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Jahreszeitliche Verteilung und Lebenszyklen der Proseriata (Turbellaria) eines Sandstrandes der Nordseeinsel Sylt
Sopott, B. (1973). Jahreszeitliche Verteilung und Lebenszyklen der Proseriata (Turbellaria) eines Sandstrandes der Nordseeinsel Sylt. Mikrofauna des Meeresbodens, 15. Akademie der Wissenschaften und der Literatur: Mainz. 106 pp.
Deel van: Mikrofauna des Meeresbodens. Akademie der Wissenschaften und der Literatur: Wiesbaden. ISSN 0342-3247
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| Trefwoorden |
ANE, Germany, Schleswig-Holstein, Sylt I.
Cycles > Life cycle
Distribution > Temporal distribution > Seasonal distribution
Proseriata [WoRMS]
Sylt [Marine Regions]
Marien/Kust |
| Abstract |
Quantitative investigations were made on the seasonal distribution and the life cycles of the Proseriates in a sandy beach of the island of Sylt (North Sea). Within the Turbellaria, the Proseriates are the dominating group. In the wadden areas, mainly the upper two centimeters of the sand are inhabited. The highest density of population is to be found in the anterior part of the sand flat and the lower beach slope. Proseriates are less abundant in the landward parts of the beach. The horizontal and vertical distribution of 17 species is described. The factors affecting the dispersion on the beach are considered. Besides temperatures, salinity, pore water content and sulfide layers, the food offered can be a major factor controlling density. For several species, abundances are demonstrated in relationship to seasonal changes in temperatures of the sea-water and the sediment. Whereas animal numbers of many species are highest in summer, other species reach a maximum of density in winter. The Proseriates, living in the middle and the upper beach slope, in some cases show a significant seasonal vertical movement. The animals migrate down to the deeper layers of sediment in winter and remove towards the sand surface in spring time. Species with a population density in the lower beach slope and in the damp sand above the subsoil water do not migrate downwards in winter. A tidal rythm of vertical migrations is given for all Parotoplaninae inhabiting the beach slope. The animals live in the layers of damp sand at low tide. When sediment is flooded, they move up towards the surface. 9 Proseriates have an annual life cycle. The period of reproduction of most species takes place in spring; but there are differences among the species in attaining male maturity. Coelogynopora distortofolio and Dicoelandropora atriopapillata have a time of dormancy in summer. Itaspiella helgolandica reproducts in winter. Nematoplana coelogynoporoides probably lives more than one year. Full maturity do not occur in the first year. No one of the Proseriates investigated seems to have more than one generation in the year. The egg capsules of 16 species are described. Nematoplana coelogynoporoides forms egg cocoons with 9 embryons. |
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