CASE STUDIES OF THE INVASION BY FOUR ALIEN FISH SPECIES (CYPRINUS CARPIO, MICROPTERUS SALMOIDES, OREOCHROMIS MACROCHIRANDO. MOSSAMBICUS) OF FRESHWATER ECOSYSTEMS IN SOUTHERN AFRICA

Abstract

The history of the invasion of 42 catchment regions in southern Africa (excluding Mozambique) by an altricinl species (Cyprinus carpio), a moderately precocial s p i e s (Micropferur saltmides) and two highly precocial species (Omochromis macrochir and 0. mossambicus) is examined. The abundance of these species in different catchments is discussed in relation to the diversity of indigenous species. Results suggest that: a. Dcpauperate catchments of the southern C a p are vulnerable to invasion irrespective of the life-history style of the alien species, compand to catchments (in Zimbabwe and north eastern Transvaal) with a higher diversity of indigenous species.Prccocial species are more successful than altricial species in establishing populations in natural waters in more diverse ecosystems.Degradation and modification of the environment (particularly the buiiding of impoundmmts) has played an important rob in increasing the susceptibility of freshwater ecosystems to invasion.b.c.

An evaluation of the current extent and potential spread of Black Bass invasions in South Africa

“…These delays are mainly influenced by propagule pressure (Simberloff 2009) and the conditions in the novel environments, i.e. competition (De Moor 1996;Jackson et al 2017) and climate (Jackson and Sax 2009). The results of this study suggest that there is a considerable area-based invasion debt for Largemouth Bass and Smallmouth Bass.…”

Age, growth and reproduction of non-native largemouth bassMicropterus salmoides(Lacépède, 1802) populations in two temperate African impoundments

“…The success of an introduced species is dependent on its life history characteristics, which determine its ability to overcome abiotic conditions (Moyle & Light, ), and on the nature of the receiving environment (Elton, ). Temperate South Africa has a relatively species‐poor freshwater environment with few native predators, thus making it particularly susceptible to invasion (de Moor, ). Coupled with the robust life history style of M. salmoides, a moderately precocial or guarding (de Moor, ) predator of the equilibrium life history strategy described by Mims et al.…”

“…Temperate South Africa has a relatively species‐poor freshwater environment with few native predators, thus making it particularly susceptible to invasion (de Moor, ). Coupled with the robust life history style of M. salmoides, a moderately precocial or guarding (de Moor, ) predator of the equilibrium life history strategy described by Mims et al. (), which characterises a medium‐bodied fish that reaches a moderate age at maturity and has low fecundity and high juvenile survivorship, with inevitable establishment success.…”

Assessing the effect of tagging and the vulnerability to predation in tigerfish (Hydrocynus vittatus, Castelnau 1861) in a water-stressed system using telemetry methods

“…Fish kills and population declines are often reported worldwide as a result of deteriorating aquatic ecosystems (Ferreira & Pienaar 2011;Thronson & Quigg 2008). This deterioration has been attributed to several factors, including river fragmentation, flow modification, pollution, the introduction of alien species and global climate change (De Moor 1996;Ellender & Weyl 2014;O'Brien et al 2019). Fish make use of the available physical habitat as refugia, for feeding and spawning, and as nurseries for their offspring (Godin 1997;O'Brien et al 2013).…”