Responses of insectivorous bats and nocturnal insects to local changes in street light technology

Artificial light at night is a pervasive anthropogenic stressor for biodiversity. Many fast‐flying insectivorous bat species feed on insects that are attracted to light‐emitting ultraviolet radiation (10–400 nm). Several countries are currently focused on replacing mercury vapour lamps, which emit ultraviolet light, with more cost‐efficient light‐emitting diode (LED) lights, which emit less ultraviolet radiation. This reduction in ultraviolet light may cause declines in insect densities in cities, predatory fast‐flying bats, and some edge‐foraging and slow‐flying bats. Capitalising on a scheme to update streetlights from high ultraviolet mercury vapour to low ultraviolet LED in Sydney, Australia, we measured the activity of individual bat species, the activity of different functional groups and the bat and insect communities, before and after the change in technology. We also surveyed sites with already LED lights, sites with mercury vapour lights and unlit bushland remnants. Species adapted to foraging in cluttered vegetation, and some edge‐space foraging species, were more active in unlit bushland sites than in all lit sites and decreased in activity at lit sites after the change to LED lights. The change to LED streetlights caused a decrease in the fast‐flying Chalinolobus gouldii but not Miniopterus schreibersii oceanensis, the latter being more influenced by seasonal and environmental variables. Insect biomass was not affected by changing light types, but instead was negatively correlated with the moon's percentage illuminance. Changing streetlights to LEDs could result in a decline in some insectivorous bats in cities. This study confirms that unlit urban bushland remnants are important refuges for high bat diversity, particularly for more clutter‐adapted species and some edge‐space foraging species. Preventing light penetration into unlit bushland patches and corridors remains essential to protect the urban bat community.     

The impacts of new street light technologies: experimentally testing the effects on bats of changing from low-pressure sodium to white metal halide

Artificial light at night is a major feature of anthropogenic global change and is increasingly recognized as affecting biodiversity, often negatively. On a global scale, newer technology white lights are replacing orange sodium lights to reduce energy waste. In 2009, Cornwall County Council (UK) commenced replacement of existing low-pressure sodium (LPS) high intensity discharge (HID) street lights with new Phillips CosmoPolis white ceramic metal halide street lights to reduce energy wastage. This changeover provided a unique collaborative opportunity to implement a before-after-control-impact field experiment to investigate the ecological effects of newly installed broad spectrum light technologies. Activity of the bat species Pipistrellus pipistrellus, P. pygmaeus and Nyctalus/Eptesicus spp. was significantly higher at metal halide than LPS lights, as found in other studies of bat activity at old technology (i.e. mercury vapour) white light types. No significant difference was found in feeding attempts per bat pass between light types, though more passes overall were recorded at metal halide lights. Species-specific attraction of bats to the metal halide lights could have cascading effects at lower trophic levels. We highlight the need for further research on possible ecosystem-level effects of light technologies before they are installed on a wide scale.     

Spectral composition of light sources and insect phototaxis,with an evaluation of existing spectral response models

Artificial illumination attracts insects, but to what extent light attracts insects, depends on the spectral composition of the light. Response models have been developed to predict the attractiveness of artificial light sources. In this study we compared attraction of insects by existing light sources used for streetlights as well as newly developed environment friendly alternatives, and used this data to test the predictive ability of the existing response models. Light sources differed in overall attractiveness to insects and relative attractiveness was dependent on insect order. The attraction patterns predicted by the two models correlated weakly with the number of insects attracted when the only light source rich in UV, a mercury vapour light, was included in the tested spectra. When the mercury vapour light, which is going to be banned in Europe, was not included in the test no correlation was found between predicted and observed attraction patterns. We conclude that currently existing attraction response models are insufficiently sensitive to evaluate new light sources.     

Illumination preferences of pigs

The illumination preferences of pigs have been examined by placing individual animals in light-proof chambers in which they could turn the lights on or off by interrupting an infrared beam switch with their snouts. The pigs were tested, on separate occasions, at two light intensities; bright (110 lux) and dim (10 lux). During 24-h periods, pigs spent an average of 54% of the time with the lights on when they were in bright light. When tested in dim light they spent an average of 63% of each 24 h with the lights on. Their motivation to obtain light was investigated using operant tests in which pigs, in darkness, obtained 40 s of light for interrupting an infrared beam. They obtained 1.5–2 h of light per 24 h. By contrast, pigs in continuous light would not operate the beam switch to obtain 40-s periods of darkness.     

Toenail mercury concentration as a biomarker of methylmercury exposure

The aim of the study was to assess the value of toenail mercury as an alternative biomarker of methylmercury exposure compared with blood and hair. Blood, hair and toenail total mercury concentrations were determined simultaneously in a southern urban sea n = 35 and an eastern rural lake n = 37 group and separately in a central Finnish rural lake n = 39 group. A questionnaire based index was used for estimating frequency of exposure taking into account high vs low mercury fish. Total mercury concentration was determined by cold vapour atomic absorption spectrophotometry. The mean Fish Consumption Frequency Index varied from 4.7 to 9.9 on a scale of 1-20. The blood, hair and toenail mercury mean concentrations ranged from 2.9 to 14.6 g l-1, 0.45 to 1.57 mg kg-1 and 0.20 to 0.54 mg kg-1, respectively. In the combined southern and eastern groups n = 72 sampled simultaneously, the correlations between blood and hair mercury were r = 0.92 and that of blood and toenails r = 0.78 p 0.0001 . In the central Finnish group the correlations were more moderate. In the three groups all three biomarkers correlated highly with the fish consumption index, r = 0.43-0.76 p 0.0001 . Men consumed high mercury fish more frequently than women, 8.6 vs 6.6 n.s. The mean mercury levels of blood and hair were two fold, but toenail mercury levels were only 30 higher in men compared with those of the women. The relative sensitivity slope of the sources decreased in the order, blood hair toenails. In conclusion, toenails, an easily accessible tissue for the estimation of methylmercury exposure, have been shown to be closely correlated with the well established samples for biomarkers, viz. blood and hair mercury.     

Toenail mercury concentration as a biomarker of methylmercury exposure

The aim of the study was to assess the value of toenail mercury as an alternative biomarker of methylmercury exposure compared with blood and hair. Blood, hair and toenail total mercury concentrations were determined simultaneously in a southern urban sea n = 35 and an eastern rural lake n = 37 group and separately in a central Finnish rural lake n = 39 group. A questionnaire based index was used for estimating frequency of exposure taking into account high vs low mercury fish. Total mercury concentration was determined by cold vapour atomic absorption spectrophotometry. The mean Fish Consumption Frequency Index varied from 4.7 to 9.9 on a scale of 1-20. The blood, hair and toenail mercury mean concentrations ranged from 2.9 to 14.6 g l-1, 0.45 to 1.57 mg kg-1 and 0.20 to 0.54 mg kg-1, respectively. In the combined southern and eastern groups n = 72 sampled simultaneously, the correlations between blood and hair mercury were r = 0.92 and that of blood and toenails r = 0.78 p 0.0001 . In the central Finnish group the correlations were more moderate. In the three groups all three biomarkers correlated highly with the fish consumption index, r = 0.43-0.76 p 0.0001 . Men consumed high mercury fish more frequently than women, 8.6 vs 6.6 n.s. . The mean mercury levels of blood and hair were two fold, but toenail mercury levels were only 30 higher in men compared with those of the women. The relative sensitivity slope of the sources decreased in the order, blood hair toenails. In conclusion, toenails, an easily accessible tissue for the estimation of methylmercury exposure, have been shown to be closely correlated with the well established samples for biomarkers, viz. blood and hair mercury.     

Green light stimulates somatic growth in the barfin flounder Verasper moseri

We examined the effects of different light wavelengths-blue, green, and red-on the somatic growth of the barfin flounder Verasper moseri, a flatfish. The light sources used were fluorescent lamps and a combination of daylight and fluorescent lamps that produced ambient light. These light sources were filtered using blue, green, or red filters. During the experiments, the fish were reared in indoor tanks with running seawater of natural temperature and fed with commercial pellets twice daily until satiety. The tanks were white in color. Fish were exposed to constant light emitted from the fluorescent lamps (9:15, light:dark; 08:00-17:00, light) for 14 weeks from October or September to January or to ambient light with a 14-week natural photoperiod from September to December. The wavelengths that were filtered from the fluorescent lamp light modified the growth of the fish, i.e., fish reared under green or blue light exhibited a greater total length (TL; P<0.01) and body weight (BW; P<0.01) than those reared under red light. In contrast, in the case of fish exposed to filtered ambient light, fish reared under green light exhibited a greater TL (P<0.01) and BW (P<0.01) than fish exposed to other wavelengths-blue-, red-, and nonfiltered ambient light. Our results indicate that flounder growth was modified by certain wavelengths, namely, green and red light, which had growth-stimulating and growth-inhibiting effects, respectively.     

Preferences of age-0 white sturgeon for different colours and strobe rates of LED lights may inform behavioural guidance strategies

Many populations of migratory fish species, including white sturgeon (Acipenser transmontanus Richardson), are threatened due to modification of riverine systems and may experience downstream displacement or mortality at water intake structures. Efforts to reduce the impacts of these structures are beginning to incorporate behavioural guidance, where the sensory capabilities of fishes are exploited to repel them from high-risk areas or attract them towards desirable paths. Artificial lighting has been tested before, but consisted of single-spectrum lights. Using a new programmable LED-based light guidance device (LGD), we exposed age-0 white sturgeon to light strobing at 1 Hz, 20 Hz, or constant illumination with colours (green, red, blue) matching the absorbance maxima of their retinal photopigments. The behavioural responses of the sturgeon were assessed using y-maze dichotomous choice tests under both day (light) and night (dark) conditions. Sturgeon demonstrated positive phototaxis under both day and night conditions, and approached the LGD more often when light was continuous or strobing at 20 Hz compared to strobing at 1 Hz. Green light elicited the greatest rates of attraction overall. The combination of strobing and colour may help to protect imperiled fish from waterway development and serve as an effective form of mitigation at hydropower facilities and other human infrastructure where fish may be entrained or impinged.     

Mercury in Fish-eating Communities of the Andean Amazon,Napo River Valley,Ecuador

This exploratory study aimed to examine the relationship between fish eating habits, human mercury levels, and mercury levels in fish in three communities of the Napo River Valley, Ecuadorian Andean Amazon, a region without gold mining but with significant deforestation and volcanic soils with naturally high mercury levels. By recognizing the politicoeconomic factors which cause deforestation, the cultural factors which influence diet, and the biogeochemical factors which contribute to mercury levels, this study employs an ecosystem approach. Interviews on diet were conducted, hair samples from 99 individuals were collected, and samples of commonly eaten fish were taken. Samples were analyzed using cold vapor atomic fluorescence spectrometry (CVAFS). Two rural communities were found to have higher fish consumption and hair mercury levels (8.71 μg/g and 5.32 μg/g) as compared to an urban community (1.87 μg/g). A sequential analysis of hair established mercury levels by month. No seasonal tendencies were noted. Piscivorous fish (0.36 μg/g) were found to be more contaminated in mercury than herbivorous fish (0.05 μg/g). The study shows that sociocultural factors are important in determining mercury exposure. The two village communities consume different species of fish with different frequencies, leading to differential exposure and mercury concentrations in hair samples. The levels of mercury in these two villages were similar to those found in Brazil where neurobehavioral tests showed a correlation between these relatively low levels of mercury and decreased psychomotor capacities. These findings are concerning and should be followed by further studies on the multiple factors that affect the health status of these exposed communities.     

Effects of strobe lights on the behaviour of freshwater fishes

When dealing with invasive fishes, permanent barriers may be best in preventing spread; however, they may not be feasible due to various costs and/or logistical constraints. Alternatively, various non-permanent barriers using electricity, light, sound, pressure, bubbles, and CO₂ are being developed and deployed in efforts to limit the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable, and testing is often lacking for both target and non-target species. We conducted a series of laboratory trials to examine the effects of strobe light on behaviour of Common Carp, Brown Bullhead, and Largemouth Bass. In response to strobe lights, Common Carp and Brown Bullhead stayed significantly farther away compared to the control period and resumed their normal activity once the strobe light was turned off. This suggests that strobe lights may prove to be a useful fish deterrent in the field. Our results also highlight the importance of examining the response of both target and non-target species when evaluating fish deterrent technologies.     

Total mercury and methylmercury in garfish (Belone belone) of different body weights,sizes, ages,and sexes

BackgroundGarfish, (Belone belone) is a migratory pelagic fish that inhabits the waters of coastal Europe, North Africa, the North Sea, the Mediterranean Sea. Little information about garfish has been disseminated mainly because of its low abundance and its brief occurrence in various water bodies. Data is lacking on mercury compounds, particularly dangerous the toxic organic form of methylmercury (MeHg), which endangers the health of fish and their consumers.MethodsThe research material was garfish caught off the southern Baltic Sea coast in Puck Bay during the spawning period. Total mercury (THg) content was assayed with the cold vapour atomic absorption method in an AMA 254 mercury analyser. The MeHg extraction procedure was based on three-step sequential extraction method: hydrolysis using of hydrochloric acid, extract by toluene, bind the MeHg by L-cysteine.ResultsThe concentrations of THg and MeHg was determined in the muscle of garfish. The highest concentrations of THg (0.210 mg kg-1) and MeHg (0154 mg kg-1) were detected in the longest specimens (80 cm). The THg and MeHg concentrations in garfish muscles increased with specimens length, weight and age, which was confirmed by positive correlations. Differences were also noted depending on sex. Males accumulated more THg and MeHg than did females. The mercury in garfish from the southern Baltic Sea occurred mainly in its organic form MeHg and accounted for 84.7% of the THg.ConclusionSignificant differences were noted in mercury concentrations depends on length, weight, age and sex. Concentration of MeHg in garfish must be done by length class, and fish sex when selecting this fish for contamination studies and risk assessment. The toxic MeHg in garfish tissues did not pose a threat to the health of consumers, as indicated by the low values of EDI, TWI and THQ indices.     

Polarization-based brightness discrimination in the foraging butterfly, Papilio xuthus

The human eye is insensitive to the angular direction of the light e-vector, but several animal species have the ability to discriminate differently polarized lights. How the polarization is detected is often unclear, however. Egg-laying Papilio butterflies have been shown to see false colours when presented with differently polarized lights. Here we asked whether this also holds in foraging butterflies. After training individuals to feed on nectar in front of an unpolarized spectral light, we carried out three dual-choice tests, where the discrimination of (i) the spectral content, (ii) the light intensity, and (iii) the e-vector orientation were investigated. In the first test, the butterflies selected the trained spectrum irrespective of its intensity, and in the second test they chose the light with the higher intensity. The result of the e-vector discrimination test was very similar to that of the second test, suggesting that foraging butterflies discriminate differently polarized lights as differing in brightness rather than as differing in colour. Papilio butterflies are clearly able to use at least two modes of polarization vision depending on the behavioural context.     

Mercury as a risk factor for cardiovascular diseases

Mercury is a heavy metal that exists naturally in the environment. Major sources include the burning of fossil fuels (especially coal) and municipal waste incineration. Mercury can exist in several forms, with the most hazardous being organic methylmercury. In waterways (lakes, rivers, reservoirs, etc.), mercury is converted to methylmercury, which then accumulates in fish, especially in large predatory fish. Fish and fish products are the major--if not the only--source of methylmercury in humans. Mercury has long been recognized as a neurotoxin for humans, but in the last 10 years, its potentially harmful effects on cardiovascular diseases (CVD) have raised a cause for concern, mostly due to the proposed role of mercury in oxidative stress propagation. Some epidemiological studies have indeed found an association between increased levels of mercury in the body and risk of CVD. There are several plausible mechanisms to explain the association; these are discussed in this review. We also review the epidemiological studies that have investigated the association between mercury and CVD.     

Perception of heterochromatic flicker by honeybees: a behavioural study

Freely flying honeybees were trained to discriminate a stimulus consisting of two alternating chromatic lights (heterochromatic flicker) from a steady mixture of the same two lights, using 3 different pairs of lights: blue-UV, UV-green, and green-UV. With each light pair, training to the heterochromatic flicker was conducted at several flicker frequencies, using experimentally naive bees in each training. In subsequent tests, the trained bees were given a choice between the two lights that constituted the flicker, presented steady, as well as between either of them and the steady mixture. We find that bees trained to particular frequencies of heterochromatic flicker prefer one of the component lights over the other as well as over the steady mixture, suggesting that the colour they perceive in the heterochromatic flicker to which they have been trained is shifted in the direction of one of the lights contained in the flicker. The colour shift occurs at flicker frequencies that depend on the pair of lights used. We propose that the shift is generated by an effect similar to the Brücke-Bartley phenomenon known from human vision. This effect is based on the enhancement of the photoreceptors' response upon onset of stimulation, causing an intermittent light to appear brighter than a steady light of identical physical intensity. We propose that the degree of enhancement might differ among the 3 spectral classes of photoreceptor, causing the colour perceived in a heterochromatic flicker to differ from that perceived in a steady mixture of its two light components.     

测定细胞内自由钙的显微荧光光度计的研制和应用

以ＸＳＪ－２型荧光显微镜为基础,建立了测定细胞内自由钙的显微荧光光度计,为建立这套装置,对荧光显微镜主要作了如下改动：首先,为提供稳定的激光光源,交流汞灯被换成直流氙灯;其次光路中安装了镶有两块干涉滤色片的激发滤色片转盘,使生物样品交地被两种不同波长的光激发。整套装置的运转在微机控制下,在这套装置上,成功地用Ｆｕｒａ－２测定了细胞内自由钙变化,文中提供了应用实例。     

The eye of the blue acara (Aequidens pulcher, Cichlidae) grows to compensate for defocus due to chromatic aberration

By rearing fish in various monochromatic illuminations we investigated (1) the potential for compensation of refractive error due to chromatic aberration, (2) the contributions of the chromatic channels to emmetropization, and (3) the role of color cues in the control of eye growth. Cichlid fish (Aequidens pulcher) were reared for 6 months (12 h light/12 h dark) in monochromatic lights (623.5, 534.1, 485.0 nm; spectral purity 5–10 nm). Light levels were isoirradiant at 1.1·10¹² quanta/s/cm². Two control groups were reared in white light with down-welling illuminances of 0.2 and 33 lx. Nasotemporal diameters (NTDs) of the eyes were measured in relation to lens size. Due to the oblique axis of highest acuity vision in cichlids, NTD is considered to be a more important dimension than axial length. Variances in NTD were equally small in all rearing groups. NTDs were enlarged with increasing wavelengths of the rearing lights with highly significant values over controls in the red-light group. The wavelength-dependent size of the eyes matched the changes in focal length due to longitudinal chromatic aberration. Complete recovery from eye enlargement was observed after fish reared in red light were exposed to a white light regime for 5 weeks. Small variances in NTD in all groups indicated stringent control of eye growth in the absence of color cues. The reversibility of the increase in NTD in fish reared in red light suggests that the eyes were emmetropized by visually guided mechanisms. Eye size in fish reared in white light was intermediate between the values expected if only blue-sensitive single or the red- and green-sensitive double cones contributed to the control of eye growth. This suggests that all chromatic channels participate in emmetropizing the fish eye.     

Diel cycles inHoplosternum littorale (Teleostei): entrainment of feeding activity by low intensity colored light

Synopsis Low intensity colored light is very often used to observe or manipulate fish during the scotophase. According to data on fish vision, most species can perceive these wavelengths of light since their cone pigments have maximum absorption peaks around 455, 530 and 625 nm. To test whetherHoplosternum littorale can detect low intensity red or blue light, we attempted to entrain feeding activity, known to be nocturnal and synchronized by the circadian light/dark alternation, to such light. Feeding activity was entrained with either red or blue light, indicating that these fish can perceive these lights. In all cases, the fish fed during the darker phase of the light cycle.     

Mercury toxicity in livers of northern pike (Esox lucius) from Isle Royale, USA

Many laboratory studies have documented that mercury can be toxic to fish, but it is largely unknown if mercury is toxic to fish in their natural environments. The objective of our study was to investigate the toxic effects of mercury on northern pike (Esox lucius) at Isle Royale, Michigan. In 124 northern pike from eight inland lakes, concentrations of total mercury in skin-on fillets ranged from 0.069 to 0.622 microg/g wet mass (wet wt). Concentrations of total mercury in livers increased exponentially compared with concentrations in fillets, to a maximum of 3.1 microg/g wet wt. Methylmercury constituted a majority of the mercury in livers with total mercury concentrations <0.5 microg/g wet wt, but declined to 28-51% of the mercury in livers with total mercury concentrations >0.5 microg/g wet wt. Liver color (absorbance at 400 nm) varied among northern pike and was positively related to liver total mercury concentration. The pigment causing variation in liver color was identified as lipofuscin, which results from lipid peroxidation of membranous organelles. An analysis of covariance revealed lipofuscin accumulation was primarily associated with mercury exposure, and this association obscured any normal accumulation from aging. We also documented decreased lipid reserves in livers and poor condition factors of northern pike with high liver total mercury concentrations. Our results suggest (i) northern pike at Isle Royale are experiencing toxicity at concentrations of total mercury common for northern pike and other piscivorous fish elsewhere in North America and (ii) liver color may be useful for indicating mercury exposure and effects in northern pike at Isle Royale and possibly other aquatic ecosystems and other fish species.     

Mercury Exposure Assessment in Iranian Pregnant Women’s Hair with Respect to Diet, Amalgam Filling, and Lactation

Our aim for carrying out this study was to estimate the levels of mercury in the hair of pregnant women and its association with fish consumption and amalgam fillings. From November 2007 to January 2008, 100 hair samples were collected randomly from three groups of pregnant women: Ahvaz in the south of Iran, Noushahr in the north, and the countryside of Noushahr. Significant differences were found in these three groups of pregnant women's samples (p>0.05). The mean mercury level in women's hair was found to be 0.37 μg/g (range, 0.11-3.57 μg/g). Only in 2 % of collected hair samples did the total mercury (THg) level exceed the United States Environmental Protection Agency-recommended 1.0 μg/g. In addition, there was a positive correlation of THg content in Ahvaz group's samples with respect to fish consumption (r=0.41, p=0.02) and a negative correlation of THg content in those who consumed vegetables and fruit. The level of education also played an indicating factor in this group. Moreover, significant association was found between the residence time and Hg concentration of women's hair samples collected from Noushahr (p>0.05). Similarly, the same correlations were found between hair mercury levels and the time since the first filling, number of dental fillings, pregnancy interval, and lactating period.     

Efficacy of passive sand filtration in reducing exposure of salmonids to the actinospore of Myxobolus cerebralis

The aquatic oligochaete Tubifex tubifex parasitized by Myxobolus cerebralis releases triactinomyxon (TAM) actinospores that can infect some species of salmonids and cause salmonid whirling disease. Silica sand was tested as a filtration medium for removal of TAMs from water containing the parasite. Laboratory tests indicated sand filtration removed > 99.99% of TAMs. In 2 different field tests, groups of 1 mo old rainbow trout Oncorhynchus mykiss were exposed for 2 wk to filtered and unfiltered water from a spring-fed pond enzootic for M. cerebralis. In November 2000, the exposure dose was estimated as between 3 and 5 TAMs fish(-1). During a March 2001 exposure, the estimated dose was between 286 and 404 TAMs fish(-1). Fish were held for 6 mo post exposure (p.e.) in laboratory aquaria for observation and evidence of clinical signs of whirling disease. We used 4 diagnostic techniques to assess the prevalence and severity of infection by M. cerebralis among fish exposed to filtered and unfiltered water. These included polymerase chain reaction (PCR) for genomic DNA of the parasite, histological evaluation for tissue damage, tissue digestion for quantification of cranial myxospores of the parasite, and total non-sampling mortality that occurred over 6 mo p.e. All diagnostic tests verified that the prevalence and severity of infection was significantly reduced among fish in treatment groups exposed to filtered water compared to those exposed to unfiltered water in both the low-dose and high-dose exposures.