Environmental influence on the bottom and near-bottom megafauna communities of the Dogger Bank: a long-term survey

Abstract

This paper deals with climate-driven changes of the species composition of the bottom and near-bottom megafauna of the Dogger Bank (central North Sea), which was sampled each summer with a 2-m beam trawl on a yearly basis since 1991. The station grid consists of 37 stations, covering an area of approximately 17.000 km 2 . A selection of commoner species is analysed and correlated with temperature data gained during the research period. Temperatures are derived from our own measurements, combined with CTD data from the International Council for the Exploration of the Sea. The results show a decrease in biodiversity and a clear regime shift around the beginning of the 21st century, combined with rising mean bottom temperatures. In addition, details are given about the Dogger Bank hydrography and the climate sensitivity and abundance of the main species caught with the beam trawl. Our long-term study reveals the changes in the community structure of the megafauna of the Dogger Bank over a period of almost two decades. It suggests a link between changes in species composition/abundance and changes in the environment, especially the marine climate.

An annotated checklist of macrozoobenthic species in German waters of the North and Baltic Seas

“…1) is a sand bank situated between the deeper parts of the central North Sea (up to 70 m water depth in the German EEZ) and the shallower parts of the German Bight (between 30 and 40 m). Thus, it represents an ecologically special area in the German EEZ, forming a transition zone containing species with dominantly northern or southern distributions in the North Sea [60][61][62]. Northern species, however, do not extend further southwards than the northern edge of the Dogger Bank; southern species do not occur further northwards than the 100 m depth contour [43].…”

“…Northern species, however, do not extend further southwards than the northern edge of the Dogger Bank; southern species do not occur further northwards than the 100 m depth contour [43]. Species distribution is mainly influenced by environmental factors such as temperature, stratification (in summer), differing water masses, sediment types and food supply [60,62,63], leading to a diverse fauna on the Dogger Bank.…”

Natural history collections recapitulate 200 years of faunal change

“…A good congruence between our museum metadata analysis and long-term ecological studies exists for warm water species that expanded into the North Sea recently, such as the crab Goneplax rhomboides (e.g. [52,53]).…”

“…Eight species are known as invasive alien species ( [40], www.nobanis. Another four species are confirmed warm water species that have expanded their ranges into the North Sea from more southern latitudes during the last 30 years: Goneplax rhomboides (Linnaeus, 1758) [49,50], Necora puber (Linnaeus, 1767) [51][52][53], Thia scutellata (Fabricius, 1793) [49,54] and Diogenes pugilator (P. Roux, 1829) [55]. It is important to note that most of these species were identified as range-expanding based on a subset of the data we analysed, specifically based on the collections of the SMF from the 1970s on.…”

Recent spreading of Xandarovula patula (Mollusca: Gastropoda: Ovulidae) towards the central North Sea suggests a link to rising water temperatures

“…It was chosen for long-term monitoring because of its uniform depth and sediment composition, providing an ideal place to study its epibenthic faunal assemblages and associated changes over time. Since 1991, the epifauna is monitored yearly with a 2 m beam trawl (Sonnewald & Türkay, 2011a, 2011b. Due to the fact that until 2009, the surveys were only undertaken during summer, the composition of the epifauna of the Dogger Bank during winter remained unclear.…”