Unravelling population structure of black musselcracker Cymatoceps nasutus: evidence for multiple populations in South African coastal waters

  • TS Murray
  • G Gouws
  • M Mwale
  • BQ Mann
  • PD Cowley

Abstract

Genetic studies on South African marine fishes have shown that many species exist as single, well-mixed stocks throughout their core distribution. The black musselcracker or poenskop Cymatoceps nasutus is a slow-growing, late-maturing and long-lived sparid (Perciformes: Sparidae) that is endemic to South African coastal waters. Conventional tagging studies suggest that it is resident, with limited connectivity between different regions along the coast. Mitochondrial and nuclear DNA were used to investigate the genetic structure of C. nasutus along the South African coastline and showed evidence of at least two populations. Samples collected from the Tsitsikamma Marine Protected Area on the South Coast to KwaZulu-Natal on the East Coast showed no significant population structure over much of the distribution. Gene flow for C. nasutus within this region is not limited by geographic distance and appears to be unaffected by various oceanographic barriers and biogeographical boundaries. Samples from the Western Cape to the west of Tsitsikamma, however, showed moderate to substantial differentiation for both markers, which may be influenced by a temperature barrier – a coldwater ridge – along the South Coast. These data provide the first genetic assessment of this South African sparid, and suggest that a two-stock management strategy would be appropriate for the species.

Keywords: gene flow, genetic differentiation, haplotype and nucleotide diversity, marine conservation

African Journal of Marine Science 2014, 36(4): 493–503

Author Biographies

TS Murray
Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa; South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
G Gouws
South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
M Mwale
South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
BQ Mann
Oceanographic Research Institute, Durban, South Africa
PD Cowley
South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
Published
2015-04-01
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X