Marine algae of Helgoland. Benthic green, brown and red algae. This report represents a photographic documentation of the more conspicuous species of the marine algal vegetation of the island FIelgoland (North Sea), based on collections and observations made since 1959. The catalogue is largely restricted to macroscopic forms, as adequate knowledge of most of the microscopic ones is not yet available. Remarks on some rare species are added in a special chapter; the list includes some 150 species. With a few exceptions, the figures have been obtained from living algae; they illustrate aspects of reproduction and development and, occasionally, demonstrate different seasonal habits. The simplified key may be useful for providing a guide both for naturalists and students of marine phycology. In addition, this algal flora enhances our knowledge of the distribution of benthic species along the European coasts, as the rocky island of Helgoland intervenes between southern Norway and the shores of the English Channel.
The Blidingia-species of Helgoland (Ulvales, Chlorophyta). Based on tield studies and cultivation, four Blidingia-species have been established for Helgoland (North Sea). One of them, hitherto not separated from B. minima, is regarded as being B. chade [audii, though differing from its original description in an important morphological feature: the inner cell wall is not considerably thi&ened. The species is characterized by habit, development and zonation. There is good reason for conferring to B. subsalsa the rank of an independent species, classified up to now as subspecies of B. marginata. As shown in detail, the tubular frond of Blidingia-species develops directly from the raising of the center of a monostromatic prostrate disc. Contrary to previous statements in the literature, a preceding distromatic stage does not OCCUI', EINLEITUNG
Marine algae of Helgoland: Supplementation. Complementary to a previous publication (Kornmann & Sahling, 1977), this investigation deals mainly with microscopic algae occurring in the rocky littoral of Helgoland island (North Sea). Based on the results obtained from cultivation experiments, the heterogeneous Ulvella-complex of Dangeard has been rearranged and partly included in a new genus Stromatella, and Planophila respectively. The life history of Chlorocystis cohnii proved to be heteromorphic, the zygotes developing into a Codiolum-sporophyte. Also in Halochlorococcum marinum, some of the biflagellate swarmers give rise to Codiolum-like cells. Chlorocystis and Halochlorococcum, up to now members of the Chlorococcales, are incorporated into the new Codiolophycean order, Chlorocystidales. Three new Halochlorococcum species are described, the epiphytic "'Chlorochytrium'" moore/ also being combined with this genus. Supplementary observations on some crustose red algae from transparent substrates are included in this study, as well as findings of some species not previously reported for the Helgoland area. EINLEITUNGDie vorliegende Erg~inzung der "Meeresalgen von Helgoland" ist anderer Art als der 1977 erschienene Teil, in dem haupts~chlich die makroskopischen Algen dargestellt sind. Das Buch sollte in erster Linie den Teilnehmern an meeresbiologischen Kursen als Orientiemngshilfe dienen, die Erg~nzung wendet sich haupts~chlich an den fachlich interessierten Leser. Die meisten der hier behandelten Formen sind epi-oder endophytisch lebende sowie aus Kulturen mit bewachsenem Substrat -Steinen, Muschetschalen oder Glasscherben -isoIierte GrO_nalgen. Dabei wttrden mehrere Arten wiedergefunden, die Dangeard (1965a-d) mit ~hnlicher Methodik entdeckt und beschrieben hatte. Wahrscheinlich sind diese bisher nur von den franz6sischen Kiisten bekanntgewordenen Kleinalgen in europ~ischen Gew~ssern welt verbreitet.Nach Form und Inhalt k6nnen auch drei Arbeiten als Erg~nzungen zur Algenflora von Helgoland gelten, die inzwischen erschienen sind. Die. Gattung Blidingia wurde ausfiihrlich bearbeitet (Korninann & Sahling, 1978). Scinaia und Helminthocladia, seit vielen Jahrzehnten nicht mehr am Standoff gefunden, sind als kalkbohrende Mikrothalli vorhanden und wurden aus diesen kultiviert (Kornmann & Sahling, 1980a).Ostreobium quekettii, eine kalkbohrende Grfinalge, vermehrt sich mit ungeschlechtlichen Zoosporen zu gleichartigen Generationen (Kommann & Sahling, 1980b).
Prasiolales (Chlorophyta) of Helgoland. In their natural habitats, some representatives of Prasiolales are regularly, or often, washed by waves; others are sprayed with sea-water only occasionally, or not at ai1. In correspondance to this ecological grouping, species require marine or freshwater media respectively for optimal growth in cultures. The halophilic group consists of Prasiola stipitata and Rosenvingiella constricta. Though not analysed in detail, morphological characters and behaviour in cultures suggest that several different species are united under the name Prasiola stipitata. Rosenvingiella constricta, new for Helgoland and thus far reported only twice in Europe, is a dioecious hapIont; both meiosis and genotypic sex-determination occur in the germinating zygote. The parenchymatous "Gayella-stage" of Rosenvingiella polyrhiza proved to be male and female gametangia, producing spermatozoids and non-motile eggs respectively. Fertile threads were extremely rare in natural material and -contrary to Rosenvingiella constricta -did not occur in cultures, so the life cycle could not be elucidated. Prasiola calophylla is frequently associated with Rosenvingiella polyrhiza. The life cycle includes heterornorphic asexual generations, the spores of the leafy thallus giving rise to unicellular aplanosporangia. Prasiola furfuracea reproduces only by spores. Samples of Rosenvingiella polyrhiza frequently contain Praslolopsis in addition to a number of other Chlorophyceae. Consequently, it is easy to appreciate that previous investigators came to erroneous conclusions about life histories and biological relations in studies based only on field material. E I N L E I T U N G
Ostreobiurn quekettii (Codiales, Chlorophyta). The shell-inhabiting, marine alga Ostreobium quekettii Bornet & Flahault is a distinct species reproducing by zoospores with four flagella. Sporangium formation and the development of zoospores are described. The material obtained from Helgoland (North Sea) is assumed to be identical with the type specimen from the French Atlantic coast. O. quekettii is said to be of worldwide distribution; in the absence of further information, it must be doubted whether other finds reported to belong to this species are identical with the type species. EINLEITUNGEs gibt wohl keine Alge, fiber die in der Literatur so viele einander widersprechende und so wenige klare Angaben vorliegen wie yon Ostreobium quekettii. Die
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