The Effects of Artificial Light at Night on Behavior of Eastern Mosquitofish in, Iran

doi:10.21203/rs.3.rs-1715111/v1

83 percent of the world's population live in light-polluted areas, of which 40 percent live in places that are continuously lit by “ALAN (Artificial Light at Night)”. The light pollution caused by “ALAN” is growing day by day. Thus, the risk of environmental damages is growing in aquatic areas by increasing the “ALAN”. In this way this research, investigates the artificial light at night “ALAN” effect on Gambusia Holbrooke “mosquitofish” in Iran. To obtain the ALAN data, we relied on the information of the operational linear satellite scanning data related to the Metrological Defense Satellite Program (DMSP/OLS). the data provided by the DMSP satellite were belonged to 1992 and 2013 as images. The images were clipped by the geographical information systems (GIS), the images were classified into five classes based on the light pollution intensity. Afterward, the changes of light pollution by area and were calculated and reported. The aim of this research is to examined the effect of ALAN on the G. holbrooki. Two types of treatments were provided for G. holbrooki: control and ALAN treatments. In both treatments, fishes were kept for 60 days, and after that period, their shoaling and hiding behaviors were examined and recorded by a web camera. The results indicated that by increasing the ALAN, especially near the coastlines, the risk of harmful effects on G. holbrooki could be increased. The findings suggested that the ALAN might influence G. holbrooki behavior. The shoaling behavior of the ALAN treatments samples revealed that the time spent shoaling individually at night and during the day was decreased. As a result, in the hiding behavior experiment, G. holbrooki moved less at night after ALAN exposure but did not hide, indicating that the fish are unlikely to swim away or hide when exposed to light at night. As a result, they may be more vulnerable to predation.

DMSP

GIS

ALAN

Iran

Mosquitofish

The advancement of electrical lighting technologies has changed human communities, extending the time available for both work and leisure (Gaston et al. 2015). Large regions of the Earth are now experiencing an illumination differing from regular patterns in terms of spacing, intensity, and spectrum. In line with human settlements, transport networks, and manufacturing, the natural night-time climate has also changed deeply (Gaston et al. 2013)(Gaston, Visser, and Hölker, 2015). The increased unplanned artificial lightning is generally considered as a type of light pollution (Lo 2002). Some studies illustrate that light pollution can be considered in the presence of heavy artificial light during the nighttime, adversely affects the environment and humans (Raap, Pinxten, and Eens 2015). The light disturbance affects the physiological activity of many insects, birds, and mammals. Even an insignificant amount of artificial light can disrupt their natural behaviors (Pun and So 2012). Anthropogenic disturbances and intensified human use of natural resources lead to biodiversity destruction and modification and climate change (Dudgeon et al., 2006) (Ellis 2011). A class of anthropogenic emissions that alters the natural light and dark cycle of the environment is “artificial light at night” (ALAN) (Swaddle et al., 2015). The “ALAN” has caused an anthropogenic pressure on natural biological systems, because firstly such systems are most commonly organized by light, specifically by daily and seasonal light-dark cycles (Bradshaw and Holzapfel 2010). Secondly, given the seasonal periods of light and darkness, there are no natural analogs to the shape, extent, distribution, timing, or pace of the spread of artificial illumination on any timeline (Gaston, Visser, and Hölker 2015).

As global urbanization is dramatically increased, “ALAN” is becoming so prevalent that 83 percent of the world's population live in light-polluted areas, of which 40 percent live in places that are continuously lit by “ALAN” (Swaddle et al., 2015) (Falchi et al., 2016). In Iran, the light pollution caused by “ALAN” is growing day by day because the rate of migration to the large cities is increasing due to the better social services and more job opportunities that these cities provide in comparison with small cities. Thus, it causes an unbalanced distribution of population and results in the extreme growth of electricity consumption (Brahmandzadeh and Rezaei Ghahroudy 2014). Every major city in Iran has been exposed to the threat of light pollution due to a lack of legal provisions on light pollution (Salehipour Milani 2020). Thus, the risk of environmental damages is growing in aquatic areas by increasing the “ALAN” in Iran. Furthermore, the shipments, have been increasing in Iran in the last decades; thus, they can affect aquatic species by their “ALAN” pollution.

Aquatic species are affected by “ALAN” because they are affected by photoperiod during life history, including reproduction, growth, development, and behavior (Downing and Litvak 2002). Among the restricted studies of “ALAN” on aquatic ecosystems and aquatic species reproduction, there is a knowledge gap regarding the impact of “ALAN” on some fish species in terms of increasing their activity, changing their shoaling behavior, and spending more time in open (riskier) areas, physiology, and ecology (Miner et al., 2021). Mosquitofish, Gambusia. holbrooki (G.holbrooki) is one of the species frequently found in freshwater all around the world, in Iran an exotic species introduced to all basins (Fig. 1). Males translucent grey to light olive with a blue, sheen on sides and opercle. Iris with a purple sheen. Females with a large, triangular, black blotch on lower flank, behind pectoral fin (gravid spot). Peritoneum black. Males recognized by anal fin rays modified into an elongate gonopodium for intromittent fertilization. Inhabits clear and weedy streams and ditches, margins of rivers and lakes and brackish lagoons, over mud or sand bottoms. Maximum age 4 years and total length 63 mm in females and 45 mm in males. Survive in salinities up to 10‰, temperatures of 0.5–42°C, pH = 4.46–10.2 and DO levels as low as 0.2 mg/l. Maturity in 2–3 months at 16 mm total length. About 17 days after fertilization female gives birth to as many as 428 live fish over a period of about 1 month. Eggs up to 1.8 mm in diameter and embryos about 6–8 mm at birth. Sperm transferred in a spermatophore by several males and can be stored for up to 10 months. Omnivore, food include aquatic and terrestrial insects, and also filamentous algae and worms. Females cannibalize larvae (Yazdan Keivany, Manoochehr Nasri 1395). Mosquitofish has an important effect on the environment. It acts as an ecological and biological agent for eliminating Anopheles spp and controlling the mosquitoes population (Pyke 2008) (Pyke 2005).

Studying light pollution based on field methods are costly and it is problematic to compare them with timely data. In contrast with other methods such as (ground observation technologies using remote sensing), night light remote sensing technology enables quick access to the night light image in local and global scale (Cinzano et al. 2000), The database Operational Linear Scanning Satellite Data for the Meteorological Defense Satellite Program (DMSP / OLS) contains a wide range of data, from daily data to Stable Light data throughout time. DMSP / OLS satellite night light images have been widely utilized all over the world to save energy and electricity (He et al. 2014), monitor human settlements (Division, Centre, and Henares 1997), Socio-economic activities (Sutton and Costanza 2002), Estimation of urban population (Dobson et al. 2019) and population density (Paul Sutton, Dar Roberts, Chris Elvidge 1997) .

The aim of this study is finds out the “ALAN” growth between 1992, and 2013; also the possible catastrophic effects of “ALAN” on “G.holbrooki” behavior. These investigations were approved by monitoring the “ALAN” of Iran and analyzing the G.holbrooki shoaling and hiding behavior under “ALAN” and normal conditions at laboratory. There are no studies about the effect of “ALAN” on Iran’s aquatic environment. Thus, this problem needs more attention due to the possible environmental damages.

2.1. Monitoring the Light at Night

Iran is located between 25°03´ to 39° 47´ north latitude and 44° 05° to 63° 18 minutes’ east longitudes, with an area about 1,648,000 km. The light at night “ALAN” of the year 1992, and 2013 was investigated by the data obtained from the DMSP/OLSP satellite with a resolution of 850 meters, which was provided from two satellites (F10, and F18). The GIS software was used to clip images according to the national borders; For better analysis of images, we classified the night brightness of images into five classes. The brightness in DMSP/OLS images are extracted from digital numbers (DN), all pixels of the images are in the range of zero to 63. Classes with “DN” of 0-3.4 are divided as areas with very low luminosity, 3.4–12.3 areas with low luminosity, 12.3–26.1 areas with medium luminosity, 26.1–45.4 areas with high luminosity, 45.4–63 areas with very high luminosity. In order to illustrate the changes of light pollution in 1992 and 2013, the percentage of area were calculated in all classes based on “DN”. The high and very high luminosity classes was sets on as light pollution’s indicator. This data would help us to indicate the possible effect of light pollution on “G. holbrooki” by modeling the high polluted areas.

2.2. Collection and Sustaining Mosquitofish (Gambusia. Holbrooki) and the ALAN design

In this research, G. holbrooki collected from the Caspian Sea coastlines in Gilan Province were collected from the low water levels shores during the breeding season (April-October). The collected fish (N = 100 female) are placed in two tankers separately. Afterward, they were placed in two laboratory aquariums (volume of 50 L) filled with dechlorinated water and gravel at the bottom (Fig. 2). We fed them ad libitum with ISO flake food daily and frozen bloodworms and brine shrimps three times a week. We prepared four aquariums, each of which contains N = 50 females. Two of them with N = 50 females were used in control treatment of 14:10 hours light-dark cycles, and the two other aquariums were used in (ALAN) experimental treatment of 14:10 hours light-dark cycles (i.e., 10 hours of ALAN) for a total of 10 replicates in each treatment for 50–60 days.

The light levels at night in Caspian Sea shores has a great difference, we used a lux meter (Extech LT 45) to measure the light levels at our fish selection location; the night level was almost 250 lux near the crowded places, ports and harbors. In direct sunlight, the full daylight levels can reach up to 25,000 lux, with illuminances up to 100,000 lux. To provide the ALAN environment conditions in the laboratory, white LED lamps were used at 250 lux, and the daylight was stimulated by white LED lights at 850 lux, both were bought from (keyhan.co). Because lights from bridges, highways, boardwalks, and residences near water sources are ubiquitous, our measurements show the amount of light reaching the water where organisms can be located. The LED lamps are hung 50 cm above the aquariums, and all the aquariums are monitored every day (Fig. 3).

2.3. Hiding behavior

In this part of the experiment, a 30 L aquarium was filled with deionized water (5 L) and water temperature was maintained between 23°C and 25°C. Then, a PVC pipe (45 cm long and opaque) was used as a hiding place, and another smaller pipe (30 cm long) was used for hiding out of the view. Afterward, N = 25 female animals from both treatments were selected and placed into the aquarium after day 50 for the hiding test. After day 50, we took the fish from the ALAN treatment and placed them individually in the testing tank under an ALAN illumination, where they acclimated for 10–12 minutes under a transparent, plastic 1 L container. We used black paper to cover the sides of the tanks in case the fish were still distracted by their surroundings at night. We removed the transparent container after acclimating and began recording for 10–12 minutes.

2.4. Shoaling behavior

To investigate the shoaling behavior in this study, N = 25 female animals from both treatments are selected after day 60, and placed into five containers filled with deionized water (2 L) in groups of five for observing the shoaling behavior. In this study, the shoal size used based on Tobler and Schlupp pervious study of Poeciliidae (Tobler and Schlupp 2008). The groups of fish stay within the containers for 45 min, and their behaviors are recorded for analyzing shoaling (keeping a 2 cm distance from each other). We then recorded the shoaling behavior for almost 24h for logistical purpose, the average distance moved (cm), resting time, and shoaling (during day 14 h and night 10 h) were analyzed.

3.1. monitoring the ALAN

In this research, the area and the percentage of light pollution therefore the changes of the luminosity classes were measured in order to monitoring the light pollution and find the trend light pollution changes. Increasing the light pollution has a possible effect on G. holbrooki’s life.

In 1992, just 3.87% of area in Iran has been classified as low to high brightness areas. The (table.1.) shows those classification, according to calculations made on night light images of this class (table. 1.), 1362469 (96.1%) belong to a region with very low luminosity, 32528 (2.29%) to the area with low luminosity, 12517 (0.88%) to the area with moderate luminosity, 5516 (0.38%) to the area with high luminosity and 4676 (0.32%) very high luminosity area. The results show that in 2013, the area of the region with very low luminosity was 1308182 (92.27%), the region with low luminosity was 71711 (5.05%), the region with average luminosity was 19395 (1.36%), an area with a high luminosity was 8670 (0.61%) and an area with a high luminosity was 9743 (0.68%).

The dramatic growth in light pollution in Iran may be seen in the increase in the size and percentage of regions with very illumination (also known as areas with a very high degree of artificial light supply), (Fig. 4). According to data extracted from DMSP / OLS night sky satellite data, night light increased over the past years in Iran and the luminosity has increased in all classes (very low, low, moderate, high and very high). However, increasing trend in night light between 1992 and 2013 has not been the same in all provinces of the country, but that is not the focus of this research to calculate and compare the nigh light changes in the scale of province. The point of discovering night light is to describe the increasing process of night light in Iran in order to better understanding of possible night light effect on aquatic species. Thus, by relying on the changes of night light between 1992 and 2013 all around the Iran the eastern mosquitofish G. holbrooki is under the effect of “ALAN”.

3.2. Hiding behavior

After the hiding behavior test, the obtained data showed that the female G. holbrooki from the ALAN treatment spent more time resting compared to the fishes in control treatments (LM: treatment: F_1,25 = 7.025, P = 0.018, Table 2, and Fig. 5).

3.3. Shoaling behavior

The results of the shoaling behavior test indicated that in the ALAN conditions, female G. holbrooki showed a significant increase of shoaling time during the day compared to the control treatment (Repeated measure ANOVA: F_1,25 = 6.81, P = 0.038). Furthermore, the samples from both conditions showed significant movements by keeping a greater distance (in cm) during the daytime compared to the nighttime (F_1,25 = 9.02, P = 0.023) (Fig. 6).

After 60 days of exposure to "ALAN" in the lab, G. holbrooki movement was generally reduced at night. After being exposed to "ALAN," G. holbrooki activity was reduced individually at night and in shoaling throughout the day. From and important point of view, G. holbrooki may be more vulnerable to predation since they did not spend more time hiding at night. This might lead to a better understanding of the mechanism underlying the previous discovery that fish exposed to ALAN reported greater predation rates (O’Connor et al. 2019). Recent findings imply that the effects of ALAN differ depending on the species. There are several studies shows the effect of “ALAN” on various species, some of them describe that the “ALAN” could increasing fish activity (Foster et al. 2016),(Kurvers et al. 2018), anoles (Dananay and Benard 2018) and zebra finches(Batra, Malik, and Kumar 2019) after exposure to “ALAN”. Shoaling is an essential advantage because it protects fish from predation. As a result, foraging becomes more efficient. Unfortunately, female G. holbrooki spent less time shoaling throughout the day following the same lab exposure to "ALAN." As a result of the absence of shoaling, they are more vulnerable to predators and have a harder time finding food (Pitcher 1986)(LALAND and WILLIAMS 1997). There was a definite demonstration of diel shoaling activity in the control group, with fish being more active and swimming in closer proximity during the day than at night; this activity disappeared after exposure to “ALAN”. At least, G. holbrooki in “ALAN” situation showed us less shoaling at the day and decreasing movement at night, this behavior could cause a risk of being more susceptible to predation.

G. holbrooki is highly distributed and could be found in almost developed urban settings in Iran (Fig. 1), in this research we used the maximum levels of light than we found in the cost line of Caspian Sea (250 lux). This species is living in the harsh light pollution condition, and of course tend to be found in low depth, slow-moving water (Belk and Lydeard 1994). G. holbrooki moved less at night following ALAN exposure and did not hide, showing that the fish are unlikely to swim away from or hide when exposed to light at night.

In this research, the light pollution -light at night “ALAN”- in Iran and the harmful effects of ALAN on nature (in this case, G. holbrooki) were investigated. The growing population has led to extensive urbanization, and thereby, day-by-day increasing ALAN in the last decades. The ALAN can affect human life and also mammals, birds, and aquatic species. The subject of our study is G. halbrooki, which is one of the ecologically important aquatic species frequently found in the freshwaters all around the world. Mosquitofish has an important effect on the environment. It acts as an ecological and biological agent for eliminating Anopheles spp and controlling mosquitos’ population. The ALAN intensity all over the Iran was investigated by using the DMSP/OLS satellite images, the obtained images were clipped by the GIS program, which were then classified into five categories based on the ALAN intensity. Furthermore, in these experiments, the ALAN effects on shoaling and hiding behavior of G. holbrooki were investigated based on two “ALAN” and control treatments. The findings suggested that the ALAN might influence the behavior of G. holbrooki. The shoaling behavior of the samples from ALAN treatments revealed that the time spent shoaling individually at night and during the day was decreased. As a result, in the hiding behavior experiment, G. holbrooki moved less at night after ALAN exposure and did not hide, indicating that the fish are unlikely to swim away from or hide when exposed to light at night. As a result, they might be more vulnerable to predation.

- ALAN

artificial light at night

- G. holbrooki

Gambusia. holbrooki

- GIS

geographical information systems

- DN

digital numbers

Ethics approval and consent to participate

'Not applicable'

Consent for publication

All of authors (The authors: Hossein Barzegar, Sharareh Pourebrahim, Mohammad Ali Zahed, Mehrdad Hadipour) are given their consent for the publication of identifiable details, which include all details within the text (“Material”) to be published in this Journal.

Availability of data and material

The datasets generated during and/or analyzed during the current study are not publicly available due [significant file size] but are available from the corresponding author on reasonable request.]

Competing immtrests

The authors: (Hossein Barzegar, Sharareh Pourebrahim, Mohammad Ali Zahed, Mehrdad Hadipour) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Funding

The authors did not receive support from any organization for the submitted work.

Authors' contributions

Authors: Hossein Barzegar and Mehrdad Hadipour, have made substantial contributions to conception and design, or acquisition of data, or analysis and interpretation of data.

Authors: Sharareh Pourebrahim and Mohammad Ali Zahed, have been involved in revising manuscript critically for important intellectual content

Acknowledgement

'Not applicable'

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Table. 1. Changes in the amount of night light in Iran between 1992 and 2013

Class range	Area 1992 km²	%Area 1992 km²	Area 2013 km²	%Area 2013 km²	Changes area (km²) between 1992-2013
0-3.4	1362469	96.1	1308182	92.27	54287
3.4-12.3	32528	2.29	71711	5.05	39183
12.3-26.1	12517	0.88	19395	1.36	6878
26.1-45.4	5516	0.38	8670	0.61	3154
45.4-63	4676	0.32	9743	0.68	5067

Table 2. Results of the general linear model testing of the ALAN effect on female G. holbrooki

		Estimate ± SE	t-value	df	P-value	Lower 95% Cl	Upper 95% Cl
Resting	Intercept	216.2 ± 152.3	1.58	25	0.19	-100	586.23
	SL (mm)	0.03 ± 4.56	0.0125	25	0.96	-91	10.08
	control	-49.8 ± 18.35	-3.012	25	0.02	-12	-12.56
	SL*control	-3.98 ± 4.21	-0.89	25	0.36	-18.5	4.89
Hiding	Intercept	-48.36 ±138.13	-0.35	25	0.69	-365.2	256.21
	SL (mm)	2.97 ± 3.98	0.65	25	0.52	-6.032	12.89
	control	3.12 ± 13.58	0.19	25	0.88	-30.65	38.21
	SL*control	-0.45 ± 4.15	-0.16	25	0.96	-9.12	6.51

No competing interests reported.

The Effects of Artificial Light at Night on Behavior of Eastern Mosquitofish in, Iran

Status:

Version 1

Abstract

Figures

1. Introduction

2. Materials And Methods

2.1. Monitoring the Light at Night

2.2. Collection and Sustaining Mosquitofish (Gambusia. Holbrooki) and the ALAN design

2.3. Hiding behavior

2.4. Shoaling behavior

3. Result And Discussion

3.1. monitoring the ALAN

3.2. Hiding behavior

3.3. Shoaling behavior

4. Conclusion

Abbreviations

Declarations

References

Tables

Additional Declarations

Status:

Version 1