Urban green spaces and parks offer opportunities for retaining and increasing bird richness, diversity, and species abundance. However, urbanisation influences predator–prey interactions, leading to high predation ra...Urban green spaces and parks offer opportunities for retaining and increasing bird richness, diversity, and species abundance. However, urbanisation influences predator–prey interactions, leading to high predation rates in urban areas, in the UK notably through the presence of large populations of domestic cats and increased populations of synanthropic species, such as rats and squirrels. These high predation rates are assumed to be a significant cause of reproductive failure in birds. Some ecologists advocate for the use of buffer zones with reduced human influence to reduce potential hunting pressure in eco-sensitive areas. However, the buffer effect on predation rates of nesting birds in suburban areas is rarely investigated. In this study, we investigated how edge effects (how close nest sites are to housing) and nest height (i.e., ground vs. above-ground) affected nest predation rates in a suburban park using camera traps to monitor artificial nests containing quail eggs. Our hypothesis was that nests in the buffer area (<300 m inward from university boundary) and at low height would suffer higher predation rates than nests in the core area (>300 m from the university boundary) and at height, as the buffer zone effect, and ease of access to ground predators would result in higher predation rates. We found no significant effect of nest height in nest predation rates. However, contrary to our expectations, nests in the core zone suffered higher predation rates than those in the buffer zone, and corvids were responsible for almost half of the egg loss events. We speculate that this may be a consequence of higher levels of anthropogenic disturbance (e.g., pedestrians, dog walking, vehicles) adjacent to our buffer zone acting as a deterrent to avian nest predators. This work suggests that protecting urban sites from disturbance may not always act to support bird abundance.展开更多
Artifcial light at night(ALAN)is a common anthropogenic disturbance,which alters animal behavior.However,little is known about the impact of the spectral composition of ALAN and co-occurring predation risk on the beha...Artifcial light at night(ALAN)is a common anthropogenic disturbance,which alters animal behavior.However,little is known about the impact of the spectral composition of ALAN and co-occurring predation risk on the behavior of aquatic organisms.We experimentally investigated how ALAN of different spectra(cool white LED and HPS light)affects the behavior and foraging of Gammarus jazdzewskii(Amphipoda)on chironomid prey,both as a single stressor and in combination with an olfactory predation cue.Gammarids exposed to ALAN in the absence of predation cues consumed less,compared with darkness,mainly due to their lower activity.Moreover,gammarids showed a stronger response to LED light,spending more time in the shelter and increasing prey handling time in this treatment.The addition of predation cues did not enhance the negative impact of ALAN on the foraging success.Gammarids maintained similar consumption levels as in the ALAN treatment without predation cues and in darkness with predation cues.However,gammarids in LED light altered their behavior in response to predation threat:they decreased prey handling time and consumed prey faster,which may have compensated for the higher food demand in stressful conditions.They also tended to exhibit risky behavior,leaving the shelter and moving towards the lit area,presumably to escape and avoid the combined effects of light and predation cues.Therefore,when assessing the effects of ALAN on organisms,light quality and co-occurring biotic factors should be considered,as predator pressure is common in natural environments.展开更多
Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.n...Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.展开更多
Anthropogenic noise can affect a number of behavioral,physiological,and ecological aspects of animals from major taxonomic groups,raising serious conservation concerns.For example,noise pollution impacts communicative...Anthropogenic noise can affect a number of behavioral,physiological,and ecological aspects of animals from major taxonomic groups,raising serious conservation concerns.For example,noise pollution impacts communicative behavior and perception of signals,movements and distribution,as well as predator–prey interactions,such as hunting success or predator detection and predation risk assessment.We have carried out an experimental playback study,in which we investigated whether exposure to anthropogenic noise(sound of a tractor)distracts free-ranging barn swallows Hirundo rustica from paying attention to an approaching human“predator”(the“cognitive distraction”hypothesis),or whether noise leads to increased responsiveness to this“predator”(the“increased threat”hypothesis).The subjects were male barn swallows attending their breeding territories during the time when the females were incubating.We found that barn swallow males initiated fight at signifcantly greater distances to the approaching human“predator”in the noise treatment than during the quiet control trials.These results suggest that anthropogenic noise causes increased vigilance and reactivity rather than a distraction,enabling birds to avoid the“predator”more quickly.We further discuss the mechanism behind the increased alertness in response to noise and contrast the“increased threat”mechanism,usually tested in previous studies,with an alternative“cognitive sensitization”mechanism.展开更多
As ecosystem degradation becomes more widespread, there is a growing need for efficient and effective forest restoration methods. Direct seeding is one such method that can be used to cover a relatively large area, pa...As ecosystem degradation becomes more widespread, there is a growing need for efficient and effective forest restoration methods. Direct seeding is one such method that can be used to cover a relatively large area, particularly places with difficult-to-access terrain. One major obstacle hampering successful restoration via direct seeding is seed predation, as seeds are damaged or eaten. We tested the effectiveness of encrusting six species of native seeds with biochar-based coating in reducing the seeds’ chances of being predated on degraded hillsides and landslide scars in Hong Kong. The six seeded species are native trees and shrubs, including both late-successional and pioneer species that are present in forests and shrublands. Our results show that biochar-based seed coats were able to significantly reduce overall seed predation by 5.77% (SE = 1.41, p < 0.05). Additionally, we found varied effectiveness of the biochar-based seed coats across species and seed morphology. Of the six species that were included, four of them had significantly reduced seed predation after encrusting with biochar-based seed coats, while two other species were not significantly affected by the biochar-based seed coats. When we investigated seed predation against seed morphology, we found that while the species with larger seeds were more likely to be predated when sown without any biochar-based seed coat, the effectiveness of the biochar-based seed coat to reduce predation also increased with larger seeds. Our results suggest that encrusting seeds with biochar-based seed coats is an effective means of reducing seed predation.展开更多
[Objective] This study was conducted to explore the predation of Pardosa pseudoannulata and Pirata procurva_ on Plutela xylostela larvae. [Method] The quantities of P. xylostela larvae predated by the two spider speci...[Objective] This study was conducted to explore the predation of Pardosa pseudoannulata and Pirata procurva_ on Plutela xylostela larvae. [Method] The quantities of P. xylostela larvae predated by the two spider species at different temperatures and the quantities of P. xylostela larvae predated by P. pseudoannula-ta_in different volumes were analyzed. Based on three factors at five levels, the quadratic general regression rotation combination design was used to study the combined control effect of the two spider species on P. xylostela_larvae and the control effect of P. pseudoannulata on the larvae of P. xylostela and Spodoptera litura. [Result] The quantities of P. xylostela_ larvae predated by the two spider species increased first and then decreased with the increase of temperature, and the functional predation response of P. pseudoannulata and P. procurva_ on the fourth instar larvae of P. xylostela_fitted the Hol ing-Ⅱ model, and the Hol ing-Ⅲmodel could perfect the evaluation on the predation effect. Volume had great effect on the feeding of P. pseudoannulata. lnstantaneous attack ability （a’）, the time to handle one prey （Th） and predation function （a’/Th） in a smal er volume were al higher than that in a larger volume. The predation of the two spider species on P. xylostela_larvae was positively correlated with their densities. The overal effect of the three factors was： the density of P. xylostela＆gt;the density of P. procurva＆gt;the density of P. pseudoannulata. The densities of P. xylostela and S. litura larvae could affect the feeding amount of P. pseudoannulata. But there was no predation preference for P. pseudoannulata on the larvae of P. xylostela and S. litura. [Con-clusion] The results wil provide a reference for the evaluation of control effect of_P. xylostela_by P. pseudoannulata_and P. procurva in the field.展开更多
This paper proposes a new stochastic optimizer called the Colony Predation Algorithm(CPA)based on the corporate predation of animals in nature.CPA utilizes a mathematical mapping following the strategies used by anima...This paper proposes a new stochastic optimizer called the Colony Predation Algorithm(CPA)based on the corporate predation of animals in nature.CPA utilizes a mathematical mapping following the strategies used by animal hunting groups,such as dispersing prey,encircling prey,supporting the most likely successful hunter,and seeking another target.Moreover,the proposed CPA introduces new features of a unique mathematical model that uses a success rate to adjust the strategy and simulate hunting animals'selective abandonment behavior.This paper also presents a new way to deal with cross-border situations,whereby the optimal position value of a cross-border situation replaces the cross-border value to improve the algorithm's exploitation ability.The proposed CPA was compared with state-of-the-art metaheuristics on a comprehensive set of benchmark functions for performance verification and on five classical engineering design problems to evaluate the algorithm's efficacy in optimizing engineering problems.The results show that the proposed algorithm exhibits competitive,superior performance in different search landscapes over the other algorithms.Moreover,the source code of the CPA will be publicly available after publication.展开更多
The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has pro- vided invaluable insight...The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has pro- vided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask： 1） Is there evidence for a gradient in predation risk？ 2） Does the ranking of sites （by risk） change with the defi- nition of the predator community （in terms of species composition and abundance currency）, and 3） Are site rankings consistent over time？ We find compelling evidence that sites lie along a contin- uum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study sug- gests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.展开更多
Since its 2018 invasion of eastern Asia,the fall armyworm Spodoptera frugiperda(Lepidoptera:Noctuidae)has become a key pest in local maize production.Though pesticides have been widely used to mitigate the initial S.f...Since its 2018 invasion of eastern Asia,the fall armyworm Spodoptera frugiperda(Lepidoptera:Noctuidae)has become a key pest in local maize production.Though pesticides have been widely used to mitigate the initial S.frugiperda attack,biological control is receiving ample attention as a desirable,environmentally-sound alternative to chemical control.Hoverflies(Diptera:Syrphidae)are abundant natural enemies in Chinese maize fields and have been observed to consume S.frugiperda larvae.In this study,we use laboratory assays to study the two-way interaction between immature stages of S.frugiperda and the endemic syrphid Eupeodes corollae.To mimic natural conditions,assays were performed in the presence of fresh maize leaves.Those 2 nd or 3 rd instar larvae of E.corollae preyed on 1 st and 2 nd instar S.frugiperda larvae with a Holling type III response,consuming a respective theoretical maximum of 43.48 and 83.33 larvae over a 24-h period.Conversely,once S.frugiperda larvae reached 3 rd instar,they exhibited aggressive behavior and equally preyed on syrphid larvae with a Holling type III response.Those 5 th and 6 th instar larvae of S.frugiperda consumed a respective 16.39-19.23,6.02-19.61 and 6.76-8.26 of 1 st,2 nd and 3 rd instar E.corollae larvae per day.Though our results await field-level validation,S.frugiperda agonistic(i.e.,defensive)and consumptive behavior towards resident natural enemies such as E.corollae possibly degrades biotic resistance and raises its invasion potential.Our findings shine new light on the interaction between lepidopteran herbivores and their natural enemies,and can help advance the development of conservation biological control and other integrated pest management(IPM)strategies against S.frugiperda in China and abroad.展开更多
Alien species are one of the most serious threats to the decline and extinction of native amphibian populations. In this study, we examined the predation of invasive Western Mosquitofish Gambusia affinis on the eggs, ...Alien species are one of the most serious threats to the decline and extinction of native amphibian populations. In this study, we examined the predation of invasive Western Mosquitofish Gambusia affinis on the eggs, embryos, and tadpoles of Duttaphrynus melanostictus and Pelophylax nigromaculatus in south China. Our results suggested that the survival of eggs and embryos remaining in the egg capsules of P. nigromaculatus and D. melanostictus was significantly higher than those removed from the egg capsule at 12-h intervals within 72 h in the presence of G. affinis. The survival of P. nigromaculatus eggs and embryos without egg capsules was significantly lower than those of D. melanostictus without egg capsules. The survival of P. nigromaculatus eggs and embryos with egg capsules was significantly higher than those of D. melanostictus with egg capsules from 24 h to 72 h except for 12 h. The survival of D. melanostictus tadpoles was significantly higher than that of P. nigromaculatus tadpoles in the presence of G. affinis. The survival of Gosner stage 26 tadpoles of P. nigromaculatus was significantly higher than that of Gosner stage 30 tadpoles from 12 h to 60 h, but there were no significant differences at 72 h. In contrast, the survival of Gosner stage 26 tadpoles of D. melanostictus was significantly lower than that of Gosner stage 30 tadpoles within 72 h, recording every 12 h. The increasing temperature caused a significant increase in predation by G. affinis on P. nigromaculatus eggs and embryos. The outer jelly capsule surrounding anurans eggs might serve as a mechanical defense against predation by G. affinis due to its large diameter, relatively stationary state and unpalatability. The differences in the vulnerability of P. nigromaculatus and D. melanostictus embryos and tadpoles to G. affinis probably due to differences in the unpalatability, black skin and activity. Based on the magnitude of predation by G. affinis on the eggs, embryos and tadpoles of these two species and the combined impact of temperature, we might speculate that invasive G. affinis and global warming would have more detrimental impacts on population viability of P. nigromaculatus than D. melanostictus in China.展开更多
There are many situations in which the ability of animals to distinguish between two similar looking objects can have significant selective consequences. For example, the objects that require discrimination may be edi...There are many situations in which the ability of animals to distinguish between two similar looking objects can have significant selective consequences. For example, the objects that require discrimination may be edible versus defended prey, predators versus non-predators, or mates of varying quality. Working from the premise that there are situations in which discrimi- nation may be more or less successful, we hypothesized that individuals find it more difficult to distinguish between stimuli when they encounter them sequentially rather than simultaneously. Our study has wide biological and psychological implications from the perspective of signal perception, signal evolution, and discrimination, and could apply to any system where individuals are making relative judgments or choices between two or more stimuli or signals. While this is a general principle that might seem intuitive, it has not been experimentally tested in this context, and is often not considered in the design of models or experiments, or in the interpretation of a wide range of studies. Our study is different from previous studies in psychology in that a） the level of similarity of stimuli are gradually varied to obtain selection gradients, and b） we discuss the implications of our study for specific areas in ecology, such as the level of perfection of mimicry in predator-prey systems. Our experiments provide evidence that it is indeed more difficult to distinguish between stimuli - and to learn to distinguish between stimuli - when they are encountered sequentially rather than simultaneously, even if the intervening time interval is short .展开更多
Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been f...Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been fruitful. An ecological genetics approach compares populations that experi ence different environments and asks whether population differences are adaptive and are the result of genetic and/or environmental variation. The multifaceted effects of signaling environ ments are wellexemplified by the bluefin killifish. In this system, males with blue anal fins are abundant in tanninstained swamps that lack UV/blue light but are absent in clear springs where UV/blue light is abundant. Past work indicates that lighting environments shape genetic and envir onmental variation in color patterns, visual systems, and behavior. Less is known about the select ive forces creating the across population correlations between UV/blue light and the abundance of blue males. Here, we present three new experiments that investigate the roles of lighting environ ments on male competition, female mate choice, and predation. We found strong effects of lighting environments on male competition where blue males were more likely to emerge as dominant in teastained water than in clear water. Our preliminary study on predation indicated that blue males may be less susceptible to predation in teastained water than in clear water. However, there was little evidence for female preferences favoring blue males. The resulting pattern is one where the effects of lighting environments on genetic variation and phenotypic plasticity match the direction of selection and favor the expression of blue males in swamps.展开更多
Bird photography is a popular and growing form of ecotourism that contributes to the economic growth of local communities,but its disturbance to bird reproduction remains understudied.We worked in a tropical forest of...Bird photography is a popular and growing form of ecotourism that contributes to the economic growth of local communities,but its disturbance to bird reproduction remains understudied.We worked in a tropical forest of southern China,which has experienced a sharp increase in the number of photographers in recent years.We compared nests that were photographed and those that were not,in their nest predation and parental feeding rates.Including nests of 42 species,the results demonstrate that the predation rate of nests that were not photographed(incubation stage:43.3%of 194 nests;nestling stage:34.5%of 110 nests)was significantly higher than that of photographed ones(incubation:2.4%of 83 nests;nestling:11.1%of 81 nests).Among different nest types,open cup nests in shrub and trees were most affected by photography,in both incubation and nestling stages.Of five factors investigated,including three natural factors(nest stage,structure and position),and two anthropogenic factors(photography and distance to forest edge),only photographic disturbance and nest structure had significant effects(open nests had higher predation).The feeding frequency at nests when photographers were present was not strongly different from when they were not present.Human activity therefore had no negative effects on the birds,but showed a positive effect on their nesting success,in terms of reducing nest predation rates.However,there needs to be further assessment of other aspects of nesting(e.g.,clutch size,duration of nestlings in nests),and other kinds of stress responses(e.g.,hormonal changes),before the total effect of bird photography can be understood.展开更多
Predation is thought to be one of the main structuring forces in animal communities. However, se- lective predation is often measured on isolated traits in response to a single predatory species, but only rarely are s...Predation is thought to be one of the main structuring forces in animal communities. However, se- lective predation is often measured on isolated traits in response to a single predatory species, but only rarely are selective forces on several traits quantified or even compared between different predators naturally occurring in the same system. In the present study, we therefore measured be- havioral and morphological traits in young-of-the-year Eurasian perch Perca fluviatilis and com- pared their selective values in response to the 2 most common predators, adult perch and pike Esox lucius. Using mixed effects models and model averaging to analyze our data, we quantified and compared the selectivity of the 2 predators on the different morphological and behavioral traits. We found that selection on the behavioral traits was higher than on morphological traits and perch predators preyed overall more selectively than pike predators. Pike tended to positively se- lect shallow bodied and nonvigilant individuals （i.e. individuals not performing predator inspec- tion）. In contrast, perch predators selected mainly for bolder juvenile perch （i.e. individuals spend- ing more time in the open, more active）, which was most important. Our results are to the best of our knowledge the first that analyzed behavioral and morphological adaptations of juvenile perch facing 2 different predation strategies. We found that relative specific predation intensity for the di- vergent traits differed between the predators, providing some additional ideas why juvenile perch display such a high degree of phenotypic plasticity.展开更多
Invasive rats （Rattus spp.） are known to have pervasive impacts on island birds, particularly on their nesting success. To conserve or restore bird populations, numerous invasive rat control or eradication projects ...Invasive rats （Rattus spp.） are known to have pervasive impacts on island birds, particularly on their nesting success. To conserve or restore bird populations, numerous invasive rat control or eradication projects are undertaken on islands worldwide. However, such projects represent a huge investment and the decision-making process requires proper assessment of rat impacts. Here, we assessed the influence of two sympatric invasive rats （Rattus rattus and R. exulans） on native bird eggs in a New Caledonian rainforest, using artificial bird-nest monitoring. A total of 178 artificial nests containing two eggs of three different sizes were placed either on the ground or 1.5 m high and monitored at the start of the birds＇ breeding season. Overall, 12.4% of the nests were depredated during the first 7 days. At site 1, where nests were monitored during 16 days, 41.8% of the nests were depredated. The main predator was the native crow Corvus moneduloides, responsible for 62.9% of the overall predation events. Rats were responsible for only 22.9% of the events, and ate only small and medium eggs at both heights. Our experiment suggests that in New Caledonia, predation pressure by rats strengthens overall bird-nest predation, adding to that by native predators, Experimental rat control operations may allow reduced predation pressure on nests as well as the recording of biodiversity responses after rat population reduction.展开更多
The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence t...The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t 1/2)for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cross sectional area of A.coerulea(size from 0.3 to 7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t 1/2 for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.展开更多
Nest predation is an essential factor affecting bird population density,reproductive ecology and life cycle.However,there are still contradictory results about how nest predation pressure changes with urbanization.One...Nest predation is an essential factor affecting bird population density,reproductive ecology and life cycle.However,there are still contradictory results about how nest predation pressure changes with urbanization.One of the reasons for the controversy is that previous studies often use artificial nests to investigate nest predation,but the result of artificial nests is often biased and contrary to that of natural nests.Therefore,it is important to perform nest predation experiments simultaneously with both natural and artificial nests.In this study,we examined the change of nest predation pressure on the Chinese Bulbul(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 148 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.After the breeding season,we placed artificial eggs in natural nests of Chinese Bulbuls to investigate the changes in nest predation pressure and used infrared cameras to record the predators.We then calculated the urbanization synthetic index(USI)as the measure of the degree of urbanization and examined its relationship with nest predation pressure.We found that no matter whether natural nests or artificial eggs were used,the nest predation pressure always decreased significantly with the degree of urbanization.The average height of shrubs within 10 m of the nest differed significantly between the predated and unpredated nests,which also affected the risk of nest predation.Our study highlights the importance of using natural and artificial nests simultaneously to conduct nest predation experiments,which can reduce the bias or errors caused by only using artificial nests.We also recommend the use of infrared cameras in future nest predation studies,which has obvious advantages in monitoring and identifying potential predators.展开更多
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
Background:Research activities have often been thought to potentially influence avian nesting success by increasing nest predation rates.Although recent studies of species building open nests and cavity nests suggest ...Background:Research activities have often been thought to potentially influence avian nesting success by increasing nest predation rates.Although recent studies of species building open nests and cavity nests suggest that research disturbance does not generally induce nest predation,whether it is also the case in species building domednests remains unknown.In birds,domed-nest species exist in about half of the passerine families,and research disturbance to the domed nests may differ from that to the nests of other types for their different nest structures.Methods:We investigated if research activities affected nest predation rate by analyzing the relationships of the daily nest survival rate with the research activities at the egg and nestling stages of a domed-nest species,the Silverthroated Tit(Aegithalos glaucogularis).Results:Our results showed that nest daily survival rate was significantly affected by the laying date and nest age during the egg stage,and by the hatching date only during the nestling stage.By contrast,there were no significant effects of research activities,in terms of visiting nests and filming nests,on the nest survival of the Silver-throated Tit at both the egg and nestling stages.Conclusions:Our results coincide with the findings in species building other types of nests that research activities do not always have negative effects on avian nesting success.展开更多
文摘Urban green spaces and parks offer opportunities for retaining and increasing bird richness, diversity, and species abundance. However, urbanisation influences predator–prey interactions, leading to high predation rates in urban areas, in the UK notably through the presence of large populations of domestic cats and increased populations of synanthropic species, such as rats and squirrels. These high predation rates are assumed to be a significant cause of reproductive failure in birds. Some ecologists advocate for the use of buffer zones with reduced human influence to reduce potential hunting pressure in eco-sensitive areas. However, the buffer effect on predation rates of nesting birds in suburban areas is rarely investigated. In this study, we investigated how edge effects (how close nest sites are to housing) and nest height (i.e., ground vs. above-ground) affected nest predation rates in a suburban park using camera traps to monitor artificial nests containing quail eggs. Our hypothesis was that nests in the buffer area (<300 m inward from university boundary) and at low height would suffer higher predation rates than nests in the core area (>300 m from the university boundary) and at height, as the buffer zone effect, and ease of access to ground predators would result in higher predation rates. We found no significant effect of nest height in nest predation rates. However, contrary to our expectations, nests in the core zone suffered higher predation rates than those in the buffer zone, and corvids were responsible for almost half of the egg loss events. We speculate that this may be a consequence of higher levels of anthropogenic disturbance (e.g., pedestrians, dog walking, vehicles) adjacent to our buffer zone acting as a deterrent to avian nest predators. This work suggests that protecting urban sites from disturbance may not always act to support bird abundance.
文摘Artifcial light at night(ALAN)is a common anthropogenic disturbance,which alters animal behavior.However,little is known about the impact of the spectral composition of ALAN and co-occurring predation risk on the behavior of aquatic organisms.We experimentally investigated how ALAN of different spectra(cool white LED and HPS light)affects the behavior and foraging of Gammarus jazdzewskii(Amphipoda)on chironomid prey,both as a single stressor and in combination with an olfactory predation cue.Gammarids exposed to ALAN in the absence of predation cues consumed less,compared with darkness,mainly due to their lower activity.Moreover,gammarids showed a stronger response to LED light,spending more time in the shelter and increasing prey handling time in this treatment.The addition of predation cues did not enhance the negative impact of ALAN on the foraging success.Gammarids maintained similar consumption levels as in the ALAN treatment without predation cues and in darkness with predation cues.However,gammarids in LED light altered their behavior in response to predation threat:they decreased prey handling time and consumed prey faster,which may have compensated for the higher food demand in stressful conditions.They also tended to exhibit risky behavior,leaving the shelter and moving towards the lit area,presumably to escape and avoid the combined effects of light and predation cues.Therefore,when assessing the effects of ALAN on organisms,light quality and co-occurring biotic factors should be considered,as predator pressure is common in natural environments.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060203)the National Natural Science Foundation of China(Nos.42076166,42130411)+4 种基金the Natural Science Foundation of Shandong Province(No.ZR2021QD061)the CAS-CSIRO Project Fund(No.GJHZ1888)the Mount Tai Scholar Climbing Plan to Song SUNthe Innovation Team of Fishery Resources and Ecology in the Yellow Sea and Bohai Sea(No.2020TD01)the Hainan Province Basic and Applied Basic Research Program(Natural Science Field)High-Level Talent Project(No.2019RC353)。
文摘Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.
基金This study was supported by the Cardinal Stefan Wyszyhski University in Warsaw(grant to P.M.).
文摘Anthropogenic noise can affect a number of behavioral,physiological,and ecological aspects of animals from major taxonomic groups,raising serious conservation concerns.For example,noise pollution impacts communicative behavior and perception of signals,movements and distribution,as well as predator–prey interactions,such as hunting success or predator detection and predation risk assessment.We have carried out an experimental playback study,in which we investigated whether exposure to anthropogenic noise(sound of a tractor)distracts free-ranging barn swallows Hirundo rustica from paying attention to an approaching human“predator”(the“cognitive distraction”hypothesis),or whether noise leads to increased responsiveness to this“predator”(the“increased threat”hypothesis).The subjects were male barn swallows attending their breeding territories during the time when the females were incubating.We found that barn swallow males initiated fight at signifcantly greater distances to the approaching human“predator”in the noise treatment than during the quiet control trials.These results suggest that anthropogenic noise causes increased vigilance and reactivity rather than a distraction,enabling birds to avoid the“predator”more quickly.We further discuss the mechanism behind the increased alertness in response to noise and contrast the“increased threat”mechanism,usually tested in previous studies,with an alternative“cognitive sensitization”mechanism.
文摘As ecosystem degradation becomes more widespread, there is a growing need for efficient and effective forest restoration methods. Direct seeding is one such method that can be used to cover a relatively large area, particularly places with difficult-to-access terrain. One major obstacle hampering successful restoration via direct seeding is seed predation, as seeds are damaged or eaten. We tested the effectiveness of encrusting six species of native seeds with biochar-based coating in reducing the seeds’ chances of being predated on degraded hillsides and landslide scars in Hong Kong. The six seeded species are native trees and shrubs, including both late-successional and pioneer species that are present in forests and shrublands. Our results show that biochar-based seed coats were able to significantly reduce overall seed predation by 5.77% (SE = 1.41, p < 0.05). Additionally, we found varied effectiveness of the biochar-based seed coats across species and seed morphology. Of the six species that were included, four of them had significantly reduced seed predation after encrusting with biochar-based seed coats, while two other species were not significantly affected by the biochar-based seed coats. When we investigated seed predation against seed morphology, we found that while the species with larger seeds were more likely to be predated when sown without any biochar-based seed coat, the effectiveness of the biochar-based seed coat to reduce predation also increased with larger seeds. Our results suggest that encrusting seeds with biochar-based seed coats is an effective means of reducing seed predation.
基金Supported by the Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(ASTIP-IBFC09)Technical System of Vegetable Industry of Hunan Province+1 种基金National Natural Science Foundation of China(31501653)Earmarked fund for Modern Agro-industry Technology Research System of China(CARS-19-E09)~~
文摘[Objective] This study was conducted to explore the predation of Pardosa pseudoannulata and Pirata procurva_ on Plutela xylostela larvae. [Method] The quantities of P. xylostela larvae predated by the two spider species at different temperatures and the quantities of P. xylostela larvae predated by P. pseudoannula-ta_in different volumes were analyzed. Based on three factors at five levels, the quadratic general regression rotation combination design was used to study the combined control effect of the two spider species on P. xylostela_larvae and the control effect of P. pseudoannulata on the larvae of P. xylostela and Spodoptera litura. [Result] The quantities of P. xylostela_ larvae predated by the two spider species increased first and then decreased with the increase of temperature, and the functional predation response of P. pseudoannulata and P. procurva_ on the fourth instar larvae of P. xylostela_fitted the Hol ing-Ⅱ model, and the Hol ing-Ⅲmodel could perfect the evaluation on the predation effect. Volume had great effect on the feeding of P. pseudoannulata. lnstantaneous attack ability （a’）, the time to handle one prey （Th） and predation function （a’/Th） in a smal er volume were al higher than that in a larger volume. The predation of the two spider species on P. xylostela_larvae was positively correlated with their densities. The overal effect of the three factors was： the density of P. xylostela＆gt;the density of P. procurva＆gt;the density of P. pseudoannulata. The densities of P. xylostela and S. litura larvae could affect the feeding amount of P. pseudoannulata. But there was no predation preference for P. pseudoannulata on the larvae of P. xylostela and S. litura. [Con-clusion] The results wil provide a reference for the evaluation of control effect of_P. xylostela_by P. pseudoannulata_and P. procurva in the field.
基金This research was supported by the National Natural Science Foundation of China(62076185,U1809209).
文摘This paper proposes a new stochastic optimizer called the Colony Predation Algorithm(CPA)based on the corporate predation of animals in nature.CPA utilizes a mathematical mapping following the strategies used by animal hunting groups,such as dispersing prey,encircling prey,supporting the most likely successful hunter,and seeking another target.Moreover,the proposed CPA introduces new features of a unique mathematical model that uses a success rate to adjust the strategy and simulate hunting animals'selective abandonment behavior.This paper also presents a new way to deal with cross-border situations,whereby the optimal position value of a cross-border situation replaces the cross-border value to improve the algorithm's exploitation ability.The proposed CPA was compared with state-of-the-art metaheuristics on a comprehensive set of benchmark functions for performance verification and on five classical engineering design problems to evaluate the algorithm's efficacy in optimizing engineering problems.The results show that the proposed algorithm exhibits competitive,superior performance in different search landscapes over the other algorithms.Moreover,the source code of the CPA will be publicly available after publication.
文摘The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has pro- vided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask： 1） Is there evidence for a gradient in predation risk？ 2） Does the ranking of sites （by risk） change with the defi- nition of the predator community （in terms of species composition and abundance currency）, and 3） Are site rankings consistent over time？ We find compelling evidence that sites lie along a contin- uum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study sug- gests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.
基金supported by the earmarked fund for China Agriculture Research System(CARS-15-19)。
文摘Since its 2018 invasion of eastern Asia,the fall armyworm Spodoptera frugiperda(Lepidoptera:Noctuidae)has become a key pest in local maize production.Though pesticides have been widely used to mitigate the initial S.frugiperda attack,biological control is receiving ample attention as a desirable,environmentally-sound alternative to chemical control.Hoverflies(Diptera:Syrphidae)are abundant natural enemies in Chinese maize fields and have been observed to consume S.frugiperda larvae.In this study,we use laboratory assays to study the two-way interaction between immature stages of S.frugiperda and the endemic syrphid Eupeodes corollae.To mimic natural conditions,assays were performed in the presence of fresh maize leaves.Those 2 nd or 3 rd instar larvae of E.corollae preyed on 1 st and 2 nd instar S.frugiperda larvae with a Holling type III response,consuming a respective theoretical maximum of 43.48 and 83.33 larvae over a 24-h period.Conversely,once S.frugiperda larvae reached 3 rd instar,they exhibited aggressive behavior and equally preyed on syrphid larvae with a Holling type III response.Those 5 th and 6 th instar larvae of S.frugiperda consumed a respective 16.39-19.23,6.02-19.61 and 6.76-8.26 of 1 st,2 nd and 3 rd instar E.corollae larvae per day.Though our results await field-level validation,S.frugiperda agonistic(i.e.,defensive)and consumptive behavior towards resident natural enemies such as E.corollae possibly degrades biotic resistance and raises its invasion potential.Our findings shine new light on the interaction between lepidopteran herbivores and their natural enemies,and can help advance the development of conservation biological control and other integrated pest management(IPM)strategies against S.frugiperda in China and abroad.
基金funded by grants from the National Natural Science Foundation of China(31270443,31500329)the Science Foundation of Zhejiang Provincial Committee of Education(Y201534237)the Scientific Research Foundation of Ph.D.,Lishui University(QD1423)
文摘Alien species are one of the most serious threats to the decline and extinction of native amphibian populations. In this study, we examined the predation of invasive Western Mosquitofish Gambusia affinis on the eggs, embryos, and tadpoles of Duttaphrynus melanostictus and Pelophylax nigromaculatus in south China. Our results suggested that the survival of eggs and embryos remaining in the egg capsules of P. nigromaculatus and D. melanostictus was significantly higher than those removed from the egg capsule at 12-h intervals within 72 h in the presence of G. affinis. The survival of P. nigromaculatus eggs and embryos without egg capsules was significantly lower than those of D. melanostictus without egg capsules. The survival of P. nigromaculatus eggs and embryos with egg capsules was significantly higher than those of D. melanostictus with egg capsules from 24 h to 72 h except for 12 h. The survival of D. melanostictus tadpoles was significantly higher than that of P. nigromaculatus tadpoles in the presence of G. affinis. The survival of Gosner stage 26 tadpoles of P. nigromaculatus was significantly higher than that of Gosner stage 30 tadpoles from 12 h to 60 h, but there were no significant differences at 72 h. In contrast, the survival of Gosner stage 26 tadpoles of D. melanostictus was significantly lower than that of Gosner stage 30 tadpoles within 72 h, recording every 12 h. The increasing temperature caused a significant increase in predation by G. affinis on P. nigromaculatus eggs and embryos. The outer jelly capsule surrounding anurans eggs might serve as a mechanical defense against predation by G. affinis due to its large diameter, relatively stationary state and unpalatability. The differences in the vulnerability of P. nigromaculatus and D. melanostictus embryos and tadpoles to G. affinis probably due to differences in the unpalatability, black skin and activity. Based on the magnitude of predation by G. affinis on the eggs, embryos and tadpoles of these two species and the combined impact of temperature, we might speculate that invasive G. affinis and global warming would have more detrimental impacts on population viability of P. nigromaculatus than D. melanostictus in China.
文摘There are many situations in which the ability of animals to distinguish between two similar looking objects can have significant selective consequences. For example, the objects that require discrimination may be edible versus defended prey, predators versus non-predators, or mates of varying quality. Working from the premise that there are situations in which discrimi- nation may be more or less successful, we hypothesized that individuals find it more difficult to distinguish between stimuli when they encounter them sequentially rather than simultaneously. Our study has wide biological and psychological implications from the perspective of signal perception, signal evolution, and discrimination, and could apply to any system where individuals are making relative judgments or choices between two or more stimuli or signals. While this is a general principle that might seem intuitive, it has not been experimentally tested in this context, and is often not considered in the design of models or experiments, or in the interpretation of a wide range of studies. Our study is different from previous studies in psychology in that a） the level of similarity of stimuli are gradually varied to obtain selection gradients, and b） we discuss the implications of our study for specific areas in ecology, such as the level of perfection of mimicry in predator-prey systems. Our experiments provide evidence that it is indeed more difficult to distinguish between stimuli - and to learn to distinguish between stimuli - when they are encountered sequentially rather than simultaneously, even if the intervening time interval is short .
文摘Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been fruitful. An ecological genetics approach compares populations that experi ence different environments and asks whether population differences are adaptive and are the result of genetic and/or environmental variation. The multifaceted effects of signaling environ ments are wellexemplified by the bluefin killifish. In this system, males with blue anal fins are abundant in tanninstained swamps that lack UV/blue light but are absent in clear springs where UV/blue light is abundant. Past work indicates that lighting environments shape genetic and envir onmental variation in color patterns, visual systems, and behavior. Less is known about the select ive forces creating the across population correlations between UV/blue light and the abundance of blue males. Here, we present three new experiments that investigate the roles of lighting environ ments on male competition, female mate choice, and predation. We found strong effects of lighting environments on male competition where blue males were more likely to emerge as dominant in teastained water than in clear water. Our preliminary study on predation indicated that blue males may be less susceptible to predation in teastained water than in clear water. However, there was little evidence for female preferences favoring blue males. The resulting pattern is one where the effects of lighting environments on genetic variation and phenotypic plasticity match the direction of selection and favor the expression of blue males in swamps.
基金supported by the National Natural Science Foundation of China(Grant No.31870370)the Graduate Education Innovation Program of Guangxi(No.YCSW2020023)。
文摘Bird photography is a popular and growing form of ecotourism that contributes to the economic growth of local communities,but its disturbance to bird reproduction remains understudied.We worked in a tropical forest of southern China,which has experienced a sharp increase in the number of photographers in recent years.We compared nests that were photographed and those that were not,in their nest predation and parental feeding rates.Including nests of 42 species,the results demonstrate that the predation rate of nests that were not photographed(incubation stage:43.3%of 194 nests;nestling stage:34.5%of 110 nests)was significantly higher than that of photographed ones(incubation:2.4%of 83 nests;nestling:11.1%of 81 nests).Among different nest types,open cup nests in shrub and trees were most affected by photography,in both incubation and nestling stages.Of five factors investigated,including three natural factors(nest stage,structure and position),and two anthropogenic factors(photography and distance to forest edge),only photographic disturbance and nest structure had significant effects(open nests had higher predation).The feeding frequency at nests when photographers were present was not strongly different from when they were not present.Human activity therefore had no negative effects on the birds,but showed a positive effect on their nesting success,in terms of reducing nest predation rates.However,there needs to be further assessment of other aspects of nesting(e.g.,clutch size,duration of nestlings in nests),and other kinds of stress responses(e.g.,hormonal changes),before the total effect of bird photography can be understood.
文摘Predation is thought to be one of the main structuring forces in animal communities. However, se- lective predation is often measured on isolated traits in response to a single predatory species, but only rarely are selective forces on several traits quantified or even compared between different predators naturally occurring in the same system. In the present study, we therefore measured be- havioral and morphological traits in young-of-the-year Eurasian perch Perca fluviatilis and com- pared their selective values in response to the 2 most common predators, adult perch and pike Esox lucius. Using mixed effects models and model averaging to analyze our data, we quantified and compared the selectivity of the 2 predators on the different morphological and behavioral traits. We found that selection on the behavioral traits was higher than on morphological traits and perch predators preyed overall more selectively than pike predators. Pike tended to positively se- lect shallow bodied and nonvigilant individuals （i.e. individuals not performing predator inspec- tion）. In contrast, perch predators selected mainly for bolder juvenile perch （i.e. individuals spend- ing more time in the open, more active）, which was most important. Our results are to the best of our knowledge the first that analyzed behavioral and morphological adaptations of juvenile perch facing 2 different predation strategies. We found that relative specific predation intensity for the di- vergent traits differed between the predators, providing some additional ideas why juvenile perch display such a high degree of phenotypic plasticity.
文摘Invasive rats （Rattus spp.） are known to have pervasive impacts on island birds, particularly on their nesting success. To conserve or restore bird populations, numerous invasive rat control or eradication projects are undertaken on islands worldwide. However, such projects represent a huge investment and the decision-making process requires proper assessment of rat impacts. Here, we assessed the influence of two sympatric invasive rats （Rattus rattus and R. exulans） on native bird eggs in a New Caledonian rainforest, using artificial bird-nest monitoring. A total of 178 artificial nests containing two eggs of three different sizes were placed either on the ground or 1.5 m high and monitored at the start of the birds＇ breeding season. Overall, 12.4% of the nests were depredated during the first 7 days. At site 1, where nests were monitored during 16 days, 41.8% of the nests were depredated. The main predator was the native crow Corvus moneduloides, responsible for 62.9% of the overall predation events. Rats were responsible for only 22.9% of the events, and ate only small and medium eggs at both heights. Our experiment suggests that in New Caledonia, predation pressure by rats strengthens overall bird-nest predation, adding to that by native predators, Experimental rat control operations may allow reduced predation pressure on nests as well as the recording of biodiversity responses after rat population reduction.
基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0504-3)the National Key Research and Development Program of China(No.2017YFC1404405)Mount Tai Scholar Climbing Plan to SUN Song。
文摘The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t 1/2)for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cross sectional area of A.coerulea(size from 0.3 to 7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t 1/2 for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.
基金supported by the National Natural Science Foundation of China(Grant No.31971545,31071908)。
文摘Nest predation is an essential factor affecting bird population density,reproductive ecology and life cycle.However,there are still contradictory results about how nest predation pressure changes with urbanization.One of the reasons for the controversy is that previous studies often use artificial nests to investigate nest predation,but the result of artificial nests is often biased and contrary to that of natural nests.Therefore,it is important to perform nest predation experiments simultaneously with both natural and artificial nests.In this study,we examined the change of nest predation pressure on the Chinese Bulbul(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 148 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.After the breeding season,we placed artificial eggs in natural nests of Chinese Bulbuls to investigate the changes in nest predation pressure and used infrared cameras to record the predators.We then calculated the urbanization synthetic index(USI)as the measure of the degree of urbanization and examined its relationship with nest predation pressure.We found that no matter whether natural nests or artificial eggs were used,the nest predation pressure always decreased significantly with the degree of urbanization.The average height of shrubs within 10 m of the nest differed significantly between the predated and unpredated nests,which also affected the risk of nest predation.Our study highlights the importance of using natural and artificial nests simultaneously to conduct nest predation experiments,which can reduce the bias or errors caused by only using artificial nests.We also recommend the use of infrared cameras in future nest predation studies,which has obvious advantages in monitoring and identifying potential predators.
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.
基金This study was funded by the National Natural Science Foundation of China(Grant Nos.31970421,31472011,31101644).
文摘Background:Research activities have often been thought to potentially influence avian nesting success by increasing nest predation rates.Although recent studies of species building open nests and cavity nests suggest that research disturbance does not generally induce nest predation,whether it is also the case in species building domednests remains unknown.In birds,domed-nest species exist in about half of the passerine families,and research disturbance to the domed nests may differ from that to the nests of other types for their different nest structures.Methods:We investigated if research activities affected nest predation rate by analyzing the relationships of the daily nest survival rate with the research activities at the egg and nestling stages of a domed-nest species,the Silverthroated Tit(Aegithalos glaucogularis).Results:Our results showed that nest daily survival rate was significantly affected by the laying date and nest age during the egg stage,and by the hatching date only during the nestling stage.By contrast,there were no significant effects of research activities,in terms of visiting nests and filming nests,on the nest survival of the Silver-throated Tit at both the egg and nestling stages.Conclusions:Our results coincide with the findings in species building other types of nests that research activities do not always have negative effects on avian nesting success.
