Fluorescent Transgenic Zebra Danio More Vulnerable to Predators than Wild‐Type Fish

Abstract

There is a knowledge gap in the ecological risk assessment of transgenic fish as to whether novel traits change their vulnerability to predation and thus their ability to establish themselves in nature. The U.S. commercialization of ornamental transgenic zebra danios Danio rerio and the approaching commercialization of other transgenic fish heighten the need for ecologically realistic models with which to address this question. Transgenic zebra danios with fluorescent body colors represent a good model system because marketed lines are likely to be released by hobby aquarists and it is relatively easy to study their interspecific interactions under nearly natural conditions. In experiments including habitat complexity, transgenic red‐fluorescent‐protein zebra danios were approximately twice as vulnerable as the wild type to predation by largemouth bass Micropterus salmoides and eastern mosquitofish Gambusia holbrooki, two native predators that potentially resist invasion by introduced fish. Increased predation vulnerability should decrease the risk of transgenics’ becoming established if other fitness‐related traits are equivalent in nature. The zebra danio model is ideal for further testing the generality of this result under more complex ecological conditions.

Collapse of a reproducing population of non-native African jewelfish (Hemichromis letourneuxi) in a Florida lake

“…Research suggests that eastern mosquitofish harass and consume small-bodied non-native fishes and reduce refuge quality of shallows and structurally complex habitat via agonistic interactions (Hill et al 2011, Thompson et al 2012. Eastern mosquitofish had no effect on adult African jewelfish survival in experimental tanks and no observations suggest that eastern mosquitofish attack or displace African jewelfish from refuge habitat.…”

“…The other experiment tested the effects of eastern mosquitofish on African jewelfish (eastern mosquitofish challenge). Largemouth bass and eastern mosquitofish are common native species in Florida, are thought to resist invasion by non-native fishes (Hill et al 2011, Thompson et al 2012, and present non-native fishes with differing challenges (Hill et al 2011). Largemouth bass is a large-bodied (up to > 500 mm TL) gape-limited predator that often restricts the use of open waters by small-bodied fishes (Werner et al 1983, Hambright et al 1991, Hill et al 2006).…”

“…Largemouth bass is a large-bodied (up to > 500 mm TL) gape-limited predator that often restricts the use of open waters by small-bodied fishes (Werner et al 1983, Hambright et al 1991, Hill et al 2006). Eastern mosquitofish is small-bodied (~60 mm TL) predator and aggressive competitor (Meffe 1985, Hill et al 2011) that influences use of structured habitats by small fishes (Thompson et al 2012). Fish were collected from research ponds at the UF/IFAS Tropical Aquaculture Laboratory, Ruskin, Florida.…”

“…Fish were removed and counted after 10 days. All surviving African jewelfish were scored for caudal fin damage, a common sign of eastern mosquitofish attack (Meffe 1985, Hill et al 2011.…”

“…), where elimination of dense stands of the submersed macrophyte Hydrilla verticilata was thought to have facilitated predation by largemouth bass (Shafland et al 2008). Despite the lack of data on the influence of biotic resistance on field populations of non-native fishes in Florida, experimental evidence shows that predation and aggres-sive competition from natives offer resistance against establishment of many smallbodied (<150 mm total length [TL]) non-natives (Hill et al 2011, Thompson et al 2012. Such resistance is hypothesized to result in an overall lack of successful smallbodied invaders despite strong introduction pathways (Thompson et al 2012).…”