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As both food and source of a kappa-carrageenan, Hypnea musciformis represents a species of great economic interest. It also synthesizes substances with antiviral, anti-helminthic and anti-inflammatory potential and shows promise for use as a bioindicator of cadmium. In this study, we investigated the combined effects of seawater from three urbanized areas (area 1: natural runoff, NRA; area 2: urbanized runoff and sewage with treatment, RTA; area 3: urbanized runoff and untreated sewage, RUS) and three different temperatures (15, 25 and 30 °C) on the growth rate, photosynthetic efficiency, photosynthetic pigments and cell morphology of H. musciformis. After 4 days (96 h) of culture, the biomass of H. musciformis showed differences that fluctuated among the areas and temperature treatments. Specifically, the specimens cultivated in 35 °C had low values of ETRmax, α(ETR), β(ETR), and Fv/Fm photosynthetic parameters, as well as changes in cell morphology, with reduction in photosynthetic pigments and drastic reduction in growth rates. When combined with the extreme temperatures, high concentrations of ammonium ion in seawater effluent caused an inhibition of photosynthetic activity, as well as significant variation in chlorophyll a and carotenoid contents. As observed by light microscopy, the synergism between different temperatures and pollutants found in eutrophic waters caused changes in cellular morphology with increased cell wall thickening and decreased floridean starch grains. H. musciformis also showed important changes in physiological response to each factor independently, as well as changes resulting from the synergistic interaction of these factors combined. Therefore, we can conclude that extreme temperature combined with the effect of eutrophic waters, especially RUS, caused distinct morphological and physiological changes in the red alga H. musciformis.

The effect of ultraviolet (UV) radiation and copper (Cu) on apical segments of Pterocladiella capillacea was examined under two different conditions of radiation, PAR (control) and PAR+UVA+UVB (PAR+UVAB), and three copper concentrations, ranging from 0 (control) to 0.62, 1.25 and 2.50 μm. Algae were exposed in vitro to photosynthetically active radiation (PAR) at 70 μmol photons m(-2)  s(-1) , PAR + UVB at 0.35 W m(-2) and PAR +UVA at 0.70 W m(-2) during a 12-h photocycle for 3 h each day for 7 days. The effects of radiation and copper on growth rates, content of photosynthetic pigments and photosynthetic performance were analyzed. In addition, samples were processed for light and transmission electron microscopy. The content of photosynthetic pigments decreased after exposure to radiation and Cu. Compared with PAR radiation and copper treatments modified the kinetics patterns of the photosynthesis/irradiance curve. The treatments also caused changes in the ultrastructure of cortical and subcortical cells, including increased cell wall thickness and accumulation of plastoglobuli, as well as changes in the organization of chloroplasts. The results indicate that the synergistic interaction between UV radiation and Cu in P. capillacea, led to the failure of protective mechanisms and causing more drastic changes and cellular imbalances., (© 2014 The American Society of Photobiology.)

Recently, the application of copper oxide nanoparticles (CuO-NPs) has increased considerably, primarily in scientific and industrial fields. However, studies to assess their health risks and environmental impacts are scarce. Therefore, the present study aims to evaluate the toxicological effects of CuO-NPs on the duckweed species Landoltia punctata, which was used as a test organism. To accomplish this, duckweed was grown under standard procedures according to ISO DIS 20079 and exposed to three different concentrations of CuO-NPs (0.1, 1.0, and 10.0 g L(-1)), with one control group (without CuO-NPs). The toxicological effects were measured based on growth rate inhibition, changes in the plant's morphology, effects on ultrastructure, and alterations in photosynthetic pigments. The morphological and ultrastructural effects were evaluated by electronic, scanning and light microscopic analysis, and CuO-NPs were characterized using transmission electron microscopy (TEM), zeta potential, and superficial area methods of analysis. This analysis was performed to evaluate nanoparticle size and form in solution and sample stability. The results showed that CuO-NPs affected morphology more significantly than growth rate. L. punctata also showed the ability to remove copper ions. However, for this plant to be representative within the trophic chain, the biomagnification of effects must be assessed.