Artificial structures in harbors and their associated ascidian fauna
In: Aquatic Invasions. Regional Euro-Asian Biological Invasions Centre (REABIC): Helsinki. ISSN 1798-6540; e-ISSN 1818-5487, more
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harbor; non-native ascidians; floating dock; fouling community |
| Authors | | Top |
- Gittenberger, A., more
- van Stelt, R.
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| Abstract |
e tested the hypothesis that marine non-native fouling species are more abundant than native species on artificial structures, focusing on ascidians and using fouling plates deployed in various Dutch harbors. A more detailed study was conducted in the pleasure craft harbor of Breskens, in the south of The Netherlands, where a species assessment was done of iron harbor walls, wooden pilings, diagonal stone rip-rap dikes, fouling plates, and the inside, outside and underside of the floats of floating docks. Ascidians were found only on the floating structures. Non-native ascidians were not found to be significantly more abundant than native ascidians, however. Solitary and colonial tunicates were compared, assuming that they fundamentally differ in their abilities to occupy space. In general, colonial species like the native Botryllus schlosseri and the non-native Botrylloides violaceus were more abundant on fouling community plates, while solitary ascidians like the native species Ciona intestinalis and Ascidiella aspersa appeared to be more successful later in succession. The inside, outside and underside of a floating dock harboured significantly different species communities. Ascidiella aspersa for example was found significantly more often on the underside than on the inside and outside of the dock floats. When assessing the ascidian species diversity in a harbor it is therefore advised to search several different habitats on floating structures. |
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