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[Display omitted] • H. rivularis spread very widely in Europe during recent decades. • H. rivularis is no longer a simple indicator for oligotrophic ecosystems. • H. rivularis occurs mainly in habitats with eu- and hypertrophic waters. • H. rivularis is a poor indicator of the good ecological status of waters. • Classification of H. rivularis as an endangered species in Poland is unfounded. Our knowledge about the size of benthic red alga populations inhabiting European freshwater ecosystems is still insufficient. For many years, in Europe, Hildenbrandia rivularis (Rhodophyta, Hildenbrandiaceae) was believed to be a very rare species of crustaceous red algae, valuable for oligotrophic system biomonitoring. In this paper, we challenge this assumption and show the phenomenon of H. rivularis expansion (i.e., from mountains and highlands to lowlands) in Europe based on detailed data from Poland. We collected over 311 records of H. rivularis occurring in rivers, streams and lakes (not typical habitats for this alga) across the country, including historical data. Here, we show the detailed distribution of this endangered species in Poland, one of the largest European countries. To examine the mechanism of H. rivularis population expansion, physicochemical data from 122 aquatic ecosystems were investigated. A comparison between three subperiods (1860–1944, 1945–1999, and 2000–2019) revealed an increase in the average abundance of the H. rivularis population in the lowlands area. However, the studied species seems to be disappearing in mountain and upland ecosystems. We found altitude and water flow and quality (i.e., alkalinity, oxygenation and biogens) to be the main determinants of H. rivularis occurrence within the study area. The results indicate that this red alga can be described as an expansive species, and its occurrence does not always indicate good water quality and fast water flow. Surprisingly, in contrast to observations from the last century, the population of H. rivularis in Poland currently occurs mainly in habitats with eu- and hypertrophic waters. We point out here that in the zone with temperate climate influence, H. rivularis is no longer an obvious indicator for oligotrophic ecosystems. We suggest that climate warming and eutrophication–reoligotrophication may have contributed to the increased spread of H. rivularis in Europe over recent decades. In addition, we see no reason to classify H. rivularis as an endangered species in Poland. This species most often inhabits anthropogenic water systems and occurs at high abundance in waters with high concentrations of biogens. For these reasons, H. rivularis is more ubiquitous than a cosmopolitan species (i.e., with a wide range of occurrence but associated with only a specific type of habitat and specific environmental parameters). Thus, the value of H. rivularis as a bioindicator for oligotrophic water ecosystems is very low. [ABSTRACT FROM AUTHOR]

Recent global spread of the freshwater alga Didymosphenia geminata (Didymo) has caused major biosecurity and freshwater management concerns. Didymo degrades river esthetics, alters ecosystems, negatively impacts recreation experiences and may require strict containment measures. This paper assesses the impact of Didymo on nonmarket values for recreational angling using a case study from New Zealand, where Didymo is extraordinarily prolific. Choice experiment data are used to fit a latent class model, identifying five distinct angler preference profiles. For the largest class of anglers the presence of Didymo had no significant effect on angling benefits. However, other classes were negatively affected. Overall, Didymo reduced fishing values by about NZ$44 per visit. Anglers were sensitive to the scale of Didymo infestation, suffering significantly higher costs when more water bodies are affected. Closure of Didymo-infected mainstem-rivers to prevent spread of Didymo resulted in a significant reduction in angler net benefits, even if the policy were 100% effective. The latent class model identified distributional implications. While three angler classes would not have significantly different benefits if mainstem-rivers were closed to prevent the spread of Didymo, two classes of anglers would be highly impacted by such a policy, particularly those who regularly fish mainstem-rivers for salmon. [Copyright &y& Elsevier]

Abstract: In this paper, the multifaceted Cr(VI) toxicity over the freshwater green alga Monoraphidium convolutum was assessed by concomitantly monitoring thiol-dependent redox balances, photosynthesis activity and growth-survival scores. Control group showed exponential growth rate at (5.78±0.29) division/day until 8th day with linear increasing chlorophyll a/protein ratios (CHLa/PROT) throughout the period. Cultures of M. convolutum were exposed for 5 days to Cr(VI) concentrations from 0 up to 100mg/L showing that CHLa/PROT ratios were sensibly affected, in agreement to the calculated LC50,48h (5.38±0.72)mg/L from the concentration-response curve of cell mortality after 48h. Regarding photosynthesis effects, Cr(VI) concentrations >1.0mg/L showed significant increases in short-term (after 2h) electron transfer rates (ETR) and quantum yields of photosystem II (Φ PSII), followed by subsequent decline of both parameters after 48 and 72h. Biochemical analyses showed that maximal GSH concentrations in algal cultures were observed upon 1mg Cr(VI)/L and higher dichromate concentrations dramatically increased the activity of antioxidant GSH-dependent enzymes ascorbate peroxidase and glutathione reductase. However, no variation was observed in the cellular GSH levels, whereas GSSG and lipid peroxidation indexes abruptly increased upon 10mg Cr(VI)/L exposure. Altogether, plant physiology, photosynthesis and biochemical data suggest that the GSH-dependent antioxidant system is capable to sustain M. convolutum viability through efficient photosynthesis activity and adequate antioxidant responses up to Cr(VI) concentrations of 1.0mg/L, when redox unbalances were first evidenced. [Copyright &y& Elsevier]

Abstract: The combination of microalga-based biodiesel production and wastewater treatment is a promising approach to solve problems related to the energy crisis as well as eutrophication in bodies of water. A freshwater microalga, Chlorella ellipsoidea YJ1, with a high capacity for biomass production and lipid accumulation in secondary effluent was isolated. C. ellipsoidea YJ1 could achieve a biomass of 425mgL−1 (dry weight) in domestic secondary effluent treated with activated sludge technology; and the lipid content per unit of algal biomass was as high as 43% (w/w) in this condition. The lipid growth rate of C. ellipsoidea YJ1 in domestic secondary effluents could attain 11.4mg/L. Furthermore, after the cultivation of C. ellipsoidea YJ1, the removal efficiencies of nitrogen and phosphorus from the secondary effluent studied in this paper were more than 99% and 90%, respectively. Logistic and Monod models were used successfully to simulate the growth of C. ellipsoidea YJ1, and its maximum biomass and maximum population growth rate under different initial concentrations of nitrogen and phosphorus could be simulated and predicted using the models. . [Copyright &y& Elsevier]

Coastal morphodynamics and environmental changes have been obviously altered by global warming, sea-level fluctuations, and human activities. Palynological analysis is one of the most important tools for providing information on vegetation, climate, and environmental change, which can be relatively sensitive indicators of human activity during the Holocene. However, Holocene coastal morphodynamics and palynological evidence from the Pearl River Delta and coastal areas has not been sufficiently studied. In this paper, we carry out analyses using detailed grain-size and palynological records of pollen, spores, freshwater algae, and marine dinoflagellate cysts from Borehole QZK13 in the Pearl River Estuary (PRE), southern China. The results show information relating coastal morphodynamics, vegetation evolution, climate changes, and anthropogenic activities during the Holocene based on radiocarbon chronology. In general, the PRE experienced marine transgressive processes; sea-level and the coastline tended to migrate landward between 10,700 and 4250 cal yr BP. Meanwhile, abundant arboreal pollen (mainly Castanopsis , Quercus -evergreen, Oleaceae, and Castanea) and small amounts of non-arboreal pollen (mainly Poaceae, Cyperaceae, and Artemisia) were observed in Borehole QZK13, which suggests that subtropical evergreen broadleaved forests were distributed throughout the PRE and adjacent areas, and relatively warm and moist climatic conditions were present during the early-middle Holocene. After that, there were relatively cool and wet climatic conditions, and marine regressive processes occurred in the PRE during the Late Holocene (ca. 4250–960 cal yr BP) indicated by an abrupt increase in aquatic herbs and Dicranopteris. Moreover, we hypothesize that the Neolithic "cultural fault" in the PRE is likely related to frequent storm surges induced by extreme typhoon events that occurred ca. 3000–2700 yr BP. • Grain size, pollen, spores, freshwater algae and dinoflagellate cysts from the Pearl River Estuary were investigated. • Three major phases shown by palynological results were corresponding to the changes in vegetation and climate. • We hypothesized that the Neolithic "cultural fault" is probably related to the storm surges induced by extreme typhoon events. • Natural vegetation cover has suffered large-scale destruction by ancient humans during the Late Holocene. [ABSTRACT FROM AUTHOR]

Abstract: Precious ecological information extracted from limnological long-term time series advances the theory on functioning and evolution of freshwater ecosystems. This paper presents results of applications of artificial neural networks (ANN) and evolutionary algorithms (EA) for ordination, clustering, forecasting and rule discovery of complex limnological time-series data of two distinctively different lakes. Ten years of data of the shallow and hypertrophic Lake Kasumigaura (Japan) are utilized in comparison with 13 years of data of the deep and mesotrophic Lake Soyang (Korea). Results demonstrate the potential that: (1) recurrent supervised ANN and EA facilitate 1-week-ahead forecasting of outbreaks of harmful algae or water quality changes, (2) EA discover explanatory rule sets for timing and abundance of harmful outbreaks algal populations, and (3) non-supervised ANN provide clusters to unravel ecological relationships regarding seasons, water quality ranges and long-term environmental changes. [Copyright &y& Elsevier]

The effects of cypermethrin, a commonly used pyrethroid insecticide, were studied in small in situ enclosures situated in an eutrophic lake over an 11-day period. The experimental design used a regression principle that included three untreated controls and a gradient of six unreplicated cypermethrin concentrations, ranging from 0.01 to 6 μg/l. This paper is the second in a series of two and describes the effects on the species composition of the crustacean, rotifer, periphyton and phytoplankton communities. Multivariate ordination technique (redundancy analysis (RDA) combined with Monte Carlo permutation tests) showed that exposure to cypermethrin caused significant changes in the species composition of the communities. Changes in the structure of the communities were observed following exposure to a nominal concentration of 0.13 μg cypermethrin per litre above. The direct acute effect of exposure to cypermethrin was a rapid decrease of many species of crustacean zooplankton. The alterations in crustacean species composition were probably due to variations in susceptibility to the direct toxic effects of cypermethrin. No effects concentration (NEC) for individual zooplankton species were calculated using inverse regression and revealed that copepod nauplii were the most sensitive (NEC=0.01 μg/l) of the crustacean groups examined. The observed alterations of the species composition of the autotrophic communities as well as of the rotifers were most likely caused indirectly by cypermethrin, mediated through the direct negative effects of the insecticide on the crustacean grazers. The results of this experiment provide further knowledge about the direct and indirect effects of pesticide stress on the ecosystem level. They also show that there is a variation in sensitivity between different species of zooplankton under natural conditions and thus exemplify the necessity of multispecies approaches in the risk assessment of pesticides. [Copyright &y& Elsevier]

Antibiotics in water and wastewater have been determined extensively. The treatment of antibiotics in water needs evaluation of possible harmful effects on aquatic ecosystems and human health. This paper presents the toxicity evaluation of antibiotics after their treatment with ferrate (VI) (FeVIO 4 2−, Fe(VI)) in water. The antibiotics (sulfamethoxazole (SMX), erythromycin (ERY), ofloxacin (OFL), ciprofloxacin (CIP), tetracycline (TET), oxytetracycline (OXY), and trimethoprim (TMP)) were treated at pH 8.0 by applying two concentrations of Fe(VI) to have molar ratios of 5:1 and 10:1 ([Fe(VI)]:[antibiotic]). Under the studied conditions, incomplete removal of antibiotics was observed, suggesting that the treated solutions contained parent antibiotics and their transformation products. The toxicity of antibiotics without Fe(VI) treatment was tested against freshwater green alga Raphidocelis subcapitata and cyanobacterium Synechococcus elongatus , which were determined to be generally sensitive to antibiotics, with EC 50 < 1.0 mg/L. The toxicity of Fe(VI) treated solution was tested against R. subcapitata. Results found no toxicity for the treated solutions of OFL, CIP, and OXY. However, SMX, ERY, and TET remained toxic after Fe(VI) treatment (i.e., more than 75% growth inhibition of R. subcapitata). Results demonstrated that R. subcapitata may be applied to test the toxicity of antibiotics after oxidative treatments. [Display omitted] • Studied antibiotics have EC 50 < 1.0 mg/L against R. subcapitata and S. elongatus. • Excess Fe(VI) compared to antibiotics has high removal efficiency at pH 8.0 • Excess Fe(VI) treatment of antibiotics gave varied decreases in algal toxicity. • OFL, CIP, and OXY lose algal toxicity after excess Fe(VI) treatment. • SMX, ERY, TET, and their degradation byproducts remain toxic after Fe(VI) treatment. [ABSTRACT FROM AUTHOR]

Abstract: Microalgae have received much attention for the inorganic nutrient removal in tertiary treatment of domestic wastewater. Effect of different kinds of nitrogen sources on the growth and nitrogen/phosphorus removal properties of a newly isolated freshwater microalga, Scenedesmus sp. LX1, from a low-nutrient environment condition was studied and reported in this paper. The order of specific growth rate of the microalga with different nitrogen sources was NH4-N>urea-N>NO3-N. With nitrate or urea as nitrogen source, the microalga could grow well and remove both nitrogen and phosphorus efficiently (90% nitrogen and nearly 100% phosphorus were removed). However, with ammonium as the nitrogen source, the maximum algal density was relatively low, and the nitrogen and phosphorus removal efficiencies were as low as 31.1% and 76.4%, respectively. This was caused by the inhibitory effect of algal culture''s acid pH due to H+ releasing from NH4 + during algal cultivation process. [Copyright &y& Elsevier]