The demography of recovery of an overexploited bull trout, Salvelinus confluentus, population

2007 ◽  
Vol 64 (1) ◽  
pp. 113-126 ◽  
Author(s):  
Fiona D Johnston ◽  
John R Post ◽  
Craig J Mushens ◽  
Jim D Stelfox ◽  
Andrew J Paul ◽  
...  
Keyword(s):  
Adult Population ◽  
Fold Increase ◽  
Recovery Process ◽  
Data Sets ◽  
Adult Density ◽  
Life Stages ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Compensatory Response ◽  
Density Dependent

An exploited bull trout, Salvelinus confluentus, population experienced a 28-fold increase in adult density during a 10-year period from a minimum of 60 individuals. This demonstrates the extent to which this population was overharvested. Its ability to respond in fewer than two generations to the implementation of zero-harvest regulations suggests this population was growth-overfished not recruitment-overfished. Examination of stock–recruitment relationships of various life stages indicates that recovery of this population was regulated by the density-dependent survival of juveniles in the rearing creek. This compensatory response occurred between egg deposition and age-1 and regulated the number of fish recruiting into the adult population. A second population bottleneck became apparent later in the recovery process when density-dependent survival of the adult population resulted in its approach to an asymptote, highlighting the necessity of long-term data sets for examining these compensatory responses. Results from this study demonstrate the importance of understanding the influence of individual life stages on the ability of overexploited populations such as threatened bull trout to recover and for their future management.

scholarly journals Density-dependent adult recruitment in a low-density tropical tree

2018 ◽  
Vol 115 (44) ◽  
pp. 11268-11273 ◽  
Author(s):  
James R. Kellner ◽  
Stephen P. Hubbell
Keyword(s):  
Tree Species ◽  
Adult Population ◽  
Adult Density ◽  
Tree Recruitment ◽  
Density Dependent ◽  
Conspecific Density ◽  
Density Dependent Mortality ◽  
Conspecific Adult ◽  
Adult Tree ◽  
Dependent Mortality

The Janzen–Connell hypothesis is a well-known explanation for why tropical forests have large numbers of tree species. A fundamental prediction of the hypothesis is that the probability of adult recruitment is less in regions of high conspecific adult density, a pattern mediated by density-dependent mortality in juvenile life stages. Although there is strong evidence in many tree species that seeds, seedlings, and saplings suffer conspecific density-dependent mortality, no study has shown that adult tree recruitment is negatively density dependent. Density-dependent adult recruitment is necessary for the Janzen–Connell mechanism to regulate tree populations. Here, we report density-dependent adult recruitment in the population of Handroanthus guayacan, a wind-dispersed Neotropical canopy tree species. We use data from high-resolution remote sensing to track individual trees with proven capacity to flower in a lowland moist forest landscape in Panama and analyze these data in a Bayesian framework similar to capture–recapture analysis. We independently quantify probabilities of adult tree recruitment and detection and show that adult recruitment is negatively density dependent. The annualized probability of adult recruitment was 3.03% ⋅ year−1. Despite the detection of negative density dependence in adult recruitment, it was insufficient to stabilize the adult population of H. guayacan, which increased significantly in size over the decade of observation.

Evidence of density-dependent oviposition behaviour byListronotus bonariensis(Coleoptera: Curculionidae) in Canterbury pasture

1998 ◽  
Vol 88 (5) ◽  
pp. 527-536 ◽  
Author(s):  
M.R. McNeill ◽  
D.B. Baird ◽  
S.L. Goldson
Keyword(s):  
Biological Control ◽  
Field Experiments ◽  
Adult Population ◽  
Egg Laying ◽  
Oviposition Behaviour ◽  
Initial Population ◽  
Adult Density ◽  
Control Effort ◽  
Density Dependent ◽  
Age Related

AbstractArgentine stem weevil (Listronotus bonariensis) (Kuschel) is a pasture pest ofLoliumspp. in New Zealand and is the target of a classical biological control programme using the parasitoidMicroctonus hyperodaeLoan. However, laboratory experiments have indicated a strong density-dependent egg laying response which may have important implications for the biological control effort. Two field experiments were conducted using a manipulated range of weevil densities within 2.0–2.4 m–2field enclosures and oviposition activity measured by weekly sampling of grass tillers within the enclosures. In both experiments, density had no effect on general oviposition behaviour although the percentage of tillers found to be infested with eggs increased significantly at higher densities. In experiment 1,L. bonariensisexhibited strong density-dependent oviposition with a significant decline in eggs/tiller/female with increasing adult density. An initial population of fiveL. bonariensism−2oviposited 32 times more eggs/tiller/female than 200L. bonariensism−2. By comparison, density-dependent oviposition was absent in experiment 2 with eggs/tiller/female comparable for all densities. The dramatic difference between the two experiments in the expression of density-dependent oviposition was attributed to prevailing spring temperatures during the sampling interval, which in the second experiment were much cooler and delayed the onset of egg laying. It is probable that in experiment 2, oviposition was not regulated by density-dependent cues but limited by temperature and age related mortality in the adult population. The mechanism for density-dependent oviposition, its occurrence in the field and impact on the effectiveness of the parasitoidM. hyperodaeare discussed.

Density-dependent intercohort interactions and recruitment dynamics: models and a bull trout (Salvelinus confluentus) time series

2000 ◽  
Vol 57 (6) ◽  
pp. 1220-1231 ◽  
Author(s):  
Andrew J Paul ◽  
John R Post ◽  
George L Sterling ◽  
Carl Hunt
Keyword(s):  
Time Series ◽  
Survival Rates ◽  
Effective Density ◽  
Bull Trout ◽  
Age Classes ◽  
Salvelinus Confluentus ◽  
Density Dependent ◽  
Age Cohorts ◽  
Juvenile Mortality ◽  
Stochastic Version

A simple theoretical model shows that mechanisms of density-dependent survival that result in stable dynamics for populations with only intracohort interactions during the juvenile phase can produce cyclic behaviour when cohorts interact together. We compared these theoretical results with a time series (1971-1985) on juvenile bull trout (Salvelinus confluentus) from Eunice Creek, Alberta. Abundance of bull trout in Eunice Creek ranged over two orders of magnitude over the 15 years. By assigning age-classes to the abundance data (using a probabilistic length-frequency analysis), we assessed yearly survival rates for age-classes 1-3. Survival rates for age-classes 1 and 2 were negatively correlated (P < 0.05) with the effective density (an index of total consumption) of all juvenile bull trout in Eunice Creek. These observations support the hypothesis that different age cohorts of juvenile bull trout do interact. Using a stochastic version of the model and parameter values estimated from Eunice Creek, we hypothesize that even moderate levels of adult mortality (an average adult spawns during two seasons) coupled with random variation in the density-independent component of juvenile mortality can result in an apparent cyclic pattern for bull trout. Finally, stock- recruitment relationships for these populations are not represented by a single average curve.

The Worrying Trend of Diabetes Mellitus in Saudi Arabia: An Urgent Call to Action

2020 ◽  
Vol 16 (3) ◽  
pp. 204-210 ◽  
Author(s):  
Asirvatham A. Robert ◽  
Mohamed A. Al Dawish
Keyword(s):  
Diabetes Mellitus ◽  
Saudi Arabia ◽  
Present Report ◽  
Adult Population ◽  
Current Trend ◽  
Fold Increase ◽  
Developed Countries ◽  
Evidence Base ◽  
Small Sample ◽  
Cross Sectional

From last few years, the pervasiveness of diabetes mellitus (DM), in Saudi Arabia, is growing at a frightening rate. Overall, one-fourth of the adult population is affected by DM, which is further predicted to rise to more than double by the year 2030. The most alarming is possibly the escalation propensity of diabetes, in recent years, where a nearly ten-fold increase has been witnessed over the past thirty years in Saudi Arabia. However, the number of research arbitrations on the prevalence and incidence of DM is woefully inadequate, as compared to developed countries. Apart from this, most of the existing research data carried out in Saudi Arabia is cross-sectional, with small sample sizes, which most often involve only certain parts of the country. Consequently, the present scenario demands more multidimensional and multisectoral research to strengthen the evidence base and to accumulate greater knowledge as a basis for measures and programmes to confront diabetes and its complications. Thus, the present report makes an attempt to depict the current trend of diabetes as well as intends to put forward essential measures for controlling diabetes in Saudi Arabia.

scholarly journals Age-dependent intra-specific competition in pre-adult life stages and its effects on adult population dynamics

2015 ◽  
Vol 27 (1) ◽  
pp. 131-156
Author(s):  
RONGSONG LIU ◽  
GERGELY RÖST ◽  
STEPHEN A. GOURLEY
Keyword(s):  
Disease Transmission ◽  
Adult Population ◽  
Adult Life ◽  
Life Stages ◽  
Larval Competition ◽  
Amphibian Species ◽  
Age Dependent ◽  
Age Structured ◽  
Delay Differential ◽  
Boundedness And Persistence

Intra-specific competition in insect and amphibian species is often experienced in completely different ways in their distinct life stages. Competition among larvae is important because it can impact on adult traits that affect disease transmission, yet mathematical models often ignore larval competition. We present two models of larval competition in the form of delay differential equations for the adult population derived from age-structured models that include larval competition. We present a simple prototype equation that models larval competition in a simplistic way. Recognising that individual larvae experience competition from other larvae at various stages of development, we then derive a more complex equation containing an integral with a kernel that quantifies the competitive effect of larvae of ageāon larvae of agea. In some parameter regimes, this model and the famous spruce budworm model have similar dynamics, with the possibility of multiple co-existing equilibria. Results on boundedness and persistence are also proved.

The Future of Aging Research: Should the Focus Be On Not Growing Old or Growing Old Better?

2016 ◽  
Vol 5 (1) ◽  
pp. 65-74
Author(s):  
Debra J. Rose
Keyword(s):  
Scientific Inquiry ◽  
Healthy Lifestyle ◽  
Adult Population ◽  
Life Stages ◽  
Lifestyle Behaviors ◽  
Aging Research ◽  
Negative Stereotypes ◽  
Conducting Research ◽  
Older Adult Population

Despite the significant increase in years that an individual can now expect to live in the 21st century, there is growing evidence that the price for greater longevity may be worsening health due to the higher prevalence of nonfatal but disabling conditions. This sobering news suggests the need for expanded scientific inquiry directed at understanding the multilevel factors that promote or prevent physical activity (PA) participation and the adoption of healthy lifestyle behaviors and the types of intervention strategies that will be most effective in positively changing behavior at different life stages. Fruitful areas of future scientific inquiry include exploring other types and intensities of PA aimed at increasing PA participation while reducing sedentary behavior, better understanding the role of the physical and social environment in promoting PA participation, and designing and evaluating multilevel PA interventions that are better tailored to the activity preferences, goals, and expectations of a diverse older adult population, and flexibly delivered in real-world settings. Finally, conducting research aimed at better differentiating normal age-associated changes from those that are disease-related will be fundamental to reversing the negative stereotypes that currently shape the public’s view of the aging process.

Genetic clustering methods reveal bull trout (Salvelinus confluentus) fine-scale population structure as a spatially nested hierarchy

2009 ◽  
Vol 11 (4) ◽  
pp. 1421-1433 ◽  
Author(s):  
Will G. Warnock ◽  
Joseph B. Rasmussen ◽  
Eric B. Taylor
Keyword(s):  
Population Structure ◽  
Bull Trout ◽  
Fine Scale ◽  
Clustering Methods ◽  
Salvelinus Confluentus ◽  
Scale Population ◽  
Nested Hierarchy ◽  
Genetic Clustering

Oxygen Availability as a Control Factor in the Density-Dependent Regulation of Protein Synthesis in Cell Culture

1974 ◽  
Vol 14 (2) ◽  
pp. 331-337
Author(s):  
DESH PAL S. VERMA ◽  
A. MARCUS
Keyword(s):  
Cell Culture ◽  
Protein Synthesis ◽  
Respiratory Rate ◽  
Initial Function ◽  
Fold Increase ◽  
Oxygen Availability ◽  
Control Factor ◽  
Atp Level ◽  
Density Dependent ◽  
Inadequate Nutrition

Dilution of a density-inhibited Arachis culture results in a 10-fold increase in capacity for protein synthesis during the first 2 h after dilution. The limitation in the density-inhibited state is not inadequate nutrition, inappropriate pH, or a diffusible inhibitor as the dilution can be carried out in medium obtained by filtration of 14-day cells. The respiratory rate of the culture increases 2-fold immediately after dilution and the ATP level increases 3-fold dunng the 2-h period subsequent to dilution. These observations suggest that the initial function activated by dilution is an increased availability of oxygen and that this increase in oxygen provides an increased level of ATP, finally resulting in an increased rate of protein synthesis. This idea is further supported by the finding that both the increase in cellular ATP and the acceleration of the rate of protein synthesis can be obtained in dense culture, in the absence of dilution, by maintaining the cells for 2 h under oxygen.

Geographic distribution, species displacement, and niche overlap for lake trout and bull trout in mountain lakes

1993 ◽  
Vol 71 (2) ◽  
pp. 238-247 ◽  
Author(s):  
David B. Donald ◽  
David J. Alger
Keyword(s):  
Trophic Structure ◽  
Lake Trout ◽  
Niche Overlap ◽  
Mountain Lakes ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
East Central ◽  
Allopatric Populations ◽  
Trout Population ◽  
The One

Indigenous lacustrine populations of bull trout (Salvelinus confluentus) and lake trout (S. namaycush) are spatially separated within the southern part of the zone of distributional overlap (northern Montana, southwestern Alberta, and east-central British Columbia). In this area, lake trout occurred primarily in mountain lakes of 1032–1500 m elevation, while bull trout were found primarily in lakes between 1500 and 2200 m. Introductions of lake trout in the twentieth century and data obtained from beyond the study area indicated that both fishes can establish significant allopatric populations (more than 5% of the catch) in large, deep lakes (>8 ha in area and >8 m deep) over a wide elevation range. We tested the hypothesis that lake trout displace or exclude bull trout from lakes by determining the outcome of introductions of lake trout into two lakes that supported indigenous bull trout. Lake trout were introduced into Bow Lake in 1964, and by 1992 the bull trout population was decimated there and in another lake (Hector) situated 15 km downstream. Thus, lake trout can displace bull trout and may prevent bull trout from becoming established in certain low-elevation lakes. Population age-structure analyses also suggest that lake trout adversely affected bull trout. Bull trout populations in sympatry with lake trout, including the one extirpated from Hector Lake, had few old fish (18% were more than 5 years old; N = 40 fish from three lakes) compared with allopatric populations (49% were more than 5 years old; N = 235 fish from seven lakes). Niche overlap and the potential for competition between the two char species were substantial. In lakes with trophic structure ranging from simple to complex, bull trout and lake trout fed on similar foods and had similar ecological efficiencies (growth rates). Predation by lake trout on bull trout was not documented during the study.

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