Browsing by Author "Peters, Koebraa"
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- ItemFrom Chile to the South African west coast : first reports of the Chilean stone crab Homalaspis plana (H. Milne Edwards, 1834) and the South American sunstar Heliaster helianthus (Lamarck, 1816) outside their natural ranges(Regional Euro-Asian Biological Invasions Centre, 2018-10-01) Peters, Koebraa; Robinson, Tamara B.; Grabowski, MichalThe South American multiradiate sunstar Heliaster helianthus (Lamarck, 1816) and the Chilean stone crab Homalaspis plana (H. Milne Edwards, 1834) are marine predators that, previous to this report, have no invasion history. However, during subtidal maintenance of a pier within Saldanha Bay along the South African west coast during 2015–2017, a single individual of each species was detected on the seafloor. Following this, intertidal and subtidal surveys were undertaken in surrounding natural habitats, but no further individuals were recorded. Both species are native to Chile, a region with very similar environmental conditions to the west coast of South Africa and from which other South African marine alien species originate, highlighting the connectedness between these regions and the risk for future transfers and establishment. The presence of two pathways from Chile to South Africa (shipping and aquaculture imports) and closely matching environmental conditions are likely to play a role in future successful introductions of Chilean species to the South African west coast. It is, therefore, recommended that particular attention be paid to monitoring aquaculture imports from the west coast of South America and that incoming vessels from that region be inspected upon arrival. Additionally, both H. heliaster and H. plana should be added to alien species watchlists in South Africa and other regions connected to Chile via marine vectors and which experience similar environmental conditions.
- ItemRaising the flag on marine alien fouling species(Regional Euro-Asian Biological Invasions Centre, 2017) Peters, Koebraa; Sink, Kerry; Robinson, Tamara B.Harbours are known introduction foci of marine alien species. They act as recipients of new introductions and as sources for regional spread. We report on subtidal surveys of fouling communities from 14 harbours along the coastline of South Africa that were used to identify predictors of high alien species numbers in support of prioritisation of monitoring actions by authorities. The harbours varied in nature from large, international shipping hubs to small, regional fishing harbours and recreational marinas. Fouling assemblages were assessed using visual and scrape sampling to ensure the detection of large, mobile and small inconspicuous species. In total, 29 alien species were recorded, 15 of which were detected outside of their previously known ranges. The number of species recorded per harbour varied from five to. Results revealed that high numbers of alien species were associated with the presence of yachts and low primary productivity. Harbours which had yachts and occurred in areas with mean Chl a minimum levels lower than 0.21 mg.m⁻³ had the highest number of alien species, while harbours without yachts that were larger than 0.1km² supported the fewest alien species. These findings suggest that the presence of yachts can be used to identify harbours with high numbers of alien species, particularly in regions with low productivity. While the applicability of these findings to other regions remains to be tested, this work suggests that harbours that fall within this category could be prioritised for monitoring of marine alien species.