The effect of a reduction of nitrogen and phosphorus to eutrophic and mesotrophic conditions towards silver nanoparticle (AgNP) on freshwater green algae species

We investigated the sensitivity of algae towards silver nanoparticles with OECD test medium and lower nutrient concentrations under standard test conditions to improve comparability and to exclude any other confounding factor aside nutrient levels. Two unicellular freshwater microalgae Desmodesmus subspicatus and Raphidocelis subcapitata were chosen due to their status as standard test organisms for the algae growth inhibition test and the response to changes in nutrient supply was compared. The original medium was used as the reference (standard). For the other four media, the amount of either nitrogen or phosphorus in the medium was lowered from half (50%) to one-fourth (25 %) of that of the OECD guideline, resulting in the following media: 50% N, 25% N, 50% P and 25% P medium. As test substance, the OECD reference material NM-300K was used. For this reason, the characterization of AgNP was done using DLS and Absorption spectra (UV/vis). Actual silver concentrations and ionic silver concentrations were measured at the highest test concentration used (100 µg Ag L-1) in R. subcapitata treatments only to reduce the number of samples. All tests were run according to the OECD guideline 201 with sterilized 50 mL cell culture flask. Each medium was tested using the test conditions for culturing with 3 replicates. Test concentrations for both algae species were 0, 25, 50 and 100 µg Ag L-1 for OECD, 50% P and 25% P while for both N reductions, the silver concentrations were 0, 10, 25 and 100 µg Ag L-1. Samples for determining the algal density were taken at every 24 h.

Evaluation of green algae deployment for organic pollutant removal in urban wastewater through ERE-CALUX potency assessment

The interest of the scientific community towards organic pollutants in freshwater streams is fairly recent. During the past 50 years, thousands of chemicals have been synthesized and released into the general environment. Nowadays their occurrence and effects on several organism, invertebrates, fish, birds, reptiles and also humans are well documented. Because of their action, some of these chemicals have been defined as Endocrine Disrupters Compounds (EDCs) and the public health implications of these EDCs have been the subject of scientific debate. Most interestingly, among those that were noticed to have some influence and effects on the endocrine system were the estrone, the 17β-estradiol, the 17α-estradiol, the estriol, the 17α-ethinylestradiol, the testosterone and the progesterone. This project focused its attention on the 17β-estradiol. Estradiol, or more precisely, 17β-estradiol (also commonly referred to as E2) is a human sex hormone. It belongs to the class of steroid hormones. In spite of the effort to remove these substances from the effluents, the actual wastewater treatment plants are not able to degrade or inactivate these organic compounds that are continually poured in the ecosystem. Through this work a new system for the wastewater treatment was tested, to assess the decrease of the estradiol in the water. It involved the action of Chlorella vulgaris, a fresh water green microalga belonging to the family of the Chlorellaceae. This microorganism was selected for its adaptability and for its photosynthetic efficiency. To detect the decrease of the target compound in the water a CALUX bioassay analysis was chosen. Three different experiments were carried on to pursue the aim of the project. By analysing their results several aspects emerged. It was assessed the presence of EDCs inside the water used to prepare the culture media. C. vulgaris, under controlled conditions, could be efficient for this purpose, although further researches are essential to deepen the knowledge of this complex phenomenon. Ultimately by assessing the toxicity of the effluent against C. vulgaris, it was clear that at determined concentrations, it could affect the normal growth rate of this microorganism.

Dictyosphaerin: A novel bicyclic lipid from a southern Australian marine green algae, Dictyosphaeria sericea

The novel bicyclic lipid, dictyosphaerin (1), has been isolated from the southern Australian marine green alga Dictyosphaeria sericea. The molecular structure for 1 was secured by chemical derivatization and detailed spectroscopic analysis.

Ecotoxicity tests using the green algae chlorella vulgaris — a useful tool in hazardous effluents management

The treatment efficiency of laboratory wastewaters was evaluated and ecotoxicity tests with Chlorella vulgaris were performed on them to assess the safety of their environmental discharge. For chemical oxygen demand wastewaters, chromium (VI), mercury (II) and silver were efficiently removedby chemical treatments.Areduction of ecotoxicitywas achieved; nevertheless, an EC50 (effective concentration that causes a 50% inhibition in the algae growth) of 1.5% (v/v) indicated still high level of ecotoxicity. For chloride determination wastewaters, an efficient reduction of chromium and silver was achieved after treatment. Regarding the reduction of ecotoxicity observed, EC50 increased from 0.059% to 0.5%, only a 0.02% concentration in the aquatic environment would guarantee no effects. Wastewaters containing phenanthroline/iron (II) complex were treated by chemical oxidation. Treatmentwas satisfactory concerning chemical parameters, although an increase in ecotoxicitywas observed (EC50 reduced from 0.31% to 0.21%). The wastes from the kinetic study of persulphate and iodide reaction were treated with sodium bisulphite until colour was removed. Although they did not reveal significant ecotoxicity, only over 1% of the untreated waste produced observable effects over algae. Therefore, ecotoxicity tests could be considered a useful tool not only in laboratory effluents treatment, as shown, but also in hazardous wastewaters management.

Biodiversity of cyanobacteria and green algae on monuments in the Mediterranean Basin: an overview

Microbiology (2009), 155, 3476–3490

Blue-Green Algae, Iowa Department of Public Health - Division of Environmental Health, September 15, 2011

The Iowa Department of Public Health (IDPH), Division of Environmental Health, Health Assessment Program gives people information about harmful chemicals and organisms in their environment. Blue-green algae are microscopic organisms that are naturally present in lakes and streams. Some blue-green algae produce toxins that could pose a health risk to people and animals when they are exposed to them in large enough quantities. This fact sheet answers questions about blue-green algae.

Monostromatic green algae (Ulvales, Chlorophyta) of São Paulo and Paraná states (Brazil): distribution, growth, and reproduction

(Monostromatic green algae (Ulvales, Chlorophyta) of São Paulo and Paraná states (Brazil): distribution, growth, and reproduction). Culture studies were used for taxa identification and to understand aspects of the biology and physiology of monostromatic green blades growing in various sites along the coast of São Paulo state (23º30'-25ºl2'S, 45º10'-48ºW) and one site in Paraná state (25º35'S, 48º21'W), southeast and south Brazil, respectively. Possible variations of the growth rate, age of reproduction and life history were tested under different conditions of temperature, salinity and day length. Two species were found: Ulvaria oxysperma (Kützing) Bliding and Monostroma sp. The first one has been previously reported for many temperate and tropical estuaries around the world. Green monostromatic blades with the same life-history and ontogeny as Monostroma sp. have been reported so far only for the tropical coast of Brazil. Species are distinct in their ontogeny of the thallus (constant under different conditions) and limiting temperatures of survival. U. oxysperma grows and reproduces from 10 to 25ºC and dies when maintained at 30ºC; Monostroma sp. does not reproduce at 15ºC and survives at 30ºC. The different salinities and day lengths that were tested had no significant effect on either species.

Corticolous green algae from tropical forest remnants in the northwest region of São Paulo State, Brazil

The algae inhabit a wide variety of terrestrial environments and substrates; however the taxonomic knowledge for tropical regions is still scarce. This survey was conducted in ten forest remnants in São Paulo State where visible growths of algae and bryophytes were collected and studied for the main algal components of the communities. Results reveal the occurrence of nine species of green algae, distributed through the class Trebouxiophyceae (one species), Charophyceae (one species) and Ulvophyceae (seven species). Desmococcus olivaceus (Persoon ex Archerson) J. R. Laundon and Printzina effusa (Krempelhüber) Thompson & Wujek are new records for Brazil. The most frequent organisms found in the areas pertain to Trentepohliales that is mainly represented by Trentepohlia species. On the basis of results found, it is recommended that such communities receive more attention in future investigations to improve the knowledge about this important group of primary producers.

A comparison of the role of two blue-green algae in THM and HAA formation

The contribution of two blue-green algae species, Anabaeria flos-aquae and Microcystis aeruginosa, to the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was investigated. The experiments examined the formation potential of these disinfection by-products (DBPs) from both algae cells and extracellular organic matter (EOM) during four algal growth phases. Algal cells and EOM of Anabaena and Microcystis exhibited a high potential for DBP formation. Yields of total THMs (TTHM) and total HAAs (THAA) were closely related to the growth phase. Reactivity of EOM from Anabaena was slightly higher than corresponding cells, while the opposite result was found for Microcystis. Specific DBP yields (yield/unit C) of Anabaena were in the range of 2-11 mu mol/mmol C for TTHM and 217 mu mol/mmol C for THAA, while those of Microcystis were slightly higher. With regard to the distributions of individual THM and HAA compounds, differences were observed between the algae species and also between cells and EOM. The presence of bromide shifted the dominant compounds from HAAs to THMs. (C) 2009 Elsevier Ltd. All rights reserved.

Corticolous green algae from tropical forest remnants in the northwest region of São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of temperature, irradiance and photoperiod on growth and pigment content in some freshwater red algae in culture

The responses of relative growth rate (% day-1) and pigment content (chlorophyll a, phycocyanin and phycoerythrin) to temperature, irradiance and photoperiod were analyzed in culture in seven freshwater red algae: Audouinella hermannii (Roth) Duby, Audouinella pygmaea (Kützing) Weber-van Bosse, Batrachospermum ambiguum Montagne, Batrachospermum delicatulum (Skuja) Necchi et Entwisle, 'Chantransia' stages of B. delicatulum and Batrachospermum macrosporum Montagne and Compsopogon coeruleus (C. Agardh) Montagne. Experimental conditions included temperatures of 10, 15, 20 and 25°C and low and high irradiances (65 and 300 μmol photons m-2 s-1, respectively). Long and short day lengths (16:8 and 8:16 LD cycles) were also applied at the two irradiances. Growth effects of temperature and irradiance were evident in most algae tested, and there were significant interactions among treatments. Most freshwater red algae had the best growth under low irradiance, confirming the preference of freshwater red algae for low light regimens. In general there was highest growth rate in long days and low irradiance. Growth optima in relation to temperature were species-specific and also varied between low and high irradiances for the same alga. The most significant differences in pigment content were related to temperature, whereas few significant differences could be attributed to variation in irradiance and photoperiod or interactions among the three parameters. The responses were species-specific and also differed for pigments in distinct temperatures, irradiances and photoperiods in the same alga. Phycocyanin was generally more concentrated than phycoerythrin and phycobiliproteins were more concentrated than chlorophyll a. The highest total pigment contents were found in two species typical of shaded habitats: A. hermannii and C. coeruleus. The expected inverse relationship of pigment with irradiance was observed only in C. coeruleus. In general, the most favorable conditions for growth were not coincident with those with highest pigment contents.