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

Abstract

Established populations of non-natives may collapse without a clear causal mechanism. Hypothetically, fluctuations in habitat structural complexity may influence dynamics of invaders and the biotic resistance offered by predators. Herein I report observations of the collapse of a reproducing population of the nonnative African jewelfish (Hemichromis letourneuxi) in a Florida lake concurrent with an unusual low-water period. I test the hypothesis that predation may have played a key role in the collapse using a combination of field surveys of habitat and fish abundance and predator-prey experiments. Habitat complexity was high before and after the low water period but virtually nonexistent during low water. The abundance of African jewelfish and native juvenile bluegill (Lepomis macrochirus) and eastern mosquitofish (Gambusia holbrooki) declined concurrently with decreasing complexity but the native species rebounded when lake levels increased. Large-bodied natives such as largemouth bass (Micropterus salmoides) and adult bluegill showed no pattern of fluctuation related to habitat complexity. African jewelfish survival was 1.6 times greater at high versus low complexity and over 7 times higher versus no complexity in the presence of largemouth bass. Conversely, eastern mosquitofish, a species that exerts strong effects on small-bodied fishes in structurally complex habitats had no effect on African jewelfish survival. Predation effects on susceptible non-natives should be considered as a potential control action. Population collapse is understudied but may provide insights into long-term dynamics of invaders and information useful for management of problematic species.

Life history strategies differentiate established from failed non‐native freshwater fish in peninsular Florida

“…In 2012, Croaking Gourami was found in a complex of canals, ditches and wetlands nearby, suggesting undetected persistence of the original population (Schofield & Pecora, 2013; Schofield & Schulte, 2016). The African Jewelfish Hemichromis letourneuxi , although embedded in the cluster of equilibrium strategists, is unique because of its small body size and rapid spread throughout south and central regions of Florida (Hill, 2016; Langston et al, 2010; Lopez et al, 2012). Its success may be partially due to its ability to survive the harsh conditions of its native range (Langston et al, 2010; Schofield et al, 2007).…”

“…Its success may be partially due to its ability to survive the harsh conditions of its native range (Langston et al, 2010; Schofield et al, 2007). This species has been able to survive low‐water conditions in the Everglades by taking refuge in solution holes and its aggressive behaviour facilitates its survival (Hill, 2016; Lopez et al, 2012; Porter‐Whitaker et al, 2012; Schofield et al, 2014).…”

“…However, the successful armoured catfishes are medium‐ to large‐bodied species, whereas the unsuccessful species are small bodied. The reason for these failures is unknown and additional research is needed to better understand the mechanisms driving population declines (Hill, 2016; Simberloff & Gibbons, 2004) and failure to establish (Zenni & Nunez, 2013). Nevertheless, a trait‐based approach is still useful and identifies many failed species correctly using the most highly predictive traits, as has been observed in previous studies (Kolar & Lodge, 2002; Marchetti et al, 2004a, 2004b; Ribeiro et al, 2008).…”

“…A depauperate fauna might be predicted to offer less resistance to invasion than would a more diverse fauna (Elton, 1958; Lodge, 1993). Larger‐bodied fishes seemingly face low biotic resistance in Florida; nevertheless, smaller‐bodied fishes may be limited by native species such as the aggressive Eastern Mosquitofish Gambusia holbrooki (Schofield et al, 2021; Thompson et al, 2012; Tuckett, Deacon, et al, 2021), and large predatory fishes such as Florida Bass Micropterus floridanus (Hill, 2016; Hill et al, 2011; Hill & Tuckett, 2018) and Bowfin Amia calva . The equilibrium strategy which is exhibited by all but two species of successfully established non‐native fishes in Florida, increases juvenile survivorship if the habitat is stable (Winemiller & Rose, 1992).…”

Predicting successful reproduction and establishment of non-native freshwater fish in peninsular Florida using life history traits

“…When an introduced species is able to recruit offspring, the population can then grow in size which leads to establishment of a self-sustaining population. In contrast, population declines can also occur if reproduction requirements are not consistently met; this has been observed for several non-native fish species in Florida (Shafland et al 2008, Hill 2016). In the literature, the reproduction stage is often considered to be a barrier or filter to establishment that must be overcome (Copp et al 2005, Colautti et al 2006, Blackburn et al 2011 rather than a distinct stage of the invasion process.…”