Beschreibung: Increasing anthropogenic CO2 concentration in the atmosphere is altering sea water carbonate chemistry with unknown biological and ecological consequences. Whereas some reports are beginning to emerge on the effects of ocean acidification (OA) on fish, very little is known about the impact of OA on jellyfish. In particular, the benthic stages of metagenetic species are virtually unstudied in this context despite their obvious importance for bloom dynamics. Hence, we conducted tri-trophic food chain experiments using the algae Rhodomonas salina as the primary producer, the copepod Acartia tonsa as the primary consumer and the benthic life stage of the scyphozoans Cyanea capillata and Chrysaora hysoscella as secondary consumers. Two experiments were conducted examining the effects of different levels of CO2 and food quality (experiment 1) and the effect of food quality and quantity (experiment 2) on the growth and respiration of scyphozoan polyps. Polyp growth and carbon content (µg polyp−1) were not affected by the CO2 treatments, but were significantly negatively affected by P limitation of the food in C. capillata but not in Ch. hysoscella. Growth and carbon content were reduced in low-food treatments, but increased with decreasing P limitation in high- and low-food treatments in C. capillata. Respiration was not significantly influenced by food quality and quantity in C. capillata. We conclude that phosphorus can be a limiting factor affecting the fitness of scyphopolyps and that P-limited food is of poor nutritional quality. Furthermore, OA, at least using realistic end-of-century scenarios, will have no direct effect on the growth of scyphistomae

Beschreibung: Global change is affecting marine ecosystems through a combination of different stressors such as warming, ocean acidification and oxygen depletion. Very little is known about the interactions among these factors, especially with respect to gelatinous zooplankton. Therefore, in this study we investigated the direct effects of pH, temperature and oxygen availability on the moon jellyfish Aurelia aurita, concentrating on the ephyral life stage. Starved one-day-old ephyrae were exposed to a range of pCO2 (400–4000 ppm) and three different dissolved oxygen levels (from saturated to hypoxic conditions), in two different temperatures (5 and 15 °C) for 7 days. Carbon content and swimming activity were analysed at the end of the incubation period, and mortality noted. General linearized models were fitted through the data, with the best fitting models including two- and three-way interactions between pCO2, temperature and oxygen concentration. The combined effect of the stressors was small but significant, with the clearest negative effect on growth caused by the combination of all three stressors present (high temperature, high CO2, low oxygen). We conclude that A. aurita ephyrae are robust and that they are not likely to suffer from these environmental stressors in a near future.

Beschreibung: Abstract Different techniques of species distribution modeling were applied to evaluate the distribution of eight benthic marine species in Icelandic waters. The species examined were Symplectoscyphus tricuspidatus, Stegopoma plicatile (both Hydrozoa), Prionospio cirrifera, Amphicteis gunneri (both Polychaeta), Desmosoma strombergi, Eurycope producta (both Isopoda), Andaniella pectinata and Harpinia crenulata (both Amphipoda). Information on 13 environmental variables (temperature mean, temperature mean SD, temperature minimum, temperature maximum, salinity mean, salinity mean SD, oxygen content, particulate organic carbon, seasonal variation index, bottom roughness, sediment thickness, acidification) and records of occurrences of these eight species was collated in an ArcGIS project. Modeling methods applied were MARS, TreeNet, and MaxENT. According to area under the receiver operating curve (AUC) model assessment values, models with moderate to outstanding discriminatory power were found for all species. There was a good overlap in the overall pattern of prediction for most species independent on the modeling technique. Among the three applied techniques MARS seemed to generalize most whereas TreeNet predictions very precisely reflected information from the training data set. The distribution of the selected benthic invertebrate species in Icelandic waters could be linked to a variety of environmental factors related to oceanography, seabed topography and human impact. Their multivariate interactions acted as a structuring force of species distribution, instead of just their one by one individual influence. The selected predictors varied between the different models for the same species. They substituted each other in different models. The expected distribution of the examined species was mapped for a seascape of known environmental settings. Such maps will serve as excellent references in future impact studies and enable the detection of changes in the distribution of benthic marine invertebrates.

Beschreibung: Hintergrund. Vernesselungen durch Quallen gehören zu den häufigsten Verletzungen von Urlaubern an deutschen Küsten und führen regelmäßig zu Konsultationen des regionalen Wasserrettungsdienstes. Ziel der Arbeit. Diese Übersichtsarbeit soll darlegen, für welche Therapieoptionen bei Vernesselungen eine wissenschaftliche Evidenz vorliegt. Methode. Es wurde eine selektive Literaturrecherche in der medizinischen Datenbank „Pubmed“ zu den Stichworten „jellyfish treatment“, „Rasierschaum“, „shaving foam“ und „shaving lather“ durchgeführt. Anhand der Literaturverzeichnisse der gefundenen Veröffentlichungen wurden weitere Literaturstellen ausfindig gemacht und in die Auswertung mit einbezogen. Für die daraus resultierenden Empfehlungen werden die Evidenzgrade und Empfehlungsgrade entsprechend der Evidenzklassifizierung des CEBM angegeben. Ergebnisse. Es konnte experimentell gezeigt werden, dass die Beschwerden von Vernesselungen durch Cyanea capillata durch das Aufbringen von Essig verstärkt werden. Wärme oder Kälte führen zu einer Linderung der Beschwerden. Für die meisten anderen gängigen Behandlungsmethoden liegt keine ausreichende wissenschaftliche Evidenz vor. Diskussion. Nach einer Vernesselung durch Quallen soll das Gewässer verlassen werden. Sichtbare Quallengewebereste müssen mechanisch entfernt werden. Die Vernesselung kann mit lokaler Wärme- oder Kälteapplikation, Rasierschaum, Antihistaminika oder Kortison behandelt werden, nicht jedoch mit Essig. Ein unzureichender Tetanusschutz sollte aufgefrischt werden. Eine Hämolyse kann durch die Applikation von Kalziumkanalblockern oder Antioxidantien behandelt werden.

Beschreibung: Different modes of asexual and sexual reproduction are typical for the life-history of scyphozoans, and numerous studies have focused on general life history distribution, reproductive strategies, strobilation inducing factors, growth rates and predatory effects of medusae. However, bacteria associated with different life stages of scyphozoa have received less attention. In this study, bacterial communities associated with different body compartments and different life stages of two common scyphomedusae (Cyanea lamarckii and Chrysaora hysoscella) were analyzed via automated ribosomal intergenic spacer analysis (ARISA). We found that the bacterial community associated with these two species showed species-specific structuring. In addition, we observed significant differences between the bacterial communities associated with the umbrella and other body compartments (gonads and tentacles) of the two scyphomedusan species. Bacterial community structure varied from the early planula to the polyp and adult medusa stages. We also found that the free-living and particle-associated bacterial communities associated with different food sources had no impact on the bacterial community associated with fed polyps.

Beschreibung: Different modes of asexual and sexual reproduction are typical for the life-history of metagenetic Scyphozoa. Numerous studies have focused upon the general life history distribution, reproductive behavior, factors leading to strobilation, growth rates and impact of predation rate of medusa. However, bacteria associated with different life stages of Scyphozoa have received less attention. In the present study, bacterial communities associated with different body fractions and different life stages of two Scyphomedusae Cyanea lamarckii and Chrysaora hysoscella, which are common species in the German Bight, North Sea, were analyzed via automated ribosomal intergenic spacer analysis (ARISA). Regarding to the analysis of different body fractions (umbrella, gonad, tentacle and mouth arm), significant differences are revealed between umbrella and other body fractions (gonad and tentacle) in terms of the associated bacterial community in both species. With regard to the different life stages, bacterial community structure varied from the early stage planula larvae to polyp even to adult medusa with significant differences in both species by multivariate analysis. Furthermore, the free-living and attached bacterial community of food source did not influence the bacterial communities of polyps, however, polyps displayed a significantly different bacterial community in response to different food source. The bacterial community associated with scyphozoan presented species-specific structure.

Beschreibung: Morphological identification of cnidarian species can be difficult throughout all life stages due to the lack of distinct morphological characters. Moreover, in some cnidarian taxa genetic markers are not fully informative, and in these cases combinations of different markers or additional morphological verifications may be required. Proteomic fingerprinting based on MALDI-TOF mass spectra was previously shown to provide reliable species identification in different metazoans including some cnidarian taxa. For the first time, we tested the method across four cnidarian classes (Staurozoa, Scyphozoa, Anthozoa, Hydrozoa) and included different scyphozoan life-history stages (polyp, ephyra, medusa) in our dataset. Our results revealed reliable species identification based on MALDI-TOF mass spectra across all taxa with species-specific clusters for all 23 analysed species. In addition, proteomic fingerprinting was successful for distinguishing developmental stages, still by retaining a species specific signal. Furthermore, we identified the impact of different salinities in different regions (North Sea and Baltic Sea) on proteomic fingerprints to be negligible. In conclusion, the effects of environmental factors and developmental stages on proteomic fingerprints seem to be low in cnidarians. This would allow using reference libraries built up entirely of adult or cultured cnidarian specimens for the identification of their juvenile stages or specimens from different geographic regions in future biodiversity assessment studies.