Effect of invasive species on the structure and function of the Sylt-Rømø Bight ecosystem, northern Wadden Sea, over three time periods

Abstract

, respectively, in 2010. Reasons for the increases in oysters and A. modestus are related to climate change which favored strong recruitment of the invasive species during unseasonably warm summers, and the subsequent decline to weak recruitment of the invasive species and an unseasonably cold 2009/2010 winter. We used ecological network analysis (ENA) to quantify ecosystem structure and function through analyses of energy (or carbon) transfer between living and non-living compartments in each of the 3 network models. Results from ENA show an increase in most of the system attributes, but a decline in number of cycles, the trophic efficiency, the ascendency ratios, and relative redundancy from 1995 to 2007; these are ascribed to the impact of the invasive species on system organization and function. Following the dramatic decline of the invasive species from 2007 to 2010 most of the system attributes decreased. The variance in the biomass and associated flows of other compartments in addition to that of the invasive species has also played a role in the changes in system attributes and function.

Invasive versus native brachyuran crabs in a European rocky intertidal: respiratory performance and energy expenditures

“…Here, competition for food could be stronger and more complex, as macroalgae are not very abundant in the Wadden Sea intertidal zone. Energy flow models of this region should be updated to account for the impact of those successful invasive crab species (Baird et al 2004(Baird et al , 2007(Baird et al , 2012.…”

Microscopic species make the diversity: a checklist of marine flora and fauna around the Island of Sylt in the North Sea

“…Currently, the number of non-indigenous species still seems low (39 out of 2758 equivalent to 1.4%) but some of the introduced species already had fundamental effects on the communities [41]. Examples are American razor clams Ensis leei which became a dominant bivalve in terms of abundance and biomass in the subtidal zone of the Wadden Sea [42], Pacific oysters Magallana (Crassostrea) gigas which turned the former mussel (Mytilus edulis) beds into combined oyster/mussel beds [43,44], or the Japanese seaweed Sargassum muticum which forms extensive beds in the shallow subtidal zone and nowadays functionally replaces former native seagrass (Zostera marina) beds that almost went extinct in the 1930s due to a parasitic slime mould [45] and failed to recover to their original extension, up to now.…”

The invasive barnacle species, Austrominius modestus: Its status and competition with indigenous barnacles on the Isle of Cumbrae, Scotland

“…While introduced species have been found to coexist with native species (Buschbaum et al, 2006;Sax and Gaines, 2008;Heard and Sax, 2013) and even contribute to an increase in biodiversity at some locations (Mooney and Cleland, 2001;Sax and Gaines, 2008), these non-native species are more often associated with a reduction in biodiversity, which can produce changes in ecosystem structure and functioning (Baird et al, 2012;Bracewell et al, 2012). Some non-native species exhibit a 'lag phase' during which they persist within their invaded range, but do not become abundant until there has been a favourable environmental change which promotes their abundance over native species (Bax et al, 2003;Witte et al, 2010).…”