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Ulrich K Steiner - One of the best experts on this subject based on the ideXlab platform.
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ecological drivers of jellyfish blooms the complex life history of a well known Medusa aurelia aurita
Journal of Animal Ecology, 2020Co-Authors: Josephine Goldstein, Ulrich K SteinerAbstract:Jellyfish blooms are conspicuous demographic events with significant ecological and socio-economic impact. Despite worldwide concern about an increased frequency and intensity of such mass occurrences, predicting their booms and busts remains challenging. Forecasting how jellyfish populations may respond to environmental change requires considering their complex life histories. Metagenic life cycles, which include a benthic polyp stage, can boost jellyfish mass occurrences via asexual recruitment of pelagic Medusae. Here we present stage-structured matrix population models with monthly, individual-based demographic rates of all life stages of the moon jellyfish Aurelia aurita L. (sensu stricto). We investigate the life-stage dynamics of these complex populations under low and high food conditions to illustrate how changes in Medusa density depend on non-Medusa stage dynamics. We show that increased food availability can be an important ecological driver of jellyfish mass occurrences, as it can temporarily shift the population structure from polyp- to Medusa-dominated. Projecting populations for a winter warming scenario additionally enhanced the booms and busts of jellyfish blooms. We identify demographic key variables that control the intensity and frequency of jellyfish blooms in response to environmental drivers such as habitat eutrophication and climate change. By contributing to an improved understanding of mass occurrence phenomena, our findings provide perspective for future management of ecosystem health.
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ecological drivers of jellyfish blooms the complex life history of a well known Medusa aurelia aurita
bioRxiv, 2019Co-Authors: Josephine Goldstein, Ulrich K SteinerAbstract:Summary Jellyfish blooms are conspicuous demographic events with significant ecological and socio-economic impact. Despite worldwide concern about an increased frequency and intensity of jellyfish mass occurrences, predicting their booms and busts remains challenging. Forecasting how jellyfish populations may respond to environmental change requires taking into account their complex life histories. Metagenic life cycles, which include a benthic polyp stage, can boost jellyfish mass occurrences via asexual recruitment of pelagic Medusae. Here we present stage-structured matrix population models with monthly, individual-based demographic rates of all life stages of the moon jellyfish Aurelia aurita (sensu stricto) for low and high food conditions. We investigate the life stage-dynamics of such complex populations to illustrate how changes in Medusa density depend on non-Medusa stage dynamics. We show that increased food availability can be an important ecological driver of jellyfish mass occurrence, as it can temporarily shift the population structure from polyp- to Medusa-dominated. Projecting populations for a winter warming scenario additionally enhanced the booms and busts of jellyfish blooms. We identify demographic key variables that control the intensity and frequency of jellyfish blooms in response to environmental drivers such as habitat eutrophication and climate change. By contributing to an improved understanding of mass occurrence phenomena, our findings provide perspective for future management of ecosystem health.
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ecological drivers of jellyfish blooms the complex life history of a cosmopolitan Medusa aurelia aurita
bioRxiv, 2017Co-Authors: Josephine Goldstein, Ulrich K SteinerAbstract:Summary Jellyfish blooms are conspicuous demographic events with significant ecological and socio-economic impact. Despite worldwide concern about an increased frequency and intensity of jellyfish mass occurrences, predicting their booms and busts remains challenging. Forecasting how jellyfish populations may respond to environmental change requires taking into account their complex life histories. Metagenic life cycles, which include a benthic polyp stage, can boost jellyfish outbreaks via asexual recruitment of pelagic Medusae. Here we present stage-structured matrix population models with demographic rates of all life stages of the cosmopolitan jellyfish Aurelia aurita s. l. for different environments. We investigate the life stage-dynamics of such complex populations to illustrate how changes in Medusa density depend on non-Medusa stage dynamics. We show that increased food availability is an important ecological driver of jellyfish mass occurrence, as it can shift the population structure from polyp- to Medusa-dominated. Projecting populations for a winter warming scenario additionally enhanced the booms and busts of jellyfish blooms. We identify demographic key variables that control the intensity and frequency of jellyfish blooms in response to anthropogenic drivers such as habitat eutrophication and climate change. By contributing to an improved understanding of mass occurrence phenomena, our findings provide perspective for future management of ecosystem health.
Jennifer E. Purcell - One of the best experts on this subject based on the ideXlab platform.
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predicting the distribution of the scyphoMedusa chrysaora quinquecirrha in chesapeake bay
Marine Ecology Progress Series, 2007Co-Authors: Mary Beth Decker, Jennifer E. Purcell, Raleigh R Hood, Chris W Brown, Thomas F Gross, J C Matanoski, R O Bannon, E M SetzlerhamiltonAbstract:Jellyfish blooms are important events controlling plankton dynamics in coastal waters worldwide, yet factors that influence bloom development are not well understood. We used the scyphoMedusa Chrysaora quinquecirrha as a model to examine physical factors that control jellyfish populations and to develop an ecological forecasting system. Over 700 in situ observations collected from Chesapeake Bay and its tributaries during 1987-2000 were used to develop habitat models that predict the probability of occurrence and the likely concentration of Medusae as a function of sea- surface temperature and salinity. Medusae were found within a relatively narrow range of tempera- ture (26 to 30°C) and salinity (10 to 16). Regression analyses reveal that a combination of temperature and salinity is a significant predictor of Medusa occurrence. Assessments of the predictive perfor- mance of these models using Medusae and environmental data collected at independent survey sites (n = 354) indicated that model-predicted Medusa occurrence and concentration correspond well with observations. Our models can be forced with near-real time and retrospective estimates of tempera- ture and salinity to generate probability of occurrence maps of C. quinquecirrha Medusa presence and abundance in order to better understand how this top predator varies in space and time, and how this species could potentially affect energy flow through the Chesapeake Bay system.
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swimming and feeding by the scyphoMedusa chrysaora quinquecirrha
Marine Biology, 1997Co-Authors: M D Ford, John H Costello, Karla B Heidelberg, Jennifer E. PurcellAbstract:The semaeostome scyphoMedusa, Chrysaora quinquecirrha (Desor, 1848), is an abundant and important planktonic predator in estuaries and coastal waters of the eastern USA during the summer. We videotaped free-swimming Medusae in the laboratory and in the field in order to determine the relationship between swimming motions and prey encounter with capture surfaces. Medusae were collected from the Choptank River (Chesapeake Bay) in September 1992 and in the Niantic River, Connecticut, USA in July 1994. We used newly hatched Artemia sp. nauplii and fluorescein dye to trace water motions around swimming Medusae. Swimming results in a pulsed series of toroids which travel along the Medusan oral arms and tentacles. Prey are entrained in this flow and the location of naupliar encounter was influenced by the phase of the pulsation cycle during which entrainment occurred. Flow-field velocities, measured by tracking particles adjacent to the bell margin during contraction, increased with bell diameter.
Hans Toni Ratte - One of the best experts on this subject based on the ideXlab platform.
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Trophic interactions of the freshwater jellyfish Craspedacusta sowerbii
Journal of Plankton Research, 2005Co-Authors: Thomas Jankowski, Tido Strauss, Hans Toni RatteAbstract:The predatory impact and the trophic role of the freshwater jellyfish, Craspedacusta sowerbii, was studied using microcosm and enclosure experiments as well as a 3-year pond survey. The results showed a significant decrease of small herbivorous crustaceans, i.e. Bosmina longirostris and juvenile cyclopoid copepods, in the Medusa treatments of the microcosms and the enclosure experiments. Chlorophyll concentrations in the enclosure experiment were significantly increased in the Medusa treatment, suggesting that C. sowerbii may cause cascading effects in the food chain. A comparison of daily zooplankton losses during the pond survey caused by Medusae and fish (roach, Rutilus rutilus), and their food selectivities suggest food separation of these two predators and reveal a strong negative impact of Medusae on the copepod pond community. In the case of a jellyfish bloom, our results show that both food chains can co-occur in lakes because of a weak interaction between these top predators, fish and jellyfish, with simultaneous impacts on the zooplankton structure.
Kenneth M Halanych - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic analysis with multiple markers indicates repeated loss of the adult Medusa stage in campanulariidae hydrozoa cnidaria
Molecular Phylogenetics and Evolution, 2006Co-Authors: Annette F. Govindarajan, Ferdinando Boero, Kenneth M HalanychAbstract:The Campanulariidae is a group of leptoMedusan hydroids (Hydrozoa, Cnidaria) that exhibit a diverse array of life cycles ranging from species with a free Medusa stage to those with a reduced or absent Medusa stage. Perhaps the best-known member of the taxon is Obelia which is often used as a textbook model of hydrozoan life history. However, Obelia Medusae have several unique features leading to a hypothesis that Obelia arose, in a saltational fashion, from an ancestor that lacked a Medusa, possibly representing an example of a rare evolutionary reversal. To address the evolution of adult sexual stages in Campanulariidae, a molecular phylogenetic approach was employed using two nuclear (18S rDNA and calmodulin) and two mitochondrial (16S rDNA and cytochrome c oxidase subunit I) genes. Prior to the main analysis, we conducted a preliminary analysis of leptoMedusan taxa which suggests that Campanulariidae as presently considered needs to be redeWned. Campanulariid analyses are consistent with morphological understanding in that three major clades are recovered. However, several recognized genera are not monophyletic calling into question some “diagnostic” features. Furthermore, ancestral states were reconstructed using parsimony, and a sensitivity analysis was conducted to investigate possible evolutionary transitions in life-history stages. The results indicate that life-cycle transitions have occurred multiple times, and that Obelia might be derived from an ancestor with Clytia-like features. 2005 Elsevier Inc. All rights reserved.
Raleigh R Hood - One of the best experts on this subject based on the ideXlab platform.
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response of chrysaora quinquecirrha Medusae to low temperature
Hydrobiologia, 2010Co-Authors: Margaret Sexton, Raleigh R Hood, Judith Sarkodeeadoo, Amanda M LissAbstract: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 series of visual surface counts and vertical net hauls in the Choptank River, a tributary of Chesapeake Bay, showed that as temperatures approached 15°C, C. quinquecirrha Medusae disappeared from the surface, but persisted in net hauls until temperatures reached 10°C. In order to test whether Medusae sink upon cooling, we exposed C. quinquecirrha Medusae to low temperatures in large static tanks and measured their depth and pulsation rates twice daily for at least 6 days. This procedure was repeated three times through the 2008 jellyfish season. On average, individuals exposed to temperatures below 15°C were found deeper and pulsed slower than those in the warmer control tank. This suggests that low temperatures cause the Medusae to sink before cooling to the limit of their physiological tolerance and may have implications for the deposition of organic matter associated with the seasonal disappearance of Medusae from Chesapeake Bay.
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predicting the distribution of the scyphoMedusa chrysaora quinquecirrha in chesapeake bay
Marine Ecology Progress Series, 2007Co-Authors: Mary Beth Decker, Jennifer E. Purcell, Raleigh R Hood, Chris W Brown, Thomas F Gross, J C Matanoski, R O Bannon, E M SetzlerhamiltonAbstract:Jellyfish blooms are important events controlling plankton dynamics in coastal waters worldwide, yet factors that influence bloom development are not well understood. We used the scyphoMedusa Chrysaora quinquecirrha as a model to examine physical factors that control jellyfish populations and to develop an ecological forecasting system. Over 700 in situ observations collected from Chesapeake Bay and its tributaries during 1987-2000 were used to develop habitat models that predict the probability of occurrence and the likely concentration of Medusae as a function of sea- surface temperature and salinity. Medusae were found within a relatively narrow range of tempera- ture (26 to 30°C) and salinity (10 to 16). Regression analyses reveal that a combination of temperature and salinity is a significant predictor of Medusa occurrence. Assessments of the predictive perfor- mance of these models using Medusae and environmental data collected at independent survey sites (n = 354) indicated that model-predicted Medusa occurrence and concentration correspond well with observations. Our models can be forced with near-real time and retrospective estimates of tempera- ture and salinity to generate probability of occurrence maps of C. quinquecirrha Medusa presence and abundance in order to better understand how this top predator varies in space and time, and how this species could potentially affect energy flow through the Chesapeake Bay system.