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The discharge of pharmaceuticals via wastewater into the environment is a great concern due to the constant threat posed to photosynthetic organisms since they are vital for the sustenance of the aquatic food web. To compare the photosynthetic and growth responses of green algae to human antibiotics, Raphidocelis subcapitata and Chlorella vulgaris were exposed to erythromycin and sulfamethoxazole for 96 h. A much higher sensitivity was shown by Raphidocelis to the antibiotics. Although erythromycin was more acutely toxic to photosynthesis (EC50, 24.6 μg/L; EC10, 14.6 μg/L) than growth (EC50, 160 μg/L; EC10, 27 μg/L) in Raphidocelis, chronic effects in terms of EC10 were alike. Interestingly, sulfamethoxazole exhibited similar toxicity towards growth and photosynthesis with the acute and chronic toxicity parameters for growth (EC50, >2000 μg/L; EC10, 260 μg/L for Raphidocelis; and EC50, 47,900 μg/L; EC10, 19,100 μg/L for Chlorella) in consonance with those of photosynthesis (EC50, >2000 μg/L; EC10, 340 μg/L for Raphidocelis; and EC50, 47,500 μg/L; EC10, 13,400 μg/L for Chlorella). Growth and photosynthesis in Raphidocelis were strongly inhibited in this study at environmentally relevant concentrations of erythromycin. The findings from this study demonstrated that photosynthetic yield was a reliable indicator of sulfamethoxazole and erythromycin effects and thus, may be useful as an alternative approach to growth in assessing chronic toxicity in antibiotics.

Seven algal species were used to conduct toxicity assays with 12 herbicides to determine differences in species sensitivity. A fluorescence microplate toxicity assay was used as an efficient and economical high-throughput assay. The obtained toxicity data were standardized based on the species sensitivity distribution concept. The most-sensitive individual species differed among herbicides: Desmodesmus subspicatus was most sensitive to chloronitrofen and pendimethalin; Achnanthidium minutissimum was most sensitive to chlorpropham; Nitzschia palea was most sensitive to diquat, glyphosate, and dichlobenil; Navicula pelliculosa was most sensitive to trifluralin; and Pseudanabaena foetida was most sensitive to glufosinate, asulam, and 2,4-D. Surprisingly, Raphidocelis (formerly Pseudokirchneriella) subcapitata, a standard green alga, was not the most sensitive to any of the herbicides. The results clearly showed that a single algal species cannot represent the algal assemblage in terms of sensitivity. Therefore, multispecies algal toxicity data sets are essential for assessing the ecological effect of herbicides.

Huanglonbing, or citrus greening, is the most serious disease of citrus which cause large economic losses. One of the strategies to avoid the spread of the disease is the control of Diaphorina citri psyllid, its insect vector, by the application of insecticides. Development of nanoinsecticides, which are less harmful to the environment and more efficient (in terms of cost and performance) than the existing formulations, is a current challenge. In this work, nanocarriers composed of chitosan–tripolyphosphate (by ionic gelification approach) and poly-e-caprolactone (PCL)–chitosan (by double-emulsion–solvent evaporation method) for thiametoxam insecticide were developed and characterized. Toxicological assessments using Raphidocelis subcapta, Artemia salina and Caernohabditis elegans were performed comparing PCL–chitosan nanoparticle and PCL–chitosan loaded thiamethoxam in comparison to commercial pesticide. The nanoparticles obtained from optimized conditions resulted in positive charged nanoparticles, with medium dispersity. The double-emulsion method resulted in smaller nanoparticles (313.5 ± 7 nm) and increased encapsulation efficiency (36.6 ± 0.2%) in comparison to chitosan–tripolyphosphate nanoparticles. The lower encapsulation efficiency was observed in chitosan–tripolyphosphate, impairing agricultural applications. The EC50 values (mg L−1) of Raphidocelis subcapitata and C. elegans obtained for poly-e-caprolactone with thiamethoxam were 56.15 (18.91–131.21) and 66.07 (1.20–274.14), respectively, and poly-e-caprolactone without thiamethoxam 94.26 (22.42–166.10) and 214.63 (139.08–494.3), respectively. No toxicity was found in Artemia salina. Our results indicate that nanoparticles (with and without thiamethoxam) were more toxic to soil organisms (C. elegan) than commercial formulations.

Nanoparticles (NPs) often serve as carriers of background toxins and enhance their toxicity on aquatic organisms such as Ceriodaphnia dubia (C. dubia). However, foods, especially algae, are also present in natural water and impacts this type of toxicity. This study investigated the effect of algae on the combined toxicity of nano-TiO2 and lead (Pb). A mixture of yeast-trout chow-cereal leaves (YTC) was also used as another model food. Results indicated that, both algae and YTC significantly reduce the combined toxicity of nano-TiO2 and Pb. Further investigation indicated that the ingestion of algae had minimal impacts on Pb uptake by, Pb depuration from, and Pb distribution within the C. dubia. Therefore, the toxicity reduction from algae ingestion should come from mechanisms other than the change in Pb mass and speciation in C. dubia, which will need future investigation. Nevertheless, the effect of food on the mitigation of combined toxicity of NPs and heavy metals must be considered when assessing the toxicity of nanoparticles in the natural environment because food always exists in natural waterbodies where aquatic organisms grow.

Silver, known for its antibacterial properties and for its toxicity to aquatic organisms, is one of the most frequently used nanomaterials and silver nanoparticles can be found in a range of consumer products as well as medical applications. The present study investigated the toxicity of three different silver nanomaterials (Mesosilver (M-Ag), NM300K and NM302) and AgNO3, in the algae Raphidocelis subcapitata. Exposures in the low μg L−1 range were combined with characterization of exposure media to determine whether differences in toxicity could be linked to changes in Ag speciation and/or any nanospecific mechanisms. All tested Ag compounds, except the NM302, reduced growth in the following order AgNO3 ≥ M-Ag > NM300K > NM302 with 50% effect concentrations of 7.09 (3.83–10.52), 9.7 (range not calculated) and 24.18 (15.66–98.16) μg L−1, for AgNO3, Mesosilver and NM300K, respectively. Characterization of exposure media showed that both concentration and time influenced the speciation and stability of Ag in algal test media, regardless of Ag source, and also affected the toxicity to R. subcapitata. In both AgNO3 and Mesosilver exposure the toxicity was correlated with the presence of dissolved Ag species (

Gold nanorods (AuNRs) are promising nanoscale materials for several technological and biomedical applications. The physicochemical properties of AuNRs, including size, shape and surface features, are crucial factors affecting their cytotoxicity. In this study, we investigated the effects of different aspect ratios of AuNRs (1.90, 2.35, 3.25 and 3.50) at concentrations of 2 and 10 μg mL−1 on their cytotoxicity and cellular uptake in green algae Raphidocelis subcaptata. The experiment was performed in oligotrophic freshwater medium in a growth chamber with constant agitation of 80 rpm under controlled conditions (120 μEm−2s−1 illumination; 12:12h light dark cycle and constant temperature of 22 ± 2 °C). The algal growth was monitored daily for 96 h via electronic absorbance scanning at 600–750 nm. Oxidative stress, cell viability and autofluorescence were evaluated using a flow cytometer. Oxidative stress quantified by loading cultures with the fluorescent dye 2′, 7′-dichlorofluorescein diacetate. To assess algal cell viability, propidium iodide was selected as the fluorescent probe. Our results indicated that the aspect ratio of AuNRs mediates their biological effects in green algae R. subcaptata. A positive correlation between oxidative stress and increase of aspect ratio was found at concentration of 10 μg mL−1. Higher cytotoxicity and mortality were observed for algae incubated with higher aspect ratios AuNRs (3.50). These findings may be useful to understand the impact of the AuNRs in aquatic environments, contributing to ecosystem management and nanomaterials regulation.

The generic concept of coccoid green algae exhibiting a crescent-shaped morphotype is evaluated using SSU rRNA gene sequence analyses and light and electron microscopical observations. These common chlorophytes evolved polyphyletically in 10 different clades of the Chlorophyceae and three clades of the Trebouxiophyceae. Six clades are assigned to known genera of Selenastraceae: Kirchneriella, Nephrochlamys, Raphidocelis, Rhombocystis, Selenastrum, and Tetranephris. Four other clades, named following their present genus designation as Ankistrodesmus-like I and II and Monoraphidium-like I and II, require further investigation. One crescent-shaped morphotype, which evolved within the Trebouxiophyceae, is designated as Neocystis mucosa sp. nov. The other two lineages containing trebouxiophycean algae with this morphotype are the Elliptochloris and the Watanabea clades. The taxonomic placement of the widely used bioassay strain "Selenastrum capricornutum" NIVA-CHL 1 in the genus Raphidocelis (species name Raphidocelis subcapitata) is indicated by molecular data.

Isolates of the genera Monoraphidium Kom.-Legn., Ankistrodesmus Corda and Raphidocelis Hindak emend. Marvan et al. were cultured from two areas in Minnesota and North Dakota, USA. These isolates were identified to species level (when possible), using light microscopy and standard monographs and then characterized by 18S rDNA sequence analysis. Phylogenetic analyses indicated that in some cases, 18S rDNA sequences from these isolates were very similar, but not identical to the sequences of other isolates of the same morphospecies from different parts of the world. However, some isolates that were identified as the same species actually belong to different lineages within the Selenastraceae, whereas other isolates with identical or nearly identical 18S rDNA sequences possessed rather different morphologies. Overall, our data suggest that the application of a broad morphospecies concept to the Selenastraceae has resulted in an underestimation of the species diversity of this family and probably erroneous conclusions about the distribution of species.

Toxicities of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were tested using growth miniaturized algal bioassay with Chlorella kessleri, Raphidocelis subcapitata (= Selenastrum capricornutum), Scenedesmus quadricauda and Scenedesmus subspicatus. Toxicity hierarchy for all organisms, according to their mean values is: Cd> Co> Cr> Cu> Pb> Ni> Zn> Al> Fe. The sensitivity hierarchy is: Raphidocelis >Scenedesmus subspicatus > Chlorella > Scenedesmus quadricauda. The most toxic element was Cd, which was the first in toxicity hierarchy for all tested organisms. Cd has a gradual toxic curve, and has showed no stimulation, similar to Pb. Scenedesmus quadricauda showed a peak shape of growth curve with stationary phase about 300 h. Another algae showed prolonged and approximately stabile stationary phase in the period of 300-700 h, under PhAR 180 μE.m -2 . s -1 , (40 W.m -2 ) 30°C, and CO 2 supply ca 2% (v/v).

Scientific research using nanotechnology is a relatively recent development with a variety of potential applications in many fields of science. Within this field of research, many new products, with improved performances, have been developed. Despite increased research on its toxicity to ecosystem, the knowledge about this area is still limited. To evaluate the toxicity and genotoxicity of different sizes silica nanoparticles (SiNP)to the environment, different species, on different trophic levels (Vibrio fisheri, Raphidocelissubcapitata, Daniorerio and Allium cepa) were exposed to TM40 (22 nm), HS30 (12 nm), SM30 (7 nm) with concentrations ranging from0.19 to 163.8 g/L (TM40) and 0.29 to 122.85 g/L (HS30 and SM30), and the following parameters were monitored during exposure: production of bioluminescence (V. fischeri), growth rate (R. subcapitata), embryonic development and DNA damage (D. rerio) and germination rate, growth and DNA damage (A. cepa). Within each test SiNPpresent a size dependent chronic toxicity. The bioluminescence test present a EC50 of 29.11, 32.34 and 4.58 g/L for TM40, HS30 and SM30, respectively. For the growth rate assay the EC50 was 9.32, 9.07 and 7.93 g/L for TM40, HS30 and SM30, respectively. And for the zebra fish embryonic development test for TM40, HS30 and SM30, the EC50 was 5.85, 1.13 and 2.68 g/L respectively. All particles also induce phytotoxicity in A.cepa, growth and germination reduce significatively when expose to SiNP. Futhermoregenotoxic effects were also induced by the particles for both A.cepaand D. rerio. Therefore, SiNP can cause toxicity to the environment and size can strongly influence this toxicity Com uma variedade de aplicações potenciais, em diversos campos da ciência, as pesquisas científicas utilizando nanotecnologia são de desenvolvimento relativamente recente. Dentro deste campo de pesquisa, vários novos produtos, com desempenhos melhorados têm sido desenvolvidos. Apesar do aumento de pesquisas sobre a toxicidade dessas tecnologias à biota, o conhecimento sobre esta área ainda é limitado. Visando avaliar a toxicidade e genotoxicidade denanopartículasde sílica (SiNP) no meio ambiente diferentes espécies pertencentes a diversos níveis tróficos (Vibriofisheri, Raphidocelissubcapitata, DaniorerioandAllium cepa) foram expostos a Ludox TM40 (22 nm), Ludox HS30 (12 nm) e Ludox SM30 (7 nm). As espécies de teste foram expostas a concentrações de nanopartículas (NP) variando de 0.29 a 163.8 g/L (TM40) e 0.19 a 122.85 g/L (HS30 e SM30) e os seguintes parâmetros monitorizados durante a exposição: a produção de bioluminescência (V. fischeri), o crescimento taxa (R. subcapitata), inibição de alimentação (D. magna), desenvolvimento embrionário e dano ao DNA (D. rerio) e taxa de germinação, crescimento e danos ao DNA (A. cepa). Nos testes feitos com as SiNPfoi observado que a toxicidade é dependente do tamanho da partícula. O ensaio de bioluminescência apresentou um EC50 de 29.11, 32.34 e 4.58 g/L para TM40, HS30 e SM30, respectivamente. Para o ensaio de taxa de crescimento o EC50 foi 9.32, 9.07 e 7.93 g/Lpara TM40, HS30 e SM30, respectivamente. E para o teste de desenvolvimento embrionário com peixe zebra, para o TM40, HS30 e SM30 o EC50 foi de 5.85, 1.13 e 2.68g/L, respectivamente. Todas as partículas também induziram fitotoxicidade em A. cepa, crescimento e germinação reduziram significativamente quando o organismo foi exposto a SiNP. Efeitos genotóxicos também foram induzir pelas partículas, tanto para A. cepa quanto paraD. rerio. Portanto, as SiNP podem causar toxicidade ao ambiente e o tamanho pode influenciar fortemente a essa toxicidade

Heat-shock proteins (Hsp) or stress proteins are strong candidates for biomarkers of environmental pollution since they are activated very early in the cascade of cellular events that follow toxic exposure and at concentrations below the lethal dose. Included in a test battery comprised of different bioassays, Hsp induction could provide a general purpose tier I indicator of pollution. Still, little is known on the induction of Hsp under different environmental conditions. In the present study we have made use of an Enzyme Linked Immunosorbent Assay (ELISA) to detect the synthesis of Hsp70 in Raphidocelis subcapitata in response to changes in pH, temperature, humic acids, nitrates and phosphates. The results show that algae respond to these changes in the environment by a transient increase in Hsp70 levels, the extend of which is dependent on the actual parameter under investigation. Out of these five parameters studied, only temperature and possibly pH were able to induce acquired tolerance, i.e. algae grown at a pH or at a temperature different from control conditions were shown to have acquired resistance to a subsequent challenge with Zn (10 −5 M). Adjustment of the pH and temperature in two physico-chemically different natural surface waters was demonstrated to be sufficient to obtain similar induction patterns of Hsp70 upon exposure to zinc. These results qualify Hsp70 as a good biomonitor for environmental pollution provided essential environmental parameters such as pH and temperature are kept constant.

Svrha je ovog rada odrediti osjetljivost vrsta na parametre za koje se u današnjim istraživanjima i rutinskim analizama ustanovilo da najjače koreliraju s mortalitetom, odnosno inhibicijom rasta. Metodama multivarijantne statističke analize utvrđen je utjecaj svakog izmjerenog parametra na rezultate testiranja, te sličnosti i različitosti organizama. Utvrđeni su optimalni uvjeti sustavnog testiranja za uspješnije donošenje procjene ekološkog rizika na temelju rezultata primijenjenih testova.

Brominated flame retardants belong to a new class of environmental contaminants. To obtain new information regarding the effects of 2,2',4,4',5-brominated diphenyl ether (BDE-99), one of the most frequently reported congeners in freshwater biota, the inhibition of algal growth of Raphidocelis subcapitara (also known as Selenastrum capricornutum) and acute toxicity to Daphnia magna were examined. The experimental design also involved a comparison with the polychlorinated biphenyl (PCB) Aroclor 1254. The uptake of BDE-99 by R. subcapitata and the transfer to D. magna (i.e., a higher level of aquatic biota in the food chain) was also assessed to verify the bioaccumulation phenomenon. After 24 h, BDE-99 appeared to be less toxic than Aroclor 1254 to D. magna, but the two compounds showed a similar toxicity at 48 h. In contrast to Aroclor 1254, BDE-99 was nontoxic to R. subcapitata at up to 100 microM, the highest tested concentration. However, the dose-dependent decrease in survival and impairment of reproduction of D. magna fed with BDE-99-treated algal culture demonstrate uptake by R. subcapitata. Because of the high persistence and bioconcentration, polybrominated diphenyl ethers as well as PCBs might be of environmental concern for years.

Summary Three new species of coccal green algae Amphikrikos heynigii (Chlorellaceae), Coenochloris granulata (Radiococcaceae), and Raphidocelis pseudomucosa (Selenastraceae) are described. The morphological characteristics and ontogeny of these algae are presented and discussed.