Nicole Schwartz (& Franz Schöll)
Assessing the role of transport modes for the introduction and spread of IAS – an intermodal approach
As many landscapes undergo extensive and rapid changes due to human activities, ecosystems become more susceptible to invasion by non‐native species. Transport, traffic routes and infrastructure are considered as major drivers for the introduction and spread of invasive alien species. Many IAS establish in green corridors adjacent to traffic routes and pose similar problems for the different modes of transport (i.e. railway lines, roads and waterways). Therefore, an intermodal examination of the introduction and spread of IAS is needed for efficient management and prevention. The ‘Network of Experts’ established in 2016 by the German Federal Ministry of Transport and Digital Infrastructure stands out through its unique intermodal approach aiming at creating new concepts for a sustainable mobility.
Within this network, we conducted different intermodal surveys to assess the role of traffic modes as vectors and distribution pathways for non‐native species. One subproject investigates the role of inland water vessels. In contrast to the maritime shipping, where vessels have been investigated intensively during the last years, only few cursory studies provide indications for a possible introduction and spread of IAS with inland water vessels. We investigated two aspects : The spread of IAS a) via hull fouling and b) via ballast water.
a) We surveyed the hull fouling of recreational crafts (along the coast and inland waterways) and commercial vessels in different shipyards. After a visual inspection and photo documentation we sampled different areas of the ship hulls, classified the degree of fouling (Level of Fouling, LoF) and identified the species in the fixed samples subsequently in the lab. Additionally to the sampling we interviewed the skippers or boat‐owners regarding the usage and maintenance of each sampled vessel. The hull fouling of recreational crafts and the usage is more intense in coastal‐ compared to inland waters but the ship areas with highest fouling intensity are the same in both regions. The degree of fouling of commercial ships is stronger compared to recreational crafts which might be explained by the use of antifouling paints and regular cleaning of recreational crafts.
b) In contrast to the maritime shipping, loading and discharge of ballast water by inland water vessels is not regulated or documented. Thus, we developed and evaluated a questionnaire in order to assess the role of ballast water in inland navigation for different vessel types and waterways. The majority of surveyed skippers (65 %) stated to load ballast water regardless of the vessel type. However, the proportion of vessels using ballast water was higher in channels (75 %) compared to other waterways (54 %).
Our assessment of inland water vessels and recreational crafts regarding their role for the introduction and spread of IAS contributes to an efficient management of vectors and pathways. Our approach is highly appropriate for formulating intermodal strategies to prevent further introductions of IAS efficiently and to control already existing IAS under consideration of costs and benefits.
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