Roland Krone

Defecation behaviour of the Lined Bristletooth Surgeonfish Ctenochaetus striatus (Acanthuridae)

The feeding and defecation behaviour of the surgeonfish Ctenochaetus striatus was investigated at Ras Mohammed National Park (South Sinai, Red Sea). The fish feed on coral rock mainly by sweeping loose sediment with their flexible broom like teeth into their mouths. Feeding occurred exclusively on coral rock, but defecation took place only outside the grazing area above sand in small, precisely defined areas.

Comparative analysis of time series of marine litter surveyed on beaches and the seafloor in the southeastern North Sea.

The comparative analysis of marine litter in different marine compartments has rarely been attempted. In this study, long-term time series of marine litter abundance on the seafloor and on the coast, both from the southeastern North Sea, were analyzed for temporal trends and correlations. On four beach sections of 100 m length, mean abundances of total beach litter collected four times a year from 2002 to 2008 varied between 105 and 435 items. Mean densities of total inorganic litter on the seafloor amounted to 10.6 ± 9.7 kg km(-2) in the offshore region (2001-2010) and 13.7 ± 12.6 kg km(-2) in the Wadden Sea (1998-2007), respectively. In the offshore region, there was no significant long-term trend, while in the Wadden Sea, densities of marine litter declined significantly. Correlations between time series were weak, indicating different sources and transport processes responsible for compositions of beach litter and litter on the seafloor. Decreases in inputs from fisheries and substantial export due to resuspension are discussed as reasons for the decrease in litter on the seafloor in the Wadden Sea.

A special palate structure of Ctenochaetus striatus—a hidden tool for bioerosion

A particular characteristic of C. striatus are the bristle teeth. During aquarium experiments a second dentiform structure was detected.

Wrecks as artificial lobster habitats in the German Bight

Once, the European lobster could be found in high abundances on rocky substrate around the island of Helgoland. Since the 1960s, the stock has been decreasing dramatically. Until now, it has been assumed that the lobster stock of Helgoland is the only one in the German Bight. Here, we provide first information about lobster distribution inside the German Bight off Helgoland. Diving in situ observations revealed that lobsters inhabit at least 15.6% of all 64 investigated wrecks. Considering the difficulties of detecting lobsters at wrecks, the true percentage is most likely much higher. Their locations are spatially homogenously distributed throughout the inspected area. The study indicates a broad distribution of the European lobster over the German Bight. The habitats provided by a considerable fraction of the more than one thousand wrecks outside the Wadden Sea are potential lobster refuges within the mud and sand dominated sea floor. Besides providing additional habitats, they represent stepping stones enhancing the connectivity of the North Sea lobster population.

Rapid increase of benthic structural and functional diversity at the alpha ventus offshore test site

The ecological importance of benthic organisms, which provide valuable ecosystem goods and services, necessitates careful research into the effects of offshore windfarms on the marine benthos. This chapter summarizes the results from benthos research activities within the StUKplus programme. The results showed considerable effects of the windfarm alpha ventus on the abundance and biomass of the benthic fauna. The major effect of the introduction of numerous wind turbine constructions into the marine environment was the aggregation and production of marine biota on the submersed structures, resulting in a substantial increase of the structural and functional biodiversity of the benthic system.