Intermittently Closed Estuaries and Tadpole Communities: Influence of Artificial Breaching

Occurrence of Amphibians in Saline Habitats: A Review and Evolutionary Perspective

“…Interestingly, the distinction between natural vs. anthropogenic salinization can also be blurred, as is the case with salt water intrusion into freshwater bodies due to rising sea levels associated with human-induced climate change (Nicholls et al 1999). In addition, the influx of seawater into natural coastal estuaries, lagoons, and wetlands can also be heavily managed, causing salinities to change dramatically when artificial barriers are purposely breached (Smith and Reis 1997;Moreira et al 2015). Several species of anurans have been found inhabiting and breeding in these natural/anthropogenic brackish water bodies (Smith and Reis 1997;Moreira et al 2015) and, intriguingly, it is possible that this management technique actually promotes vs. discourages amphibian occupancy (Moreira et al 2015).…”

“…Salinity is known as a driving force governing the composition of aquatic ecological communities (Gunter 1956), and recent work has suggested that salinity can affect the interactions of amphibians with other community members (e.g., food-web dynamics) both directly and indirectly (Petranka and Doyle 2010;Chambers 2011;Van Meter et al 2011;Petranka and Francis 2013;Moreira et al 2015;Van Meter and Swan 2014). Adaptation to salinity could certainly lead to novel predation opportunities for amphibians in these environments, as has been shown in some South American anurans eating marine invertebrates, for example (Sazima 1971;Brasileiro et al 2010;Ferreira and Tonini 2010).…”

“…Adaptation to salinity could certainly lead to novel predation opportunities for amphibians in these environments, as has been shown in some South American anurans eating marine invertebrates, for example (Sazima 1971;Brasileiro et al 2010;Ferreira and Tonini 2010). It is also possible that salinity intolerance of freshwater invertebrate predators could lead amphibians to adapt to saline habitats to escape predation pressure (Moreira et al 2015; although this must be balanced by potentially increased pressure from marine predators; Pyke et al 2013). Differential susceptibility to salt can also affect amphibian species diversity and community composition in saline habitats (Karraker et al 2008;Collins and Russell 2009;Karraker et al 2010;Brown and Walls 2013;Gallagher et al 2014;Moreira et al 2015).…”

“…It is also possible that salinity intolerance of freshwater invertebrate predators could lead amphibians to adapt to saline habitats to escape predation pressure (Moreira et al 2015; although this must be balanced by potentially increased pressure from marine predators; Pyke et al 2013). Differential susceptibility to salt can also affect amphibian species diversity and community composition in saline habitats (Karraker et al 2008;Collins and Russell 2009;Karraker et al 2010;Brown and Walls 2013;Gallagher et al 2014;Moreira et al 2015). Thus, an escape from competitors or predators, or novel prey opportunities (in short, changes in community composition and structure), may be driving forces in the evolution of salt tolerance in amphibians.…”

“…as they increase in frequency with climate change (Thirion 2002;Gunzburger et al 2010;Brown and Walls 2013). Thus, amphibians in these habitats have been forced to evolve tolerance in response to these intermittent salinity events (Gunzburger et al 2010;Brown and Walls 2013;Moreira et al 2015). The salinity of coastal areas can also be affected by anthropogenic management activities, such as artificially opening and closing estuaries, resulting in the same pattern of disruptive, intermittent salinity inundation (Moreira et al 2015).…”