ALBERT

Description: This paper describes (i) the Recent distribution pattern of various types of carbonate sediments in Troms county (northern Norway), and (ii) the onset of carbonate sedimentation after the final deglaciation of the Fennoscandian ice-shield. The distribution of major facies belts is strongly dependent on hydrographic and topographic constraints. The main bulk of carbonate deposits is derived from maerl-producing coralline algal biotopes that are restricted to the photic zone of waveprotected areas and influenced by tidal currents. Furthermore, extended mollusc and echinoderm-rich arenites are present in the area investigated. In deeper subtidal areas, terrigenous sediments of Late Weichselian to Early Holocene age are preserved. However, these are strongly influenced by later winnowing processes, generating a coquina lag deposit that serves as a secondary hardground for a diverse fouling community. The Holocene facies successions can be seen in several raised outcrops, containing the transition from glacigenic to Recent non-glacigenic depositional conditions. Autochthonous radiocarbon dated rhodolith banks, which mark the onset of carbonate sedimentation, yielded surprisingly young ages of 5,500 YBP. Around 5,500 YBP, present-day oceanographic and climatic conditions had already been firmly established. This time-lag can be explained with the behaviour of postglacial sea level fluctuations in the area. From 10,000 their cooperation in this project. We address our sincere thanks specifically to Prof. T.O. Vorren, Dr. M. Hald, Dr. B. Gulliksen, Dr. J. Hansen, Dr. J.J. Møller, Dr. E. Thomsen, and Dr. G. Corner for their dedicate help in organizing our field trips in Troms and for extensive scientific discussions. Special thanks to capitain K. Bendiksen for his patience and professional skill while operating the vessel ‘OTTAR’ in the skerry area even under bad weather conditions. S. Rasmussen and G. Ellingsen assisted during the cruises and very kindly introduced us to the Norwegian way of life. Special thanks to the two reviewers (Prof. Dr. W.-Ch. Dullo and anonymus) for their critical but constructive remarks. J. Welling and Dr. M. Kaminski improved the language of the final version of the manuscript. This project is part of the German Science Foundation’s main research program ‘Globale und regionale Steuerungsprozesse biogener Sedimentation”. Financial support was kindly provided by the Deutsche Forschungs-gemeinschaft (He 1671/1-1, 2).

Description: This manuscript reports the first sightings and collection of the swimming crab Cronius ruber (Lamarck, 1818) on the coast of Madeira Island, Portugal. After the recent record in the Canary Islands, this represents a further step northward on this species’ expansion in distribution in the eastern Atlantic. The crab was first spotted during underwater visual census surveys done by scuba diving in July 2018 and was repeatedly observed during the following months, in different locations on the south coast of Madeira. Analysis of temperature data from several geographic locations where C. ruber is present was performed to assess how thermal regimes and ongoing changes may influence this recent distribution shift. Current temperature trends in Madeira suggest that the arrival and establishment of C. ruber to Madeira might have been facilitated this thermophilic species, adding evidence for the ongoing tropicalization of this area. Finally, the current spread of C. ruber in both Canaries and Madeira island systems highlights the need for a long-term monitoring program targeting this and other non-indigenous species (NIS).

Description: As alien invasive species are a key driver of biodiversity loss, understanding patterns of rapidly changing global species compositions depends upon knowledge of invasive species population dynamics and trends at large scales. Within this context, the Ponto-Caspian region is among the most notable donor regions for aquatic invasive species in Europe. Using macroinvertebrate time series collected over 52 years (1968–2020) at 265 sites across 11 central and western European countries, we examined the occurrences, invasion rates, and abundances of freshwater Ponto-Caspian fauna. We examined whether: (i) successive Ponto-Caspian invasions follow a consistent pattern of composition pioneered by the same species, and (ii) Ponto-Caspian invasion accelerates subsequent invasion rates. In our dataset, Ponto-Caspian macroinvertebrates increased from two species in 1972 to 29 species in 2012. This trend was parallelled by a non-significant increasing trend in the abundances of Ponto-Caspian taxa. Trends in Ponto-Caspian invader richness increased significantly over time. We found a relatively uniform distribution of Ponto-Caspian macroinvertebrates across Europe without any relation to the distance to their native region. The Ponto-Caspian species that arrived first were often bivalves (46.5% of cases), particularly Dreissena polymorpha, followed secondarily by amphipods (83.8%; primarily Chelicorophium curvispinum and Dikerogammarus villosus). The time between consecutive invasions decreased significantly at our coarse regional scale, suggesting that previous alien establishments may facilitate invasions of subsequent taxa. Should alien species continue to translocate from the Ponto-Caspian region, our results suggest a high potential for their future invasion success highly connected central and western European waters. However, each species’ population may decline after an initial ‘boom’ phase or after the arrival of new invasive species, resulting in different alien species dominating over time.