Fish predation and trapping for rusty crayfish (Orconectes rusticus) control: a whole-lake experiment

2006 ◽  
Vol 63 (2) ◽  
pp. 383-393 ◽  
Author(s):  
Catherine L Hein ◽  
Brian M Roth ◽  
Anthony R Ives ◽  
M Jake Vander Zanden
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Fish Predation ◽  
Reproductive Value ◽  
Orconectes Rusticus ◽  
Long Term Effects ◽  
Structured Population Model ◽  
Rusty Crayfish ◽  
Crayfish Population

Improved methods are needed for the prevention and control of invasive species. We investigated the potential to control a rusty crayfish (Orconectes rusticus) population in an isolated lake in northern Wisconsin by trapping adult crayfish and restricting fishing, thereby increasing fish populations and predation on small crayfish. Over a 3 year period, traps and predatory fishes removed substantial portions of the rusty crayfish population. We used an age-structured population model to determine which removal method had the largest effect on crayfish population growth rates. Because more crayfish were vulnerable to and removed by fish predation than by trapping, fish predation caused a larger decline in the population growth rate. However, trapping removed crayfish with the highest reproductive value and caused the largest decline in population growth rate per individual crayfish removed. Consideration of density-dependent responses to removal is necessary to predict long-term effects on rusty crayfish population dynamics. Nonetheless, our results suggest that the combination of trapping and fish predation can control established rusty crayfish populations and deserves further consideration for management.

scholarly journals Biological scaling in green algae: the role of cell size and geometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helena Bestová ◽  
Jules Segrestin ◽  
Klaus von Schwartzenberg ◽  
Pavel Škaloud ◽  
Thomas Lenormand ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Internal Diffusion ◽  
Scaling Exponent ◽  
Power Scaling ◽  
Nutrient Distribution ◽  
Metabolic Scaling ◽  
Key Factor ◽  
Size And Morphology

AbstractThe Metabolic Scaling Theory (MST), hypothesizes limitations of resource-transport networks in organisms and predicts their optimization into fractal-like structures. As a result, the relationship between population growth rate and body size should follow a cross-species universal quarter-power scaling. However, the universality of metabolic scaling has been challenged, particularly across transitions from bacteria to protists to multicellulars. The population growth rate of unicellulars should be constrained by external diffusion, ruling nutrient uptake, and internal diffusion, operating nutrient distribution. Both constraints intensify with increasing size possibly leading to shifting in the scaling exponent. We focused on unicellular algae Micrasterias. Large size and fractal-like morphology make this species a transitional group between unicellular and multicellular organisms in the evolution of allometry. We tested MST predictions using measurements of growth rate, size, and morphology-related traits. We showed that growth scaling of Micrasterias follows MST predictions, reflecting constraints by internal diffusion transport. Cell fractality and density decrease led to a proportional increase in surface area with body mass relaxing external constraints. Complex allometric optimization enables to maintain quarter-power scaling of population growth rate even with a large unicellular plan. Overall, our findings support fractality as a key factor in the evolution of biological scaling.

Climate‐driven carry‐over effects negatively influence population growth rate in a food‐caching boreal passerine

2020 ◽  
Author(s):  
Alex O. Sutton ◽  
Dan Strickland ◽  
Nikole E. Freeman ◽  
D. Ryan Norris
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Food Caching ◽  
Carry Over

Lessons from a century of conservation translocations

2021 ◽  
Author(s):  
Shane D Morris ◽  
Katherine E. Moseby ◽  
Barry W. Brook ◽  
Christopher N. Johnson
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Historical Context ◽  
Extrinsic Factors ◽  
Global Database ◽  
Terrestrial Vertebrates ◽  
Failure Classification ◽  
High Population Growth ◽  
Number Of Individuals

Translocation—moving individuals for release in different locations—is among the most important conservation interventions for increasing or re-establishing populations of threatened species. However, translocations often fail. To improve their effectiveness, we need to understand the features that distinguish successful from failed translocations. Here, we assembled and analysed a global database of translocations of terrestrial vertebrates (n=514) to assess the effects of various design features and extrinsic factors on success. We analysed outcomes using standardized metrics i.e. a categorical success/failure classification, and population growth rate. Probability of categorical success and population growth rate increased with the total number of individuals released but with diminishing returns above about 20-50 individuals. There has been no increase in numbers released per translocation over time. Positive outcomes—reported success and high population growth—were less likely for translocation in Oceania, possibly because invasive species are a major threat in this region and are difficult to control at translocation sites. Increased rates of categorical reported success and population growth were found for Europe and North America, suggesting the key role of historical context in positive translocation outcomes. Categorical success has increased throughout the 20th century, but that increase may have plateaued at about 75% since about 1990. Our results suggest there is potential for further increase in the success of conservation translocations. This could be best achieved by greater investment in individual projects, as indicated by total number of animals released.

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