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  • 1
    Publication Date: 2017-06-26
    Description: Introduction: Many marine planktonic crustaceans such as copepods have been considered as widespread organisms. However, the growing evidence for cryptic and pseudo-cryptic speciation has emphasized the need of re-evaluating the status of copepod species complexes in molecular and morphological studies to get a clearer picture about pelagic marine species as evolutionary units and their distributions. This study analyses the molecular diversity of the ecologically important Paracalanus parvus species complex. Its seven currently recognized species are abundant and also often dominant in marine coastal regions worldwide from temperate to tropical oceans. Results: COI and Cytochrome b sequences of 160 specimens of the Paracalanus parvus complex from all oceans were obtained. Furthermore, 42 COI sequences from GenBank were added for the genetic analyses. Thirteen distinct molecular operational taxonomic units (MOTU) and two single sequences were revealed with cladistic analyses (Maximum Likelihood, Bayesian Inference), of which seven were identical with results from species delimitation methods (barcode gaps, ABDG, GMYC, Rosenberg’s P(AB)). In total, 10 to 12 putative species were detected and could be placed in three categories: (1) temperate geographically isolated, (2) warm-temperate to tropical wider spread and (3) circumglobal warm-water species. Conclusions: The present study provides evidence of cryptic or pseudocryptic speciation in the Paracalanus parvus complex. One major insight is that the species Paracalanus parvus s.s. is not panmictic, but may be restricted in its distribution to the northeastern Atlantic.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 2
    Publication Date: 2015-05-13
    Description: In October 2010, specimens of Oithona were taken from the List Tidal Basin in the northern Wadden Sea (North Sea) for a biogeographic study on Oithona similis. These specimens could not be assigned to O. similis or any of the other Oithona species known from the North Sea genetically. These specimens were identified as Oithona davisae Ferrari and Orsi 1984, a Northwest Pacific species, known as an invasive species from the Black Sea and the northwestern Mediterranean Sea. Recent sampling provided evidence that O. davisae is still present in the northern Wadden Sea and may thus now be a permanent plankton species.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 3
    Publication Date: 2016-03-01
    Description: Most of what is known about the effects of ocean acidification on zooplankton relates to a few species composed of calcium carbonate, or comes from laboratory and mesocosm studies that observe a relatively small number of species, primarily copepods. So far little is known about how entire zooplankton communities may change due to elevated carbon dioxide levels. We examined changes in zooplankton residential to coral reefs at two reefs in Papua New Guinea where underwater seeps create a natural pH gradient. Traditional net tows, emergence traps, and acoustical instruments were used to collect and observe zooplankton over three separate seasons and emerging from different types of substrata. All methods indicated a dramatic loss in zooplankton abundance where pH was reduced to 7.8 compared to healthy reefs with a normal pH of 8.1. We observed both changes in the overall zooplankton community, and examined each taxonomic group separately to investigate differences in the sensitivity between taxonomic groups. Reduced quantities of zooplankton will likely affect marine organisms that feed on them.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 4
    Publication Date: 2017-08-23
    Description: In the epipelagic ocean the genus Oithona is considered as one of the most abundant and widespread copepods and plays an important role in the trophic food web. Despite its ecological importance, little is known about the Oithona and cyclopoid copepods genomics. Therefore, we sequenced, assembled and annotated the genome of Oithona nana. The comparative genomic analysis integrating available copepod genomes highlighted the expansions of genes related to stress response, cell differentiation, and development, including genes coding Lin12-Notch-Repeat (LNR) domain proteins. The Oithona biogeography based on 28S sequences and metagenomic reads from the Tara Oceans expedition showed the presence of O. nana mostly in the Mediterranean Sea (MS) and confirmed the bipolar distribution of O. similis. The population genomics analyses of O. nana in the Northern Mediterranean Sea (MS), integrating the Tara Oceans metagenomic data and the O. nana genome, led to the identification of genetic structure between populations from the MS basins. Furthermore, 20 loci were found to be under positive selection including four missense and eight synonymous variants, harboring soft or hard selective sweep patterns. One of the missense variants was localized in the LNR domain of the coding region of a male-specific gene. The variation of the B-allele frequency with respect to the MS circulation pattern showed the presence of genomic clines between O. nana and another undefined Oithona species possibly imported through Atlantic waters. This study provides new approaches and results in zooplankton population genomics through the integration of metagenomic and oceanographic data.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 5
    Publication Date: 2016-11-28
    Description: The in situ effects of ocean acidification on zooplankton communities remain largely unexplored. Using natural volcanic CO2 seep sites around tropical coral communities, we show a threefold reduction in the biomass of demersal zooplankton in high-CO2 sites compared with sites with ambient CO2. Differences were consistent across two reefs and three expeditions. Abundances were reduced in most taxonomic groups. There were no regime shifts in zooplankton community composition and no differences in fatty acid composition between CO2 levels, suggesting that ocean acidification affects the food quantity but not the quality for nocturnal plankton feeders. Emergence trap data show that the observed reduction in demersal plankton may be partly attributable to altered habitat. Ocean acidification changes coral community composition from branching to massive bouldering coral species, and our data suggest that bouldering corals represent inferior daytime shelter for demersal zooplankton. Since zooplankton represent a major source of nutrients for corals, fish and other planktivores, this ecological feedback may represent an additional mechanism of how coral reefs will be affected by ocean acidification.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 6
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    Springer Verlag, Berlin
    Publication Date: 2017-01-04
    Description: Das Pelagial ist der Lebensraum des freien Wassers mit allem, was darin schwimmt und driftet, vom winzigen Bakterioplankton über Phyto-, Zooplankton und Fische bis hin zu den den riesigen Walen. In welchen Bereichen und Tiefen leben die unterschiedlichen Organismen? Horizontale und vertikale, tages- und jahreszeitliche Wanderungen sowie die Wechselwirkungen zwischen den unterschiedlichen Organismengruppen und ihre Rolle im Nahrungsgefüge werden erläutert.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 7
    Publication Date: 2017-01-04
    Description: Im Teil Zooplankton wird das breite und vielfältige Spektrum von Organismen des Holoplanktons von einzelligen Protisten bis zu metergroßen Quallen vorgestellt. Kurz wird auf das Vorkommen und die Ernährung der verschiedenen Organismengruppen eingegangen, etwas ausführlicher bei den häufigsten Gruppen der Metazoen, den Krebsen (Crustaceen), Manteltieren (Tunicaten) und Nesseltieren (Cnidariern).
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 8
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    Unknown
    Springer Verlag, Berlin
    Publication Date: 2017-01-04
    Description: Für die Wissenschaft ist die Frage, wer noch zu einer bestimmten biologischen Art gehört und welche Individuen bereits eine andere Art repräsentieren, von grundsätzlichem Interesse. Lange standen fast nur morphologische Merkmale für die Identifizierung von Arten zur Verfügung. In den letzten zwei Jahrzehnten jedoch ist die Erbsubstanz DNA selbst als Datenquelle hinzugekommen. In diesem kurzen Kapitel wird u.a. die molekulargenetische Identifizierung kryptischer Arten von Meerestieren beschrieben.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 9
    Publication Date: 2017-06-23
    Description: Für die Wissenschaft ist die Frage, wer noch zu einer bestimmten biologischen Art gehört und welche Individuen bereits eine andere Art repräsentieren, von grundsätzlichem Interesse. Lange standen fast nur morphologische Merkmale für die Identifizierung von Arten zur Verfügung. In den letzten zwei Jahrzehnten jedoch ist die Erbsubstanz DNA selbst als Datenquelle hinzugekommen. In diesem kurzen Kapitel wird u.a. die molekulargenetische Identifizierung kryptischer Arten von Meerestieren beschrieben.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 10
    Publication Date: 2017-09-04
    Description: The population genetic structure of Calanoides natalis (ex Calanoides carinatus; Copepoda, Calanoida), an ecologically important component of African upwelling systems, was studied in order to (i) search for potential cryptic species, (ii) describe spatial patterns in the distribution of genetic variance and (iii) identify potential barriers to gene flow. Samples were obtained in the eastern Atlantic Ocean from the Iberian Peninsula to Namibia. Analysis of mitochondrial (cytochrome c oxidase subunit I; COI) and nuclear (citrate synthase; CS) marker genes revealed a genetically cohesive population of C. natalis with a prevalent shift in allele frequencies. The discovery of a deep split solely present in the mitochondrial dataset does not point to cryptic speciation, but rather suggests the occurrence of nuclear mitochondrial pseudogenes or incomplete reproductive isolation upon secondary contact. Genetic differentiation between the northern and southern hemisphere was significant, which may point to a potential, but permeable barrier close to the equator. No vertical genetic structuring was detected in the northern Benguela implying that horizontal differentiation was more pronounced than vertical structuring. Retention mechanisms and the oxygen minimum zone did not have a strong impact on genetic differentiation of C. natalis in the Benguela region.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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