The degree of dietary specialization has a fundamental impact on the ecological function and interactions of suspension feeders.While niche differentiation by food particle size is common among obligate suspension fee...The degree of dietary specialization has a fundamental impact on the ecological function and interactions of suspension feeders.While niche differentiation by food particle size is common among obligate suspension feeders,its role is not evident in facultative ones.In this study,we aimed at providing new insights on the matter by focusing on sympatric mysid species.As mysids use different mechanisms for raptorial and filter-feeding,they represent a more adequate model system than for example,the more extensively studied copepods.We made morpholog-ical measurements on the 4 coexisting invasive Ponto-Caspian mysid species to determine the areas and mesh sizes of their filters.We also quantified their clearance rates on the microalga Cryptomonas sp.in a laboratory experiment to reveal how morphological differences manifest in their overall filtering capacity.We found relatively small but consistent differences in the primary filter area among the species,indicating that morphological constraints due to the enclosed position of the setae might limit the possibility for differentiation.The primary filter mesh sizes were small in all 4 species(0.69-2.73μm)with moderate but consistent intraspecific differences,suggesting that the benefit of being able to capture small particles might outweigh the pressure for differentiation.The observed clearance rates were in accordance with the morphological characteristics of the species,highlighting that auxiliary filters(present in one of the species,Limnomysis benedeni)are needed to increase filtering capacity considerably.Our study confirmed that food particle size can contribute to the niche differentiation of facultative filter feeders,but also indicated that they can tolerate a higher overlap than obligate ones.The observed differences were related to the habitat preferences and predatory potentials of the species,suggesting that complementarity among the different niche axes might further facilitate theircoexistence.展开更多
Tip clearance cavitation is one of the most common cavitation phenomena exist on duct propellers,pumps and some hydraulic turbines,which may lead to erosion of the components.Due to the influence of the nearby wall,ca...Tip clearance cavitation is one of the most common cavitation phenomena exist on duct propellers,pumps and some hydraulic turbines,which may lead to erosion of the components.Due to the influence of the nearby wall,cavitation inside the tip clearance is more complicated than other cases without interaction.So far,the understanding about the impact mechanism of tip clearance cavitation is still limited.In this paper,to obtain the impact behavior of tip clearance cavitation,a high-speed camera was used to capture the cavitation behavior inside the tip clearance of a hydrofoil,and surface paint coating peeling method was applied to show the impact region.Results indicated that cavitation around the tip of the hydrofoil was composed of a tip separation cavity and a tip leakage vortex cavity,and the one with contribution to impact was the tip separation cavity.Through the comprehensive analysis of the paint peeling region and dynamic behavior of tip separation cavity,the impact was found to be related to the local collapse and rebound of the cloud cavitation shed from the attached part.In addition,the influence of tip clearance size on the behavior of tip clearance cavitation was also investigated.As the tip clearance size increased,the tip separation cavity tended to transfer from sheet cavitation to vortex cavitation.These findings can provide a sound basis for evaluating the erosion risk arising from the tip clearance cavitation.展开更多
基金The authors thank Peter Dobosy,Adam Egri,Bence Gergacz,Eszter Laczkovszki,Sarah Lecoq,Nicolas Malinge,and Karoly Palffy for their assistance in various phases of the research.Project no.132605 has been implemented with the support provided from the National ResearchDevelopment and Innovation Fund of Hungary,financed under the FK_19 funding scheme.VR acknowledges further support by the NKFIH-138215project.
文摘The degree of dietary specialization has a fundamental impact on the ecological function and interactions of suspension feeders.While niche differentiation by food particle size is common among obligate suspension feeders,its role is not evident in facultative ones.In this study,we aimed at providing new insights on the matter by focusing on sympatric mysid species.As mysids use different mechanisms for raptorial and filter-feeding,they represent a more adequate model system than for example,the more extensively studied copepods.We made morpholog-ical measurements on the 4 coexisting invasive Ponto-Caspian mysid species to determine the areas and mesh sizes of their filters.We also quantified their clearance rates on the microalga Cryptomonas sp.in a laboratory experiment to reveal how morphological differences manifest in their overall filtering capacity.We found relatively small but consistent differences in the primary filter area among the species,indicating that morphological constraints due to the enclosed position of the setae might limit the possibility for differentiation.The primary filter mesh sizes were small in all 4 species(0.69-2.73μm)with moderate but consistent intraspecific differences,suggesting that the benefit of being able to capture small particles might outweigh the pressure for differentiation.The observed clearance rates were in accordance with the morphological characteristics of the species,highlighting that auxiliary filters(present in one of the species,Limnomysis benedeni)are needed to increase filtering capacity considerably.Our study confirmed that food particle size can contribute to the niche differentiation of facultative filter feeders,but also indicated that they can tolerate a higher overlap than obligate ones.The observed differences were related to the habitat preferences and predatory potentials of the species,suggesting that complementarity among the different niche axes might further facilitate theircoexistence.
基金supported by the National Natural Science Foundation of China(Grant No.11902295).
文摘Tip clearance cavitation is one of the most common cavitation phenomena exist on duct propellers,pumps and some hydraulic turbines,which may lead to erosion of the components.Due to the influence of the nearby wall,cavitation inside the tip clearance is more complicated than other cases without interaction.So far,the understanding about the impact mechanism of tip clearance cavitation is still limited.In this paper,to obtain the impact behavior of tip clearance cavitation,a high-speed camera was used to capture the cavitation behavior inside the tip clearance of a hydrofoil,and surface paint coating peeling method was applied to show the impact region.Results indicated that cavitation around the tip of the hydrofoil was composed of a tip separation cavity and a tip leakage vortex cavity,and the one with contribution to impact was the tip separation cavity.Through the comprehensive analysis of the paint peeling region and dynamic behavior of tip separation cavity,the impact was found to be related to the local collapse and rebound of the cloud cavitation shed from the attached part.In addition,the influence of tip clearance size on the behavior of tip clearance cavitation was also investigated.As the tip clearance size increased,the tip separation cavity tended to transfer from sheet cavitation to vortex cavitation.These findings can provide a sound basis for evaluating the erosion risk arising from the tip clearance cavitation.
