Article Review: “Suburbs: Dangers or Drought Refugia for Freshwater Turtle Populations?”

Earlier this semester, our class was asked to read an article discussing the effectiveness of buffer zones and reserve boundaries for turtles of the Kinosternidae family. Overall, we found that the boundaries designated by law don’t encompass all individuals within a species that need to be protected. That got me thinking about how the construction of cities, roads, and other features of modern human life affect local species and whether there’s something we can do to prevent more deaths.

The development of urban areas can have dramatically negative effects on local populations of species. However, the level of impact can differ based on the type of development (road, building, etc.) and the characteristics of the species in question. Turtles have adapted fairly well to certain types of development such as storm drains, gardens, and even golf course ponds. Some even thrive in these altered environments better than in their natural habitat. Still, man-made environments can lead to fragmented populations due to road mortalities. A major problem is that these urban environments are visually pleasing, luring species towards it, but the journey results in the death of that individual. Ultimately, human manipulations of local environments are thought to result in an increase in mortality over time. When looking at numbers in a suburban population of the eastern long-necked turtle in comparison to a nearby nature reserve over the span of one year, researchers only saw a slight dip in numbers in the suburban area. 

            To look at this from a broader perspective, researchers expanded their study to looking at eastern long-necked turtle numbers within the highly-developed suburb of Gungahlin, Australia vs. nearby reserves of Mulligan’s Flat and Goorooyarroo. Together, these two reserves take up an area of 1,600 ha. 19 bodies of water (10 urban and 9 reserves) from September 2006 through November 2007 were monitored on many levels: surface area, max depth, pH, conductivity, vegetation, and prey abundance. Eastern long-necked turtles tend to move from wetlands to terrestrial environments, so a 500m radius of each body of water was examined, which caused overlaps to occur, reducing to 7 reserve water bodies and 8 from the suburban site. 546 turtles in total were captured, with about 2.9x more turtles found in the suburban area than in the reserves. Faster growth rates and larger plastron lengths were also seen within urbanized areas. One belief is that this species of turtle has been able to travel through drains to migrate between environments, leading to low mortality rates. Another theory is that when droughts occur, suburban areas are less affected than natural ones. Also, there was surprisingly no major difference in nutrient quality within each of the bodies of water.

            Out of this article, developers might be able to gain ways of modifying areas in a manner that DOESN’T disrupt a species’ behavioral/reproductive patterns. They can begin to observe hotspots of where certain species of turtle migrate so that roads don’t cut through, saving the lives of many individuals. If roads do obstruct their migratory paths, special drains need to be added that allow for safe passage. Also, they can change their design of these urban environments to allow local species and humans to cohabitate. It appears as though the addition of drains, ponds, vegetation (if not exotic) can all benefit turtles within these urbanized habitats. Because many turtles migrate to nest, the inclusion of pathways underneath highways can cut down on the number of turtles killed by vehicles on the road. Also, if we adapted to make urban environments less dramatically different from natural ones, this could help turtle longevity. Perhaps the inclusion of a forest area within these cities could cut down on mortality rates. More research needs to be done on which types of features in suburban environments benefit local wildlife most since this research is exclusive to this exact area and species. 

Reference:

Roe, John H., Martha Rees, and Arthur Georges. "Suburbs: Dangers or Drought Refugia for Freshwater Turtle Populations?." Journal of Wildlife Management. Vol. 75.No. 7 (2011): 1544-1552. Print. <http://onlinelibrary.wiley.com.nuncio.cofc.edu/doi/10.1002/jwmg.219/pdf>.