共查询到20条相似文献,搜索用时 15 毫秒
1.
Dubovskaya Olga P. Gladyshev Michail I. Gubanov Vladimir G. Makhutova Olesia N. 《Hydrobiologia》2003,504(1-3):223-227
We studied non-consumptive (non-predatory) mortality of Daphnia and Cyclops vicinus during four sampling seasons. Mortality estimations were based on live/dead sorting using special staining and measurements of sedimentation rates for dead individuals, depended on wind speed. Original equations were used for calculations. The estimated specific non-consumptive mortality never had biologically senseless negative values, which were often obtained on the basis of the other ways of mortality estimations, and was in a good agreement with other components of population dynamics. As found, the non-consumptive mortality was the important, often the determinant component of the zooplankton population dynamics. 相似文献
2.
Mayfly larvae were abundant and diverse in riffle zones of three control streams in southeastern Ohio. But none were found in such zones of three streams having current or past histories of mine acid pollution, despite vegetative recovery of reclaimed land bordering two of the streams. Laboratory studies showed stepwise increases in non-predatory mortality of mayfly larvae with increased mine acidity. Dragonfly larvae predation on mayfly larvae was constant at pH 8.1–4.1, but decreased at pH 3.1 despite tolerance of dragonfly larvae to low pH conditions. Extensive acid mine pollution thus may threaten aquatic biota through removal of food sources or reduced feeding rates as well as through direct mortality. 相似文献
3.
Kit Magellan 《Journal of fish biology》2020,96(5):1278-1283
This study investigated recognition of, and behavioural responses to, predatory and non-predatory heterospecifics by a small cryptically coloured fish species, Galaxias ‘nebula’. Nebula recognised and differentiated between predatory and non-predatory heterospecifics and altered its behaviour facultatively. With both predatory and non-predatory fishes, the proportion of time spent motionless increased, whereas refugia use was affected only by predators and neither heterospecific affected the time spent active. Although nebula appeared to face no conflict, in that their responses to predatory and non-predatory heterospecifics varied in the same direction and differed only in intensity, the presence of both heterospecifics together induced responses midway between those for each heterospecific separately. Non-predatory heterospecifics thus modified nebula's responses towards predators, potentially making time available for other essential activities such as foraging. This modified predator response may aid its survival in an increasingly threatened habitat. 相似文献
4.
Three hundred forty-three birds representing six orders and 22 species were examined serologically for antibodies against rabies. Low passive hemagglutination titers were observed in 23 samples. Fifteen of 65 (23.1%) predatory birds and 8 of 278 (2.9%) non-predatory birds were positive. Rabies antibody positive sera from non-predatory species were from species commonly thought to be scavengers suggesting the importance of the oral route for the presentation of rabies virus to birds. 相似文献
5.
The relative importance of lethal and non-lethal effects of fish on insect colonisation of ponds 总被引:2,自引:0,他引:2
1. We hypothesised that adult insects actively monitor potential habitats for the presence of fish by means of chemical cues and avoid sites that pose significant risks. This was examined by quantifying colonisation of insects in outdoor pools with no fish (controls), fish (direct predation effect) or caged fish (chemical predator cues).
2. A significant direct effect of predation was found, but no indirect effect (avoidance of chemical cue pools), on the total biomass of colonising insects. However, predatory insects avoided fish-cue pools, thus releasing non-predatory insects from predation. This resulted in significantly greater biomass of non-predatory insects in fish-cue pools than control pools.
3. Fish reduced the number of species of colonising insects in pools through predation. This negative influence of fish implies that caution is necessary when stocking wetlands and ponds with fish if the goal is to maximise biodiversity.
4. Our data suggest that although predatory aquatic insects may use chemical signals to assess the quality of potential habitats with respect to predation risk, direct predation is the main method by which fish affect insect assemblages in ponds. Because fish and invertebrate predators may both have strong effects on prey mortality, behavioural adjustment by insects to the actual predator regime within a habitat should be more important than avoiding colonisation of habitats with fish. 相似文献
2. A significant direct effect of predation was found, but no indirect effect (avoidance of chemical cue pools), on the total biomass of colonising insects. However, predatory insects avoided fish-cue pools, thus releasing non-predatory insects from predation. This resulted in significantly greater biomass of non-predatory insects in fish-cue pools than control pools.
3. Fish reduced the number of species of colonising insects in pools through predation. This negative influence of fish implies that caution is necessary when stocking wetlands and ponds with fish if the goal is to maximise biodiversity.
4. Our data suggest that although predatory aquatic insects may use chemical signals to assess the quality of potential habitats with respect to predation risk, direct predation is the main method by which fish affect insect assemblages in ponds. Because fish and invertebrate predators may both have strong effects on prey mortality, behavioural adjustment by insects to the actual predator regime within a habitat should be more important than avoiding colonisation of habitats with fish. 相似文献
6.
Ocean acidification disrupts the innate ability of fish to detect predator olfactory cues 总被引:3,自引:0,他引:3
While ocean acidification is predicted to threaten marine biodiversity, the processes that directly impact species persistence are not well understood. For marine species, early life history stages are inherently vulnerable to predators and an innate ability to detect predators can be critical for survival. However, whether or not acidification inhibits predator detection is unknown. Here, we show that newly hatched larvae of the marine fish Amphiprion percula innately detect predators using olfactory cues and this ability is retained through to settlement. Aquarium-reared larvae, not previously exposed to predators, were able to distinguish between the olfactory cues of predatory and non-predatory species. However, when eggs and larvae were exposed to seawater simulating ocean acidification (pH 7.8 and 1000 p.p.m. CO2 ) settlement-stage larvae became strongly attracted to the smell of predators and the ability to discriminate between predators and non-predators was lost. Newly hatched larvae were unaffected by CO2 exposure and were still able to distinguish between predatory and non-predatory fish. If this impairment of olfactory preferences in settlement-stage larvae translates to higher mortality as a result of increased predation risk, there could be direct consequences for the replenishment and the sustainability of marine populations.
Ecology Letters (2010) 13: 68–75 相似文献
Ecology Letters (2010) 13: 68–75 相似文献
7.
Responses of a eutrophic pond community to separate and combined effects of N:P supply and planktivorous fish: a mesocosm experiment 总被引:4,自引:3,他引:1
Ray W. Drenner J. Durward Smith John R. Mummert Holli F. Lancaster 《Hydrobiologia》1990,208(3):161-167
We conducted an outdoor mesocosm experiment of factorial design consisting of three levels of nutrient supply (no nutrient addition and additions of nitrogen and phosphorus in ratios of 10:1 and 45:1) cross-classified with two levels of bluegill (Lepomis macrochirus) (presence and absence). Nutrient supply significantly affected total phosphorus (TP), total nitrogen (TN), TN: TP ratio, turbidity, Secchi depth, phytoplankton chlorophyll, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers. The presence of bluegill significantly increased TP, turbidity, diatoms, unicellular green algae, colonial blue-green algae, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers, and decreased Secchi depth, cladocerans, cyclopoid copepodids, copepod nauplii and chironomid tube densities. Nutrient supply and fish effects were not independent of each other as shown by significant nutrient × fish interaction effects for TP, Secchi depth, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers. 相似文献
8.
Brian G. Gall & Alicia Mathis 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(1):47-58
Innate predator recognition typically only occurs when there is an evolutionary history between predator and prey. Predator introductions thus can pose a substantial threat to native fauna that rely heavily on inherent identification of predators. In permanent aquatic habitats prey often encounter a variety of predatory and non-predatory fish species, and the ability to distinguish between the two is essential to avoid wasted time and energy spent in unnecessary antipredatory efforts. Here, we present a study evaluating the ability of lab-reared larvae of an endangered fully aquatic salamander (hellbenders: Cryptobranchus alleganiensis ) to recognize chemical cues from native and introduced fish predators. We recorded responses of hellbender larvae to chemical stimuli from native and non-native predatory fishes, a non-predatory fish and a blank control. Eastern hellbender larvae ( C. a. alleganiensis ) significantly reduced activity in response to chemical stimuli from native predators ( Micropterus salmoides , Micropterus dolomieu , Ambloplites rupestris , Sander vitreus , and Cottus carolinae ), but responses to non-native rainbow ( Oncorhynchus mykiss ) and brown ( Salmo trutta ) trout were not significantly different from responses to the non-predatory control (redhorse sucker, Moxostoma spp.). Responses of larval Ozark hellbenders ( C. a. bishopi ) to brown trout were similar to that of the native fishes and different from the blank control, but responses to rainbow trout did not differ from the blank control. The generally weak responses of larval hellbenders to chemical cues from introduced predatory trout could lead to increased predation in the wild, which may have exacerbated the decline of hellbender populations. 相似文献
9.
Anti-predatory behaviour is widespread among a broad range of animal taxa, including birds. Nest defence is not without risk, however, and parent birds face a trade-off between the survival of their offspring and the risk of injury or mortality to themselves. This study focused on the anti-predator behaviour of the Sabines gull (Xema sabini), a ground-nesting, Arctic breeder. Specifically, we quantified the gulls behavioural response towards natural predators, a human intruder, experimental predator decoys, and a non-predatory decoy. Neither the distance at which nesting Sabines gulls first reacted to natural predators, nor the relative intensity of their response, differed with incubation stage or predator type. However, response behaviour was highly variable among pairs. In response to decoys, Sabines gulls responded strongly towards predatory species, compared with a non-predatory species. The distance at which they first swooped at a human intruder was also variable, and there was no seasonal trend. Sabines gulls were often joined in nest defence by conspecifics, Arctic terns, and shorebirds nesting nearby, although the number of conspecifics involved in attacks was not related to the proximity of neighbouring nests. 相似文献
10.
Kazantseva TI 《Zhurnal obshche? biologii》2003,64(2):128-145
A model of energy budget of Lake Bolshoi Okunenok ecosystem was based on the data received during field studies from May through November 1986. The model takes into account 36 components including dissolved organic matter, bacteria, phytoplankton, zooplankton, meiobenthos, macrobenthos, fish, suspended and sediment detritus. The growing season has been divided into 16 intervals according to the number of observations. The balance equation for each live component describes the change in its biomass for a time interval between two successive sampling dates. The change is considered as a balance of energy input with assimilation or feeding, and energy loss due to respiration, excretion, predation, natural mortality, fishery catchment or and emergence of imago insects. For non-live components we estimate an increase and a decrease in their mass due to the activity of living organisms, as well as organic matter exchange between water and sediments. Seasonal value of balance elements for each component are equal to sums of appropriate interval value. Comparison of energy flows through different links of a trophic web has shown that the role of a bacterial-detrial link was extremely important in Lake Bolshoi Okunenok for the growth season of 1986. Detritus constituted 58% of seasonal diet of non-predatory zooplankton, 39% of diet of predatory zooplankton, 50% of diet of planktivorous fish (fry of whitefish) and 92% of diet of benthivorous fish (fry of carp). The contribution of bacteria to the total seasonal decomposition amounted to 46%. Approximately 57% of the forage phytoplankton production, 86% of non-predatory benthos production, and 23-38% of the other trophic groups production were consumed by all grazers. "Coefficient of energy transformation" is proposed. It is calculated as: CET(s, k) = Ps(k)/Pk, where Ps(k) is production of consumers "s", built due to consumption of source "k"; Pk is production of source "k" itself. In Lake Bolshoi Okunenok only 14% of energy built by phytoplankton were accumulated in organic matter of zooplankton due to direct consumption. 相似文献
11.
Freshwater and marine snails serve as intermediate hosts fornumerous species of larval trematodes. Any particular populationof snails may be infected by several species. It is commonlyobserved that mixed species infections are less frequent thanexpected by change in collections of host snails from naturalpopulations. While several mechanisms might generate such negativeassociations, laboratory studies of freshwater snail-trematodeassociations have demonstrated the presence of strong antagonisticinteractions between intramolluscan larval stages (rediae andsporocysts) of species that infect the same host individual.Both predatory and non-predatory antagonism has been observed,the former taking the form of predation by large, dominant redialforms on the sporocysts and rediae of subordinate species. Theseinteractions are largely hierarchical, although in some systemspriority effects have been observed, and in one case a sporocystspecies replaced a redial species by strong non-predatory antagonism.Several instances of positive association between larval trematodespecies have also been observed. In such cases, interferencewith host defense mechanisms by the first parasite appears toenhance superinfection by the second. My own study of the larvaltrematode guild that infects the salt marsh snail, Cerithideacalifornica, has revealed patterns of association and interactionthat are very similar to those demonstrated by laboratory studiesof freshwater systems. Ultimately, the frequency of interactionsamong larval trematodes depends on the availability, relativeto the numbers of susceptible snails, of infective eggs andmiracidial larvae transmitted from definitive hosts. 相似文献
12.
哺乳动物化石群落线指示的甘肃临夏盆地晚新生代环境演变 总被引:1,自引:1,他引:0
哺乳动物群的演替过程在重建古环境和古气候中具有重要的作用。群落线(cenogram)是将陆生哺乳动物群中非肉食性种类按体重分布顺序排列的一种曲线,并可在图中将肉食性种类单独排序,以便显示动物群的整体组成。通过与现生哺乳动物群的比较,化石动物群的群落线已经被用来推断古环境及其在地质历史时期的变化。基于甘肃临夏盆地晚新生代哺乳动物群的群落线进行古环境重建,时代从晚渐新世直到早更新世。大多数化石种类的体重通过下第一臼齿面积与体重的回归公式来估计,少数种类用其他牙齿或肢骨来估计。大多数体重估计的测量数据来自临夏盆地的化石,少数取自文献。对7个化石动物群分别计算群落线的统计结果,在此基础上进行古环境解释。这些分析揭示了临夏盆地在晚中新世、早上新世和早更新世具有开阔的环境,晚渐新世是半开阔的林地,而中中新世为比较紧密的森林;在晚渐新世和晚中新世早期气候干燥,晚中新世的其他时段以及早上新世和早更新世为半干旱环境,而中中新世时期相当湿润。 相似文献
13.
The trophic role of rotifers in the zooplankton community of dimictic, oligotrophic lake Kozjak, the largest lake of the Plitvice
Lakes, NW Dinarid Mountains, is analyzed. Their spatial and temporal biomass distribution in relation to that of protozoans,
cladocerans and copepods shows that they form a significant part of the non-predatory zooplankton of this karstic standing
water. 相似文献
14.
social stressors typically elicit two distinct behavioural responses in vertebrates: an active response (i.e., "fight or flight") or behavioural inhibition (i.e., freezing). Here, we report an interesting exception to this dichotomy in a Caribbean cleaner fish, which interacts with a wide variety of reef fish clients, including predatory species. Cleaning gobies appraise predatory clients as potential threat and become stressed in their presence, as evidenced by their higher cortisol levels when exposed to predatory rather than to non-predatory clients. Nevertheless, cleaning gobies neither flee nor freeze in response to dangerous clients but instead approach predators faster (both in captivity and in the wild), and interact longer with these clients than with non-predatory clients (in the wild). We hypothesise that cleaners interrupt the potentially harmful physiological consequences elicited by predatory clients by becoming increasingly proactive and by reducing the time elapsed between client approach and the start of the interaction process. The activation of a stress response may therefore also be responsible for the longer cleaning service provided by these cleaners to predatory clients in the wild. Future experimental studies may reveal similar patterns in other social vertebrate species when, for instance, individuals approach an opponent for reconciliation after a conflict. 相似文献
15.
Mixed effects of habitat fragmentation on species richness and community structure in a microarthropod microecosystem 总被引:1,自引:0,他引:1
Abstract. 1. Theory is unclear about the optimal degree of isolation of habitat fragments where the aim is to maximise species richness. In a field-based microecosystem of Collembola and predatory and non-predatory mites, moss patches of the same total area were fragmented to varying degrees. The habitat was left for several months to allow the communities to approach a new state of equilibrium.
2. The species richness (in particular of predatory mites) of a given area of habitat was greater when it was part of a large mainland area than part of an island, in agreement with theory.
3. Conversely, species richness and abundance were largely unaffected by fragmentation of a fixed area of island habitat. In this case, it is suggested here that the advantages of several small patches (e.g. reduced impact of environmental stochasticity, wider range of habitats overall) were equally balanced by the advantages of a single large patch (e.g. reduced effect of demographic stochasticity, wider range of habitats within a single patch, reduced edge effect), or that both effects were small.
4. The shapes of rank–abundance curves were similar among the levels of fragmentation of a fixed area of island habitat, implying that fragmentation had little impact on community structure. Conversely, the species composition of non-predatory mites varied weakly, but significantly, by fragmentation. 相似文献
2. The species richness (in particular of predatory mites) of a given area of habitat was greater when it was part of a large mainland area than part of an island, in agreement with theory.
3. Conversely, species richness and abundance were largely unaffected by fragmentation of a fixed area of island habitat. In this case, it is suggested here that the advantages of several small patches (e.g. reduced impact of environmental stochasticity, wider range of habitats overall) were equally balanced by the advantages of a single large patch (e.g. reduced effect of demographic stochasticity, wider range of habitats within a single patch, reduced edge effect), or that both effects were small.
4. The shapes of rank–abundance curves were similar among the levels of fragmentation of a fixed area of island habitat, implying that fragmentation had little impact on community structure. Conversely, the species composition of non-predatory mites varied weakly, but significantly, by fragmentation. 相似文献
16.
A marine bacterium provisionally identified as Vibrio alginoliticus, which is associated withtetrodotoxin production, was isolated from severalspecies of marine nemerteans. The presence of thisbacterium strongly supports the potential use oftetrodotoxins by nemerteans for protection againstingestion by predators or as an agent in their ownpredatory activities. Tetrodotoxins may facilitatethe ability of the nemertean proboscis to subdue preyduring capture. One commensal nemertean speciesappears not to possess the bacterium. This may bedue, in part, to its non-predatory life style. 相似文献
17.
A.E. Irish 《欧洲藻类学杂志》2013,48(1):11-15
Gymnodinium helveticum f. achroum in Blelham Tarn was occasionally noted to exhibit phagotrophy. Various algae were observed inside Gymnodinium cells. The seeding of an experimental enclosure with dead Lycopodium spores resulted in some of the Gymnodinium cells containing a spore. From the results, it is suggested that this dinoflagellate exhibits non-selective and non-predatory phagotrophy. 相似文献
18.
Joachim G. Frommen Fabian Herder Leif Engqvist Marion Mehlis Theo C. M. Bakker Julia Schwarzer Timo Thünken 《Evolutionary ecology》2011,25(3):641-656
Predation risk is one of the major forces affecting phenotypic variation among and within animal populations. While fixed
anti-predator morphologies are favoured when predation level is consistently high, plastic morphological responses are advantageous
when predation risk is changing temporarily, spatially, or qualitatively. Three-spined sticklebacks (Gasterosteus aculeatus) are well known for their substantial variability in morphology, including defensive traits. Part of this variation might
be due to phenotypic plasticity. However, little is known about sticklebacks’ plastic ability to react morphologically to
changing risks of predation and about the proximate cues involved. Using a split-clutch design we show that odour of a predatory
fish induces morphological changes in sticklebacks. Under predation risk, i.e., when exposed to odour of a predator, fish
grew faster and developed a different morphology, compared to fish reared under low predation risk, i.e., exposed to odour
of a non-predatory fish, or in a fish-free environment. However, fast growing comes at cost of increased body asymmetries
suggesting developmental constraints. The results indicate that sticklebacks are able to distinguish between predatory and
non-predatory fishes by olfactory cues alone. As fishes were fed on invertebrates, this reaction was not induced by chemical
cues of digested conspecifics, but rather by predator cues themselves. Further, the results show that variation in body morphology
in sticklebacks has not only a strong genetical component, but is also based on plastic responses to different environments,
in our case different predation pressures, thus opening new questions for this model species in ecology and evolution. 相似文献
19.
Predatory bacteria seek and consume other live bacteria. Although belonging to taxonomically diverse groups, relatively few bacterial predator species are known. Consequently, it is difficult to assess the impact of predation within the bacterial realm. As no genetic signatures distinguishing them from non-predatory bacteria are known, genomic resources cannot be exploited to uncover novel predators. In order to identify genes specific to predatory bacteria, we developed a bioinformatic tool called DiffGene. This tool automatically identifies marker genes that are specific to phenotypic or taxonomic groups, by mapping the complete gene content of all available fully-sequenced genomes for the presence/absence of each gene in each genome. A putative ‘predator region’ of ~60 amino acids in the tryptophan 2,3-dioxygenase (TDO) protein was found to probably be a predator-specific marker. This region is found in all known obligate predator and a few facultative predator genomes, and is absent from most facultative predators and all non-predatory bacteria. We designed PCR primers that uniquely amplify a ~180bp-long sequence within the predators’ TDO gene, and validated them in monocultures as well as in metagenetic analysis of environmental wastewater samples. This marker, in addition to its usage in predator identification and phylogenetics, may finally permit reliable enumeration and cataloguing of predatory bacteria from environmental samples, as well as uncovering novel predators. 相似文献
20.
Animal population dynamics in open systems are affected not only by agents of mortality and the influence of species interactions
on behavior and life histories, but also by dispersal and recruitment. We used an extensive data set to compare natural loss
rates of two mayfly species that co-occur in high-elevation streams varying in predation risk, and experience different abiotic
conditions during larval development. Our goals were to generate hypotheses relating predation to variation in prey population
dynamics and to evaluate alternative mechanisms to explain such variation. While neither loss rates nor abundance of the species
that develops during snowmelt (Baetis bicaudatus) varied systematically with fish, loss rates of the species that develops during baseflow (Baetis B) were higher in streams containing brook trout than streams without fish; and surprisingly, larvae of this species were
most abundant in trout streams. This counter-intuitive pattern could not be explained by a trophic cascade, because densities
of intermediate predators (stoneflies) did not differ between fish and fishless streams and predation by trout on stoneflies
was negligible. A statistical model estimated that higher recruitment and accelerated development enables Baetis B to maintain larger populations in trout streams despite higher mortality from predation. Experimental estimates suggested
that predation by trout potentially accounts for natural losses of Baetis B, but not Baetis bicaudatus. Predation by stoneflies on Baetis is negligible in fish streams, but could make an important contribution to observed losses of both species in fishless streams.
Non-predatory sources of loss were higher for B. bicaudatus in trout streams, and for Baetis B in fishless streams. We conclude that predation alone cannot explain variation in population dynamics of either species;
and the relative importance of predation is species- and environment-specific compared to non-predatory losses, such as other
agents of mortality and non-consumptive effects of predators.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献