RESUMEN
The potential ecotoxicological hazard of gaphene oxide (GO) is not fully clarified for photoautotrophic organisms, especially when the interactions of GO with other environmental toxicants are considered. The objective of the current study was to better understand the mechanisms of toxicity of GO in the cyanobacteria Microcystis aeruginosa, and to identify its interactions with cadmium (Cd). The individual and combined contribution of both pollutants in cyanobacteria were evaluated after 96 hours of exposure to GO and/or Cd, using photosynthetic pigments, photosynthetic parameters, cellular indicators of peroxidative damage, viability, and intracellular ROS formation as indicators of toxicity. Interactions between GO and Cd were evaluated using Toxic Units based on the EC50 of each parameter evaluated. The results of this study indicate that single concentrations ≥ 5 µg mL-1 of GO and ≥ 0.1 µg mL-1 of Cd induced a decrease in cell biomass and a change in the photosynthetic parameters associated with primary productivity in M. aeruginosa. In the combined experiments, higher GO ratios (≥ 9.1 µg mL-1) in terms of Toxic Units decreased photochemical processes and cellular metabolism, increased oxidative stress, and ultimately affected the size of M. aeruginosa. Finally, the relationship between GO concentration, Cd concentration, and the adsorption capacity of GO with respect to the co-pollutant must be taken into account when assessing the environmental risk of GO in aquatic environments.
Asunto(s)
Cianobacterias , Microcystis , Contaminantes Químicos del Agua , Microcystis/metabolismo , Cadmio/metabolismo , Contaminantes Químicos del Agua/toxicidad , Fotosíntesis , Estrés Oxidativo , Cianobacterias/metabolismo , Óxidos/metabolismoRESUMEN
The cellular capacity of marine organisms to address rapid fluctuations in environmental conditions is decisive, especially when their bathymetric distribution encompasses intertidal and subtidal zones of estuarine systems. To understand how the bathymetric distribution determines the oxidative damage and antioxidant response of the estuarine anemone Anthopleura hermaphroditica, individuals were collected from upper intertidal and shallow subtidal zones of Quempillén River estuary (Chile), and their response analysed in a fully orthogonal, multifactorial laboratory experiment. The organisms were exposed to the effects of temperature (10°C and 30°C), salinity (10 ppt and 30 ppt) and radiation (PAR, > 400-700 nm; PAR+UV-A, > 320-700 nm; PAR+UV-A+UV-B, > 280-700 nm), and their levels of lipid peroxidation, protein carbonyl and total antioxidant capacity were determined. The results indicated that the intertidal individuals of A. hermaphroditica presented higher levels of tolerance to the stressful ranges of temperature, salinity, and radiation than individuals from the subtidal zone, which was evident from their lower levels of oxidative damage to lipids and proteins. These results were consistent with increased levels of total antioxidant capacity observed in subtidal organisms. Thus intertidal individuals could have greater plasticity to environmental variations than subtidal individuals. Future studies are needed to understand the mechanisms underlying stress adaptation in individuals from this estuarine anemone subjected to different environmental stressors during their life cycles.
Asunto(s)
Anemone , Humanos , Antioxidantes , Estuarios , Aclimatación , TemperaturaRESUMEN
The pesticide azamethiphos used by the salmon industry to treat sea lice, is applied as a bath and subsequently discharged into the sea. The effects of azamethiphos concentration (0, 15 and 100 µg L-1) on the physiology of the Chilean oyster (Ostrea chilensis) at two temperatures (12 and 15 °C) was examined. In all azamethiphos treatments, oysters kept at 15 °C had clearance rates (CR) higher than oysters kept at 12 °C. The oxygen consumption rate (OCR) increased at higher temperatures, except with 100 µg L-1 of azamethiphos, where no changes were observed. Sixty days after the exposure, survival rates of 91 and 79% (15 and 100 µg L-1, respectively), were observed compared to the controls, a situation independent of the experimental temperature. The interaction between temperature and pesticide has detrimental effects on the physiological performance and survival of O. chilensis, and these effects should also be assessed for other non-target species.
Asunto(s)
Ostrea , Plaguicidas , Animales , Plaguicidas/toxicidad , Temperatura , Organotiofosfatos/toxicidadRESUMEN
Anthopleura hermaphroditica is an intertidal anemone that lives semi-buried in soft sediments of estuaries and releases its brooded embryos directly to the benthos, being exposed to potentially detrimental ultraviolet radiation (UVR) levels. In this study, we investigated how experimental radiation (PAR: photosynthetically active radiation; UVA: ultraviolet A radiation; and UVB: ultraviolet B radiation) influences burrowing (time, depth and speed) in adults and juveniles when they were exposed to PAR (P, 400-700 nm), PAR + UVA (PA, 315-700 nm) and PAR + UVA + UVB (PAB, 280-700 nm) experimental treatments. The role of sediment as a physical shield was also assessed by exposing anemones to these radiation treatments with and without sediment, after which lipid peroxidation, protein carbonyls and total antioxidant capacity were quantified. Our results indicate that PAB can induce a faster burial response compared to those anemones exposed only to P. PAB increased oxidative damage, especially in juveniles where oxidative damage levels were several times higher than in adults. Sediment offers protection to adults against P, PA and PAB, as significant differences in their total antioxidant capacity were observed compared to those anemones without sediment. Conversely, the presence or absence of sediment did not influence total antioxidant capacity in juveniles, which may reflect that those anemones have sufficient antioxidant defenses to minimize photooxidative damage due to their reduced tolerance to experimental radiation. Burrowing behavior is a key survival skill for juveniles after they have been released after brooding.
RESUMEN
Ocean contamination mostly comes from anthropogenic contamination in watercourses. However, what happens in desert areas where watercourses are few or nonexistent? Are these coastal areas exempt from contamination? Do the remote locations of desert areas enable pristine coastal areas? Atacama is widely known for its desert aridity and mining resources; however, human impacts in its coastal areas have not been widely studied. Coastal zone uses of this region of Chile were analyzed per province in relation to the population settlements and economic activities on the coastal edge. This study includes a review of the contamination in this desert coastal area in relation to the territorial organization, activities, and land uses. The results determined that most of the coastal edge was used for fishing and aquaculture (52%) and for conservation and protected areas (39%). However, 2% of the coastal edge was susceptible to conflicts due to shared uses. A strong lack of scientific research was detected despite environmental interest (Humboldt Current, diversity hot spots, desert blooming, algae kelps, protected areas, etc.) and economic development (impact of mining, agriculture and tourism) in the area. Most studies focused on metal concentrations in aquatic environments in the north part of the region. Studies on emerging contaminants have not been carried out in the area despite intense human settlement.
Asunto(s)
Desarrollo Económico , Efectos Antropogénicos , Acuicultura , Chile , Conservación de los Recursos Naturales , Clima Desértico , Humanos , CazaRESUMEN
In photosynthetic microorganisms, the toxicity of carbon nanomaterials (CNMs) is typically characterized by a decrease in growth, viability, photosynthesis, as well as the induction of oxidative stress. However, it is currently unclear how the shape of the carbon structure in CNMs, such as in the 1-dimensional carbon nanotubes (CNTs) compared to the two-dimensional graphene oxide (GO), affects the way they interact with cells. In this study, the effects of GO and oxidized multi-walled CNTs were compared in the cyanobacterium Microcystis aeruginosa to determine the similarities or differences in how the two CNMs interact with and induce toxicity to cyanobacteria. Using change in Chlorophyll a concentrations, the effective concentrations inducing 50% inhibition (EC50) at 96 h are found to be 11.1 µg/mL and 7.38 µg/mL for GO and CNTs, respectively. The EC50 of the two CNMs were not found to be statistically different. Changes in fluorescein diacetate and 2',7'-dichlorodihydrofluorescein diacetate fluorescence, measured at the EC50 concentrations, suggest a decrease in esterase enzyme activity but no oxidative stress. Scanning and transmission electron microscopy imaging did not show extensive membrane damage in cells exposed to GO or CNTs. Altogether, the decrease in metabolic activity and photosynthetic activity without oxidative stress or membrane damage support the hypothesis that both GO and CNTs induced indirect toxicity through physical mechanisms associated with light shading and cell aggregation. This indirect toxicity explains why the intrinsic differences in shape, size, and surface properties between CNTs and GO did not result in differences in how they induce toxicity to cyanobacteria.
Asunto(s)
Grafito , Microcystis , Nanotubos de Carbono , Clorofila A , Grafito/toxicidad , Nanotubos de Carbono/toxicidadRESUMEN
Anthropogenic CO2 emissions have led to ocean acidification and a rise in the temperature. The present study evaluates the effects of temperature (10, 15 and 20 °C) and pCO2 (400 and 1200 µatm) on the early development and oxygen consumption rate (OCR) of the sea louse Caligus rogercresseyi. Only temperature has an effect on the hatching and development times of nauplius I. But both factors affected the development time of nauplius II (Asunto(s)
Copépodos
, Phthiraptera
, Animales
, Dióxido de Carbono/toxicidad
, Concentración de Iones de Hidrógeno
, Agua de Mar
, Temperatura
RESUMEN
The copepod Caligus rogercresseyi is an ectoparasite of several salmonid species. The pumping activity of filter-feeding molluscs could reduce the abundance of copepod dispersive larval stages in the water column. In this research, nauplius II and copepodid larvae of C. rogercresseyi were exposed to filtering mussels (Mytilus chilensis) of different sizes. These mussels were able to filter both larval stages, although they were more efficient in catching nauplius II. The fact that nauplius II were ingested more efficiently could be explained by their smaller size, lower swimming velocity (escape) and longer resting times between movements, when they were exposed to the influx of water around the inhalant area of the mussels. Larger mussels were more effective filtering C. rogercresseyi larvae due to their larger inhalant area and the related water influx. Additionally, the results suggest that larvae captured by the mussels can be incorporated into pseudofaeces or ingested and then released as part of the faeces. Thus, high concentrations of M. chilensis surrounding salmon farms may act as biological barriers, reducing the density of copepod dispersive larval stages and, thus, salmon infestations.
Asunto(s)
Copépodos , Infestaciones Ectoparasitarias/veterinaria , Enfermedades de los Peces/prevención & control , Cadena Alimentaria , Mytilus/fisiología , Salmo salar , Animales , Chile , Copépodos/crecimiento & desarrollo , Infestaciones Ectoparasitarias/parasitología , Infestaciones Ectoparasitarias/prevención & control , Conducta Alimentaria , Enfermedades de los Peces/parasitología , Larva/crecimiento & desarrolloRESUMEN
Species of the genus Ulva (Chlorophyta) are regarded as opportunistic organisms, which efficiently adjust their metabolism to the prevailing environmental conditions. In this study, changes in chlorophyll-a fluorescence-based photoinhibition of photosynthesis, electron transport rates, photosynthetic pigments, lipid peroxidation, total phenolic compounds, and antioxidant metabolism were investigated during a diurnal cycle of natural solar radiation in summer (for 12 h) under two treatments: photosynthetically active radiation (PAR: 400-700 nm) and PAR+ ultraviolet (UV) radiation (280-700 nm). In the presence of PAR alone, Ulva rigida showed dynamic photoinhibition, and photosynthetic parameters and pigment concentrations decreased with the intensification of the radiation. On the other hand, under PAR+UV conditions a substantial decline up to 43% was detected and an incomplete fluorescence recovery, also, P-I curve values remained low in relation to the initial condition. The phenolic compounds increased their concentration only in UV radiation treatments without showing a correlation with the antioxidant activity. The enzimatic activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased over 2-fold respect at initial values during the onset of light intensity. In contrast, catalase (CAT) increased its activity rapidly in response to the radiation stress to reach maxima at 10 a.m. and decreasing during solar. The present study suggests that U. rigida is capable of acclimating to natural radiation stress relies on a concerted action of various physiological mechanisms that act at different times of the day and under different levels of environmental stress.
Asunto(s)
Chlorophyta , Ulva , Aclimatación , Chile , Fotosíntesis , Rayos UltravioletaRESUMEN
The application of iron nanoparticles (FeNPs) to the removal of various pollutants has received wide attention over the last few decades. A synthesis alternative to obtain these nanoparticles without using harmful chemical reagents, such as NaBH4, is the use of extracts from different natural sources that allow a lesser degree of agglomeration, in a process known as green synthesis. In this study, FeNPs were synthesized by 'green' (hereafter, BB-Fe NPs) and 'chemical' (hereafter, nZVI) methods. Extracts of leaves and blueberry shoots (Vaccinium corymbosum) were used as reducing agents for FeCl3·6H2O solution in the green synthesis method. FeNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrophoretic migration, Brunauer-Emmett-Teller (BET) surface area analysis and X-ray diffraction (XRD) and evaluated for the removal of As(V) from aqueous systems. In both synthesis methods, XRD analysis confirmed the presence of the different kinds of iron nanoparticles. SEM analysis showed that the average size of BB-Fe NPs was 52.4nm and that a variety of nanoparticles of different forms and associated structures, such as lepidocrocite, magnetite, and nZVI, were present, while the dimensions of nZVI were 80.2nm. Comparatively significant differences regarding the electrophoretic mobility were found between both materials pre- and post-sorption of As(V). The velocity of As(V) removal by BB-Fe NPs was slower than that by nZVI, reaching equilibrium at 120min compared to 60min for nZVI. The removal kinetics of As(V) were adequately described by the pseudo-second-order kinetic model, and the maximum adsorbed amounts of this analyte are in close accordance with the experimental results. The Langmuir-Freundlich model is in good agreement with our experimental data, where the sorption capacity of nZVI and BB-Fe NPs was found to be 52.23 ± 6.06 and 50.40 ± 5.90 (mg·g-1), respectively. The use of leaves of Vaccinium corymbosum affords an easy-to-synthesize, low-cost, and eco-friendly material with capabilities similar to nZVI. BB-Fe NPs are promising for arsenic remediation, which has emerged as a new alternative for water purification and sanitation.
Asunto(s)
Arseniatos/análisis , Arándanos Azules (Planta)/química , Hierro/química , Nanopartículas/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Compuestos Férricos/química , Tecnología Química Verde , Propiedades de SuperficieRESUMEN
Intertidal macroalgae are constantly subjected to high variations in the quality and quantity of incident irradiance that can eventually generate detrimental effect on the photosynthetic apparatus. The success of these organisms to colonize the stressful coastal habitat is mainly associated with the complexity of their morphological structures and the efficiency of the anti-stress mechanisms to minimize the physiological stress. Lessonia spicata (Phaeophyceae), a brown macroalga, that inhabits the intertidal zone in central-southern Chile was studied in regard to their physiological (quantum yield, electron transport rate, pigments) and biochemical (phlorotannins content, antioxidant metabolism, oxidative stress) responses during a daily light cycle under natural solar radiation. Major findings were that F v/F m, photosynthetic parameters (ETRmax, alpha, E k) and pigments in L. spicata showed an inverse relationship to the diurnal changes in solar radiation. Phlorotannins levels and antioxidant activity showed their highest values in treatment that included UV radiation. There was an increase in SOD and APX in relation at light stress, with a peak in activity between 5.2 and 10.1 W m-2 of biologically effective dose. The increase in peroxidative damage was proportional to light dose. These results indicated that different light doses can trigger a series of complementary mechanisms of acclimation in L. spicata based on: (i) down-regulation of photochemistry activity and decrease in concentration of photosynthetic pigments; (ii) induction of phenolic compounds with specific UV-screening functions; and (iii) reactive oxygen species (ROS) scavenging activity via complementary repair of the oxidative damage through increased activity of antioxidant enzymes and potentially increased amounts of phenolic compounds.
Asunto(s)
Ritmo Circadiano , Phaeophyceae/fisiología , Especies Reactivas de Oxígeno/metabolismo , Taninos/metabolismo , Rayos Ultravioleta , Regulación hacia Abajo , Peroxidación de Lípido , Phaeophyceae/metabolismo , Fotosíntesis , Pigmentos Biológicos/metabolismo , Espectrometría de FluorescenciaRESUMEN
The estuarine slipper limpet Crepipatella dilatata is a gastropod that can survive prolonged periods of low salinities (< 24 PSU) caused by tidal changes and/or prolonged periods of rain. During low salinity events, C. dilatata can isolate its body from the outside environment, by sealing its shell against the substrate on which it grows. Prolonged isolation periods from the surrounding environment can greatly lower available oxygen levels inside of the pallial cavity, impacting on the physiology of both females and their incubated encapsulated embryos. When salinity levels return to normal, isolation is terminated and the inflow of seawater results in re-oxygenation. In this study we show that when re-oxygenation of the pallial cavity takes place, oxidative damage, in the form of increased levels of lipid peroxides and protein carbonyls, occurs in both maternal tissues and in incubated embryos. To avoid terminal oxidative damage both females and their embryos increase their levels of the glyoxalase pathway enzymes (GLX-I and GLX-II) and general antioxidant metabolism (SOD, CAT, GR, GPOX and GST). As a result the levels of oxidative damage decline to basal levels within 24 h of reoxygenation. Thus the combination of isolation, a behavioural strategy, combined with encapsulation of embryos and a capacity to up regulate relatively rapidly the glyoxylase pathway and general antioxidant metabolism, play major roles in facilitating the survival of C. dilatata in the small estuaries of Southern Chile.
Asunto(s)
Estuarios , Gastrópodos/fisiología , Lactoilglutatión Liasa/metabolismo , Salinidad , Estrés Fisiológico , Animales , Catalasa/metabolismo , Chile , Embrión no Mamífero/efectos de los fármacos , Embrión no Mamífero/fisiología , Desarrollo Embrionario/efectos de los fármacos , Femenino , Gastrópodos/embriología , Glutatión Transferasa/metabolismo , Hipoxia , Superóxido Dismutasa/metabolismoRESUMEN
Rapid adjustments of the photosynthetic machinery and efficient antioxidant mechanisms to scavenge harmful ROS are physiologic adaptions exhibited by intertidal seaweeds to persist in temperate regions. This study examines short-term (3 h) responses of three large kelps from the cold-temperate coast of Chile, normally adapted to water temperatures <16°C, but exposed abruptly to simultaneous high temperatures and UV radiation during low tide in summer. The kelps were exposed in the laboratory to three temperatures (10, 20 and 28°C) with and without UV radiation, and photochemical reactions, concentration of phlorotannins and antioxidant activity were examined. The exposure to elevated temperature (slightly exacerbated by the presence of UV radiation) decreased photochemical processes (measured as fluorescence kinetics) in the three studied species and increased lipid peroxidation in two of them. The concentration of total soluble phlorotannins was variable and correlated with the antioxidant activity in the presence of UV radiation. Insoluble phlorotannins did not change during the exposure. In all, the downregulation of the photochemical machinery, which was expressed as dynamic photoinhibition, and the rapid induction of soluble phlorotannins triggered by UV radiation minimized the effects of oxidative stress and maintained the operation of photochemical processes during short-term thermal stress.