Ralph Kuhlenkamp

The marine macroalgae of Helgoland (North Sea): an annotated list of records between 1845 and 1999

Abstract. The earliest known records of marine macroalgae from Helgoland (German Bight, North Sea) date from the mid-19th century. Since then, 274 marine macroalgal species have been reported: 77 species of Chlorophycota, 100 species of Phaeophycota and 97 species of Rhodophycota. Additionally 11 species were only recorded as drift and 51 species as doubtful for Helgoland. The remains of the herbarium of Paul Kuckuck, the first curator for botany at the Helgoland Biological Station between 1892 and 1914, are still located there and consist of 173 macroalgal species from Helgoland. On comparing this 100-year-old herbarium and other old sources with recent macroalgal records, it became clear that changes in species composition have occurred. After World War II, several species such as Arthrocladia villosa, Corynophlaea crispa, Cutleria multifida, Eudesme virescens, Mesogloia vermiculata, Sporochnus pedunculatus, Antithamnion cruciatum, Apoglossum ruscifolium, Chondria dasyphylla, Helminthora divaricata, Jania rubens and Osmundea ramosissima were not found again. Other species such as Dictyota dichotoma, Leathesia difformis, Stictyosiphon soriferus, Helminthocladia calvadosii and Scinaia furcellata became very rare. Significantly, perhaps, most of these species have a heteromorphic life history with the appearance of the macroscopic phase restricted to (spring and) summer. Many new species of green algae were recorded for Helgoland after 1959, due to new substrata and the research activities of Peter Kornmann, curator for botany after 1959, and Paul-Heinz Sahling his technical assistant. Introductions of species during the considered time period were: Bonnemaisonia hamifera, Codium fragile, Mastocarpus stellatus and Sargassum muticum. Type material of the following species is located at the Marine Biological Station at Helgoland: Mikrosyphar porphyrae, Porphyra insolita and Ulva tenera.

Discovery of the non-indigenous bryozoan Smittoidea prolifica Osburn, 1952 near Helgoland: first record in 2011 for the German North Sea

Since 2011, the non-indigenous Pacific bryozoan Smittoidea prolifica Osburn, 1952 was observed repeatedly on shell gravel in the trench Tiefe Rinne during annual long-term monitoring assessments of subtidal sites around the island Helgoland. It is the earliest discovery for the German North Sea and three years earlier than its first detection at commercial harbour sites on the German Wadden Sea coast. Introduction to the North-East Atlantic is assumed to have occurred before 1995 with oyster transfers to The Netherlands for aquaculture purposes. The presence of S. prolifica in the natural habitat of the Tiefe Rinne, relatively distant from the main shipping routes and commercial ports in the German North Sea and without nearby mussel cultures, requires the consideration of introduction vectors other than intentional shellfish transport and international shipping traffic.

Introduction of Non-indigenous Species

With the commencement of anthropogenic transcontinental movements followed by a continually increasing global traffic and intentional transfer of organisms, a diverse array of human-mediated pathways appeared responsible for transporting numerous marine species between different eco-regions. World-wide shipping increased dramatically over the last centuries emerging now as the most important vector for un-intentional artificial range-extensions of marine organisms thereby causing a steady raise in the introduction rate of non-indigenous species to most coastal regions of all oceans. Such neobiota pose a high functional risk if they develop stable populations and turn invasive with often detrimental effects on diversity and foodwebs of the indigenous ecosystems, even imposing high social-economic damage. Science is advancing in the attempt to understand the mechanisms of introduction and invasiveness which are crucial for further management approaches on national as well as international levels. Non-indigenous species have to be understood as a major pollution problem connected to every-day activities on all levels of society. Since the establishment of invasive species is nearly irreversible and attempts to eradicate populations of invasive organisms are mostly futile, a stringent prevention management on a global scale has to be anticipated.