South Africa: Raising the flag on marine alien fouling
species (10/10/16)<http://www.reabic.net/journals/mbi/2016/Accepted/MBI_2016_Peters_etal_correctedproof.pdf>
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 15]. 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.
