Article Review: Wetland Conectivity: How Fully Aquatic Species Reach Isolated Wetlands by: Ben Sagara

 

I have always been interested in wetland management, and specifically the effects of development on wetland ecosystems.  After our recent literature discussion from class I decided to follow up by doing some wetland research.  I came across a few interesting studies, but I found one to be particularly intriguing.   Christopher M. Schalk and Thomas M. Luhring conducted a study published by The Society for the Study of Amphibian and Reptiles that assessed the vagility (the ability for these salamanders to disperse) of 2 fully aquatic salamanders; the Greater Siren and the Two-Toed Amphiuma in two semi-permanent shallow water ponds on the Department of Energy's Savannah River Site in Aiken, South Carolina.  The researchers observed that these fully aquatic species were prevalent in an array of isolated wetland in the Southeastern region.   Many previous studies have investigated the vagility (dispersal mechanisms) for many terrestrial and semi-terrestrial species, but there is little knowledge as to how fully aquatic species reach isolated wetlands.  Dr. Schalk and his team set out to capture both Greater Sirens (Siren lactertina), and Amphiuma (Amphiuma means) around their study sites in Akin, South Carolina.   They subjected each individual (N=55, but they caught many more Siren than Amphiumia) to one of thee treatments to assess vagility.  They predicted that these species disperse to near by wetlands during heavy rain and flooding events.  To test their dispersal (vagility), salamander distance was measured as they traveled through varying levels of water (3 treatments).  The first treatment had almost no water, while the last treatment had 5 cm, which was enough for the salamander to be submerged.   

The study showed that both aquatic salamanders have trouble dispersing significant distances under very moist and shallow standing water conditions, traveling fewer than 10 m.  Under fully submerged conditions however, vagility increased significantly, with some individuals traveling over 40m.  The fact that fully aquatic species persist in an array of isolated wetlands suggests that there are some corridors through which even fully aquatic species can disperse.  The results support the assumption that heavy rains and flood events are the conditions needed to create these ephemeral corridors that aid in the vagility of aquatic species.  A lesion can be learned as increased development, for example, building roads, power lines, and plumbing, all create potential blocks to these ephemeral corridors.  Much of this infrastructure seems negligible, but they create obstacles to large for many species to overcome.  They block gene flow and isolate adjacent populations, which lessons variation among the populations through a process called habitat fragmentation, which weakens the overall health of the populations.

We must maintain landscapes that protect these ephemeral corridors and enhance periodic wetland connectivity so that we can reduce the loss of local populations of aquatic species in wetland ecosystems.   Our infrastructure should not alter the dynamic flow of the natural processes that exist, but should account for the immigration and emigration of meta-populations within their natural environment.   

ArticleLink:

 http://www.jstor.org.nuncio.cofc.edu/stable/pdf/40665011.pdf?acceptTC=true 

or
http://www.jstor.org/stable/40665011