Density-dependent growth of double-crested cormorant colonies on Lake Huron

2006 ◽  
Vol 84 (10) ◽  
pp. 1409-1420 ◽  
Author(s):  
Mark S. Ridgway ◽  
J. Bruce Pollard ◽  
D.V. Chip Weseloh
Keyword(s):  
Time Series ◽  
Population Growth ◽  
Carrying Capacity ◽  
Colony Size ◽  
Lake Huron ◽  
Population Increase ◽  
Density Dependent ◽  
Georgian Bay ◽  
The North ◽  
Dependent Growth

By analyzing 20+ years of data, we found that the nesting colonies of double-crested cormorants ( Phalacrocorax auritus (Lesson, 1831)) in the North Channel and Georgian Bay of Lake Huron exhibit density-dependent population regulation. This conclusion is based on four lines of evidence. First, a time series of nest counts at specific colonies (1979–2001) showed density-dependent growth based on randomization tests of the time series. Second, the per capita rate of change in colony size declined with increasing colony size over a 10-year period. Third, a Ricker model of aggregate nest counts showed that population growth of nesting double-crested cormorants stabilized in recent years (through 2003), with K, the carrying capacity parameter, being 11 445 nests in the North Channel and 10 815 nests in Georgian Bay. Fourth, a colony area index showed near complete coverage of coastal areas by adult nesters coinciding with overall declines in population growth. High rates of population increase of double-crested cormorants on Lake Huron have largely come to an end, but changes in fish abundance may result in changes in carrying capacity.

scholarly journals Evaluation of the Shepherd and Cushing (1980) model of density-dependent survival: a case study using striped bass (Morone saxatilis) larvae in the Potomac River, Maryland, USA

2003 ◽  
Vol 60 (6) ◽  
pp. 1275-1287 ◽  
Author(s):  
Edward S Rutherford ◽  
Kenneth A Rose ◽  
James H Cowan
Keyword(s):  
Regression Model ◽  
Striped Bass ◽  
Carrying Capacity ◽  
Field Data ◽  
Larval Growth ◽  
Fish Population ◽  
Potomac River ◽  
Average Growth ◽  
Density Dependent ◽  
Dependent Growth

Abstract Quantifying the degree of density-dependence in stock–recruit relationships is critical to understanding fish population dynamics. The Shepherd and Cushing (1980) model couples a simple model of density-dependent larval growth with a constant rate of mortality to predict numbers surviving to recruitment. The model has not been evaluated using field data, nor have its predictions been compared with those from other models. Here, the S&C model, an individual-based model (IBM), and a regression model are applied to 8 years of field data for striped bass larvae in the Potomac River, Maryland, USA, to predict larval carrying capacity (K) and percentage of recruitment lost as a consequence of density-dependent growth. The IBM and the regression model were corroborated by comparing their predictions of average growth rates of larvae and relative recruitment strengths to observed values for the 8 years of field data. Although the IBM and the regression model differed in their predictions of several important intermediate variables, both models predicted higher values of K and lower values of density-dependent growth than did the S&C model. Over the 8 years, the IBM and the regression model predicted an average of 0.3 and 1.8% recruitment lost as a result of density-dependent growth, respectively. In contrast, the S&C model predicted much higher recruitment lost (average of 27%). Slight differences in the assumed rate of mortality used in the S&C model resulted in values of carrying capacity similar to those predicted by the IBM and the regression model. Difficulties in estimating parameters of the S&C model from field data are discussed.

Lake Huron: Effects of Exploitation, Introductions, and Eutrophication on the Salmonid Community

1972 ◽  
Vol 29 (6) ◽  
pp. 877-887 ◽  
Author(s):  
A. H. Berst ◽  
G. R. Spangler
Keyword(s):  
Water Quality ◽  
Fishery Management ◽  
Management Practices ◽  
Quality Criteria ◽  
Sea Lamprey ◽  
Lake Huron ◽  
Water Quality Criteria ◽  
Saginaw Bay ◽  
Georgian Bay ◽  
The North

Lake Huron is a large, deep, oligotrophic lake, centrally located in the St. Lawrence Great Lakes system. Manitoulin Island and the Bruce Peninsula divide the lake into the relatively discrete water masses of the North Channel, Georgian Bay, and Lake Huron proper. Water quality in Lake Huron has deteriorated only slightly since the early 1800s. The only significant changes are confined to areas adjacent to centers of human activity, chiefly Saginaw Bay and various harbours and estuaries in Georgian Bay and the North Channel. The lake has supported a commercial fishery which has produced annual catches as high as 13000 metric tons. A dramatic decline in landings of commercially valuable species and an instability in fisheries resources has occurred in all areas of the lake since the 1940s. This depression of populations of valued species was associated with the accidental introduction of the sea lamprey, instances of overfishing and deterioration of water quality in Saginaw Bay. The present depressed state of the fisheries will undoubtedly persist until sea lamprey control is achieved and climax predators are reestablished. Governments are proceeding toward the establishment of water quality criteria and fishery management practices which, hopefully, will stabilize the fisheries and prevent further deterioration of the aquatic environment.

scholarly journals Rapid plastic shifts in body size precede and determine population growth

2021 ◽  
Author(s):  
Jean Philippe Gibert ◽  
Ze-Yi Han ◽  
Daniel J Wieczynski ◽  
Andrea Yammine
Keyword(s):  
Time Series ◽  
Body Size ◽  
Population Density ◽  
Population Growth ◽  
Carrying Capacity ◽  
Rapid Evolution ◽  
The Other ◽  
Phenotypic Change ◽  
Ecological Processes ◽  
Ecological Dynamics

1. Body size is a fundamental trait linked to many ecological processes-from individuals to ecosystems. Although the effects of body size on metabolism are well-known, how body size influences, and is influenced by, population growth and density is less clear. Specifically, 1) whether body size, or population dynamics, more strongly influences the other, and, 2) whether observed changes in body size are due to plasticity or rapid evolutionary change, are not well understood. 2. Here, we address these two issues by experimentally tracking population density and mean body size in the protist Tetrahymena pyriformis as it grows from low density to carrying capacity. We then use state-of-the-art time-series analyses to infer the direction, magnitude, and causality of the link between body size and ecological dynamics. Last, we fit two alternative dynamical models to our empirical time series to assess whether plasticity or rapid evolution better explains changes in mean body size. 3. Our results clearly indicate that changes in body size precede and determine changes in population density, not the other way around. We also show that a model assuming that size changes via plasticity more parsimoniously explains these observed coupled phenotypic and ecological dynamics than one that assumes rapid evolution drives changes in size. 4. Together these results suggest that rapid, plastic phenotypic change not only occurs well within ecological timescales but may even precede -and causally influence- ecological dynamics. Furthermore, large individuals may be favored and fuel high population growth rates when population density is low, but smaller individuals may be favored once populations reach carrying capacity and resources become scarcer. Thus, rapid plastic changes in functional traits may play a fundamental and currently unrecognized role in familiar ecological processes like logistic population growth.

scholarly journals Density dependence in the camelid Vicugna vicugna: the recovery of a protected population in Chile

Oryx ◽  
2002 ◽  
Vol 36 (2) ◽  
pp. 118-125 ◽  
Author(s):  
C. Bonacic ◽  
D. W. Macdonald ◽  
J. Galaz ◽  
R. M. Sibly
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Density Dependence ◽  
Primary Productivity ◽  
Carrying Capacity ◽  
Population Growth Rate ◽  
Census Data ◽  
South American ◽  
Density Dependent ◽  
Vicugna Vicugna

The vicuña Vicugna vicugna is a wild South American camelid. Following over-exploitation, which brought the species to the brink of extinction in Chile in the 1960s, the population was protected. Since 1975 the population has been censused annually, generating one of the most extensive long-term census databases for any South American mammal. In this paper we use these data, and measures of environmental parameters, to describe the population growth trend of the species and to estimate carrying capacity. Our results indicate that the vicuña has been protected successfully in northern Chile. The census data reveal that, following protection, the population displayed logistic growth between 1975 and 1992. Population growth rate declined linearly with population size, which indicates a degree of density dependence. Density independent factors, such as rainfall, may also have been important. The principal density dependent effect observed was that birth rate declined in those family groups with the most breeding females. The carrying capacity of the study area was estimated from the census data and from models based on precipitation and local primary productivity. Using the census data, an estimation of carrying capacity as the asymptote of the fitted logistic curve suggested that the vicuña population should reach approximately 26,000 vicuñas, whereas estimation when the population growth rate was equated to zero gave a carrying capacity of c. 22,000. Coe's method based on local precipitation predicted 31,000 vicuña, whereas Lavenroth's method based on local primary productivity predicted 26,000 vicuña. In reality, the census data showed that the population peaked at 22,463 vicuñas in 1990. The results are discussed in relation to the need for better census techniques and the implications of density dependent effects for the management of the vicuña in Chile.

A generic target for species recovery

2014 ◽  
Vol 92 (5) ◽  
pp. 371-376 ◽  
Author(s):  
Jeffrey A. Hutchings ◽  
Anna Kuparinen
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Threatened Species ◽  
Carrying Capacity ◽  
First Principles ◽  
Conservation Status ◽  
Basic Density ◽  
Species Recovery ◽  
Density Dependent

Recovery targets for threatened species are typically developed on a species- or population-specific basis. Such narrow taxonomic specificity stands in contrast with widely applied species-independent metrics of conservation status. Here, we propose a generic protocol that can be used to specify broadly applicable targets intended to recover the ecological and evolutionary functionality of threatened species. The method is based on basic density-dependent population dynamics, draws on first principles related to population growth, and explicitly incorporates habitat by accounting for changes in carrying capacity. It offers a consistently applied, methodologically transparent, and predictable biological benchmark for recovery purposes. The benefits of a generic method for articulating recovery targets, particularly from a policy- and statute-implementation perspective, are substantive.

scholarly journals FITNESS AND DENSITY-DEPENDENT POPULATION GROWTH IN DROSOPHILA MELANOGASTER

Genetics ◽  
1981 ◽  
Vol 97 (3-4) ◽  
pp. 667-677
Author(s):  
Laurence D Mueller ◽  
Francisco J Ayala
Keyword(s):  
Drosophila Melanogaster ◽  
Population Growth ◽  
Carrying Capacity ◽  
The Other ◽  
Relative Fitness ◽  
Transfer System ◽  
Chromosome 2 ◽  
Serial Transfer ◽  
Density Dependent ◽  
Entire Chromosome

ABSTRACT The density-dependent rates of population growth were determined for 26 populations of Drosophila melanogaster maintained in the serial transfer system. Twenty-five populations were homozygous for an entire chromosome 2 sampled from nature; the other was a random heterozygous population. Rates of population growth around the carrying capacity cannot explain the large fitness depression of these lines. However, the homozygous lines show large differences in rates of population growth at low densities relative to the random heterozygous standard. The average relative fitness of the homozygous lines, as determined from the growth rates at the lowest density, is 0.51.

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