Tolerance of nonindigenous cichlid fishes (Cichlasoma urophthalmus, Hemichromis letourneuxi) to low temperature: laboratory and field experiments in south Florida

Abstract

The cold tolerance of two non-native cichlids (Hemichromis letourneuxi and Cichlasoma urophthalmus) that are established in south Florida was tested in the field and laboratory. In the laboratory, fishes were acclimated to two temperatures (24 and 28°C), and three salinities (0, 10, and 35 ppt). Two endpoints were identified: loss of equilibrium (11.5-13.7°C for C. urophthalmus; 10.8-12.5°C for H. letourneuxi), and death (9.5-11.1°C for C. urophthalmus; 9.1-13.3°C for H. letourneuxi). In the field, fishes were caged in several aquatic habitats during two winter cold snaps. Temperatures were lowest (4.0°C) in the shallow marsh, where no fish survived, and warmest in canals and solution-holes. Canals and ditches as shallow as 50 cm provided thermal refuges for these tropical fishes. Because of the effect on survival of different habitat types, simple predictions of ultimate geographic expansion by non-native fishes using latitude and thermal isoclines are insufficient for freshwater fishes.

Origins of functional connectivity in a human-modified wetland landscape

“…As water depths decreased and became more spatially complex inside marshes, fish dispersal into this habitat became more limited in spatial extent. The frequency and distance of Mayan cichlid dispersal from canals, combined with their often high abundance in these artificial habitats, supports the contention that canals play an important role in spread of this invasive species into the Florida Everglades (Schofield et al 2010). Florida largemouth bass, on the other hand, dispersed outside canals less frequently and over smaller spatial scales than Mayan cichlids.…”

“…We used radio telemetry to measure how spatiotemporal patterns of connectivity for Mayan cichlids (Cichlasoma urophthalmus) and Florida largemouth bass (Micropterus salmoides floridanus) within and from canals is affected by landscape structure of the marshes bordering canals. Mayan cichlids are a nonnative species considered invasive in the Florida Everglades (Harrison et al 2013), and canals are thought to play a role in their spread (Schofield et al 2010). The Florida largemouth bass is an ecologically important predator native to peninsular Florida (Loftus and Kushlan 1987) and supports a very large recreational fishery (Quinn and Paukert 2009).…”

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

“…One of the most prevalent mechanisms to explain boom-and-bust cycles of native fishes is the effect of the interaction of environmental factors and life history traits on annual recruitment (e.g., Lobon-Cervia 2009, Matthews and MarshMatthews 2011). This is likely a rich area of future research investigating population fluctuations of Florida non-natives (e.g., the influence of major cold events; Schofield et al 2010, Harrison et al 2013, Boucek and Rehage 2014. As suggested by the present study, biotic resistance through predation likewise may prove an important mechanism.…”

“…Population size was fairly large and the species was distributed throughout the entire littoral zone where vegetation was present, suggesting that Allee effects and stochasticity of small population demographics were not important (Dennis 2002). Cold winter temperatures may eliminate this species from small, shallow aquaculture ponds in this region, though populations in nearby lakes of smaller surface area and lesser depth than Lake St. Clair persisted through a major cold event of the winter of 2009-2010 (Hill personal observations; see also Schofield et al 2010). Moreover, African jewelfish were present in surveys done in early 2007 (late winter) prior to the extreme low-water conditions.…”

Dietary habits of juveniles of the Mayan cichlid, Cichlasoma urophthalmus, in mangrove ponds of an offshore islet in Belize, Central America

“…This species seems to prefer freshwater and lower salinities, but is tolerant to wide ranges of salinity, from freshwater to marine conditions (i.e., 0 to 35) (Martinez-Palacios et al, 1990). Cichlasoma urophthalmus is also highly tolerant to fluctuations of water temperature (14°C to 28°C) (Schofield et al, 2010) and can resist hypoxic conditions (dissolved oxygen < 1.0 mg/L) by using aquatic surface respiration and buccal bubble holding techniques (Schofield et al, 2009). Therefore, this species occurs over a diversity of habitats, such as rivers, brackish lagoons, mangroves, seagrass beds and barrier reefs (Martinez-Palacios & Ross, 1988;Greenfield & Thomerson, 1997;Smith et al, 2003;Chávez-López et al, 2005).…”