共查询到20条相似文献,搜索用时 15 毫秒
1.
Robert S. Easton Donald J. Orth J. Reese Voshell Jr. 《Environmental Biology of Fishes》1996,46(4):383-392
Synopsis We measured macroinvertebrate densities and abundance, size, and diet of juvenile smallmouth bass, Micropterus dolomieu, at five sites located at varying distances from a metalimnetic release dam. We used these data to determine the influence of high prey abundances on stomach fullness and age-0 year-class strength. Summer diets of juvenile smallmouth bass (27.7–107.7 mm total length) were dominated by Ephemeroptera (primarily Baetidae) but diet composition was highly variable among years and sites. A linear index of prey selection showed that Ephemeroptera were preferred and Trichoptera were avoided at all sites in all years; but, selection indices were not consistent for Chironomidae or Amphipoda and Isopoda. In two of three years, stomach fullness (gut content mass relative to predicted maximum) of juvenile smallmouth bass decreased with distance downstream of the dam, which reflected patterns observed in benthic macroinvertebrate densities. However, in 1989 when flooding and increased turbidity reduced abundances of juvenile smallmouth bass, no differences in stomach fullness were found among sites. High stomach fullness of juvenile smallmouth bass was attributed to high prey abundances near the dam in years of low or normal streamflow. However, patterns in juvenile smallmouth bass abundances in mid-summer could not be attributed to longitudinal variation in prey abundance. 相似文献
2.
Although iridoviruses vary widely within and among genera with respect to their host range and virulence, variation within iridovirus species has been less extensively characterized. This study explores the nature and extent of intraspecific variation within an emerging iridovirus of North American warm-water fishes, largemouth bass virus (LMBV). Three LMBV isolates recovered from three distinct sources differed genetically and phenotypically. Genetically, the isolates differed in the banding patterns generated from amplified fragment length polymorphism analysis but not in their DNA sequences at two loci of different degrees of evolutionary stability. In vitro, the isolates replicated at identical rates in cell culture, as determined by real-time quantitative PCR of viral particles released into suspension. In vivo, the isolates varied over fivefold in virulence, as measured by the rate at which they induced mortality in juvenile largemouth bass. This variation was reflected in the viral loads of exposed fish, measured using real-time quantitative PCR; the most virulent viral strain also replicated to the highest level in fish. Together, these results justify the designation of these isolates as different strains of LMBV. Strain variation in iridoviruses could help explain why animal populations naturally infected with iridovirus pathogens vary so extensively in their clinical responses to infection. The results of this study are especially relevant to emerging iridoviruses of aquaculture systems and wildlife. 相似文献
3.
Many behaviours have differential fitness consequences across thermal and ecological contexts, indicating that both ecological shifts and warming temperatures induced by climatic change may alter how organisms behave. However, empirical evidence of temperature-driven behavioural selection in natural systems is lacking. We compared behaviours and behavioural syndromes related to activity, exploration, boldness and aggression in populations of largemouth bass (Micropterus salmoides) from ambient lakes to the those from artificially warmed, power plant cooling lakes to investigate changes in behaviours associated with warmer environments. Activity, exploration, boldness and aggression of juvenile largemouth bass were assessed in laboratory conditions using a novel environment assay and a risky situation assay. We found that activity and exploratory behaviours were higher and decreased through first year ontogeny in populations from heated lakes, whereas these behaviours were lower and showed no relationship through ontogeny in populations from ambient lakes. We attribute these differences to the changes in food source availability in heated lakes associated with temperature-driven ecological effects. Bold and aggressive behaviours tended to differ between populations, as did correlations between behaviours, but did not differ between ambient and heated lakes. The findings of this work identify that large ecological changes associated with warming environments, such as food availability, may drive changes in some aspects of behavioural expression in largemouth bass but that other aspects of behavioural expression may be driven by lake-specific factors not related to warming. 相似文献
4.
1. Non‐native predators might inflict proportionally higher mortality on prey that have no previous experience of them, compared to species that have coexisted with the predator for some time. 2. We tested whether juvenile Chinook salmon (Oncorhynchus tshawytscha) were less able to recognise a non‐native than a native predator, by investigating behavioural responses to the chemical cues of the invasive smallmouth bass (Micropterus dolomieu) and the native northern pikeminnow (Ptychocheilus oregonensis) in both laboratory and field experiments. 3. Laboratory results demonstrated strong innate antipredator responses of individual juvenile Chinook salmon to northern pikeminnow; fish spent 70% of time motionless and exhibited 100% greater panic response than in controls. By contrast, antipredator responses to the chemical cues of smallmouth bass did not differ from controls. 4. These results were supported by similar differences in recognition of these predator odours by groups of juvenile Chinook salmon in fully natural conditions, though responses reflected a greater range of antipredator behaviours by individuals. In field trials, responses to northern pikeminnow odour resulted in increased flight or absence, reductions in swimming and foraging, and increased time spent near the substratum, compared to smallmouth bass odour. 5. Given that survival of juvenile fish is facilitated by predator recognition, our results support the hypothesis that naivety may be an important factor determining the effect of non‐native predators on prey populations. Efforts to manage the effect of native and non‐native predators may benefit by considering complex behavioural interactions, such as these at the individual and group levels. 相似文献
5.
Studies of population dynamics of long-lived species have generally focused on adult survival because population growth should be most sensitive to this parameter. However, actual variations in population size can often be driven by other demographic parameters, such as juvenile survival, when they show high temporal variability. We used capture–recapture data from a long-term study of a hunted, migratory species, the greater snow goose (Chen caerulescens atlantica), to assess temporal variability in first-year survival and the relative importance of natural and hunting mortality. We also conducted a parasite-removal experiment to determine the effect of internal parasites and body condition on temporal variation in juvenile survival. We found that juvenile survival showed a higher temporal variability than adult survival and that natural mortality was more important than hunting mortality, unlike in adults. Parasite removal increased first-year survival and reduced its annual variability in females only. Body condition at fledging was also positively correlated with first-year survival in treated females. With reduced parasite load, females, which are thought to invest more in their immune system than males according to Bateman’s principle, could probably reallocate more energy to growth than males, leading to a higher survival. Treated birds also had a higher survival than control ones during their second year, suggesting a developmental effect that manifested later in life. Our study shows that natural factors such as internal parasites may be a major source of variation in juvenile survival of a long-lived, migratory bird, which has implications for its population dynamics. 相似文献
6.
Dietary habits of fish populations in the Lower Medway Estuary 总被引:1,自引:0,他引:1
Populations of mainly first-year fish overwinter in the Medway Estuary, an area offering shelter and a rich and varied food supply. In the absence of previous investigations, the present study examines the dietary habits of four fish species; gadoids Merlangius merlangus and Trisopterus luscus , and pleuronectids Platichthys flesus and Pleuronectes platessa .
Gadoids fed predominantly on fast moving nektonic organisms such as brown shrimps, mysids and fish while pleuronectids preferred the slower moving tubificid and polychaete worms. Seasonal fluctuations of the dietary constituents are considered in relation to changes within the populations of both prey and predator organisms. 相似文献
Gadoids fed predominantly on fast moving nektonic organisms such as brown shrimps, mysids and fish while pleuronectids preferred the slower moving tubificid and polychaete worms. Seasonal fluctuations of the dietary constituents are considered in relation to changes within the populations of both prey and predator organisms. 相似文献
7.
R. M. Coloso D. P. Murillo-Gurrea I. G. Borlongan M. R. Catacutan 《Zeitschrift fur angewandte Ichthyologie》1999,15(2):54-58
The dietary requirement of juvenile Asian sea bass Lates calcarifer Bloch for total sulphur amino acids was studied. Fish (average initial weight of 2.59 ± 0.08 g) were reared in twelve 500 L fibreglass tanks provided with flow-through seawater at 26°C and salinity of 31 p.p.t. for 12 weeks. They were fed semi-purified test diets containing 6.2, 7.2, 8.1, 9.0, 10.8, or 12.6 g methionine kg−1 dry diet and a basal level of 3.1 g cystine kg−1 dry diet. The mean crude protein of the diets (containing defatted Peruvian fishmeal, squid meal, soybean meal, and free amino acid mixture to simulate the pattern of hydrolysed sea bass protein) was 46.02%. The crude fat content of the diets was 10.51% from a 1 : 1 mixture of cod liver oil and soybean oil. Survival was 100% in all treatments. On the basis of the growth response, the total sulphur amino acid requirement of juvenile Asian sea bass was estimated to be 13.4 g kg−1 dry diet (2.9% of protein). Fish fed low levels of l -methionine had significantly lower weight gains and feed efficiency ratios as well as slightly higher hepatosomatic indices. No nutritional deficiency signs were observed other than growth depression in fish fed on diets that were low in methionine. This information is valuable in further refinement of formulations of practical diets for the Asian sea bass. 相似文献
8.
J Castri R Thiéry J Jeffroy P de Kinkelin J C Raymond 《Diseases of aquatic organisms》2001,47(1):33-38
During an epidemiological survey of viral encephalopathy and retinopathy (VER) in diseased sea bass Dicentrarchus labrax, a nodavirus isolate was recovered from net pen-reared sea bream Sparus aurata harboured in the same farming premises. After the virus was isolated and identified by immunofluorescence on SSN-1 cells, sequence analysis with a PCR product from the T4 region of the capsid protein gene indicated that the virus shared 100% identity with a pathogenic virus strain isolated from sea bass. Infection trials demonstrated the pathogenicity of the sea bream virus isolate for juvenile sea bass whereas sea bream infected with the same virus isolate remained asymptomatic even following intramuscular injection of virus. Nevertheless, the sea bream appeared to be a potential carrier of nodavirus, as juvenile sea bass became infected when maintained in a tank containing experimentally contaminated sea bream. 相似文献
9.
Critical thermal minima and maxima of three freshwater game-fish species acclimated to constant temperatures 总被引:1,自引:0,他引:1
Rebecca J. Currie Wayne A. Bennett Thomas L. Beitinger 《Environmental Biology of Fishes》1998,51(2):187-200
A total of 120 critical thermal maxima (CT maxima) and 120 critical thermal minima (CT minima) were determined for channel
catfish, largemouth bass and rainbow trout acclimated to three constant temperatures: 20, 25 and 30 °C in catfish and bass,
and 10, 15 and 20 °C in trout. Highest mean CT maximum and lowest mean CT minimum measured over these acclimation temperatures
were 40.3 and 2.7 °C (catfish), 38.5 and 3.2 °C (bass) and 29.8 and ∼ 0.0 °C (trout). Temperature tolerance data were precise
with standard deviations generally less than 0.5 °C. Channel catfish had the largest thermal tolerance scope of the three
species while rainbow trout had the lowest tolerance of high temperatures and the highest tolerance of low temperatures. In
all species CT minima and CT maxima were highly significantly linearly related to acclimation temperature. Within each species,
slopes relating CT maxima to acclimation temperature were approximately half as large as those relating CT minima to acclimation
temperature, suggesting that acclimation temperature has a greater influence on tolerance to low rather than high temperatures.
Slopes relating both CT minima and CT maxima to acclimation temperature for the two warm-water species were similar and approximately
twice those for the rainbow trout.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Eric Saillant Alexis Fostier Bruno Menu 《Journal of experimental marine biology and ecology》2003,287(1):103-117
The sea bass, Dicentrarchus labrax, is an eurhyaline marine fish. Juveniles of this species are known to frequent estuaries and lagoons where salinity is lower than in the open sea. Sex determination occurs during this phase of fish life and has been shown labile and sensitive to environmental factors. In this work, the effect of rearing salinity on sex determination and early development of the sea bass was investigated. An excess of males (87%) was found in all groups and the salinity level [(natural sea water salinity, mean: 37‰) vs. (15‰)], when maintained constant, had no effect on the sex-ratio. The transfer from low to high salinity at 93 days post-fertilization (p.f.) increased the percentage of males (93%) suggesting that sexual differentiation in this species may be influenced by such an osmotic stress. Growth was improved by a 15‰ salinity at the beginning of larval rearing (14 days p.f.) and at the end of pre-growing (234-458 days p.f.), periods during which low temperatures were applied. Survival during larval rearing and nursery were also improved in the groups reared at low salinity and so was swimbladder inflation. These results show that sea bass juveniles have a low saline preferendum, a finding that corresponds to the conditions they actually encounter in the wild during their juvenile ecophase; sex determination is not directly modulated by the salinity level but seems to be subjected to complex environmental regulations. 相似文献
11.
Sarah E. Baird Anna E. Steel Dennis E. Cocherell Jamilynn B. Poletto Rhiannon Follenfant Nann A. Fangue 《Zeitschrift fur angewandte Ichthyologie》2020,36(1):14-24
Predation is a common cause of early life stage mortality in fishes, with reduced risk as individuals grow and become too large to be consumed by gape-limited predatory fishes. Large-bodied species, such as sturgeon, may reach this size-refuge within the first year. However, there is limited understanding of what this size threshold is despite the value of this information for conservation management. We conducted laboratory-based predation experiments on juvenile green sturgeon, Acipenser medirostris, to estimate vulnerability to predation during outmigration from their natal reaches in California to the Pacific Ocean. Two highly abundant and non-native predatory fish species (largemouth bass, Micropterus salmoides, and striped bass, Morone saxatilis) were captured in the wild to be tested with developing juvenile green sturgeon from the UC Davis Green Sturgeon Broodstock Program. Experimental tanks, each containing five predators, received thirty prey for 24-hr exposures. Between sturgeon prey trials, predators were exposed to alternative prey species to confirm predators were exhibiting normal feeding behaviors. In addition to green sturgeon mortality data, trials were video recorded and predatory behaviors were quantified. Overall, these predator species displayed much lower rates of predation on juvenile green sturgeon than alternate prey. Predation decreased with green sturgeon size, and predation risk diminished to zero once sturgeon reached a length threshold of roughly 20–22 cm total length, or between 38% and 58% of predator total length. Behavioral analyses showed low motivation to feed on green sturgeon, with both predators attempting predation less frequently as sturgeon grew. Results of this study imply that optimizing growth rates for larval and juvenile sturgeon would shorten the time in which they are vulnerable to predation. Future experiments should assess predation risk of juvenile green sturgeon by additional predator species common to the Sacramento-San Joaquin watershed. 相似文献
12.
Invasive carp and prey community composition disrupt trophic cascades in eutrophic ponds 总被引:1,自引:0,他引:1
The role of trophic cascades in structuring freshwater communities has been extensively studied. Most of this work, however,
has been conducted in oligotrophic northern lakes that contain highly vulnerable cyprinid prey: aquatic communities where
trophic interactions are likely to be stronger than in many other systems. Fewer studies have been conducted in eutrophic
systems or have examined the bottom-up effects of benthivorous fishes, and none have directly compared these effects to those
of piscivores on ecosystem structure and function. We conducted enclosure experiments in eutrophic ponds to examine trophic
effects of invasive benthivores (common carp—Cyprinus carpio L.), native piscivores (largemouth bass—Micropterus salmoides [Lacepède]), and their interactions with common centrarchid prey with well-developed anti-predatory behaviors (age-1 bluegill—Lepomis macrochirus Rafinesque and young-of-year largemouth bass). At the end of the 60-day experiment, common carp had strong bottom-up effects
that increased total phosphorus and turbidity while decreasing chlorophyll a biomass and macrophyte cover that resulted in decreased macroinvertebrate biomass and also decreased growth in both juvenile
largemouth bass and bluegill. Piscivorous largemouth bass, however, did not affect the survival of either planktivorous juvenile
largemouth bass or bluegill. Growth of juvenile largemouth bass was also not affected, but juvenile bluegill growth was significantly
diminished, possibly due to nonconsumptive effects of predation. Our results suggest that, in a centrarchid-dominated eutrophic
system, top-down effects of predators are overwhelmed by common carp-mediated bottom-up effects. These bottom-up effects strongly
affected multiple trophic levels, thus altering aquatic community structure and function. 相似文献
13.
Maud C. O. Ferrari Lynn Ranåker Kelly L. Weinersmith Matthew J. Young Andrew Sih J. Louise Conrad 《Environmental Biology of Fishes》2014,97(1):79-90
Anthropogenic activities lead to changes in characteristics of aquatic ecosystems, including alteration of turbidity and addition of invasive species. In this study, we tested how changes in turbidity and the recent invasion of an aquatic macrophyte, Egeria densa, may have changed the predation pressure by introduced largemouth bass on juvenile striped bass and delta smelt, two species that have seen a drastic decline in recent decades in the Sacramento-San Joaquin Delta. In a series of mesocosm experiments, we showed that increases in vegetation density decreased the predation success of largemouth bass. When placed in an environment with both open water and vegetated areas, and given a choice to forage on prey associated with either of these habitats, largemouth bass preyed mainly on open water species as opposed to vegetation-associated species, such as juvenile largemouth bass, bluegill or red swamp crayfish. Finally, we showed that turbidity served as cover to open water species and increased the survival of delta smelt, an endemic species at risk. We also found that such open water prey tend not to seek refuge in the vegetation cover, even in the presence of an imminent predation threat. These results provide the beginning of a mechanistic framework to explain how decreases in turbidity and increases in vegetation cover correlate with a decline of open water species in the Sacramento-San Joaquin Delta. 相似文献
14.
Joshua J. Traylor Ray T. Alisauskas Stuart M. Slattery Kiel L. Drake 《The Journal of wildlife management》2012,76(6):1135-1144
Large increases in several populations of North American arctic geese have resulted in ecosystem-level effects from associated herbivory. Consequently, some breeding populations have shown density dependence in recruitment through declines in food availability. Differences in population trajectories of lesser snow geese (Chen caerulescens caerulescens; hereafter snow geese) and Ross's geese (C. rossii) breeding in mixed-species colonies south of Queen Maud Gulf (QMG), in Canada's central arctic, suggest that density dependence may be limiting snow goose populations. Specifically, long-term declines in age ratios (immature:adult) of harvested snow geese may have resulted from declines in juvenile survival. Thus, we focused on juvenile (first-year) survival of snow and Ross's geese in relation to timing of reproduction (annual mean nest initiation date) and late summer weather. We banded Ross's and snow geese from 1991 to 2008 in the QMG Migratory Bird Sanctuary. We used age-structured mark-recapture models to estimate annual survival rates for adults and juveniles from recoveries of dead birds. Consistent with life history differences, juvenile snow geese survived at rates higher than juvenile Ross's geese. Juvenile survival of both species also was lower in late seasons, but was unrelated to arctic weather measured during a 17-day period after banding. We found no evidence of density dependence (i.e., a decline in juvenile survival over time) in either species. We also found no interspecific differences in age-specific hunting vulnerability, though juveniles were more vulnerable than adults in both species, as expected. Thus, interspecific differences in survival were unrelated to harvest. Lower survival of juvenile Ross's geese may result from natural migration mortality related to smaller body size (e.g., greater susceptibility to inclement weather or predation) compared to juvenile snow geese. Despite lower first-year survival, recruitment by Ross's geese may still be greater than that by snow geese because of earlier sexual maturity, greater breeding propensity, and higher nest success by Ross's geese. © 2012 The Wildlife Society. 相似文献
15.
16.
Morphological variation between lake- and stream-dwelling rock bass and pumpkinseed populations 总被引:1,自引:0,他引:1
Pumpkinseed Lepomis gibbosus and rock bass Ambloplites rupestris stream populations of both sexes were significantly different in external morphology from lake populations in a central Ontario, Canada, watershed. The predictions that stream fishes would be more slender-bodied, and have a more anterior placement of lateral fins than lake fishes were generally supported. The prediction that stream fishes would have a more robust caudal peduncle was partially supported. The prediction that fin size would be larger in stream fishes was not supported, as lake rock bass generally had longer and wider fins than those from stream sites. The results suggest that in some species, smaller fins may be favoured in stream-dwelling individuals because the reduction of drag during swimming more than compensates for their reduced power and propulsion efficiency in a current. Smaller fin size in stream-dwelling centrarchids may be related to their body shape, or to their low usage of fast-moving water within the streams they inhabit. 相似文献
17.
Grant E. Brown Valerie J. LeBlanc & Lindsay E. Porter 《Ethology : formerly Zeitschrift fur Tierpsychologie》2001,107(5):401-414
Juvenile largemouth bass ( Micropterus salmoides ) undergo an ontogenetic niche shift from invertebrate feeding members of the cyprinid prey guild to piscivory during their first year of growth. We conducted laboratory and field trials to determine whether juvenile bass show a similar ontogenetic shift in their response to the alarm pheromone of finescale dace ( Phoxinus neogaeus , Cyprinidae). When exposed to dace skin extract (with alarm pheromone), juvenile bass exhibited a significant positive relationship between standard length and horizontal and vertical area use and time spent moving. Small bass (< 50 mm standard length) tended to reduce area use and time spent moving (indicative of an anti-predator response), while larger bass (> 50 mm standard length) increased area use and time spent moving (indicating a foraging response). Bass exhibited no change in behaviour when exposed to swordtail ( Xiphophorus helleri ) skin extract, which lacks Ostariophysan alarm pheromone. During field trials, small (30–45 mm standard length) and medium (46–60 mm standard length) bass actively avoided areas labelled with dace alarm pheromone and exhibited a significant increase in dashing behaviour. Large bass (61–80 mm standard length) were attracted to such areas and exhibited a significant increase in approach behaviour. These data suggest that largemouth bass undergo an ontogenetic shift in response to heterospecific chemical alarm signals. 相似文献
18.
Tulli F Vachot C Tibaldi E Fournier V Kaushik SJ 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,147(1):179-188
The role of dietary arginine in affecting nitrogen utilisation and excretion was studied in juvenile European sea bass (Dicentrarchus labrax) fed for 72 days with diets differing in protein sources (plant protein-based (PM) and fish-meal-based (FM)). Fish growth performance and nitrogen utilisation revealed that dietary Arg surplus was beneficial only in PM diets. Dietary Arg level significantly affected postprandial plasma urea concentrations. Hepatic arginase activity increased (P<0.05) in response to dietary Arg surplus in fish fed plant protein diets; conversely ornithine transcarbamylase activity was very low and inversely related to arginine intake. No hepatic carbamoyl phosphate synthetase III activity was detected. Dietary arginine levels did not affect glutamate dehydrogenase activity. A strong linear relationship was found between liver arginase activity and daily urea-N excretion. Dietary Arg excess reduced the proportion of total ammonia nitrogen excreted and increased the contribution of urea-N over the total N excretion irrespective of dietary protein source. Plasma and excretion data combined with enzyme activities suggest that dietary Arg degradation via hepatic arginase is a major pathway for ureagenesis and that ornithine-urea cycle is not completely functional in juvenile sea bass liver. 相似文献
19.
Synopsis We estimated the rate of energy consumed and expended by 43 juvenile smallmouth bass, Micropterus dolomieu, videotaped in the North Anna River during 1991. Habitat data were also collected in the areas where each individual was videotaped. The net rate of energy gained (J·min–1) increased as water depths decreased and mean water-column velocities increased. This relationship remained statistically significant even when we assumed that consumption was as little as 40% of our original estimates, and that respiratory costs were three times higher than we suspected. The net rate of energy gained by juvenile smallmouth bass was only affected by the characteristics of the area that they searched and not the foraging tactics they employed. 相似文献
20.
Analysis of high‐speed videography demonstrated that juvenile wild Florida largemouth bass Micropterus salmoides floridanus captured live prey with very rapid movements and large excursions. Hatchery fish of the same age, raised on pelleted feed, however, used slower kinematics with smaller excursions, yielding strikes with a higher degree of 'suction'. Capture events of hatchery Florida largemouth bass fed live prey for the first time were characterized by movements that had smaller excursion measurements than wild fish and resulted in a decreased level of capture success. After five exposures to elusive mosquitofish Gambusia holbrooki , hatchery Florida largemouth bass adapted their behaviour to capture prey at the kinematic level of wild fish. 相似文献