Deleterious effects by mosquitofish (Gambusia affinis) on the endangered fire salamander (Salamandra infraimmaculata)

Abstract

Invasive fishes, via competition and predation, may be an important factor in endangering populations of amphibians and other aquatic fauna. The mosquitofish, Gambusia affinis, commonly stocked into amphibian breeding sites for mosquito control worldwide, has recently been found in some breeding sites of the endangered fire salamander Salamandra infraimmaculata in northern Israel. A comparison of Salamandra larvae in natural pools varying in Gambusia densities suggested that Gambusia negatively affects Salamandra by causing damage to its appendages, in particular, its tailfin (as manifested in a smaller tail:body ratio). Comparison of the same pool before and after mosquitofish introduction suggested strong negative effects on larval performance and number of emerging metamorphs. To explicitly test the hypothesis that Gambusia negatively affects Salamandra larval development, growth and survival, we conducted a replicated outdoor mesocosm experiment. In this experiment, we also tested how habitat structural complexity, in the form of radiating cords simulating artificial vegetation, might mediate damage caused by Gambusia. We used a two‐by‐two factorial design: the presence or absence of increased structural complexity crossed with the presence or absence of mosquitofish. After a short period, mosquitofish strongly reduced larval wet weight and survival, and increased body damage in the form of a reduced larval tail:body ratio and partially missing gills and limbs. No Salamandra larvae exposed to mosquitofish survived to metamorphosis in either habitat type. We conclude that Gambusia strongly and negatively affects Salamandra larvae and that the introduction of Gambusia into sites containing Salamandra is inconsistent with the goal of preserving this endangered urodele.

Non-native freshwater fish species in China

“…For example, Nile tilapia (Oreochromis niloticus) was capable of modifying nutrient regimes by increasing nitrogen and phosphorus availability via excretion, promoting algae growth, and contributing to eutrophication of a reservoir of Brazil (Figueredo and Giani 2005). The mosquitofish (Gambusia affinis) has been reported to be responsible for the decline and extinction of some fish (Galat and Robertson 1992) and amphibian (Gamradt and Kats 1996;Segev et al 2009;Karraker et al 2010) species in North American and Asia. Competition between non-native and native salmonids has led to extinction or significant population decreases in Europe (Hasegawa and Maekawa 2006;Fausch 2007).…”

Larval salamanders are as effective at short-term mosquito predation as mosquitofish

“…Introduced populations of D r a f t mosquitofish alter food webs (Pyke 2008) and negatively affect amphibians and fishes (Blanco et al 2004;Zeiber et al 2008;Segev et al 2009;Drake et al 2014;Shulse and Semlitsch 2014).…”

Vulnerability and behavioral responses of South Chinese anuran tadpoles to native dragonfly (Pantala flavescens) naiads and introduced western mosquitofish (Gambusia affinis)

“…Amphibians are especially vulnerable to the introduction of new predators because they often have complex life cycles with aquatic eggs and larvae (Kats and Ferrer 2003;Vonesh 2005;Segev et al 2009;Smith et al 2013), which are consumed in large amounts by aquatic alien predators (G. affinis, Goodsell and Kats 1999;Gambusia holbrooki, Stanback 2010; Pomacea canaliculata, Karraker and Dudgeon 2014; P. clarkii, Polo-Cavia and Gomez-Mestre 2014). The western mosquitofish G. affinis (Poeciliidae), one of the 100 worst invasive species listed by the World Conservation Union, is native to the fresh waters of the eastern and southern United States (Lowe et al 2000).…”

“…Its widespread introduction can be attributed to its purported effectiveness in consuming larval mosquitoes (Pyke 2008). Previous studies have shown that G. affinis readily preys on amphibian eggs and larvae, both within (Walls et al 2002;Baber and Babbitt 2003;Zeiber et al 2008) and outside of its native range (Goodsell and Kats 1999;Komak and Crossland 2000;Segev et al 2009;Shulse and Semlitsch 2014;Fan et al 2016). G. affinis was introduced to China for mosquito control in 1927, and it now occurs throughout the southern water bodies of the Yangtze River (Li and Jie 2002).…”