Non-native Vaucheria sp. turfs (Xanthophyceae) have been recently regularly observed in the northern Wadden Sea (south-eastern North Sea) in the lower intertidal and shallow subtidal zone. We investigated how Vaucheria sp . adapts to small-scale site-specific differences in lower intertidal and shallow subtidal zones by evaluating its photosynthetic performance. This was assessed in July and September 2022 by using PAM fluorom...

Climate change profoundly impacts coastal ecosystems by altering temperature, light, and nutrient conditions that regulate primary production. In the European Wadden Sea, seawater temperatures have risen by nearly 2 °C over the past 60 years, promoting shifts in macroalgal communities, including the recent spread of the non-native yellow-green alga Vaucheria sp. (Xanthophyceae). We investigated how temperature and light affect...

It is in the very nature of coastal ecosystems to respond rapidly to external driving factors from land, sea, and man. Human-induced environmental change from local to global scale, and introduced species in particular, has accelerated ecological transformation at many coasts worldwide. A series of major events has fundamentally changed the macrobenthos in a tidal bay of the Wadden Sea (Königshafen, south-eastern North Sea, At...

Climate change effects on coastal ecosystems vary on large spatial scales, but can also be highly site dependent at the regional level. The Wadden Sea in the south-eastern North Sea is warming faster than many other temperate coastal areas, with surface seawater temperature increasing by almost 2 °C over the last 60 years, nearly double the global ocean mean increase. Climate warming is accompanied by rising sea levels, which...

As a result of globalization of markets and increasing marine traffic, more than 130 introduced species have so far been recorded in the Wadden Sea. This unique coastal area constitutes an ecosystem of global importance and is recognized by UNESCO as a Natural World Heritage site. Efforts are made to monitor introduced species and to study their ecological effects on native species and biodiversity, ecosystem processes, and fu...

For about a century, biodiversity in the tidal Wadden Sea (North Sea, European Atlantic) has increased by more than one hundred introduced species from overseas. Most originate from warmer waters and could facilitate the transformation of this coastal ecosystem to comply with climate warming. Some introduced species promote sediment stabilization and mud accretion. This could help tidal flats to keep up with sea level rise. Al...

A shallow subtidal area in the northern Wadden Sea was monitored over 17 years (from 2003 to 2019) for sediment parameters and macrobenthic fauna. Due to the sheltered position of the study area, sediment composition remained rather stable with only minor annual and seasonal variations in sediment granulometry. An intermittend storm (‘Kyrill’) had no significant effect on sediment composition parameters; the construction of an...

The Asian brush-clawed shore crab Hemigrapsus takanoi was introduced to the northern Wadden Sea (southeastern North Sea) in 2009 and now represents one of the most abundant brachyuran crab species. Abundance studies revealed an increase of mean crab densities on mixed reefs of native blue mussels ( Mytilus edulis ) and Pacific oysters ( Magallana gigas ) from 18 individuals m −2 in 2011 to 216 individuals m −2 in 2020. Despite...

Expected lower sea-ice cover and increased storm frequency have led to projections of an increase in seaweed detritus in Arctic marine systems in the near future. To assess whether detached seaweed affects structural and functional traits of species assemblages in soft-bottom habitats, comparable experiments were run in two intertidal sites (Longyearbyen and Thiisbukta) on Svalbard. At each site, we fixed nets containing the l...

The knowledge on the distribution and abundance of marine parasites is still limited, even for those occurring on relatively well studied host species with high ecological importance. Here we report on the first record of the entoniscid Portunion maenadis (Giard, 1886) in European shore crabs ( Carcinus maenas L., 1758) in the Wadden Sea and provide a quantitative review of the parasite’s distribution in Europe based on publis...