Browsing by Subject "light pollution"

Artificial light at night (ALAN) is an emerging environmental problem, originating from e.g. street lightning and infrastructure. It has been found to alter the behavior of many organisms and thereby influence community composition and ecosystem functions. However, most studies on the impact of ALAN on wildlife and the environment have focused on terrestrial ecosystems, while aquatic ecosystems have received less attention, yet are increasingly exposed to artificial light. Gammarus species are amphipods commonly found in freshwater and estuarian ecosystems across Eurasia and North America. They are key components of ecosystems in recycling nutrients and serving as a food source for other species. They are night active and, hence, vulnerable to ALAN. Earlier studies show that ALAN increases their predation risk and induces physiological stress. However, no study has assessed the impact of ALAN on mating behavior, although mating success is a key fitness component that influences population dynamics. Gammarus pulex is a common freshwater detritivore where females are receptive for a short period and males compete for females and then guard them through amplexus, precopulatory guarding. The aim of this master’s thesis was to study if and how ALAN affects the mating behavior of the G. pulex, and if this depends on the presence of male-male competition for females. G. pulex, individuals were collected from a stream in Helsinki and exposed to control (natural light conditions) or ALAN in the absence or presence of male competition, eight treatment combinations in total, for one week under laboratory conditions. In each trial, one female and either one or two males were placed into a tank – in the absence or presence of ALAN – and their behavior recorded for ten minutes, including active time, contact between the sexes, and pair formation and separation. The results show that ALAN influences both night and day mating behaviour, but that the effect depends on the presence of male competition. ALAN had no impact on activity during the night, while male competition decreased it. During the day, ALAN decreased activity, but male competition counteracted and increased activity. Number of contacts between female and male(s) was only impacted by male competition during the night, but by both ALAN and male competition during the day; ALAN reduced contact time during the day in the absence of male competition, while male competition increased contact time. Pair formation was negatively affected by ALAN during the night, while male competition increased formation. Pair separation was higher under ALAN during the day, independent of male competition, but unaffected at night. These results indicate that ALAN causes a carry-over effect, with light conditions during the night influencing mating behaviour during the day. This is most likely through physiological changes incurred during the night because of the artificial light, such as increased stress levels. Further studies should assess how ALAN impacts mating behavior when many individuals are present, as G. pulex is more choosy in mate selection at higher population densities. Follow up studies are also needed to determine if the effect of ALAN depends on the colour of the light, as found for other organisms, as such information is needed in conservation work aiming to reduced negative effects of ALAN on ecosystems through the development of environment friendly lighting systems. Regarding the consequences of the change in mating behaviour when exposed to ALAN, this could alter population dynamics. Given the key ecological role of the species in ecosystems, this could lead to changes in nutrient recycling and the structure of food webs. Considering that the presence and intensity of ALAN is expected to increase in the future, it is of great importance to assess its effects on organisms, not only during the night but also during the day through carry-over effects, as indicated by the present study.

Artificial light that produces some adverse effects is called light pollution. Light pollution has only recently been recognized as an environmental problem – it has been noticed to have adverse effects to organisms, ecosystems, human health and their well-being. The purpose of this study is to combine two aspects of light pollution that have so far gained little attention: the public’s point of view and the lighting solutions of municipalities and forest industry enterprises. These two aspects can be connected to each other through a concept called condition of lighting. Here the conditions of lighting consist of three areas with notable differences in lighting: city centers, countryside and forest industry production plants along with their surroundings. The study was conducted in South Karelia, Finland, and it was divided into two sections. The first section dealt with the public’s point of view on light pollution. The objective was to find out how South Karelians perceive the effects and obtrusiveness of artificial light both generally and also within areas of differing conditions of lighting. In addition, the intention was to uncover other factors that might influence the opinions of people. The second section of the study concerned the lighting solutions of municipalities and forest industry enterprises. The objective was to examine their lighting planning and implementation as well as the role of light pollution in the process. Interview was selected as the method of research in both sections of the study. The public considered electronic billboards and car headlights as the most obtrusive sources of light pollution. Bright lights and glare, on the other hand, were considered the most obtrusive types of light pollution. Most valued benefits of artificial light were its influence on safety, crime prevention and its positive effect on mood. Not being able to see the stars or experience natural darkness were considered as the biggest disadvantages of artificial light. The conditions of lighting in different areas also influenced the respondents’ experiences: people living in the countryside did not feel insecure in dark places outside the cities and did not consider abundant lighting pleasant. They also felt that being able to experience natural darkness was important. Among other factors, nature orientedness, light sensitivity, environmental attitudes and gender strongly affected the views of the respondents. In the municipalities and forest industry enterprises, the lighting planning concentrated on territorial plans. All but one of the municipalities and enterprises had taken light pollution into consideration at some level at least, but the forms and means varied. In the future both municipalities and forest industry enterprises will invest more in LED technology. The results show that artificial light can cause inconvenience to people who live outside the brightly lighted areas and who were not particularly interested in light pollution. Behind the inconvenience and disturbance were mostly the experiences, habits, values and attitudes of the respondents. The municipalities and enterprises have a lot to improve when it comes to light pollution. They should, for example, invest in comprehensive lighting planning, avoid over-illumination and pay attention to suitable direction and positioning of the light fixtures. In the future, it is important to examine the public’s opinion and to map the landscape of lights at a local scale. This would help in finding the most suitable lighting solutions for different areas. In the opinion polls, the subjective characteristics affecting the views of the respondents should be taken into consideration. Research regarding the municipalities and enterprises should be directed to the areas where light pollution is not regulated, in order to gather information on motivation and implementation of the voluntary activities reducing light pollution.