Light Pollution Prevention Plan for Sea Turtle Habitat Conservation: Isabella Ocean Residences, Carolina, Puerto Rico February 2005

Transcription

1 Light Pollution Prevention Plan for Sea Turtle Habitat Conservation: Isabella Ocean Residences, Carolina, Puerto Rico February 2005 Gregory L. Morris Engineering P.O. Box San Juan, P.R

2 TABLE OF CONTENTS 1 INTRODUCTION LIGHT POLLUTION... 2 Characteristics of Light Pollution... 2 Nest Site Selection... 3 Sea Finding... 3 Hatching Orientation... 3 Misorientation and Disorientation... 4 Lights that Cause Problems... 4 Categories of Artificial Lighting LIGHT POLLUTION RECOMMENDATIONS... 5 Project Description... 5 Vegetative Barrier... 6 Minimize Beach Lighting from Outdoor Sources... 6 Minimization of Beach Lighting from Indoor Sources... 7 Limit Hours of Lighting... 7 Education... 7

3 1 INTRODUCTION Isabella Ocean Residences is a 13-story residential project with 58 units proposed on an area of 0.90 cuerdas located at #78 and # 80 Isla Verde Avenue, Cangrejo Arriba Ward in the municipality of Carolina. As shown on the location map in Figure 1, the property is adjacent to the Atlantic Ocean. According to U.S. Fish and Wildlife Service (USFWS) communications dated October 22, 2003 & January 10, 2005, the site is located within the nesting range of the following endangered sea turtle species: Eretmochelys imbricata Dermochelys coriacea Hawksbill sea turtle Leatherback sea turtle The USFWS has requested the preparation of a Light Pollution Prevention Plan has been prepared in response to a request by the USFWS. The plan presented herein responds to the USFWS request, and outlines measures to prevent or minimize disturbances to sea turtle nesting areas caused by light pollution during and after construction of Isabella Ocean Residences. This lighting plan is being prepared prior to preparation of construction drawings for the project. The project owner and architect should review these recommendations and incorporate them into the project design drawings and operational procedures. Beachfront buildings can also impact sea turtle nests by casting shadows which reduce the temperature of the sand, affecting incubation. The building has been designed in a stair-step fashion to minimize shadowing over the Maritime Zone, thus minimizing temperature impacts over potential nesting areas. 2 LIGHT POLLUTION Characteristics of Light Pollution Light pollution may be among the most manageable of the ecological disturbances caused by humans as it differs from other pollutants both in its form (light is energy rather than substance), and because its effect is very specific to sea turtle nesting beaches. The effect of light pollution on sea turtles is 2

4 essentially psychological; it produces misinformation or disorientation as opposed to toxic impacts. Light pollution on nesting beaches is detrimental to sea turtles because it alters critical behaviors, such as: 1. How sea turtles choose nesting sites, 2. How they return to the sea after nesting, and 3. How hatchlings find the sea after emerging from their nests. Disruption of any of these activities can produce sea turtle mortality. Nest Site Selection Sea turtles select a nest site by deciding where to emerge from the surf and where on the beach to lay their eggs. One clearly demonstrated effect of artificial lighting on nesting is to deter turtles from emerging from the water. The artificial lighting of sea turtle nesting beaches can be considered a form of habitat loss. When nesting lighting deters sea turtles from nesting beaches, nesting turtles may be forced to select less appropriate nesting sites. There is also the potential that turtles deterred from nesting may shed their eggs at sea. Sea Finding After a sea turtle has camouflaged her nest, she must orient toward the sea and return there. Experiments have shown that turtles rely on vision to find the sea (Mrosovsky and Shettleworth, 1975) and the relatively greater brightness of the ocean as compared to a natural (undeveloped) vegetation for correct seaward orientation. It has been found that artificial lighting disrupts this sea finding behavior. However, adult turtles attempting to return to the sea after nesting are not misdirected nearly as often as are hatchlings emerging on the same beaches. Hatching Orientation Approximately one to seven days after hatching from eggs beneath the sand, hatchlings emerge from their nest and orient toward the sea without delay (Demmer, 1981; Christens, 1990). This emergence of hatchlings and subsequent sea-finding occurs principally at night (Hendrickson, 1958; Carr and Hirth, 1961; Bustard, 1967; Neville et al., 1988; Witherington et al., 1990). Hatchlings that have their sea-finding disrupted by unnatural stimuli and cannot find the ocean will 3

5 die from exhaustion, dehydration, predation, or other causes (McFarlane, 1963; Philkibosian, 1976; Hayes and Ireland, 1978; Mann, 1978). Misorientation and Disorientation Hatchlings instinctively orient toward the brighter horizon. On an undeveloped coastline the ocean reflects moon and star light, and is brighter than the shadows cast by shoreline vegetation. However, hatchlings on artificially lighted beaches tend to crawl toward landward light sources, which is the wrong direction. Hatchings that are oriented away from the most direct ocean path are said to be misoriented. Hatchlings that are unsure about orientation direction demonstrate their uncertainty by frequently changing direction and circling. Hatchlings lacking directed orientation are said to be disoriented. Hatchlings often become disoriented by overhead light sources. Frequently, hatchlings that are initially misoriented oriented toward an artificial light source become disoriented as they reach the source. Hatchlings also appear to become disoriented when they reach boundaries between artificially lighted areas and shadows on the beach. Turtles in this predicament may exit the shadows and move toward the lighted beach sand, become disoriented by light from the artificial source itself and move back onto the shadowed sand. This cycle is then repeated until the hatchling dies of exhaustion, dehydration, or predation. Lights that Cause Problems Although the attributes that can make a light source harmful to sea turtles are complex, a simple rule has proven to be useful in identifying problem lighting under a variety of conditions. An artificial light source is likely to cause problems for sea turtles if light from the source can be seen by an observer standing anywhere on the nesting beach. If any glowing portion of a luminary (including the lamp, globe, or reflector) is directly visible from the beach, then this source is likely to be a problem for sea turtles. But light may also reach the beach indirectly by reflecting off buildings or trees that are visible from the beach. Bright or numerous sources, especially those directed upward, will illuminate sea mist and low clouds, creating a distinct glow visible from the beach. This urban skyglow is common over brightly lighted areas. Although some indirect lighting may be perceived as nonpoint-source light pollution, contributing light sources can be readily identified and include sources that are poorly directed or are directed upward. Indirect lighting can originate far from the beach. 4

6 Although most of the light that sea turtles can detect can also be seen by humans, it should be pointed out that some sources, particularly those emitting nearultraviolet and violet light, will appear brighter to sea turtles than to humans. Categories of Artificial Lighting There are two general categories of artificial lighting that should be taken into account for purposes of preventing light pollution. Direct lighting: A luminary is considered to be direct lighting if some glowing element of the luminary (e.g., the globe, lamp, reflector) is visible to an observer at any point along the beach. A source not visible from one location may be visible from another further down the beach. Indirect lighting: A luminary is considered to contribute indirect lighting if the glowing element is not visible from the beach, but light reflected from the illuminated object (e.g., building, wall, tree) is visible from the beach. Any object on the beach or a dune that appears to glow is probably being lighted by an indirect source. 3 LIGHT POLLUTION RECOMMENDATIONS Project Description The configuration of Isabella Ocean Residences is shown in Figure 2. The proposed project consists of a 13-story residential building with 58 apartments, plus common and recreational areas. Two underground floors will provide space for parking. Proposed land use distribution on the site is summarized in Table 1. Table 1: Proposed Land Use for Isabella Ocean Residences Proposed Use Area (Square Meters) Coastal Easement 1,227 Yards 702 Access 505 Building 1,309 Total 3,743 5

7 Vegetative Barrier The project proposes to restore and vegetate the remnant sand at the maritime zone limit, along the property s northern limit. The species approved by the Department of Natural and Environmental Resources for planting in the area are: Chrysobalanus icaco, Terminalia catappa, Cocoloba uvifera, Conocarpus erectus, and Cocos nucifera. This vegetation should be planted so that it constitutes a continuous barrier to minimize the escape of either direct or indirect light from the project site and the beach. A continuous line of low level species such as Cocoloba uvifera (sea grape) should be planted. The vegetation barrier and the path leading to the beach should be set at an angle to the shoreline to prevent creation of an opening perpendicular to the shoreline through which light can easily escape onto the beach. A planting configuration which avoids a perpendicular opening between the project and the beach is illustrated in Figure 3. Minimize Beach Lighting from Outdoor Sources The following design and operational measures should be implemented to minimize light pollution on beach. o Outdoor lighting such as used for stairways, steps, handrails, pools, and walkways should use low wattage and be oriented or shielded (louvered) so it cannot be seen from the beach and to minimize indirect illumination. All outdoor lighting on the beach side of the building should be placed as close to floor level as possible to minimize indirect illumination. o Outdoor lighting should be concentrated only where it is most needed and focused to minimize the escape of light as either direct or indirect illumination. o The design and specification of lighting should consider the following elements. Avoid the use of white fluorescent tubes in situations where light will be cast outside of the building. Emphasize the use of longwavelength light sources, including the use of red lights for walkways wherever possible. Use the lowest possible wattage. o Install timers to switch off lighting when it is no longer needed in the evening in such places as common areas. 6

8 o Install motion detector switches to control lighting in areas such as walkways that are not commonly used. o Lights on outdoor balconies and terraces should be placed at low level and oriented to focus on the floor, without lighting the building walls. This may be achieved using louvered step lighting. No light should be placed so that an unshielded light source is visible from the beach. o No lights should be placed to illuminate the exterior faces of the building visible from the beach, since this will contribute to indirect illumination on the beach. Minimization of Beach Lighting from Indoor Sources Indoor light is a problem if it is visible from the beach. The impact of indoor lighting is naturally minimized by the stair-step design of this project (as compared to traditional vertical construction). Additional measures to minimize the impact of indoor lighting depend on each individual resident and include: closing curtains or blinds after dark to cover windows visible from the beach; use tinted glass for windows visible from the beach; orient directional lighting away from beachfront windows; and turn off lighting when rooms are not in use. Limit Hours of Lighting Eliminate or turn off problem lights. Many light sources illuminate outdoor areas that do not need to be lighted. Use only the lights necessary for safety or security. Also, turn on lighting only when it is needed (evening and early night) and turn off for the remainder of the night. This may be most applicable in the following cases: lights illuminating areas that require no security, and lights that illuminate areas where there is no foot traffic. Education The absence of knowledge of sea turtle conservation issues contributes to an apathetic attitude among residents and administrators. It is recommended that Isabella Ocean Residences adopt a proactive approach toward education of residents and employees by adopting the following educational strategy. o Provide to each new owner a pamphlet which describes sea turtle conservation efforts, the actions taken by the project to control light pollution, and the additional actions which each owner can take in 7

9 their apartment to limit light pollution. Post a copy of this brochure in the lobby area. o Incorporate a sea turtle related clause in the purchase agreement for apartments, indicating that owners will not be allowed to alter the exterior lighting on their balconies. o Incorporate sea turtle related clauses in the condominium regulations which provides that: (a) exterior lighting shall conform to this Light Pollution Prevention Plan, and (b) all employees shall receive instructions on management of lighting plus the procedures to follow if a sea turtle is observed on the beach. Provide simple written instructions to accompany the condominium regulation which describes a and b above. 8

10 N SITIO Figure 1. Location Map Source: San Juan Topographic Quadrangle, US Geological Survey

11 Figure 2(a). Schematic Site Plan

12 Figure 2(b). Schematic Site Plan

13 Figura 2(c). Schematic Site Plan

14 O C E A N B E A C H beach access Project Site Figure 3: A path running from the project site to the beach in a perpendicular direction will allow light to shine directly onto the beach. Vegetation in the restoration area should be planted to create an oblique path between the project site to the beach, so that light from the project site does not shine directly on the beach.