Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a b...Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.展开更多
The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermedia...The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermediate predator and top predator. First,the model without self-limitation of the predators is studied. Boundedness of the systemand existence of non-negative solutions are established. The local stability analysisof the equilibria is carried out to examine the behavior of the system. The possibilityof Hopf bifurcation around non-negative equilibria with consumption rates as bifurcationparameters is studied. Center manifold theorem and the normal form theory areapplied to obtain the formulas for determining the direction of Hopf bifurcation and thestability of bifurcating periodic solutions. Numerical simulations support the analyticalfindings, which show that the extinction of one of the predators can occur under certainrestrictions on the predation rate of the top predator. Subsequently, numerical analysisof the model with self-limitation of the predators is carried out. Simulations reveal thatthe system with intraspecific competition in the predator populations can reproducecoexistence between the three species in resource-rich environment.展开更多
基金Supported by the National Key Research and Development Program of China(No.2017YFC1404405)the Taishan Scholar Climbing Plan to Sun Song,the Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2016ASKJ02-2)。
文摘Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.
文摘The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermediate predator and top predator. First,the model without self-limitation of the predators is studied. Boundedness of the systemand existence of non-negative solutions are established. The local stability analysisof the equilibria is carried out to examine the behavior of the system. The possibilityof Hopf bifurcation around non-negative equilibria with consumption rates as bifurcationparameters is studied. Center manifold theorem and the normal form theory areapplied to obtain the formulas for determining the direction of Hopf bifurcation and thestability of bifurcating periodic solutions. Numerical simulations support the analyticalfindings, which show that the extinction of one of the predators can occur under certainrestrictions on the predation rate of the top predator. Subsequently, numerical analysisof the model with self-limitation of the predators is carried out. Simulations reveal thatthe system with intraspecific competition in the predator populations can reproducecoexistence between the three species in resource-rich environment.
