The results of our project not only detail the current situation of the occurrence of the non- native species in our marine environment, but it provides information on the most abundant and potentially invasive species. The list of these invasive species will be highly useful for us to manage these species in order to protecting and conserving the local marine biodiversity. It will also provide useful information for marine ecological studies.
Field assessment conducted in fouling communities on pier and mariculture facilities revealed that four of the six previously reported non-native species are still present in Hong Kong, including the solitary ascidian, Ciona intestinalis; the slipper limpet, Crepidula onyx; the Caribbean bivalve, Mytilopsis sallei; and the isopod Sphaeroma walkeri. The bryozoan Bugula californica and the mussel Mytilus galloprovincialis were not found and likely failed to establish. During the course of this study, the recently established non-native bivalve Xenostrobus securis was also found. The spatial distribution and abundance of the non-native species were closely related to seawater quality and habitat disturbance. The abundance of S. walkeri increased with low seawater quality. The sedentary non-native species were abundant in disturbed environments in Victoria and Tolo Harbors. Typhoon shelters with low seawater quality (due to estuarine conditions, pollution and/or habitat alteration) were the most invaded.
The field assessment indicated that seawater quality could explain the fouling community assemblages at the sampled piers. A gradient of decreasing seawater quality from the east of Hong Kong and within marine parks (oceanic conditions) to western sites (and some sites in Victoria Harbor) was related with the community assemblage measured. Typhoon shelters host more non-native species (number of species and/or abundance) than semi-enclosed bays. Kwun Tong typhoon shelter, with the lowest seawater quality among the sites of this study, has the most dissimilar fouling community assemblage in comparison to the other sites (Chapter 2) and it was the only site where all the five non-native species (including Xenostrobus securis) were recorded.
The overall distribution and abundance of the reported non-native species remains similar to that in 1980’s, suggesting that they are not highly invasive in Hong Kong. However, the presence and fast spread of the recently introduced bivalve Xenostrobus securis, which is highly invasive in other regions, could represent a threat for the local biodiversity.
A map of the distribution of the marine non-native species recorded in the literature (black symbols) and in the present study (white symbols) in Hong Kong. The recent introduced bivalve Xenostrobus securis is included.(Astudillo et al. 2014)
Astudillo, J.C., Wong, J.C.Y, Dumont, C.P., Bonebrake, T.C., Leung, K.M.Y. (2014) Status of six non-native marine species in the coastal environment of Hong Kong, 30 years after their first record. BioInvasions Records. 3(3):123-37. (PDF)