| Title: |
Population dynamics and biology of an invasive population of mosquitofish Gambusia affinisin a temperate estuarine lake system |
| Authors: |
Sloterdijk, Hans, James, Nicola C, Smith, M Kyle S, Ekau, Werner, Weyl, Olaf LF |
| Source: |
African zoology; January 2015, Vol. 50 Issue: 1 p31-40, 10p |
| Abstract: |
This study investigates the distribution, relative abundance, population growth and biology of the alien invasive fish Gambusia affinisin the Wilderness Lakes System, a coastal lake system in the warm-temperate region of South Africa. Fish were collected throughout the system during four seasonal sampling trips in spring (October 2010), summer (February 2011), autumn (May 2011) and winter (July 2011). Gambusia affiniswere widespread and abundant in all habitats from the freshwater reaches of the inflowing Touw River to the more saline lakes and estuary. Sex ratio was generally female dominated and mean length at maturity was 14.7 mm standard length (SL) for males and 20.3 mm SL for females. Reproduction was strongly seasonal with reproductively active fish sampled in spring and summer but not in autumn and winter. Relative abundance also varied seasonally, with populations following typical ‘boom and bust’ population dynamics. By winter, the population in all habitats was lower with mortality rates as high as 85%. The stronghold of the population appears to be in the channels between the lakes, where relative abundance was more consistent and winter mortality rates were lower. The survivors, which are primarily females, then reconstitute the population in the spring and summer months. |
| Database: |
Supplemental Index |
