Effect of Sub-Lethal Exposure to Ultraviolet Radiation on the Escape Performance of Atlantic Cod Larvae (Gadus morhua)

The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to depletion of the ozone layer. Several studies have reported that UV radiation reduces survival of fish larvae. However, indirect and sub-lethal impacts of UV radiation on fish behavior have been given little consideration. We observed the escape performance of larval cod (24 dph, SL: 7.6±0.2 mm; 29 dph, SL: 8.2±0.3 mm) that had been exposed to sub-lethal levels of UV radiation vs. unexposed controls. Two predators were used (in separate experiments): two-spotted goby (Gobiusculus flavescens; a suction predator) and lion's mane jellyfish (Cyanea capillata; a “passive" ambush predator). Ten cod larvae were observed in the presence of a predator for 20 minutes using a digital video camera. Trials were replicated 4 times for goby and 5 times for jellyfish. Escape rate (total number of escapes/total number of attacks ×100), escape distance and the number of larvae remaining at the end of the experiment were measured. In the experiment with gobies, in the UV-treated larvae, both escape rate and escape distance (36%, 38±7.5 mm respectively) were significantly lower than those of control larvae (75%, 69±4.7 mm respectively). There was a significant difference in survival as well (UV: 35%, Control: 63%). No apparent escape response was observed, and survival rate was not significantly different, between treatments (UV: 66%, Control: 74%) in the experiment with jellyfish. We conclude that the effect and impact of exposure to sub-lethal levels of UV radiation on the escape performance of cod larvae depends on the type of predator. Our results also suggest that prediction of UV impacts on fish larvae based only on direct effects are underestimations

Fluorescence spectroscopy for wastewater monitoring: A review

© 2016. Wastewater quality is usually assessed using physical, chemical and microbiological tests, which are not suitable for online monitoring, provide unreliable results, or use hazardous chemicals. Hence, there is an urgent need to find a rapid and effective method for the evaluation of water quality in natural and engineered systems and for providing an early warning of pollution events. Fluorescence spectroscopy has been shown to be a valuable technique to characterize and monitor wastewater in surface waters for tracking sources of pollution, and in treatment works for process control and optimization. This paper reviews the current progress in applying fluorescence to assess wastewater quality. Studies have shown that, in general, wastewater presents higher fluorescence intensity compared to natural waters for the components associated with peak T (living and dead cellular material and their exudates) and peak C (microbially reprocessed organic matter). Furthermore, peak T fluorescence is significantly reduced after the biological treatment process and peak C is almost completely removed after the chlorination and reverse osmosis stages. Thus, simple fluorometers with appropriate wavelength selectivity, particularly for peaks T and C could be used for online monitoring in wastewater treatment works. This review also shows that care should be taken in any attempt to identify wastewater pollution sources due to potential overlapping fluorophores. Correlations between fluorescence intensity and water quality parameters such as biochemical oxygen demand (BOD) and total organic carbon (TOC) have been developed and dilution of samples, typically up to ×10, has been shown to be useful to limit inner filter effect. It has been concluded that the following research gaps need to be filled: lack of studies on the on-line application of fluorescence spectroscopy in wastewater treatment works and lack of data processing tools suitable for rapid correction and extraction of data contained in fluorescence excitation-emission matrices (EEMs) for real-time studies

TiO2 Nanoparticles Are Phototoxic to Marine Phytoplankton

Nanoparticulate titanium dioxide (TiO2) is highly photoactive, and its function as a photocatalyst drives much of the application demand for TiO2. Because TiO2 generates reactive oxygen species (ROS) when exposed to ultraviolet radiation (UVR), nanoparticulate TiO2 has been used in antibacterial coatings and wastewater disinfection, and has been investigated as an anti-cancer agent. Oxidative stress mediated by photoactive TiO2 is the likely mechanism of its toxicity, and experiments demonstrating cytotoxicity of TiO2 have used exposure to strong artificial sources of ultraviolet radiation (UVR). In vivo tests of TiO2 toxicity with aquatic organisms have typically shown low toxicity, and results across studies have been variable. No work has demonstrated that photoactivity causes environmental toxicity of TiO2 under natural levels of UVR. Here we show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO2 nanoparticles to marine phytoplankton, the most important primary producers on Earth. No effect of TiO2 on phytoplankton was found in treatments where UV light was blocked. Under low intensity UVR, ROS in seawater increased with increasing nano-TiO2 concentration. These increases may lead to increased overall oxidative stress in seawater contaminated by TiO2, and cause decreased resiliency of marine ecosystems. Phototoxicity must be considered when evaluating environmental impacts of nanomaterials, many of which are photoactive

Grazing Rates of Calanus finmarchicus on Thalassiosira weissflogii Cultured under Different Levels of Ultraviolet Radiation

UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR): photosynthetically active radiation (PAR) only (4 kJ-m−2/day), and PAR supplemented with UVR radiation at two intensities (24 kJ-m−2/day and 48 kJ-m−2/day). There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66%) higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem

An integrated study of the chemical composition of Antarctic aerosol to investigate natural and anthropogenic sources

During the 2010-11 austral summer, an aerosol sampling campaign was carried out at a coastal Antarctic site (Terra Nova Bay, Victoria Land). In this work, previously published data about water-soluble organic compounds and major and trace elements were merged with novel measurements of major ions, carboxylic acids and persistent organic pollutants (polychlorobiphenyls, polycyclic aromatic hydrocarbons, polychlorinated naphthalenes, polybrominated diphenylethers and organochlorine pesticides) in order to provide a chemical characterisation of Antarctic aerosol and to investigate its sources. The persistent organic pollutants were determined using a high-volume sampler, able to collect both particulate and gaseous fractions, whereas remaining compounds were determined by performing an aerosol size fractionation with a PM10 cascade impactor. Ionic species represented 58% (350 ng m(-3)) of the sum of concentrations of all detected compounds (596 ng m(-3)) in our Antarctic PM10 aerosol samples due to natural emission. Trace concentrations of persistent organic pollutants highlighted that the occurrence of these species can be due to long-range atmospheric transport or due to the research base. Factor analysis was applied to the dataset obtained from the samples collected with the PM10 sampler in order to make a distinction between anthropogenic, crustal and biogenic sources using specific chemical markers

In situ fluorescence measurements of dissolved organic matter: a review

YesThere is a need for an inexpensive, reliable and fast monitoring tool to detect contaminants in a short time, for quick mitigation of pollution sources and site remediation, and for characterization of natural dissolved organic matter (DOM). Fluorescence spectroscopy has proven to be an excellent technique in quantifying aquatic DOM, from autochthonous, allochthonous or anthropogenic sources. This paper reviews the advances in in situ fluorescence measurements of DOM and pollutants in various water environments. Studies have demonstrated, using high temporal-frequency DOM fluorescence data, that marine autochthonous production of DOM is highly complex and that the allochthonous input of DOM from freshwater to marine water can be predicted. Furthermore, river measurement studies found a delayed fluorescence response of DOM following precipitation compared to turbidity and discharge, with various lags, depending on season, site and input of dissolved organic carbon (DOC) concentration. In addition, research has shown that blue light fluorescence (λemission = 430–500 nm) can be a good proxy for DOC, in environments with terrestrial inputs, and ultraviolet fluorescence (λemission = UVA–320–400 nm) for biochemical oxygen demand, and also E. coli in environments with sanitation issues. The correction of raw fluorescence data improves the relationship between fluorescence intensity and these parameters. This review also presents the specific steps and parameters that must be considered before and during in situ fluorescence measurement session for a harmonized qualitative and quantitative protocol. Finally, the strengths and weaknesses of the research on in situ fluorescence are identified.Authors, E.M. Carstea and C.L. Popa, acknowledge the support of the Ministry of Research and Innovation, CNCS-UEFISCDI, project number PN-III-P1-1.1-TE-2016-0646, within PNCDI III, project number 18N/2019, under the Core Program OPTRONICA VI, project number 19PFE/17.10.2018 and project number 152/2016, SMIS 108109

Diel variability of heterotrophic bacterial production and UV doses in the South East Pacific

Revue sans Comité de lectureInternational audienceDiel variability of heterotrophic bacterial production (BP) was investigated in the South East Pacific from October to December 2004 during the BIOSOPE cruise. Three sites differing by their trophic status were studied: Marquesas Islands (MAR; 08° S, 141° W), the centre of the South Pacific Gyre (SPG) (GYR; 26° S, 114° W) and the eastern part of the SPG (EGY; 32° S, 91° W). At the three sites, diel variability of BP ranged from 17 to 40% and from 13 to 22% for volumetric surface (5 m) and integrated (to Ze and Zm) data, respectively. The main feature we observed was at 5 m, an abrupt increase (×2 to ×4) in leucine activity during the afternoon-sunset period (12:00–18:00 at the site MAR and 15:00–21:00 at the site GYR) and lowest activities recorded between 10:00 and 14:00. To assess the potential influence of solar ultraviolet radiation (UVR: 280–400 nm) on this BP diel variability, we determined, from in situ optical measurements, the mean tri-hourly ultraviolet B (UVB, 305 nm) and ultraviolet A (UVA, 380 nm) doses (irradiances integrated over time) within the mixed layer (Hm(UVB) and Hm(UVA), respectively). The wavelengths 305 nm and 380 nm were used as biologically effective wavelengths for the induction of DNA damages (cyclobutane pyrimidine dimers: CPDs) and photoenzymatic repairs (PERs), respectively. In the SPG, daily Hm(UVB) and Hm(UVA) were 0.6 and 14 kJ m-2 nm-1, respectively. The latter were probably the highest daily doses ever measured in the marine environment. The Hm(UVB)/Hm(UVA) ratio (Q) increased by 58, 117 and 46% from 06:00–09:00 to 12:00–15:00, and decreased by 36, 26 and 16% from 12:00–15:00 to 15:00–18:00 at the sites MAR, GYR and EGY, respectively. The relationship between Q and BP suggested a significant influence of UVR on the diel variability of BP (BP decreased when Q increased) at the site GYR from the surface waters to Zm, likely in relation with its hyper-oligotrophic status. Therefore, possible alternance of CPD and PER periods attributed to Q ratio, as well as a strong lags between process of autotrophic production with their associated dissolved organic carbon (DOC) release and heterotrophic utilization of organic matter could explain such diel variations

Occurrence and distribution of hydrocarbons in the surface microlayer and subsurface water from the urban coastal marine area off Marseilles, Northwestern Mediterranean Sea

Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in dissolved and particulate material from surface microlayer (SML) and subsurface water (SSW) sampled at nearshore observation stations, sewage effluents and harbour sites from Marseilles coastal area (Northwestern Mediterranean) in 2009 and 2010. Dissolved and particulate AH concentrations ranged 0.05-0.41 and 0.04-4.3 mu g l(-1) in the SSW, peaking up to 38 and 1366 mu g l(-1) in the SML, respectively. Dissolved and particulate PAHs ranged 1.9-98 and 1.9-21 ng l(-1) in the SSW, amounting up 217 and 1597 ng l(-1) in the SML, respectively. In harbours, hydrocarbons were concentrated in the SML, with enrichment factors reaching 1138 for particulate AHs. Besides episodic dominance of biogenic and pyrogenic inputs, a moderate anthropisation from petrogenic sources dominated suggesting the impact of shipping traffic and surface runoffs on this urbanised area. Rainfalls increased hydrocarbon concentrations by a factor 1.9-11.5 in the dissolved phase. (C) 2011 Elsevier Ltd. All rights reserved

Diel variability of heterotrophic bacterial production and underwater UV doses in the eastern South Pacific

International audienceDiel variability of heterotrophic bacterial production (BP) was investigated in the eastern South Pacific from October to December 2004. Three sites differing by their trophic status were studied: Marquesas Islands, the center (GYR) and the eastern South Pacific Gyre. By using a Lagrangian approach and high frequency measurements, an important increase (2- to 4-fold) in BP was observed at the 3 sites during the afternoon–sunset period within surface layers. To evaluate theimpact of solar UV radiation on this variability, we determined, from in situ optical measurements, the mean UV-B (at 305 nm) and UV-A (at 380 nm) doses received within the mixed layer at a daily scale. At GYR, the doses were as high as 0.3 and 11 kJ m–2nm–1 for the whole day, respectively due to high surface irradiances and very low light attenuations in the water column. The UV-B/UV-A tri-hourly dose ratios (Q) displayed substantial variations during the daytime, with highest values recorded during the periods 9:00 to 12:00 h or 12:00 to 15:00 h. The negative linear correlation observed between Q and BP in the surface waters of GYR suggests that changes in the balance between DNA damages and photorepairs (reflected by changes in the Q-ratio) could have a significant influence on the diel variability of BP in open oceans. However, assessing the effects of UV radiation on diel variability of BP through an in situ measurement approach, independently from other causes like availability of resources, is not so evident, even in these clearest waters of the world ocean

Distribution and bacterial availability of dissolved neutral sugars in the South East Pacific

Revue sans Comité de lectureInternational audienceThe distribution and bacterial availability of dis-solved neutral sugars were studied in the South East Pa-cific from October to December 2004 during the BIOSOPE cruise. Four contrasting stations were investigated: Mar-quesas Islands (MAR), the hyper-oligotrophic South Pacific Gyre (GYR), the eastern part of the Gyre (EGY), and the coastal waters associated to the upwelling area off Chile (UPW). Total (free and combined) dissolved neutral sugar (TDNS) concentrations were in the same order of magni-tude at MAR (387±293 nM), GYR (206±107 nM), EGY (269±175 nM), and UPW (231±73 nM), with the highest and lowest concentrations found at MAR (30 m, 890 nM) and EGY (250 m, 58 nM), respectively. Their contribution to dissolved organic carbon (TDNS-C×DOC −1 %) was gen-erally low for all sites varying from 0.4% to 6.7% indicating that South East Pacific surface waters were relatively poor in neutral sugars. Free dissolved neutral sugar (FDNS; e.g. sug-ars analyzed without hydrolysis) concentrations were very low within the detection limit of our method (5–10 nM) ac-counting for <5% of the TDNS. In general, the predominant sugars within the TDNS pool were glucose, xylose, arabi-nose, and galactose, while in the FDNS pool only glucose was present. TDNS stock to bacterial production ratios (inte-grated values from the surface to the deep chlorophyll max-imum) were high at GYR with respect to the low primary production, whereas the opposite trend was observed in the highly productive area of UPW. Intermediate situations were observed for MAR and EGY. Bioavailability of dissolved or-ganic matter (DOM) exposed to natural solar radiation was also experimentally studied and compared to dark treatments. Our results showed no or little detectable effect of sunlight on DOM bacterial assimilation in surface waters of UPW and GYR, while a significant stimulation was found in MAR and Correspondence to: R. Sempéré ([email protected]) EGY. The overall results clearly suggest that DOM is less la-bile at GYR compared to UPW, which is consistent with the observed accumulation of dissolved organic carbon and the elevated C/N ratios reported by Raimbault et al. (2008)