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1.
David Monticelli Ricardo Ceia Ruben Heleno Hugo Laborda Sergio Timóteo Daniel Jare?o Geoff M. Hilton Jaime A. Ramos 《Journal of Ornithology》2010,151(3):627-636
This paper reports analyses of a capture–mark–recapture (CMR) dataset of 149 Azores Bullfinches ringed on S?o Miguel island
(Azores) between 2005 and 2007, and recaptured–resighted on a monthly basis over a 4-year period (2005–2008) throughout their
breeding range. We examined the effect of time, age (adults vs. juveniles), gender (adult males and females), and environmental
covariates (temperature, rainfall, NAO index) on survival probabilities. The modelling found a high and constant monthly survival
probability (mean ± SE) estimated at 0.96 ± 0.01, similar between both adults and juveniles and independent of environmental
conditions and gender. These findings agree with expectations from island-based life-history theory where relatively mild
conditions and lack of predators should favour high survival rates to compensate for the low reproductive output. The annual
survival rate was estimated at 0.62, which was also consistent with this pattern when compared with survival estimates of
mainland bullfinch and passerine species on other subtropical islands obtained in similar CMR studies. Based on a canonical
estimator, the size of the studied population (mean ± SE) was estimated at 1608 ± 326 individuals. Given that the population
size was only around 120–400 individuals in the early 1990s, we suggest that the high survival probabilities currently applying
to this critically endangered species may have substantially contributed to the recent recovery of this population. Future
research studies on the species’ demography should continue to monitor survival in order to measure the effect of management
interventions currently taking place within the range of the Azores Bullfinch, including the restoration of the biodiversity
rich laurel forest, but also focusing on nest success, which is important for understanding population dynamics. 相似文献
2.
Competitive effects of younger cohorts on older ones are frequently assumed to be negligible in species where older, larger
individuals dominate in pairwise behavioural interactions. Here, we provide field estimates of such competition by recruits
on an older age class in Atlantic salmon (Salmo salar), a species where observational studies have documented strong body size advantages which should favour older individuals
in direct interactions. By creating realistic levels of spatial variation in the density of underyearling (YOY) recruits over
a 1-km stretch of a stream, and obtaining accurate measurements of individual growth rates of overyearlings (parr) from capture–mark–recapture
data on a fine spatial scale, we demonstrate that high YOY density can substantially decrease parr growth. Models integrating
multiple spatial scales indicated that parr were influenced by YOY density within 16 m. The preferred model suggested parr
daily mass increase to be reduced by 39% when increasing YOY density from 0.0 to 1.0 m−2, which is well within the range of naturally occurring densities. Reduced juvenile growth rates will in general be expected
to reduce juvenile survival (via increased length of exposure to freshwater mortality) and increase generation times (via
increased age at seaward migrations). Thus, increased recruitment can significantly affect the performance of older cohorts,
with important implications for population dynamics. Our results highlight that, even for the wide range of organisms that
rely on defendable resources, the direction of competition among age classes cannot be assumed a priori or be inferred from
behavioural observations alone. 相似文献
3.
We studied territoriality and habitat use by yellow phase juvenile blue tangs, Acanthurus coeruleus, on a small fringing reef in Barbados, West Indies. Juvenile blue tangs occurred on the reef crest, spurs, and a transition zone between the reef crest and reef flat at a density of about 8 individuals per 100m2, but were much rarer on the reef flat. They were solitary and occupied stable home ranges (median=0.85m2) that increased with body size. Observational and experimental data documented aggressive defense of home ranges against conspecific and to a lesser extent congeneric, A. bahianus, juveniles (about 7.5 approaches and attacks per hour directed at intruders). Home range locations were structurally more complex and closer to a vertical face than expected by chance. Although juvenile blue tang territories overlapped considerably with those of larger and more aggressive Stegastes damselfish, which are believed to exclude solitary adult Acanthurus spp. from reef crest and spurs, the tangs avoided Stegastes and were rarely chased (<0.3 fleeing events per hour). Space use and social organization of yellow juvenile blue tangs contrast strikingly with that of both conspecific adults and congeneric juveniles. 相似文献
4.
Shortage of natural crevice shelters may produce population bottlenecks in juvenile Caribbean spiny lobsters (Panulirus argus), a socially gregarious species. We conducted a field experiment to test enhancement of a local population of juvenile P. argus with the addition of artificial shelters (“casitas”) that mimic large crevices (1.1 m2 in surface area and 3.8 cm in height). Changes in density and biomass of juvenile lobsters 15–50 mm carapace length (CL)
were assessed with a multiple before-after control-impact (MBACI) analysis. Separate analyses were also conducted on small
(15–35 mm CL) and large (35.1–50 mm CL) juveniles to assess size-related effects. First, we carried out 13 lobster surveys
on nine fixed 1-ha sites over a shallow reef lagoon (“before” period). Then, we deployed ten casitas in each of five sites
and left four sites as controls, and conducted 22 further surveys (“after” period). Deployment of casitas resulted in a sixfold
increase in juvenile density (76% contributed by small and 24% by large juveniles) and a sevenfold increase in biomass (40
and 60%, respectively). Capture–recapture results revealed that enhancement was achieved not by promoting individual growth
but by increasing survival, persistence, and foraging ranges of small and large juveniles. Casitas both mitigated shortage
of natural shelter and increased sociality, allowing for cohabitation of smaller, more vulnerable juveniles with larger conspecifics
that have greater defensive abilities. Casitas may help enhance local populations of juvenile P. argus in Caribbean seagrass habitats, typically poor in natural crevice shelters. The use of MBACI and the simultaneous assessment
of multiple interrelated response variables may be a powerful analytical approach to test shelter limitation in other species
and to examine the function of structural habitat in other systems. 相似文献
5.
K. Tanaka T. Watanabe H. Higuchi K. Miyamoto Y. Yusa T. Kiyonaga H. Kiyota Y. Suzuki T. Wada 《Population Ecology》1999,41(3):253-262
To examine density dependence in the survival, growth, and reproduction of Pomacea canaliculata, we conducted an experiment in which snail densities were manipulated in a paddy field. We released paint-marked snails of
15–20 mm shell height into 12 enclosures (pens) of 16 m2 at one of five densities – 8, 16, 32, 64, or 128 snails per pen. The survival rate of released snails was 95% and was independent
of snail density. The snail density had a significant effect on the growth and egg production of individual snails. This density
dependence may have been caused by reduced food availability. The females at high density deposited fewer and smaller egg
masses than those at low density, and consequently produced fewer eggs. The females at densities 8 and 16 deposited more than
3000 eggs per female, while the females at density 128 oviposited only 414 eggs. The total egg production per pen was, however,
higher at higher snail density. The survival rates of juvenile snails were 21%–37% and were independent of adult density.
The juvenile density was positively correlated with the total egg production per pen and hence was higher at higher adult
density. However, the density of juveniles larger than 5 mm in shell height, i.e., juveniles that can survive an overwintering
period, was not significantly different among density treatments. These results suggest that snail density after the overwintering
period is independent of the density in the previous year. Thus, density dependence in growth and reproduction might regulate
the population of P. canaliculata in paddies.
Received: October 23, 1998 / Accepted: July 16, 1999 相似文献
6.
A total of 45 juvenile [30.0–57.4 mm total length (TL)] slime flounder Microstomus achne were collected in the coastal area of southern Hokkaido from April to July in 2001 and April to June in 2002. Their diets
were analyzed. Slime flounder juveniles of 30.0–39.9 mm TL fed predominantly on small crustaceans (gammarid amphipods, harpacticoids
and cumaceans) and those of 40.0–57.4 mm TL on gammarid amphipods, cumaceans and polychaetes. The major prey items changed
with growth from small crustaceans (e.g., harpacticoids) to polychaetes, although gammarid amphipods were the major prey items
throughout the juvenile period (30.0–57.4 mm TL). 相似文献
7.
Juan Carlos Senar Lluïsa Arroyo Alba Ortega‐Segalerva Jos G. Carrillo Xavier Toms Tomas Montalvo Ana Sanz‐Aguilar 《Ecology and evolution》2019,9(2):891-898
Many species only show sexual dimorphism at the age of maturity, such that juveniles typically resemble females. Under these circumstances, estimating accurate age‐specific demographic parameters is challenging. Here, we propose a multievent model parameterization able to estimate age‐dependent survival using capture–recapture data with uncertainty in age and sex assignment of individuals. We illustrate this modeling approach with capture–recapture data from the ring‐necked parakeet Psittacula krameri. We analyzed capture, recapture, and resighting data (439 recaptures/resightings) of 156 ring‐necked parakeets tagged with neck collars in Barcelona city from 2003 to 2016 to estimate the juvenile and adult survival rate. Our models successfully estimated the survival probabilities of the different age classes considered. Survival probability was similar between adults (0.83, 95% CI = 0.77–0.87) and juveniles during their second (0.79, 95% CI = 0.58–0.87) and third winter (0.83, 95% CI = 0.65–0.88). The youngest juveniles (1st winter) showed a slightly lower survival (0.57, 95% CI = 0.37–0.79). Among adults, females showed a slightly higher survival than males (0.87, 95% CI = 0.78–0.93; and 0.80, 95% CI = 0.73–0.86, respectively). These high survival figures predict high population persistence in this species and urge management policies. The analysis also stresses the usefulness of multievent models to estimate juvenile survival when age cannot be fully ascertained. 相似文献
8.
Edward E. DeMartini Brian J. Zgliczynski Raymond C. Boland Alan M. Friedlander 《Environmental Biology of Fishes》2009,85(4):319-332
This paper describes the results of a field survey designed to test the prediction that the density of benthic juveniles of
shallow-reef fishes is greater on wind-wave “exposed” sectors of a pair of isolated oceanic atolls (Kure, Pearl and Hermes)
at the far northwestern end of the Hawaiian Islands, an archipelago in which east-northeasterly trade winds dominate onshore
water flow and transport by surface currents. The densities of recruits (juveniles ≤5 cm total length) were higher overall
on windward versus leeward sectors of carbonate rock-rubble back reefs at both atolls, and the pattern was stronger for smaller
(likely younger, more recently settled) recruits of four of the five most abundant species and the remainder pooled as an
“Other” taxon. The windward-leeward disparity was four-fold greater at Pearl Hermes (the atoll with a three-fold longer perimeter)
than at Kure. Resident predator biomass also was correlated with recruit densities, but habitat (benthic substratum) effects
were generally weak. The distribution and abundance of recruits and juveniles of the primarily endemic reef fishes on shallow
back reefs at these atolls appear partly influenced by relative rates of water flow over windward vs. leeward sectors of barrier
reef and by the size, shape, and orientation of habitat parcels that filter out postlarval fishes with relatively weak swimming
capabilities like labroids. Whole-reef geomorphology as well as fine-scale habitat heterogeneity and rugosity should be considered
among the suite of many factors used to interpret observed spatial patterns of post-settlement juvenile fish distribution
at atolls and perhaps some other tropical reefs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
We assessed density- and distance-dependence in herbivore effects and juvenile condition for four species of Shorea, the most speciose genus in the dominant canopy family of southeast Asian rain forest trees (Dipterocarpaceae). Herbivore
damage was quantified as partial leaf loss on young leaves, and whole plant foliar condition as the product of the fraction
of leaf nodes containing leaves and the fraction of tissue remaining on extant leaves. Adults of the four species were centers
of high total, as well as conspecific, density of juveniles (<1 m tall). For two species, S. hopeifolia and S. pinanga, herbivore damage declined significantly with distance, decreasing by 40% and 51% respectively, between 5 m and 35 m from
the parent. For the same two species, foliar condition improved significantly between 5 m and 35 m, increasing by 45% for
S. hopeifolia and 24% for S. pinanga. If foliar condition influences juvenile survival and growth, more widely dispersed seeds of these species are more likely
to recruit to the canopy. In contrast, there was no significant distance-dependence for S. parvifolia or S. longisperma. Among species, herbivore damage was greatest in those species with greatest local juvenile abundances, i.e., those with highest
densities, leaf size, juvenile foliar mass and/ or foliar mass/m2 ground area, but was unrelated to the toughness of mature leaves. However, distance was a better predictor of herbivore damage
than was conspecific juvenile density, as evaluated by backward elimination regressions, for both S. hopeifolia and S. pinanga. For foliar condition, the best predictor was distance for S. pinanga, but conspecific density for S. hopeifolia, whose juveniles were smallest and occurred at the highest densities. Total juvenile density (all woody plants) was eliminated
as a factor in all cases. The species-specificity of effects (i.e., their dependence on conspecific distance or density),
together with the marked differences among congeneric species, caution against generalizations regarding distance-dependent
effects in diverse forests.
Received: 21 April 1998 / Accepted: 8 July 1998 相似文献
10.
The timing of reproduction is one of the most crucial life history traits, with enormous consequences for the fitness of an
individual. We investigated the effects of season and timing of birth on local survival probability in a small mammalian hibernator,
the common dormouse (Muscardinus avellanarius). Local monthly survival probability was lowest in the early active season (May–August, ϕadult = 0.75–0.88, ϕjuvenile = 0.61–0.68), increased during the late active season (August–October), and highest during hibernation (October–May, ϕadult = 0.96–0.98, ϕjuvenile = 0.81–0.94). Consequently, dormice had an extremely high winter survival probability. We observed two peaks in the timing
of reproduction (June and August/September, respectively), with the majority of juveniles born late in the active season.
Although early investment in reproduction seems the better life history tactic [survival probability until onset of reproduction:
ϕborn early = 0.46, 95% confidence interval (CI) 0.28–0.64; ϕborn late = 0.19, 95% CI = 0.09–0.28], only females with a good body condition (significantly higher body mass) invest in reproduction
early in the year. We suggest the high over-winter survival in dormice allows for a unique life history pattern (i.e., combining
slow and fast life history tactics), which leads to a bimodal seasonal birth pattern: (1) give birth as early as possible
to allow even the young to breed before hibernating, and/or (2) give birth as late as possible (leaving just enough time for
these young to fatten) and enter directly into a period associated with the highest survival rates (hibernation) until maturity. 相似文献
11.
SMAD7 has been demonstrated to antagonize TGF-β-mediated fibrosis, carcinogenesis, and inflammation. Two previous genome-wide
association studies identified three single nucleotide polymorphisms (SNPs) (rs4939827, rs12953717 and rs4464148) in SMAD7 to be associated with colorectal cancer in a Western population. We conducted the first case–control study in a Han Chinese
population to explore the associations between these three SNPs and colorectal, gastric, and lung cancers. Of the three SNPs,
only rs12953717 was strongly associated with the three types of cancer, fitting the overdominant model. Compared with the
CC/TT (CC combined with TT) genotype, the adjusted odds ratios for the CT genotype were 2.002 (95% CI, 1.250–3.207, P = 0.004), 1.678 (95% CI, 1.048–2.689, P = 0.031), 3.825 (95% CI, 2.310–6.335, P < 1 × 10−4), and 2.294 (95% CI, 1.537–3.343, P < 1 × 10−4), respectively, for colorectal, gastric, lung, and combined cancers. These outcomes suggest that rs12953717 is a common risk
marker of these three types of cancer in the Han Chinese. 相似文献
12.
Conspecific density dependence and community structure: Insights from 11 years of monitoring in an old‐growth temperate forest in Northeast China 下载免费PDF全文
Xu Kuang Kai Zhu Zuoqiang Yuan Fei Lin Ji Ye Xugao Wang Yunyun Wang Zhanqing Hao 《Ecology and evolution》2017,7(14):5191-5200
Forest community structure may be influenced by seedling density dependence, however, the effect is loosely coupled with population dynamics and diversity in the short term. In the long term the strength of conspecific density dependence may fluctuate over time because of seedling abundance, yet few long‐term studies exist. Based on 11 years of seedling census data and tree census data from a 25‐ha temperate forest plot in Northeast China, we used generalized linear mixed models to test the relative effects of local neighborhood density and abiotic factors on seedling density and seedling survival. Spatial point pattern analysis was used to determine if spatial patterns of saplings and juveniles, in relation to conspecific adults, were in accordance with patterns uncovered by conspecific negative density dependence at the seedling stage. Our long‐term results showed that seedling density was mainly positively affected by conspecific density, suggesting dispersal limitation of seedling development. The probability of seedling survival significantly decreased over 1 year with increasing conspecific density, indicating conspecific negative density dependence in seedling establishment. Although there was variation in conspecific negative density dependence at the seedling stage among species and across years, a dispersed pattern of conspecific saplings relative to conspecific adults at the local scale (<10 m) was observed in four of the 11 species examined. Overall, sapling spatial patterns were consistent with the impacts of conspecific density on seedling dynamics, which suggests that conspecific negative density dependence is persistent over the long term. From the long‐term perspective, conspecific density dependence is an important driver of species coexistence in temperate forests. 相似文献
13.
Sevil Demirci Özkan Akar Emrah Şimşek Aydın Demirci Şükran Yalçın Özdilek 《Zeitschrift fur angewandte Ichthyologie》2020,36(6):918-923
The biological characteristics of eels from the Asi River, Turkey, were assessed between December 2017 and November 2018. Eels were sampled monthly using fyke nets (operated by professional fishermen), yielding a total of 509 specimens. Total length and weight were measured, sex, age and maturity stages (silver or yellow eel) were determined. Catch Per Unit Effort (CPUE) was calculated for both biomass per unit effort and numbers caught on a monthly and annual basis. The length-weight relationships (LWRs) of silver and yellow eel was W = 0.009*TL3.22 (n = 262) and W = 0.0106*L3.09 (n = 247), respectively. The age of the sampled fish ranged from year class II to VI. Von Bertalanffy growth parameters were estimated as L∞=69.25 cm, K = 0.43 1/year, t0= −0.41 and phi prime index ( ǿ )= 3.31 for all samples. The overall eel fishing mortality rate (F) was 0.31 year-1, and the exploitation and survival rates of silver stage eels were estimated with 30% and 39%, respectively. 相似文献
14.
Pedro Bernardo Sarmento Joana P. Cruz Catarina I. Eira Carlos Fonseca 《European Journal of Wildlife Research》2010,56(1):59-66
Using camera-trapping techniques, the present study, conducted from 2005 to 2007, provides common genet abundance estimates
in Serra da Malcata Nature Reserve (central-eastern Portugal). We estimated genet abundance using the software CAPTURE. It
was possible to obtain a capture success of 1.49 captures/100 trap-nights. Considering the heterogeneity model (Mh), which presents higher biological significance, the estimated density varied between 0.50 (95% CI = 0.43–0.56 genets/km2) to 0.92 (95% CI = 0.87–0.97 genets/km2) genets/km2 with an average density value of 0.70 genets/km2 (95% CI = 0.58–0.82 genets/km2). These estimates emphasized this technique as a reliable method for assessing average genet density over large spatial scales
and for monitoring future changes in genet numbers. In terms of habitat selection, genets selected Quercus rotundifolia and Arbutus unedo woodlands and avoided Erica spp. and Cistus ladanifer scrubland and Eucalyptus stands. Considering the landscape heterogeneity outside the reserve, our study emphasizes the importance of the protected
area for small carnivore conservation. 相似文献
15.
Aspects of the biology of Abra segmentum were investigated at low salinities in a Mediterranean coastal lagoon (Monolimni Lagoon, Northern Aegean Sea). Monthly samples
were collected during the period from February 1998 to January 1999. Recruitment occurred from mid-spring to early autumn
(0.3–5.7 psu) and recruits grew during summer and autumn (1.2–5.7 psu), while a major part vanished during next autumn, displaying
a maximum life span of about 20 months. A positive correlation was found between the percentage of individuals having a shell
length of ≤3.5 mm and temperature; age group 0 showed a growth rate of 0.97 mm per month, and the largest individual collected
had a 19.76 mm shell length. The population density sharply increased during late spring (0.3–1.2 psu); this increase was
followed by a decline during summer and, afterwards, a gradual increase up to late autumn. Secondary production calculated
by the size–frequency method gave a mean annual density (n) of 3,357 individuals m−2, a mean annual biomass (B) of 21.98 g DW m−2, an annual production (P) of 73.72 g DW m−2 and a P:B ratio of 3.35. A comparison of the present data with available data of A. segmentum populations from higher salinity habitats revealed that this bivalve in the study area showed a life history pattern similar
to that of other populations of the species and a comparatively high growth rate, maximum body size, n, B, P and P:B ratio. Our findings suggest that the studied aspects of A. segmentum biology could not be markedly affected by low salinities. 相似文献
16.
17.
Virginia R. Shervette Natalie Ibarra Frances Gelwick 《Environmental Biology of Fishes》2007,78(2):125-134
We investigated the effect of salinity on growth, survival, and condition of pinfish Lagodon rhomboides juveniles (36–80 mm standard length) in two laboratory experiments in July 2003 and June/July 2004. Our results show that
juvenile pinfish grown in laboratory conditions under a range of salinities experience rapid growth and high survival in typical
estuarine-like salinities (15–30 ppt). We also found that relative weight as an index of condition corroborates the idea that
pinfish are well adapted to survive and grow in a wide range of salinities. Such rapid growth and high survival in a dynamic
environment may afford juvenile pinfish potential ecological advantages over other estuarine-dependent fish species that are
relatively more constrained by changes in salinity regime. Because coastal development is wide-spread throughout Gulf of Mexico
and Atlantic estuaries, insights concerning the impacts of human-induced changes to estuarine environments are essential for
effective management practices. 相似文献
18.
Introduction PARP-1 plays important role in the BER (base excision repair) and maintenance of genomic integrity. Previous study found
the Val762Ala genetic variant in the PARP-1 gene contributed to susceptibility of some cancers and decreased PARP-1 enzyme
activity in response to oxidative damage. Helicobacter pylori (H. pylori) infection was thought to be one of the major causes of gastric cancer. In this study, we investigated the association between
the PARP-1 Val762Ala polymorphism, CagA+
H. pylori infection, and the risk for gastric cancer. Methods This hospital-based, case–control study was performed involving 556 individuals (236 cases with gastric cancer and 320 controls
without evidence of neoplasm and gastrointestinal disease) using a PCR-RFLP method. Chi-square test and logistic regression
analysis were used to count OR and 95% CI. Results 762Ala/Ala genotype was overrepresented in the cases (16.9%) compared with controls (10.3%), (OR, 1.942; 95% CI, 1.157–3.257,
P = 0.011). Multivariate analysis showed that two factors were significantly associated with risk of gastric cancer, including
CagA+
H. pylori infection (OR, 2.562; 95% CI, 1.174–5.240, P = 0.037), PARP-1 762AA genotype (OR, 1.772; 95% CI, 1.065–3.867; P = 0.042). Stratification analysis indicated that among Cag+
H. pylori positive subjects, 762Ala/Ala carriers had higher risk for developing gastric cancer compared with 762Val/Val carrier (OR,
2.337; 95% CI, 1.148–4.758; P = 0.017). Conclusion PARP-1 762Ala/Ala could be a risk factor for gastric cancer in Han Chinese population; PARP-1 762Val/Ala polymorphism and
Cag+
H. pylori infection jointly contribute to higher risk for gastric cancer. 相似文献
19.
The economic value of ecosystem services of vegetated habitats (seagrass and macroalgal beds) has been estimated to be among
the highest of the various ecosystems on earth. However, fish production has not been included in the evaluations due to the
difficulty of quantitative estimation of fish production in the field. In the present study, annual production and economic
value of wild juvenile black rockfish, Sebastes cheni, a dominant fish species in seagrass and macroalgal beds in the central Seto Inland Sea were estimated. Juvenile S. cheni migrated into vegetated habitats at about 20 mm total length (TL) and grew up to about 60 mm TL by late May. Juvenile abundance
was highest in April (2007) or March (2008). Eight cohorts with the same extrusion period (each cohort covering a 10-day period)
were identified using otolith daily increments. The annual estimates of S. cheni juvenile production were 13,080 g ha−1 year−1 in 2007 and 18,360 g −1 year−1 in 2008. Based on the unit price of artificially raised S. cheni juveniles, the economic value of the annual wild juvenile production was converted to 654,000 JPY (Japanese yen: 100 JPY = ca.
1 USD) ha−1 year−1 for 2007 and 918,000 JPY ha−1 year−1 for 2008. Analyses of stomach contents and stable isotope (δ13C or δ15N) showed that juvenile S. cheni were highly dependent on copepods. The planktonic trophic pathway originating from phytoplankton supports the majority of
the juvenile black rockfish production during the post-migration period (20–60 mm TL) in the seagrass and macroalgal beds
through the production of copepod zooplankton. The total economic value of the ecosystem services of the vegetated habitat
is suggested to be much higher than estimates in previous studies if the provisioning and regulating services which originate
from fish production were included in the estimates. 相似文献
20.
Erick S. Van Dyke Dennis L. Scarnecchia Brian C. Jonasson Richard W. Carmichael 《Hydrobiologia》2009,625(1):27-42
Winter concealment habitat quality was assessed and its use by juvenile spring Chinook salmon (Oncorhynchus tshawytscha) quantified in three hatching areas of the Grande Ronde River Basin, Oregon USA. Fish densities were significantly higher
in pools with a higher winter concealment habitat index than pools with a lower index. The mean fork length and mean growth
rate of fish did not differ between pools with a higher or lower winter concealment habitat index, even though residual fish
were significantly larger than fish that emigrated. Biomass–density was significantly higher in pools with a higher winter
concealment habitat index than pools with a lower index in all three hatching areas. Biomass–density was positively associated
with the amount of cobble substrate (10–24.9 cm/m2) in all three hatching areas, and inversely associated with embeddedness in two of the hatching areas. Results of this study
indicate that enhancing winter concealment habitat could improve habitat quality resulting in increased carrying capacity
and winter usage by juvenile spring Chinook salmon.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: J. A. Cambray 相似文献