion), drug- (toxin or stimulator) and environmental (temperature, salt content and pH) effects. The E. dilatata-produced RIC is affected by protein disruptors but is resistant to several chemical influences and its Rotimer component has an overwhelming cell (algae, yeast and human neuroblastoma) motility inhibitory effect, associated with low toxicity. This biopolymer-secretion-capacity is protective of rotifers against human-type beta-amyloid aggregates.