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Although jellyfish blooms are a focus of recent research, the roles that the developmental stages of species play are underestimated. Planulae, polyps and ephyrae are inconspicuous and often overlooked. The importance of production of ephyrae from the sessile polyps has become more apparent. Our objective was to establish an identification system for early ephyrae of scyphozoan species in plankton...
Blooms of the invasive ctenophore, Mnemiopsisleidyi, occurred in 2009 along the Mediterranean Sea coasts of Spain and Israel. This voracious zooplanktivore spread throughout the Black Sea basin after its introduction in the early 1980s, throughout northern European coastal waters, and now occurs throughout the Mediterranean Sea. M.leidyi occurred throughout the summer along the entire Catalan Spanish...
Although anthropogenic influences such as global warming, overfishing, and eutrophication may contribute to jellyfish blooms, little is known about the effects of ocean acidification on jellyfish. Most medusae form statoliths of calcium sulfate hemihydrate that are components of their balance organs (statocysts). This study was designed to test the effects of pH (7.9, within the average current range,...
Several species of scyphozoan medusae occur in river estuaries and other brackish waters but it is often unknown if the planulae settle and the scyphopolyps reproduce in those low-salinity waters. In the present study, scyphozoan species from the German Bight (North Sea) were tested in laboratory experiments to investigate their tolerance of low salinity. Planula larvae released from medusae in salinity...
We analyzed sea temperature as an environmental factor, in association with ENSO, affecting the migration of East Pacific black turtle, Chelonia mydas (=Chelonia agassizii Bocourt), to its foraging areas and its feeding ecology at San Andrés, Peru. A 19-year sea turtle landing database (1970–1988) was constructed to associate landing fluctuations with environmental variability represented by the Peruvian...
Four meroplanktonic scyphomedusae, Aurelia aurita, Chrysaora hysoscella, Cotylorhiza tuberculata and Rhizostoma pulmo, and the holoplanktonic, non-resident Pelagia noctiluca have formed blooms in the northern Adriatic over the last 200 years. Published data about the historical occurrences of these five scyphomedusae, in combination with our data, were used to analyse their long-term fluctuations...
In pelagic systems, thin layers (discontinuities with narrow vertical extents and high concentrations of organisms) create patches of food, and aggregations of gelatinous zooplankton can exploit such resources. The establishment, maintenance, and trophic effects of these functional relationships depend on behavioral responses to thin layers by individuals, which remain largely unexplored. In this...
Biomass distributions of the ctenophore, Mnemiopsis leidyi, were collected during a week-long survey program in a tidal front along the Patagonian shelf in December 1989. Average ctenophore biomass concentrations varied significantly along a north–south gradient and in stratified compared to unstratified waters. The relative vertical distribution of M. leidyi biomass appeared to be constrained by...
Because of their high abundance in Chesapeake Bay, Chrysaora quinquecirrha medusae may be an important reservoir of organic matter. The timing and location of the decomposition of biomass from medusae may have implications for carbon cycling in the bay. Our objective was to identify the cause of C. quinquecirrha medusa disappearance to better understand when and where decomposition occurs. A time...
One of the main objectives of research on jellyfish is to determine their effects on the food web. They are voracious consumers that have similar diets to those of zooplanktivorous fish, as well as eating microplankton and ichthyoplankton. Respiration rates (RRs) can be used to estimate the amount of food needed to balance metabolism, and thereby estimate minimum ingestion. We compiled RRs for scyphozoan...
Pelagic cnidarians are important consumers of zooplankton and ichthyoplankton in the world’s oceans, and thus harm fisheries as competitors and predators of fish. This study examined the inshore-offshore distribution of pelagic cnidarians and the trophic ecology of Pelagia noctiluca ephyrae (<12 mm diameter) and larger medusae in late spring 1995 in the NW Mediterranean Sea. The distribution of...
Knowledge of how energetic parameters relate to fluctuating factors in the natural habitat is necessary when evaluating the role of gelatinous zooplankton in the carbon flow of coastal waters. In laboratory experiments, we assessed feeding, respiration and growth of the ctenophore, Pleurobrachia pileus, and constructed carbon budgets. Clearance rates (F, l d−1) of laboratory-reared Acartia tonsa as...
The decomposition of jellyfish after major bloom events results in the release of large amounts of nutrients, which can significantly alter nutrient and oxygen dynamics in the surrounding environment. The response of the ambient bacterial community to decomposing jellyfish biomass was evaluated in two marine ecosystems, the Gulf of Trieste (northern Adriatic Sea) and Big Lake (Mljet Island, southern...
Previous analysis of the Continuous Plankton Recorder (CPR) long-term data set for the presence of ‘coelenterate’ tissue revealed changes in the frequency of jellyfish occurrence in the North Atlantic Ocean and North Sea; however, the identities of the jellyfish were unknown, causing uncertainty in interpreting these findings. To improve the utility of the ‘coelenterate’ data from the CPR, 62 CPR...
Medusae play an important role in marine ecosystems, as competitors of many invertebrate and fish species. Additionally, jellyfish stings can cause severe pain, inflammation of the affected skin, and allergic reactions in human. Climate and environmental changes are likely to affect the medusae, but it is not yet clear whether these will affect their distribution, physiology, and their toxicity. Very...
Cnidarian venoms include neurotoxins, which are able to paralyse prey organisms immediately. Important targets for neurotoxins are voltage-gated ion channels in membranes of excitable cells. By blocking specific receptor sites, neurotoxic components disturb the physiological ion channel functions. Here, we describe the isolation and characterisation of potential neurotoxic polypeptides from the crude...
Scyphozoan medusae are very successful foragers which occasionally occur in high abundances in boreal waters and may impact many different groups in the marine ecosystem by means of a variety of toxins. A rainbow trout gill cell line, RTgill-W1, was tested for its suitability as quantitative indicator of the cytotoxicity of Cyaneacapillata and Aureliaaurita; the major scyphozoan species in the North...
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