Table was taken from Schuchardt & Selvigen (2015) and modified (in italics). Possible aquatic and terrestrial vectors for global dispersal of non-indigenous and invasive alien species, ordered by significance (modified after Gollasch et al., 2013 & fao.org). Terrestrial and freshwater alien species were mainly intentionally introduced by humans because of their expected ‘beneficial’ effects. Marine alien species reached the Wadden Sea also through secondary dispersal from sites of primary introduction (Buschbaum et al., 2012). Furthermore, shellfish imports and transport for aquaculture support alien species introduction (Wolff & Reise, 2002 Schuchardt & Selvigen, 2015). The latter is the most import vector with the highest ratio of alien species (Gollasch, 2002). International shipping is the most important vector for alien species introduction (Nehring, 2002 CWSS, 2010a Buschbaum et al., 2012 see also Schuchardt & Selvigen, 2015) into the Wadden Sea, including transport with ballast water, in the tank sediment or hull fouling (Table 1). This framework considers the main vectors of introduction: ballast water, ship hulls and harbours, aquaculture, recreational crafts and marinas as well as introduction to islands by e.g., planting on dunes or in salt marshes or by escapes from aquariums to freshwater habitats (see also Table 1), although it is often unknown or uncertain how single alien species reached the Wadden Sea. In accordance with the UNESCO request of 2009, §26 of the Sylt declaration (CWSS, 2010b) and §33 of the Tønder Declaration (CWSS, 2014), a trilateral strategic framework for dealing with alien species in the Wadden Sea was drafted. Alien species of the Wadden Sea (from left to right): The Australian barnacle (Austrominius modestus) was introduced with hull fouling, the American slipper limpet (Crepidula fornicata) reached the Wadden Sea with shellfish imports and the Japanese seaweed (Sargassum muticum) was most likely introduced with oyster imports (Lackschewitz et al., 2015) (Photos: Christian Buschbaum). gigas compare report " Beds of blue mussels and Pacific oysters"). Although so far there is no evidence for extinction of native organisms by aliens species in the Wadden Sea area (Wolff, 2000 Buschbaum et al., 2012), some alien species have the potential to alter dominance structures, habitats and trophic regimes, such as e.g., the Pacific oyster Crassostrea gigas and the Japanese seaweed Sargassum muticum (Reise et al., 2005, Figure 1) (for C. This could lead to an increasing number of species and diversity in the Wadden Sea but may also cause biotic homogenization with other areas (Reise et al., 2005 Nehring et al., 2009). And more alien species are likely to come. Most alien species became inconspicuous residents and cannot be eliminated without causing collateral damage to the ecosystem. The human introduction of alien species, in particular invasive ones, poses a serious threat to the guiding principle of the trilateral Wadden Sea policy “to achieve, as far as possible, a natural and sustainable ecosystem in which natural processes proceed in an undisturbed way” (CWSS, 2010b see also Bouma et al., 2011). With increasing global trade the introduction of alien species outside their natural range speeded up and now raises concern about biological homogenization (Capinha et al., 2015), threatening of native species and ecosystems, threats for humans, their health, and economic aspects (Nehring et al., 2009). Human activities have breached those barriers and have transferred species into areas far beyond their natural range - intentionally and unintentionally (Box 1). It is, however, limited by natural geographical barriers.
Wells’ War of Worlds spawned a huge wave of speculative fiction but the roots of such fears run deep in our literature, where the mysteries of other cultures have long threatened the familiar and the comfortable.The spread of organisms is in principle a natural process.
Visitors from other planets have long obsessed us. Read a Q&A with some of the authors (including me!) at Flametree Publishing.The hardback editions from Flametree look absolutely beautiful (“Hardback Deluxe edition, printed on silver, matt laminated, gold and silver foil stamped, embossed”). The anthology will also be available from other online retailers in May. This anthology includes my story “Long As I Can See The Light”, a scifi short story set in Vancouver and originally published in the anthology “People Are Strange”. “Alien Invasion Short Stories” is a new anthology from Flametree Publishing, and it is now available in gorgeous hardcover from the publisher.