The Nile perch invasion in Lake Victoria: cause or consequence of the haplochromine decline?

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
University of Canterbury. Mathematics and Statistics
Journal Title
Journal ISSN
Volume Title
Language
Date
2016
Authors
van Zwieten, P.A.M.
Kolding, J.
Plank, M.J.
Hecky, R.E.
Bridgeman, T.B.
MacIntyre, S.
Seehausen, O.
Silsbe, G.M.
Abstract

We review alternative hypotheses and associated mechanisms to explain Lake Victoria’s Nile perch takeover and concurrent reduction in haplochromines through a (re)analysis of long term climate, limnological and stock observations in comparison with size-spectrum model predictions of co-existence, extinction and demographic change. The empirical observations are in agreement with the outcomes of the model containing two interacting species with life-histories matching Nile perch and a generalized haplochromine. The dynamic interactions may have depended on size related differences in early juvenile mortality: mouth-brooding haplochromines escape predation mortality in early life stages, unlike Nile perch that have miniscule planktonic eggs and larvae. In our model predation on the latter by planktivorous haplochromine fry act as a stabilizing factor for co-existence, but external mortality on the haplochromines would disrupt this balance in favor of Nile perch. To explain the observed switch, mortality on haplochromines would need to be much higher than the fishing mortality that can be realistically re-constructed from observations. Abrupt concomitant changes in algal and zooplankton composition, decreased water column transparency, and widespread hypoxia from increased eutrophication most likely caused haplochromine biomass decline. We hypothesize that the shift to Nile perch was a consequence of an externally caused, climate triggered, decrease in haplochromine biomass and associated recruitment failure rather than a direct cause of the introduction.

Description
Citation
van Zwieten, P.A.M., Kolding, J., Plank, M.J., Hecky, R.E., Bridgeman, T.B., MacIntyre, S., Seehausen, O., Silsbe, G.M. (2016) The Nile perch invasion in Lake Victoria: cause or consequence of the haplochromine decline?. Canadian Journal of Fisheries and Aquatic Sciences, 73, pp. 1-22.
Keywords
Lakes, Eutrophication, Predator-prey interaction, Invasive species, Climate change
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Fields of Research::31 - Biological sciences::3103 - Ecology::310304 - Freshwater ecology
Fields of Research::30 - Agricultural, veterinary and food sciences::3005 - Fisheries sciences::300502 - Aquaculture and fisheries stock assessment
Field of Research::05 - Environmental Sciences::0501 - Ecological Applications::050101 - Ecological Impacts of Climate Change
Fields of Research::41 - Environmental sciences::4102 - Ecological applications::410202 - Biosecurity science and invasive species ecology
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