Prepared by members of the Essex County Field Naturalists’ Club Executive Team, November 2020

INTRODUCTION 

By one estimate, artificial light pollution intensity has quadrupled every decade since 1960, which translates to being 1000 times brighter now than it was 50 years ago (Parker, Liipere, Kennedy, Caulfeild-Browne & Nelson, 2011). Greenhouse light pollution, or nocturnal lights, is causing unintended consequences in the Leamington Ontario community. Now, more than ever, it is important to protect and restore the nighttime environment, as unwanted light impacts human health, the environment and wildlife populations locally.

The purpose of this report is to provide information to the Municipality of Leamington and Council to provide feedback on the draft By-law 79-20, being a by-law requiring the abatement of interior greenhouse light. We aim to highlight the rich biodiversity of our region, and bring awareness to the significant impacts that increases in agricultural light pollution could be having on local wildlife. 

BIODIVERSITY IN WINDSOR-ESSEX 

Essex County faces many ecological challenges, as it is part of one of the most populated corridors in Canada. As well, it is part of a unique ecoregion, the Carolinian Life Zone. This region comprises only 1% of Canada’s total land mass, but is home to more flora and fauna species than any other area in Canada. Essex County includes an estimated 2,200 species of herbaceous plants, 64 species of ferns, 110 species of grasses, over 130 species of sedges and 70 species of trees. Over 400 species of birds have been recorded in this area, which is over half found in Canada (Carolinian Canada, 2004). 

Prior to European settlement, extensive natural areas dominated Essex including Carolinian woodlands, wetlands and tall grass prairies. Since then, much of the landscape has been removed, changed or become extremely degraded to accommodate a growing human population. This degradation is a direct or indirect result of clear cutting and increased drainage for timber, agriculture and urban development. The overall loss represents 95% of the original forest cover gone and a 97% loss of wetlands. The degradation of Essex County’s natural heritage has resulted in significant habitat loss and a decline in species populations native to the region, many of which are recognized as species at risk. As such, several parks and conservation areas have been established to aid with protecting the diminishing habitats and wildlife. Hillman Marsh and Point Pelee National Park are two examples of these, both of which are in close proximity to Leamington’s greenhouses. While many local species have managed to persist within the limited green space, they are now faced with a new obstacle that doesn’t so much affect where they live, but how. 

LIGHT POLLUTION FROM GREENHOUSES 

Different types of plants require different amounts of light to optimize photosynthesis. This is often measured in moles of light (for the purpose of this report, we will not get more technical than that). Similarly, different locations on Earth provide different levels of light, which varies throughout the year. This is referred to as the Daily Light Integral, DLI, and is measured as moles of light per square meter per day (Torres and Lopes, 2018). While the climate of Essex County has made it ideal for agriculture, sufficient light for optimal plant growth is not annually available. To accommodate, greenhouses have been using supplementary lighting to maximize the output and quality of crops year round.

Crops such as tomatoes and peppers require 20-40 moles per day to bear high quality fruit, while cannabis is up near 30-40 (Moody, 2018; Torres and Lopes, 2018). Leamington, Ontario experiences a DLI above 30 from April through September, and a sub-20 DLI from October to February (SunTracker Technologies, 2020). It must be noted that the amount of natural light that actually reaches the crops depends on the type of greenhouse. If a Leamington farmer wants to maximize their crop production year round, they will need to adjust the light within their greenhouse accordingly. For example (units will be omitted for simplicity), if their target light level is 32, during November, when outdoor DLI in Leamington is approximately 13, they will need to provide another 19 in additional light. This extra light will increase to 24 in December when the DLI is 8.  Without adequate light insulation on the greenhouse, this light will be emitted to the outside environment.  With that said, an important issue to discuss is the farmer’s desired photoperiod, i.e., how long they plan to light their crop each day (Moody, 2018). If the Leamington farmer has a 16 hour photoperiod, their supplementary light will radiate for 16 hours. If the extra light is not contained within the greenhouse, during November, when the average day length is less than 10 hours, the usually dark night sky will be disrupted for 6 hours. This extra time is often added either side of dawn and dusk. 

Figure One. Aerial photo of southern Michigan and Essex County showing the artificial light pollution on the evening of November 18, 2020.The relatively long-standing urbanized lighting of Detroit and Windsor occupy the left side of the photo, while recent clusters of bright yellow light sources dominate the otherwise dark remainder of the photo.
Photo by Bryan Jacuzzi.

IMPACTS OF GREENHOUSE LIGHT POLLUTION ON BIODIVERSITY 

This section will provide a summary of the impacts of greenhouse light pollution on different fauna taxa, as well as flora, drawing specific reference to native species to the Windsor-Essex region. It is important to consider nature’s dependence on darkness, as 30% of vertebrates and 60% of invertebrates are nocturnal (Hölker et al., 2010). Species that can exploit this new “night light niche” gain, while those that cannot, lose. Artificial adjustments to photoperiod can also affect the wildlife that rely on seasonal changes, such as day length, to signal timing and shifts in key biological processes, including foraging, food intake, reproduction, migration and other behaviours. Night pollution is one more negative effect to regional biodiversity that Windsor-Essex flora and fauna face. 

MAMMALS

Daily and seasonal cycles are synchronous with wildlife physiology and behaviour in response to environmental conditions (Russart & Nelson, 2018). As the nightscape has changed with the increase in use of artificial lighting, so is the exposure of wildlife to direct lighting and indirect lighting through sky glow at night (Russart & Nelson, 2018). Light at night can hinder the seasonal detection of shorter days, incorrectly signal long days and desynchronize seasonal and circadian physiology and behaviour activities, which can decrease individual reproductive fitness and can modify ecosystems and lead to a decline in local populations and biodiversity (Russart & Nelson, 2018). 

Mammals rely on vision to orient themselves in their environment and light pollution will affect their behaviour, especially at night. For example, during the new moon, when it is darkest, coyotes (Canis latrans) group howl and group yip-howl more. This communication behaviour is used to organize packs while hunting larger prey, and sky glow from light pollution can all but eliminate this communication pattern in affected areas (Longcore and Rich, 2004). Reduced communication would minimize effectiveness when hunting white-tailed deer (Odocoileus virginianus), which have excellent night vision. Also, small mammals, such as mice, have been found to avoid artificially lit areas in order to avoid predators, like foxes, who often use the lights to spot an easy meal (FFW Conservation Commission, 2020).

BATS

Bats are nocturnal insectivores making them one of North America’s most valuable species for controlling agricultural pests. Eight bat species have been recorded in Essex County, and all of them are insectivores. Because they live long lives and reproduce at low rates, bats are especially vulnerable to environmental impacts. Wind turbines and white-nose syndrome (WNS) are already creating high mortality rates in Ontario bat populations.  

In Leamington, light pollution is another obstacle for bats to overcome. Many bat species, including the local red bat, are attracted to insects that congregate around light sources (Frank 1988, as in Longhorn and Rich, 2004). This may seem like a good thing, but only for bats that can fly fast enough to exploit this anthropogenic-created buffet. Slower flying bats avoid lights, and over time, minor differences in predation success will lead to changes in behaviour, and local biodiversity (Longhorn and Rich, 2004). 

Artificial light that is used to extend photoperiod for crops, can simulate delayed sunset in the nearby environment, which could result in delayed hunting start time for bats. This could create a mismatch with the activity of their prey and lead to a subsequent reduction in foraging success. Unnatural ‘day length’ can hinder cues for migration or hibernation, and leave local bats unprepared for colder weather. 

BIRDS

Birds that hunt at night (for example owls) navigate the landscape by moonlight and starlight. Artificial light sources affect this activity by leading the birds off course towards more developed urban areas. Millions of birds die by colliding into structures such as buildings or towers (International Dark-Sky Association, 2020). Smaller prey often avoid lit areas, reducing the hunting efficiency of those birds drawn towards them. In addition, small songbirds, often associated as the ‘early bird that gets the worm’ could be up even earlier, without any worms, if artificial light emits hours before natural sunrise. 

Migratory birds (for example birds of prey and songbirds) depend on natural cues related to seasonal changes. Artificial lights that affect photoperiod can signal birds to begin migration too early or too late, which can lead them to miss ideal climate conditions needed for nesting, foraging and breeding activities (International Dark-Sky Association, 2020). Not only does this affect local species, but Leamington is located along a major migratory flyway, with more than 390 bird species recorded at nearby Point Pelee. Uninhibited light pollution and a disrupted night sky could drastically impede the migratory success of native and migrant species. 

INSECTS 

Many insects are drawn to natural light.  Moths are one well-known example, but other taxa include lacewings, beetles, bugs, caddisflies, crane flies, midges, hoverflies, wasps, and bush crickets (Longcore and Rich, 2004).  Artificial light can create a fatal attraction causing declining insect populations, which negatively impact all species that rely on insects for food or pollination services. Moths in particular, because there are so many, fill an important ecological niche.  They feed birds, turtles, spiders, lizards, and more.  In addition, some insect predators will exploit this fatal attraction to their advantage, which can impact local food webs in unanticipated ways (International Dark-Sky Association, 2020). 

HERPETOFAUNA (REPTILES AND AMPHIBIANS)

According to the International Dark Sky Association, glare created from artificial lights can affect wetland habitats where amphibians such as frogs and toads live. Artificial light can disrupt their nocturnal activity, particularly during their breeding periods where nighttime croaking in the spring takes place. Artificial lights disrupt this activity, which impacts reproduction and results in reducing populations locally (IDA, 2020). It is important to note that all turtle species in Ontario are now designated as Species at Risk under the Ontario Species at Risk Act. As Windsor-Essex county has degraded habitat with other environmental issues such as pollution, degraded water quality, invasive species and more, any further challenges such as artificial light pollution may exacerbate the stress these local creatures face.  

VEGETATION 

In a 2016 study, scientists studying the effects of artificial light on plants suggest that there are broad implications that disrupt seasonal light cues (Bennie, Davies, Cruse & Gaston, 2016). As plant life cycles rely on sunlight to carry out their life cycle, artificial light can impact those processes and introduce positive feedback loops to other flora and fauna (Bennie, Davies, Cruse & Gaston, 2016). Furthermore, artificial light can alter or mismatch important life cycle timing with herbivores, can alter the development of agricultural crops, can affect timing and flower development in native species, which can create barriers to nocturnal pollinator species and impedes the role that darkness plays for plant repairs from environmental pollutants (Bennie, Davies, Cruse & Gaston, 2016).

WILDLIFE CORRIDORS AND HABITAT CONNECTIVITY 

Wildlife corridors are extremely beneficial for wildlife as they create safe passage across a landscape, and aid in helping wildlife be undetected during the day, and at nighttime. Diversity of native species and ecological communities can sustain over time by a system that includes core natural areas with connecting corridors (Reid & Symmes, 1997). Core natural areas can provide habitat for a rich diversity of animals and plants, while isolated patches of smaller size habitat are not adequate to sustain healthy populations (Essex Region Conservation Authority, 2013). Many parts of the Carolinian ecoregion (Windsor-Essex county is a part of), natural habitats are fragmented and isolated (Reid & Symmes, 1997). While some species of wildlife travel through agricultural lands, shelterbelts and watercourses to move between larger natural features, some have specific needs and require vegetated corridors between major core areas, which can provide escape routes, improve biodiversity and genetic pools through immigration and emigration (Essex Region Conservation Authority, 2013). 

As ecosystem loss and degradation is a primary environmental issue in the Windsor-Essex region, artificial light sources across the landscape may present additional barriers to wildlife using wildlife corridors. In a 2016 study, the effects of light pollution on animal usage was undertaken to identify effects on movement for 23 mammals, birds, reptiles and amphibians (Bliss-Ketchum, de Rivera, Turner & Weisbaum, 2016). Results showed that barriers to movement, including artificial light, could isolate wildlife populations, impact their genetic diversity, increase susceptibility to disease, impede migration behaviour and reduce access to resources (Bliss-Ketchum et al., 2016).  

NIGHT SKY NATURAL HERITAGE 

Many people naturally peer up into a clear, dark sky to wonder in awe about the stars and other celestial objects that are far from reach. Protecting night sky natural heritage provides unspoiled star gazing opportunities, and is essential for full appreciation of nature at night. There are many anecdotal frustrations of people living in Windsor-Essex county that artificial light, in particular sources from large greenhouse operations reduce or completely take that opportunity for star gazing away anytime of year. 

In celebration of dark sky natural heritage, coupled with ecological values for conservation and protection, Point Pelee National Park received designation as a Dark Sky Preserve from the Royal Astronomical Society of Canada and the Royal Astronomical Society of Canada – Windsor Centre. This designation shows that there are people in the local community, and those that visit, that a dark sky is worth protecting for many reasons. 

RECOMMENDATIONS

There are many communities across the world that are geographically close to greenhouse operations. Artificial light pollution is not a new issue that has been brought forward by people living in these communities for environmental and personal reasons. Greenhouse operations have acknowledged these challenges and have risen to the occasion in many instances to extend an olive branch and be a good neighbour. For example, according to an article published by Greenhouse Product News, the Netherlands have put in place ordinances that require 95 to 98% of electric lighting must be contained within the facility. These greenhouses also produce high intensity produce such as fruiting vegetables and cut flowers, and operate with low solar daily light during the winter (Greenhouse Product News, 2019). 

From a local perspective, the decision to initiate a light limiting by-law in the Town of Kingsville was well received. The improvements that will be experienced from a clearer, darker sky and less artificial light will benefit individuals, homeowners, businesses, visitors, wildlife, plants and international neighbours with their eyes on changes that will come from this decision. 

The Essex County Field Naturalists’ Club thanks Leamington Council and the Municipality for offering a comment period to collect feedback on the potential initiation of a by-law to limit artificial light. Through a science-based approach that aims to provide general information about the impacts of artificial light on flora and fauna and dark sky heritage, ECFNC is in support of the proposed draft By-law 79-20, being a by-law requiring the abatement of interior greenhouse light. 

ESSEX COUNTY FIELD NATURALISTS’ CLUB

Essex County Field Naturalists’ Club is a non-profit, open-to-the-public volunteer organization that focuses on promoting the conservation and restoration of the diverse natural heritage of Essex County and the surrounding region. We also strive to provide educational opportunities for the people of Essex County to become acquainted with and better understand the natural environment.

Organized in 1984 and incorporated in March 1985, the Essex County Field Naturalists’ Club is a volunteer organization affiliated with Ontario Nature and the Canadian Nature Federation (CNF). The membership consists of people interested in nature and our local environment. Members come from various backgrounds; some work professionally in the fields of conservation and education, while others are people who wish to explore and learn about Essex County’s nature.

CONTACT INFORMATION 

If you wish to contact a member of the Essex County Field Naturalists’ Club Executive team, please visit: https://www.essexcountynature.com/contact-us/. 

REFERENCES 

Bennie, J., Davies, T.W., Cruse, D. & Gaston, K.J. (2016). Ecological effects of artificial light at night on wild plants. Journal of Ecology. 104(3), 611–620. doi:10.1111/1365-2745.12551.

Bliss-Ketchum, L.L., de Rivera, C.E., Turner, B.C., & Weisbaum, D.M. (2016). The effect of artificial light on wildlife use of a passage structure. Biological Conservation, 199, 25-28. doi: 10.1016/j.biocon.2016.04.025. 

Carolinian Canada. (2004). Carolinian species and habitats. Retrieved from: https://caroliniancanada.ca/legacy/SpeciesHabitats.htm 

Essex Region Conservation Authority. 2013. Essex Region Natural Heritage System Strategy – (An Update to the Essex Region Biodiversity Conservation Strategy). Essex, Ontario. 319 pages.

FFW Conservation Commission. (2020). Wildlife lighting: About lighting pollution. Retrieved from: https://myfwc.com/conservation/you-conserve/lighting/pollution/

Greenhouse Product News. (2019). Managing light pollution. Retrieved from: https://gpnmag.com/article/managing-light-pollution/ 

Hölker F., Moss, T., Griefahn, B., Kloas, W., Voigt, C.C., Henckel, D., Hänel, A., Kappeler, P.M., Völker, S., Schwope, A., Franke, S., Uhrlandt, D., Fischer, J., Klenke, R., Wolter, C. & Tockner, K. (2010). The dark side of light: A transdisciplinary research agenda for light pollution policy. Ecology and Society, 15(4), 13.

International Dark-Sky Association. (2020). Light pollution effects on wildlife and ecosystems. Retrieved from: https://www.darksky.org/light-pollution/wildlife/ 

Longcore, T. and Catherine Rich (2004). Review: Ecological Light Pollution. Ecological Environment 2 (4): 191 – 198. https://www.researchgate.net/publication/221959079_Ecological_Light_Pollution 

Moody, E. (2018). Demystifying light levels for Cannabis grows. Retrieved from: https://pllight.com/demystifying-light-levels-for-cannabis-grows/

Parker, S.R., S. Liipere, A. Kennedy, B. Caulfeild-Browne and J.G. Nelson. (2011). Sources of Knowledge Forum 2011: Sharing Perspectives on the Natural and Cultural Heritage of the Bruce Peninsula. in Sources of Knowledge Forum, Tobermory, Ontario.

Reid, R. & Symmes, R. (1997). Conservation strategy for Carolinian Canada. Carolinian Canada Coalition, London, Ontario. 

Russart, K.L.G. & Nelson R.J. (2018). Artificial light at night alters behavior in laboratory and wild animals. Journal of Experimental Zoology, Part A. Ecologically and Integrative Physiology, 329(8-9), 401-408. doi: 10.1002/jez.2173.

SunTracker Technologies. (2020). DLI Calculator for Leamington, ON. Retrieved from: https://www.suntrackertech.com/dli-calculator/

Torres, A. P., & Lopez, R. G. (2018). Commercial greenhouse production. Department of Horticulture and Landscape Architecture, Purdue University.