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| Titel |
Blastodinium spp. infect copepods in the ultra-oligotrophic marine waters of the Mediterranean Sea |
| VerfasserIn |
C. Alves-de-Souza, C. Cornet, A. Nowaczyk, S. Gasparini, A. Skovgaard, L. Guillou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 8 ; Nr. 8, no. 8 (2011-08-09), S.2125-2136 |
| Datensatznummer |
250006075
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| Publikation (Nr.) |
 copernicus.org/bg-8-2125-2011.pdf |
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| Zusammenfassung |
| Blastodinium are chloroplast-containing dinoflagellates which infect a wide range of
copepods. They develop inside the gut of their host, where they produce
successive generations of sporocytes that are eventually expelled through
the anus of the copepod. Here, we report on copepod infections in the
oligotrophic to ultra-oligotrophic waters of the Mediterranean Sea sampled
during the BOUM cruise. Based on a DNA-stain screening of gut contents,
16 % of copepods were possibly infected in samples from the Eastern
Mediterranean infected, with up to 51 % of Corycaeidae, 33 % of
Calanoida, but less than 2 % of Oithonidae and Oncaeidae. Parasites were
classified into distinct morphotypes, with some tentatively assigned to
species B. mangini, B. contortum, and B. cf. spinulosum.
Based upon the SSU rDNA gene sequence analyses of 15
individuals, the genus Blastodinium was found to be polyphyletic, containing at least
three independent clusters. The first cluster grouped all sequences
retrieved from parasites of Corycaeidae and Oncaeidae during this study, and
included sequences of Blastodinium mangini (the "mangini" cluster). Sequences from cells
infecting Calanoida belonged to two different clusters, one including B. contortum
(the "contortum" cluster), and the other uniting all B. spinulosum-like morphotypes
(the "spinulosum" cluster). Cluster-specific oligonucleotidic probes were
designed and tested by fluorescence in situ hybridization (FISH) in order to assess
the distribution of dinospores, the Blastodinium dispersal and infecting stage.
Probe-positive cells were all small thecate dinoflagellates, with lengths
ranging from 7 to 18 μm. Maximal abundances of Blastodinium dinospores were
detected at the Deep Chlorophyll Maximum (DCM) or slightly below. This was
in contrast to distributions of autotrophic pico- and nanoplankton,
microplanktonic dinoflagellates, and nauplii which showed maximal
concentrations above the DCM. The distinct distribution of dinospores and
nauplii argues against infection during the naupliar stage. Dinospores,
described as autotrophic in the literature, may escape the severe nutrient
limitation of ultra-oligotrophic ecosystems by living inside copepods. |
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