Investigations on the ecology of the marine centric diatom Paralia sulcata at Helgoland Roads, North Sea, Germany: Ecology of Paralia sulcata at Helgoland Roads

  • Research Questions: - What are the long-term trends and which environmental parameters influence the ecological niche of Paralia sulcata? (multivariate statistical analyses, field and laboratory experiments) - Does a genetically different population of Paralia sulcata occur at Helgoland Roads? (molecular fingerprint method) - How important is Paralia sulcata within the marine food web and as possible food source for grazers? (grazing experiments, meso- and microcosm) Topic of my thesis was the ecological role of Paralia sulcata at Helgoland Roads, North Sea. This species is a cosmopolitan marine diatom species which is common in the benthos and pelagic during winter around Helgoland. P. sulcata lives under a wide range of environmental conditions, but not much is known about its ecology. Many previous studies have been concerned with different environmental conditions and their influence on the occurrence of P. sulcata in marine and coastal areas, but often these studies provided contrasting results. Furthermore, the worldwide distribution and the wide range of adaptations to environmental parameters make it necessary to understand the current ecological characteristics of P. sulcata. One focus of my thesis was to investigate the autecological behaviour of P. sulcata in more detail with laboratory experiments and compare the results with a detailed two year field sampling campaign as well as the long-term data set provided at Helgoland. These results of the laboratory and field sampling data revealed different behaviours of P. sulcata during the seasons. Using a fingerprint method a high genetic diversity of different P. sulcata strains and a separation between January and September to December strains was detected. One possible explanation for the occurrence of P. sulcata especially in the summer period seemed to be the introduction of new clones adapted to warmer water temperatures. Furthermore, the increasing storm activity at Helgoland Roads leads to a mixing of the water column and therefore, to a mixing of the existing naturally highly diverse P. sulcata population. Additionally, the role of P. sulcata as food source in the marine food web was investigated during a mesocosm spring bloom experiment. The observed trend towards a less seasonal appearance leads to the conclusion that this diatom is now a baseline diatom occurring in the water column throughout the year.

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Publishing Institution:IRC-Library, Information Resource Center der Jacobs University Bremen
Granting Institution:Jacobs Univ.
Author:Christina Gebühr
Referee:Karen Wiltshire, Victor Benno Meyer-Rochow, Justus van Beusekom, Dieter Wolf-Gladrow, Nicole Aberle-Malzahn
Advisor:Karen Wiltshire
Persistent Identifier (URN):urn:nbn:de:101:1-201307119275
Document Type:PhD Thesis
Date of Successful Oral Defense:2010/11/29
Date of First Publication:2010/11/29
PhD Degree:Biology
School:SES School of Engineering and Science
Library of Congress Classification:Q Science / QR Microbiology / QR100-131 Microbial ecology / QR106 Seawater. Marine microbiology
Call No:Thesis 2010/41

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