Light pollution of freshwater ecosystems: principles, ecological impacts and remedies

Light pollution caused by artificial light at night (ALAN) is increasingly recognized as a major driver of global environmental change. Since emissions are rapidly growing in an urbanizing world and half of the human population lives close to a freshwater shoreline, rivers and lakes are ever more exposed to light pollution worldwide. However, although light conditions are critical to aquatic species, and freshwaters are biodiversity hotspots and vital to human well-being, only a small fraction of studies conducted on ALAN focus on these ecosystems. The effects of light pollution on freshwaters are broad and concern all levels of biodiversity. Experiments have demonstrated diverse behavioural and physiological responses of species, even at low light levels. Prominent examples are skyglow effects on diel vertical migration of zooplankton and the suppression of melatonin production in fish. However, responses vary widely among taxa, suggesting consequences for species distribution patterns, potential to create novel communities across ecosystem boundaries, and cascading effects on ecosystem functioning. Understanding, predicting and alleviating the ecological impacts of light pollution on freshwaters requires a solid consideration of the physical properties of light propagating in water and a multitude of biological responses. This knowledge is urgently needed to develop innovative lighting concepts, mitigation strategies and specifically targeted measures. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Large-scale sampling of the freshwater microbiome suggests pollution-driven ecosystem changes

Freshwater microbes play a crucial role in the global carbon cycle. Anthropogenic stressors that lead to changes in these microbial communities are likely to have profound consequences for freshwater ecosystems. Using field data from the coordinated sampling of 617 lakes, ponds, rivers, and streams by citizen scientists, we observed linkages between microbial community composition, light and chemical pollution, and greenhouse gas concentration. All sampled water bodies were net emitters of CO₂, with higher concentrations in running waters, and increasing concentrations at higher latitudes. Light pollution occurred at 75% of sites, was higher in urban areas and along rivers, and had a measurable effect on the microbial alpha diversity. Genetic elements suggestive of chemical stress and antimicrobial resistances (IntI1, blaOX₅₈) were found in 85% of sites, and were also more prevalent in urban streams and rivers. Light pollution and CO₂ were significantly related to microbial community composition, with CO₂ inversely related to microbial phototrophy. Results of synchronous nationwide sampling indicate that pollution-driven alterations to the freshwater microbiome lead to changes in CO₂ production in natural waters and highlight the vulnerability of running waters to anthropogenic stressors.

Towards Insect-Friendly Road Lighting-A Transdisciplinary Multi-Stakeholder Approach Involving Citizen Scientists

Simple Summary

Road lighting is a service provided at night, mainly to ensure the secure and safe passage of humans. However, lighting at night can have adverse effects on insects or ecosystems, which are not yet considered in planning. Here, we introduce a comprehensive approach for the design and implementation of a novel insect-friendly road luminaire. The lighting design provides an optimized radiation geometry that avoids emissions at the trajectory height of insects, reduces the attraction of insects and the fragmentation of their habitats, and at the same time provides adequate night-time illumination in residential areas. The effects of the new design on insect behavior and night sky brightness will be evaluated two years before and two years after the change of the road luminaires and additionally in a direct comparison, as some luminaires of the old design will remain as controls. Citizen scientists are involved in the identification of insects and the measurement of night sky brightness. A broad public engagement program also highlights discussions about the competing interests of different stakeholders in lighting design, explicitly including the effects of illumination on insect fauna and biodiversity.

Abstract

(1) The project “Tatort Streetlight” implements an insect-friendly road light design in a four year before–after, control–impact (BACI) approach involving citizen scientists. It will broaden the stakeholder interests from solely anthropogenic perspectives to include the welfare of insects and ecosystems. Motivated by the detrimental impacts of road lighting systems on insects, the project aims to find solutions to reduce the insect attraction and habitat fragmentation resulting from roadway illumination. (2) The citizen science approach invites stakeholders to take part and join forces for the development of a sustainable and environmentally friendly road lighting solution. Here, we describe the project strategy, stakeholder participation and motivation, and how the effects of the alternative road luminaire and lighting design can be evaluated. (3) The study compares the changes in (a) insect behavior, (b) night sky brightness, and (c) stakeholder participation and awareness. For this purpose, different experimental areas and stakeholders in four communities in Germany are identified. (4) The project transfers knowledge of adverse effects of improperly managed road illumination and interacts with various stakeholders to develop a new road lighting system that will consider the well-being of street users, local residents, and insects.

Perinatal survivin is essential for the establishment of pancreatic beta cell mass in mice

AIMS/HYPOTHESIS

Pancreatic beta cells undergo dynamic remodelling during the perinatal period, with enhanced neogenesis, proliferation and apoptosis observed. The molecular mechanisms responsible for these processes have yet to be elucidated. Survivin is an inhibitor of apoptosis, first described as being exclusively expressed in tumour and embryonic tissues with regulatory functions in mitosis and apoptosis. The aim of the present study was to define the essential physiological role of survivin in the pancreas.

METHODS

The expression profile of survivin was assessed in the mouse pancreas, and we generated a Pdx1 promoter-driven Survivin (also known as Birc5) knockout mouse using the Cre-loxP recombination system to determine the essential physiological function of survivin in the pancreas.

RESULTS

Survivin is transiently expressed in mouse pancreatic islets during the embryonic and neonatal periods. Targeted deletion of Survivin in the pancreas resulted in a significant decline in beta cell mass throughout the perinatal period, leading to glucose intolerance in the adult. Survivin-deficient islets showed decreased cell proliferation as a result of a delay in cell cycle progression with perturbations in cell cycle proteins. Survivin did not, however, play an essential role in beta cell apoptosis either during the physiological remodelling period or in response to streptozotocin. Islet development, islet architecture, microvasculature and apoptosis were not affected by the absence of survivin in the pancreas.

CONCLUSIONS/INTERPRETATION

Survivin expression in the pancreatic islets during the perinatal remodelling period is essential for the establishment of beta cell mass through cell cycle regulation.

Evaluation of adjuvants for foliar application of Steinernema carpocapsae against larvae of the diamondback moth (Plutella xylostella)

Abstract

Increasing resistance to chemical insecticides in field populations of the diamondback moth (Plutella xylostella) has stimulated research on alternative control measures. The entomopathogenic nematode Steinernema carpocapsae may be one such alternative, particularly against the third larval instar of P. xylostella. The LC50 for the second instar is 38, the third 13 and the fourth 22 nematodes/larva. Plutella xylostella pupae were not affected by the nematodes, although mortality in leaf disk bioassays after application of nematodes in water seldom surpassed 50%. Therefore, additives were tested to improve nematode performance. Only Triton X-100 (0.3%) caused phytotoxic effects. The addition of xanthan gum or potassium alginate resulted in a two-fold increase of insect mortality at 80% relative humidity (RH) and a five-fold increase at 60% RH. Mixtures of 0.3% xanthan or alginate with 0.3% surfactants further improved efficacy. In water the LT50 for S. carpocapsae against P. xylostella larvae was > 40 h. Using a mixture of 0.3% xanthan or 0.3% alginate with 0.3% surfactant, the LT50 was reduced to < 25 h.

Effectiveness of different emulsifiers for neem oil against the western flower thrips (Thysanoptera, Thripidae) and the warehouse moth (Lepidoptera, Pyralidae)

The neem tree produces highly specified acting insecticides mainly in its seeds. By pressurizing or extracting the seeds an insecticide oil can be manufactured. For successful application emulsifiers are needed to render the oil soluble in water. The heavy oil has to be stable in emulsion, but on the other hand the surfactant should not reduce the ecological property of the neem oil. The emulsifiers Lutensol TO10, Emulan ELP, Rimulgan and Tween 80 and for comparison the formulation NeemAzal-T/S were tested in their emulsion stability, as well as in their insecticidal effects towards two different insect pests: The western flower thrips Frankliniella occidentalis and the ware house moth Ephestia elutella. The emulsifiers were applied purely, and in different contents mixed in neem oil. Data showed significant differences of mortality and development on the tested pests. Lutensol TO10 and Emulan ELP caused spontaneous mortality on the western flower thrips and an additive efficacy when mixed with neem oil. Rimulgan led to mortality of the larvae of the warehouse moth. NeemAzal showed in both bioassays the highest efficacy of 95% mortality.

Relationship of study participation to health-related behaviors

This study explores the ways in which clinical trial participation influences a person's health and health-promoting behaviors. Active study subjects with a minimum of 4 months' clinical trial participation were mailed a nurse-developed questionnaire. Seventy-three percent of the targeted group returned the survey by the deadline. The majority of respondents made changes toward better health. Diet modification, initiation of an exercise program, and smoking cessation were the changes cited most frequently. The study team was found to be influential in promotion of health. The nurse, the pivotal member of the team, provided subjects with the most health-related information. Most respondents believed they had enough information to change behaviors detrimental to health.

The perspective of patients with vascular disease on participation in clinical trials

Very little objective data are available concerning the patient's perspective on clinical trial participation. Participants from the Asymptomatic Carotid Atherosclerosis Study and Clopidogrel vs. Aspirin in Patients at Risk for Ischemic Events Trial were personally interviewed by the nurse coordinator to document their views. A questionnaire including both closed-ended and open-ended questions was used. The main advantages to participation in a study were close follow-up and the opportunity for improved health. More than half of the subjects saw no disadvantages to participation. The physician was the primary motivator for entering trials. Most patients expressed an interest in future study participation.

Busulfan pharmacokinetics in bone marrow transplant patients: is drug monitoring warranted?

Pharmacokinetics were studied in relation to hepatic side-effects in 20 patients (19 adults aged 18-53 years and one child of 11 years) undergoing BMT after conditioning with 1 mg/kg busulfan (every 6 hours for 16 doses). Busulfan was quantitated in plasma samples at 10 time points within the 6 h dosing interval using HPLC before and after dose numbers 1, 2, 5, 13 and 14. For 13 patients data on all five doses are available; for the remaining seven patients three to four doses were studied. Mean maximum concentrations were 1512 ng/ml; mean trough levels for second and subsequent doses were 615 ng/ml. Maxima (Cmax) tended to be lower and times of maxima (Tmax) were later when busulfan was taken with a meal. Correlation of the area under the concentration versus time curve (AUC0-6h) between different doses was low within patients. In several patients problems with compartmental fitting of concentration data were observed mainly caused by the short dosing interval, which made estimates of T1/2 and model derived AUCs unstable. Three patients experienced hepatic veno-occlusive disease; kinetic parameters were not helpful in describing a particulate risk constellation for this subgroup. In our experience, the role of drug monitoring in this setting needs to be defined more clearly.