Mitigating Adverse Environmental Effects Arising From The Port St. John I-95 Interchange

• Introduction
• An assessment of Landscapes in Brevard County and the Threat to Bobcat Survival
• A Specific Threat: The Port St. John I-95 Interchange
• Recommendations for Mitigation and Habitat Conservation
• Implementation
• Implications to Biodiversity and Recreation
• Literature Cited

Introduction

Coryi Foundation, Inc. is a non-profit scientific organization studying bobcat (Lynx rufus) population viability in intensely developed landscapes east of the St. Johns River. This is done, in part, by radio-collaring and monitoring bobcats to assess status and document movements through corridors. Based on its findings, the Foundation develops recommendations for the preservation of wildlife corridors and larger habitat areas to which they connect. The end goals of this effort are to: (1) insure the long-term persistence of bobcats in intensely developed counties like Brevard; and (2) promote regional biodiversity through a landscape-level network of habitat cores and interconnecting corridors as demonstrated through the persistence of wide-ranging indicator species such as bobcats. The purpose of this document is to (1) Discuss the effects of the future Port St. John I-95 interchange and potentially associated development as related to local population survival, and (2) Provide landscape management recommendations that minimize these effects. Though the Foundation’s efforts span several coastal counties, this document addresses general landscape problems that exist between Mims and Melbourne, with an emphasis on the ecological effects of the Port St. John I-95 interchange project.

That the bobcat may now be vulnerable to local extinction should be of no real surprise. Florida is growing rapidly in terms of numbers of people and new developments. With its population increasing at an exponential rate, it could be predicted that east central Florida is soon to attain the same extent and degree of development as Los Angeles, California. Unless proactive steps are aggressively taken, most of the existing habitats could soon be icons of the past. Fortunately, all is not yet lost. The bobcat, Brevard County’s remaining large carnivore, continues to survive across the fragmented landscape. This is because, miraculously, large-scale natural connectivity continues to exist amidst the myriad of residential, commercial, and industrial areas. However, it will surprise most that the county may be delicately balanced on the dividing line between continued biodiversity and further significant ecological disaster. This is because a critical component of the predator-prey food web may disappear. At the focal point of this threat is our beloved bobcat, its need for large habitat blocks and corridors, and its foe, a society being drawn into an urbanization vortex. In the end, if bobcats disappear, other species may follow.

Assessment of Landscapes in Brevard County and the Threat to Bobcat Survival

Though the bobcat is not a listed species, there is the potential for its local loss in Brevard County. Development is enveloping and eliminating preferred bobcat habitat. Out of the 203,858 acres of land that exists between Mims and Melbourne, 50% is developed (see Figure 1). Another 25% consist of non-forested wetlands, specifically freshwater marsh, shrub wetlands, and wet prairie - types avoided by bobcats (Wassmer et al. 1988, Maehr 1997, Mallow 1999, Mallow unpublished data). These types are generally too wet for denning, lack sufficient numbers of preferred prey, and degrade the health of individuals (Mallow 1999). The bulk of these avoided habitats exist in the St. Johns River floodplain wetland system, toward which development is pushing and which is quickly becoming the last natural area of appreciable size. The remaining 25% (50,964 acres) constitutes the only amount available as preferred bobcat habitat and consists of wetland forests and development-vulnerable upland types. These include pine flatwoods, upland hardwoods, upland brush stages, and mixed forest wetland (Mallow 1999, Griffith and Fendley 1986). These types possess sufficient prey (rabbits and rodent) and suitable denning cover (Golley et al. 1965, Maehr and Brady 1986).

The remaining preferred 25% is extremely limited for bobcats. Bobcats are wide-ranging and solitary. Males and females defend territories that average 4800 and 2900 acres, respectively (Wassmer et al. 1988, Mallow 1999). Both sexes do not allow other adults of the same sex to occupy their ranges. These territory sizes and this social structure dictate that populations require extensive tracts of land. In order to be free of the extinction-yielding effects associated with small populations, a population requires at least 200 adults (Cox et al. 1994). This equates to about 291,000 acres, far more than all the land available between Mims and Melbourne.

This limitation of space is significant if development reaches 100% saturation from the St. Johns River floodplain to the Indian River Lagoon at several constricting locations. These locations include Mims, Port St. John, Lake Poinsett, and Lake Washington as shown in Figure 1. The net effect of this saturation could be the creation of one to three small and isolated populations, designated as the Titusville, Cocoa, and Viera Cores in Figure 1. As an example, if the landscapes at Mims and Lake Washington were to become fully developed from river to river, the population contained within would likely be isolated and have available to it only 50,964 acres of preferred habitat. This would limit the population to about 42 to 75 individuals. This population would be far smaller than that required for long-term persistence (Cox et al. 1994). If, in addition, the Port St. John and Lake Poinsett constrictions were fully developed, each of the three cores of Figure 1 would have anywhere from 14 to 30 adults each. [Note: Isolation occurs because, additionally, the St. Johns River floodplain (wide channels and hostile wetlands) effectively prevents movement into the area from the west.]

Under the above isolation scenarios, a number of events will likely occur. Inbreeding rates will increase in the small population(s) and lead to a reduction in genetic diversity. Loss of genetic diversity can limit a population’s ability to respond to changes in the environment. This is because some of the loss in variation could be due to a loss of genes that would otherwise allow a population to adapt to the changes (Franklin 1980, Allendorf and Leary 1986). Inbreeding depression can allow the expression of harmful genes that can debilitate offspring. These effects include reduced immunity to diseases, lowered reproductive success, and the onset of physical impairments (some of which are fatal) (Ralls et al. 1988). These effects have already been documented in populations of other Felidae species whose numbers have been reduced either by natural isolation, persecution, and/or habitat loss. Included in these are the Ngorongoro Crater lion (Panthera leo) (Packer et al. 1991, Packer 1992), cheetah (Acinonyx jubatus) (O’Brien and Evermann 1988), and Florida panther (Felis concolor coryi) (Roelke 1988 and 1989). Of course, countless other species are in the same predicament worldwide. Furthermore, small populations are more susceptible to epidemics and catastrophies such as fires or hurricanes. Because of isolation, individuals will not be able to move into an isolate to replenish losses that arise from mortalities. Additionally, the gene flow that is needed to offset the effects of inbreeding will not occur. These events typically spiral into an extinction vortex in which the factors that effect a small population tend to drive its size progressively lower (Gilpin and Soule 1986). The end result is extinction. Thus, if the landscapes of Brevard County fall victim to the aforementioned scenario, bobcats from Melbourne to Mims could become locally extinct.

Furthermore, river to river development at any one of the above constrictions would likely isolate all bobcats east of the St. Johns River from the mainland, from that location north to Jacksonville. This is because the St. Johns River proceeds all the way to Jacksonville where it empties into the Atlantic Ocean. Such could set the stage for future extirpation on a regional scale.

It must be mentioned that the above isolation scenario is competing with yet another undesirable scenario: urban sprawl that pushes westward to the floodplain at most, if not all points along the county’s length. Such sprawl will still create some isolated pockets. However, it imposes a less forgiving situation by effectively eliminating most upland habitats and forcing remnants to make use of the wetter floodplain areas or extremely small conservation areas (which by then would have become true museums of Brevard fauna and flora). Whereas the bobcat may be able to make use of the floodplain area for a short period of time before it disappears, many species with narrower habitat requirements will rapidly disappear. Either way, Brevard County is following the way of coastal counties such as Broward, Dade, and Palm Beach. What compounds Brevard County is that it has an effective barrier to the west that consists of a wide marsh floodplain of which most animals of concern can make little use simply because they are not adapted to non-forested wetlands. Thus, what we are ultimately addressing here is not only the potential loss of the bobcat from much of the mainland, but other species as well.

Therefore, to prevent isolation and allow for a large continuous population that is less vulnerable to local extinction, and to provide a measure of safeguard for biodiversity and other species as well, corridors need to be retained, especially at the constrictions indicated in Figure 1. A corridor is a linear habitat embedded in unsuitable habitat, that connects two or more larger cores (blocks) of suitable habitat and that is proposed for conservation on the basis that it will enhance or maintain wildlife population viability in the habitat cores. Viability is achieved because animals can make passage between the cores via the corridor. Passage is defined as travel via a corridor by individual animals from one habitat core to another. Excluded in this definition are linear habitats that support breeding populations of many species but do not connect larger habitat cores. Nonconnective linear habitats possess significant conservation issues, but in the present context of a wide-ranging species, attention is placed on linear tracts of land whose conservation value is allowing passage between more significant habitat cores. Corridors facilitate successful movement between population cores by adult breeders and dispersing juveniles. They promote the gene flow required to offset inbreeding effects and help replenish individuals. A corridor that promotes successful movement mostly consists of preferred habitats, possesses minimal impediments like highways, is sufficiently wide (Noss and Cooperrider 1994).

A Specific Threat: The Port St. John I-95 Interchange

There is a potential threat to movement through the Port St. John area. Brevard County is considering developing portions of sections 28 and 27 of Township 23S, Range 35E (Figure 2). This development is associated with the future I-95 interchange between Port St. John and Canaveral Groves. Habitats that occur in these sections are part of a corridor system that skirts the west side of Port St. John and connects the Titusville and Cocoa cores as depicted in Figure 2. Our telemetry data suggests that the corridor that wraps around the west side of Port St. John provides the quickest, shortest and most preferred route that facilitates successful passage between those cores, and that it is consistently selected for such movement above the wetlands to the west. Compared with isolated blocks of preferred habitats to the west, this route proceeds through the most continuously forested configuration. The landscape to the west not only lacks forest continuity, but also largely consists of unsuitable grass and shrub wetlands that lack forest cover and sufficient prey within their interiors. That landscape discourages passage and drains energy budgets. Bobcats are less likely to penetrate them deeply, let alone make a passage through them. Rather, they possess a greater need for and seek the preferred types located to the east. Animals need the most encouraging route that facilitates passage to a distant population. This is the true function of a corridor. The highly preferred pine flatwoods of sections 27 and 28 form the crux of the corridor system in this area. Abundant in preferred cover and prey, these flatwoods strongly encourage movement through that corridor. These flatwoods are also continuous with large forest patches that are interconnected and exist between the interstate and US 1 from Port St. John to St. Rd. 528. These areas are significant because they are sufficiently large to allow for the maintenance of several home ranges, and thus, a sub-core from which new offspring can emerge to help replenish the population. They are also among the most preferred habitat types that exist in the county and that are east of the interstate. Unfortunately, development has left very little of the land intact east of the interstate and, therefore, these areas are vulnerable to elimination. Thus, these issues require that an added emphasis be made on the protection of these lands.

The interchange project has several aspects that could diminish or destroy the corridor system’s ability to foster movement (Figure 2). First, the interchange is massive. The long lengths of the access ramps will add a significant impediment to movement by increasing the rate of road kills, and therefore, decreasing the rate of successful passage. Additionally, an increase of road kills in the population may weaken demographic stability. From 1993 to 1998, the Foundation documented 28 road kills (mean of 5.6 per year) between Mims and Melbourne. Assuming that the lower (N=42) of the two population estimates between Mims and Melbourne is the most accurate, then there is a (100*5.6)/42) = 13.3 % annual mortality rate due to a road death portion alone. Surely, more road deaths are occurring than documented. Furthermore, other causes of mortality exist such as death due to old age or disease, predation of offspring, and killings by humans as nuisance predators. Thus, the mortality rate may be reasonably closer to 30 % with all these other causes factored in. What is worse is that the majority of road kills in the county are those of young males (41%) that are in the process of dispersing from a birth range. Young females, adult males and adult females account for 9, 25, and 25%, respectively (Mallow, unpublished data). This is significant because young males disperse the farthest (Griffith and Fendley 1986) (and hence, have the greatest need for corridors) and thus, promote the greatest gene flow across a landscape. Thus, road kills in this corridor will not only decrease gene flow between the cores, but could increase the mortality rate in such a way as to significantly weaken demographic stability. Secondly, the connector road that goes east to Grissom Parkway cuts through a significant portion of preferred habitat, again increasing the rate of road kill of animals accessing the corridor. Depending on the extent, associated commercialization of those lands could prevent immediate passage to the east. Third, the paving of Pine Street from Canaveral Groves to Port St. John is being considered as part of the west connector. Paving would encourage the development of properties in section 28. This is a great threat to the corridor. Telemetry data suggests that development that is more intense than 1 - 2.5 acres per dwelling is unsuitable. Such would likely eliminate forest connectivity and render the corridor useless. Finally, concern expressed by residents regarding routing interstate traffic into the section 33 portion of Pine Street has prompted the consideration of taking a southern extension over to Satellite Boulevard. This too would attract development of lands with the potential for eliminating most of the forest in section 28.

Recommendations for Mitigation and Habitat Conservation

Clearly, the interchange and proposed access roads are not in the best interest of local ecology. However, the interchange is a reality and must be dealt with as best as possible. Since the interchange poses a significant threat to the ecological state of the area, it is necessary to mitigate its adverse effects. In light of the above discussion, it is strongly recommended that the following occur, as shown in Figure 2:

[1] Limit commercial development to the east connector road and only within 200 feet of it. Sections 27, and those to the east (26 and 25), constitute functional (and greatly needed) home range habitat for bobcats and are continuous with a system of natural areas that span southward all the way to State Road 528. As such, these sections provide critical access into a relatively large habitat core between I-95 and US 1 that provides home range space for several resident bobcats. Those sections are also on a CARL Scrub Acquisition Project list. Thus, there is great potential that funding will be provided by the state for their purchase as conservation lands. They are on this list due to the presence of scrub habitat and scrub jays.

[2] Keep the Port St. John west access close to Baltimore Avenue on a run that takes it to Golfview Avenue and do not develop Fay Lake Wilderness Park. Keeping this access road as close as possible to Baltimore Avenue will minimize its effects on habitats in Fay Lake Wilderness Park that provide access around the west side of Port St. John.

[3] Do not provide any access from the west side of the interchange (section 28) south into Canaveral Groves. This area is critical to animal movement as shown in Figure 2. It is also a suitable area for a portion of a linear park. An access road would encourage development and render the corridors useless in section 28.

[4] Do not provide any other extension to the west. All lands immediately west of the interchange are critical components of movement in the north-south direction as shown in Figure 2. Floodplain habitats are immediately to the west of Section 28 and the interchange’s western tip reaches to unfavorable habitat, thereby leaving very little room for movement through preferred habitat. Any development west of I-95 will worsen this already undesirable situation.

[5] Promote gene flow between sections 27 and 28 via the implementation of a linear park that crosses I-95 through a suitable underpass via FDOT/Metropolitan Planning Organization funding. Install wildlife underpasses at I-95 south of the interchange and at the east connector road as shown in Figure 2. Install wildlife exclusion fencing around the interchange, I-95, and connecting roadways that funnel animals into the underpasses, as shown in Figure 2. These fences should be 10-12 feet high, chain link, with three strands of barbed wire at the top (Foster and Humphrey 1992). These recommendations will help mitigate the interchange’s adverse environmental impacts by helping animals to move safely across the interstate without being killed. Habitats on the east and west sides of the interstate will be functionally connected and gene flow will be augmented.

Implementation

Coming up with funding sources to secure habitat and corridors is, and will always be a challenge. Fortunately, current interest in developing a county-wide linear park that provides the aforementioned recreation opportunities appears to be one of the best starting places for implementing a large-scale corridor network. We acknowledge that linear park concepts, as applied in the US, do not specifically address the needs of wildlife. Linear parks typically encompass "urban" uses and designs. They are often composed of narrow trails that follow canal right of ways, rather than critical ecological links. This is primarily because of the difficulty in obtaining funding to purchase land for a trail or because it is difficult to find landowners that will allow a trial to cross their lands. Despite these challenges, the linear park concept is a start at some level of connectivity. It’s a "foot in the door", if you will!

It is suggested that the connectivity depicted in Figure 2  not only provides for wildlife movement, but also introduces ideal locations for the linear park in this part of the county. If a linear park that runs through the Port St. John area is properly designed to help promote wildlife movement, then it will assimilate a course similar to that depicted in Figure 2. Furthermore, the construction of underpasses that allow both people and wildlife to safely cross a major highway is economically feasible. Linear park funds are largely derived from Florida Department of Transportation (FDOT) funding sources, ironically the same entity constructing the interchange. An underpass that is to be used for a linear park is an expense that possesses great justification for FDOT. This justification will be the best means by which underpasses can be funded. Indeed, there is a great potential for economic and conservation compatibility within this mitigation.

Implications to Biodiversity and Recreation

The bobcat is the last of Florida’s three large carnivores (Maehr 1997) in the area. The other two (now absent) large carnivores are the Florida panther and black bear (Ursus americanus floridanus). If bobcats disappear from this area, it will lose yet one more component of its old wild Florida heritage. More importantly, it must be decided if the loss can be afforded. The bobcat is a keystone species. This means that its presence determines what other species exist in the food web, as well as their abundances. Its absence as a keystone predator can cause prey populations (rabbit and rodent) to increase, over-forage and deplete their own food sources. This food depletion can increase competition between species that use the same foods. Some species may dominate the dwindling food supply and cause others to disappear. Thus, bobcats help maintain natural balance and their loss can induce the loss of other species. And because the bobcat is all that remains of the three large carnivores in the area, it could be considered the last best defense in terrestrial prey regulation. We have already witnessed the cascading effects of predator removal. When Florida panthers and red wolves (Canis rufus) were extirpated from the barrier islands, raccoon (Procyon lotor) populations increased. So significant was this increase, that the subsequent increase of predation by raccoons on sea turtle eggs is likely a major reason for sea turtle endangerment (Breininger et al. 1994). One cannot help but speculate what will happen if the bobcat disappears. That is, what kind of animal community structure erosion will follow.

The bobcat is also an umbrella species. Because bobcats need lots of forested land, efforts to maintain them automatically umbrella the preservation of the many other species that need less land, without duplicated cost. This aspect has far reaching implications for biodiversity. Except for the Florida panther and black bear, the bobcat is the only terrestrial animal that collectively spans the largest area and makes use of the greatest number of different habitat types (Mallow and Kharbanda 1998). Because of this, the bobcat is an excellent model for large-scale biodiversity and barometer of ecoregion health. That it is often referred to as a focal species has its roots in just this very thing. Its presence implies true wilderness in a landscape. If a population can survive in the long term, then it is because there is a vast amount of wilderness that likely encompasses a full spectra of habitats – habitats that benefit an extremely large number of different species (Mallow and Kharbanda 1998). Thus, when we speak of bobcat conservation, we are really speaking of large-scale biodiversity conservation.

Finally, people benefit from their presence. As a symbol of old Florida that enhances the aesthetic quality of an area, its exciting to see a bobcat and habitat protection provides natural areas for people to enjoy and travel back in time. This aspect provides a direct benefit for humans. We now have at our footsteps one of the greatest opportunities to provide high quality outdoor experiences for people. Protecting sufficient bobcat habitat that insures the retention of population viability and a decent level of biodiversity means that the landscape needs to include large natural habitat blocks that are protected and linked with each other via "true" wildlife corridors. All these areas can provide a wide assortment of recreational opportunities for people such as hiking, camping, horseback riding, bicycling, etc.

The local "fire" is hot with respects to interests in developing a corridor system and/or linear park system. In both the political and conservation arenas, local citizens are expressing a greater concern for the diversity of gene pools, habitat continuity, and large-scale biodiversity. We are now within a window of opportunity wherein the extent of habitat fragmentation is just short of the "critical mass" beyond which wide-ranging terrestrial species are not viable, yet one wherein the community has just started exhibiting a willingness to protect viability though the promotion of a corridor network. If we wait too long, the window will likely shut thereby bringing about an irreversible situation. Thus, we must act quickly and efficiently. We must increase our level of commitment to this end and entertain a number of "radical" strategies that are designed to make the conservation process more successful. These strategies include amending zoning and development regulations so that specific provisions exist that protect corridors from being destroyed. Doing so will require that sufficient scientific data exist that justify the need to protect specific corridors. In light of all the above, the current research being conducted by Coryi Foundation, Inc. (to identify critical corridors and obtain data relevant to viability) could not have been better timed.

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