Loss of Greenspace on Seabrook Island by Barry Shedrow
What are the environmental consequences?

Seabrook Island’s wildlife habitat or greenspace has been significantly diminished due to habitat  modification or land use change. Much of the island’s once extensive forestland has been  replaced by suburban development. Where greenspace does remain within the Seabrook Island  Development (SID), it is fragmented and present in isolated patches. The progressive loss of  greenspace on Seabrook Island is illustrated in Figures 1 – 3. Figure 1 shows the island in 1963.  The predominant land cover is maritime forest. Jenkin’s Point and the area northeast of  Horseshoe Creek are cleared or under cultivation. 

Figure 2 shows the island in 1973. The SID is under construction. Several roadways have been cut, water/sewerage infrastructure has been completed, and the Ocean Winds Golf course will  soon be open for play. The fragmentation and loss of greenspace within the SID has begun. 

Figure 3 shows the island in 2020. Most forestland within the SID has been replaced by suburban development. The greenspace that does remain is present in isolated patches. The largest tract  of greenspace left on the Island is the approximately 300 acres of maritime forest and salt marsh  within Camp St. Christopher (upper left-hand corner of photograph). 

FIGURE 1 Aerial Photograph of Seabrook Island in 1963

Greenspace provides multiple environmental benefits and the effects of its loss on the island’s  natural and human environments can be substantial. Following is a brief discussion of some of  the environmental consequences potentially associated with the loss of greenspace on Seabrook. 

Increased Flooding: Greenspace reduces the potential for flooding. Precipitation on greenspace  is taken up by plant roots, absorbed by the soil column, or evaporated back into the atmosphere. The loss of greenspace has reduced the island’s capacity to absorb rainfall and moderate runoff during storm events. 

Degraded Air Quality: Greenspace purifies the air we breathe. Greenspace absorbs pollutant  gases (e.g., carbon dioxide, nitrogen oxides) and traps airborne particulates, effectively removing them from the atmosphere. Greenspace also produces oxygen as a by-product of photosynthesis.  When greenspace vegetation dies, most of the carbon-laden biomass becomes buried in the soil  column, preventing the release of carbon dioxide back into the atmosphere. It is likely that air  quality on Seabrook has been diminished by the significant loss of greenspace.  

Degraded Water Quality: Greenspace protects water quality. It does this by removing dissolved  pollutants in rainfall as it flows over the vegetation and percolates through the soil column. When  greenspace is replaced by suburban development, water quality in downstream lakes and ponds  may be adversely impacted. A suburban landscape possesses impermeable surface areas (e.g.,  roadways, rooftops, parking lots, driveways) which generate an increased volume of stormwater  runoff. This runoff not only increases the potential for flooding and soil erosion but also increases pollutant loading (e.g., plant nutrients, heavy metals, organics, bacteria) to receiving lakes and  ponds. In 2017, a study of selected lakes and ponds on the island was conducted by the Seabrook  Island Property Owners Association (SIPOA). Palmetto Lake and the Finger Lakes (excluding  Mallard Lake) were found to possess high levels of plant nutrients. Elevated nutrient  concentrations can increase a waterbody’s biological productivity, making it prone to algal  blooms, oxygen depletion, and fish kills. SIPOA is planning a follow-up study of selected island  lakes and ponds to assess their water quality and determine if corrective actions are needed. 

Loss of Wildlife Habitat: Wildlife require a habitat of sufficient size and quality to survive and  propagate. Seabrook’s once expansive maritime forest supported large and diverse populations  of plants and animals. Construction of the SID transformed much of this forestland into a  suburban landscape. With this loss of greenspace, the island’s biological carrying capacity has  been significantly reduced. Seabrook can no longer support the size and diversity of wildlife  populations that it once did. 

Reduced Biodiversity: Greenspace patches within the SID are isolated from each other by a  matrix of roadways, homes, and fairways. This isolation impedes the movement of wildlife  between patches. Gene flow between the respective patch populations is restricted. Due to a  reduction in genetic variation, the ability of patch populations to produce offspring is reduced and the risk of local extinctions or diminished biodiversity is increased.

Introduction of Invasive Plant Species: Invasive plant species are defined as plants that are non native and harmful to an established ecosystem. The introduction of invasive plant species on  Seabrook Island is primarily due to human activities related to construction and landscaping. Habitat modification presents an opportunity for the establishment of invasive plant species.  When a cleared lot is adjacent to undisturbed greenspace, an ‘edge habitat’ is formed where the  two distinct ecosystems share a common boundary. Light, moisture and other environmental  conditions within an edge habitat can provide an opportunity for the establishment of non-native  plant species. A survey to determine the type, number, and location of invasive plant species on  conserved greenspace and SIPOA properties was recently conducted. A program to eradicate the  identified invasive plants has been implemented by SIPOA.  

Today, there are approximately 140 acres of undeveloped land left within the SID. Around 40 of  these acres are protected from development by trusts and conservation easements. The  remaining acreage is at risk of being lost to residential development. The SIPOA and Seabrook  Island Green Space Conservancy (SIGSC) are working jointly to acquire and conserve as much of this remaining greenspace as possible. If you wish to donate land, make a financial contribution,  or learn more about Seabrook’s land conservation program, please go to How to Help & Donate.