Among-Population Variability of Fish Growth: III. Influence of Fish Community

1989 ◽  
Vol 46 (9) ◽  
pp. 1539-1550 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Growth Rates ◽  
Yellow Perch ◽  
Fish Community ◽  
Negative Relationship ◽  
Average Density ◽  
Population Variability ◽  
Fish Growth ◽  
Taxonomic Groups ◽  
Food Consumed

We assessed the relationship between in situ fish growth and fish community descriptors in 12 yellow perch (Perca flavescens) populations that exhibited a 1.8 to 10-fold range in growth rates depending on age class. Data on the quantity and quality of food consumed were used to assess the mechanisms by which fish community composition influences in situ growth rates. Among-population variability in growth rates of the 12 perch populations was most strongly and consistently explained by the average density of the total fish community and/or the average density of cyprinids. A multivariate model involving fish average density and perch feeding levels explained 90% of the variance in perch growth. Perch growth rates decreased as fish average density increased (r2 = 0.60) and increased as feeding levels increased (r2 = 0.30). We found no significant relationship between the quantity of food consumed by perch and fish average density. The percent contribution of prey taxonomic groups to perch diet was not related to fish average density. We suggest that nonexploitative interactions (operating through increased activity costs) provides a more credible explanation for the negative relationship between perch growth and fish average density than does exploitative competition (decreased total quantities of food consumed or prey quality).

Among-Population Variability of Fish Growth: II. Influence of Prey Type.

1989 ◽  
Vol 46 (3) ◽  
pp. 468-482 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Growth Rates ◽  
Prey Size ◽  
Prey Type ◽  
Growth Efficiency ◽  
Population Variability ◽  
Fish Growth ◽  
Percent Contribution ◽  
The Mean ◽  
Taxonomic Groups ◽  
The Relationship

We tested the significance of the relationship between in situ growth and several diet descriptors using 12 yellow perch (Perca flavescens) populations that varied widely in growth rates. In addition, we tested the assumption of optimal foraging theory that mean prey size is an important regulator of fish growth. The percent contribution of four prey taxonomic groups and six prey size–classes (alone or combined with food consumption estimates) explained between 41 and 95% of among-population variability in growth rates or growth efficiency. We found no significant relationship between growth rates or growth efficiency and mean prey weight. We observed a pattern suggesting the existence of an optimal prey size for (1 mg dry weight) age I + and age II + fish, when the percent contribution of specific prey taxonomic groups or size–classes to the diet was assessed. This pattern was not apparent in the relationship between growth and the mean weight of prey consumed. The energetic advantage of feeding on a given prey type is believed to be related to its low cost/benefit ratio while foraging. Our data indicate that interactions between prey availability (index of searching component of foraging cost) and prey size (index of handling component of foraging cost) are more effectively represented by the percent contribution of a given prey type to the diet than by the mean weight of prey consumed. Our analyses lead us to conclude that the probability of deriving broadly applicable models explaining among-population variability in fish growth rates based on mean prey weight is very low.

Among-Population Variability of Fish Growth: I. Influence of the Quantity of Food Consumed

1989 ◽  
Vol 46 (3) ◽  
pp. 457-467 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Water Temperature ◽  
Food Consumption ◽  
Growth Rates ◽  
Yellow Perch ◽  
Prey Availability ◽  
Significant Proportion ◽  
Prey Type ◽  
Population Variability ◽  
Fish Growth ◽  
Growth Variability

We assessed the relationship between in situ fish growth and food consumption for a series of yellow perch (Perca flavescens) populations that exhibited a 1.8 to 10-fold range in growth rates on a weight basis. Perch from 12 populations (lakes) and three year–classes (I +, II +, and III +) were sampled at 3–4 wk intervals from late May to late September 1985. On each occasion, water temperature profile and daily ration were determined. Among-lake water temperature differences were minimal (of the 12 lakes studied 10 had mean water temperatures of 19.0 ± 1 °C) and could not explain growth differences. Food consumption covered a four-fold range within each age–class and varied significantly among populations but not among age–classes. Food consumption explained a significant proportion of among-population variability in perch growth rates only for age I + fish (r2 = 0.52). We argue that other factors such as prey type, prey availability, and fish community descriptors are important determinants of among-population growth variability in the lakes we studied, and by implication, in other systems.

Predator–Prey Relationships for Juvenile Chinook Salmon, Oncorhynchus tshawytscha, Feeding on Zooplankton in "in situ" Enclosures

1983 ◽  
Vol 40 (3) ◽  
pp. 287-297 ◽  
Author(s):  
Karl K. English
Keyword(s):  
Growth Rates ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Fish Growth ◽  
Juvenile Salmon ◽  
Predator Prey ◽  
Juvenile Chinook Salmon ◽  
Successful Search ◽  
Juvenile Chinook

Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5–6 g juvenile salmon. Mean growth rate was 1.8% wet body weight/d over 6 wk. Weekly growth rates ranged from 3.9%/d while food was abundant, to −0.5%/d when food was scarce. Zooplankton concentration inside and outside enclosures without fish were not significantly different. Organisms associated with the sides of the enclosures (non-pelagic) were not a major contributor to the growth of the juvenile chinook. There was a strong relationship between the fish growth rates and the abundance of 1.4- to 4.5-mm zooplankton. Rates of successful search varied directly with the size and inherent contrast of a prey item. The minimum rate of successful search was 2.3 m3/h for salmon feeding on 1.4- to 4.5-mm zooplankton. This rate of successful search, while far greater than previously suspected, is still within the visual capabilities of the juvenile salmon. The enclosed salmon grew rapidly on zooplankton concentrations that were 1/1000 of those required to sustain similar growth rates in tank experiments.Key words: predator–prey relationship, planktivorous salmonid, marine, "in situ" enclosures, search efficiency

Variability in First-Year Growth of Yellow Perch (Perca flavescens): Predictions from a Simple Model, Observations, and an Experiment

1994 ◽  
Vol 51 (11) ◽  
pp. 2501-2512 ◽  
Author(s):  
John R. Post ◽  
Donald J. McQueen
Keyword(s):  
Simple Model ◽  
Growth Rates ◽  
Yellow Perch ◽  
Explanatory Power ◽  
Perca Flavescens ◽  
Negative Relationship ◽  
Zooplankton Community ◽  
Prey Abundance ◽  
First Year ◽  
Growth Variability

First-year growth of yellow perch, Perca flavescens, varies by greater than an order of magnitude among populations and among cohorts within populations. The variability in growth rates of natural and enclosure-reared young-of-the-year yellow perch could be explained by the availability of benthic and/or plank-tonic prey (R2 = 0.093–0.098). Mean annual water temperature and cumulative degree-days did not add to the explanatory power of the relationships. The faster growing natural cohorts included more benthos in their diet; however, benthos is not necessary to sustain the highest growth rates because the fastest growth rates were observed in enclosure cohorts that lacked benthic invertebrates. Cohorts in lakes and enclosures that had a high proportion of Daphnia in the zooplankton community also supported higher first-year growth rates. The results of the enclosure experiment suggest that the dominant mechanism creating growth variability is density-dependent intra-age-class competition. Our empirical results, when coupled with a simple model, suggest that the assumption of a negative relationship between energetic costs of foraging and prey abundance, on a daily time scale, is the most appropriate because it acts to amplify growth variability across ranges of prey abundance.

Bioenergetic costs of heavy metal exposure in yellow perch (Perca flavescens): in situ estimates with a radiotracer (137Cs) technique

2000 ◽  
Vol 57 (2) ◽  
pp. 441-450 ◽  
Author(s):  
Graham D Sherwood ◽  
Joseph B Rasmussen ◽  
David J Rowan ◽  
Julie Brodeur ◽  
Alice Hontela
Keyword(s):  
Yellow Perch ◽  
Sublethal Effects ◽  
Perca Flavescens ◽  
Sublethal Effect ◽  
Toxicity Assessment ◽  
Fish Growth ◽  
Metal Exposure ◽  
Energetic Efficiency ◽  
Biological Organization

While the flow of energy is understood to determine the growth of organisms and the productivity of ecosystems, little is known about the sublethal effect of pollutants on the energetic efficiency of wild populations. We used field estimates of fish growth coupled to in situ estimates of food consumption rates obtained from the mass balance of a globally dispersed, trophically transferred radiotracer (137Cs) to demonstrate the bioenergetic impairment of yellow perch (Perca flavescens) from lakes polluted by heavy metals (Cd, Cu, and Zn). Annual growth increment relative to the total energy budget (conversion efficiency) was about three times lower in cortisol-impaired yellow perch from metal-polluted lakes relative to yellow perch from reference lakes (4.2% compared with 10.8%), suggesting that fish exposed to pollutants experienced greater total energetic costs. In addition, metal-polluted lakes were dominated by adult yellow perch populations and simplified prey bases, suggesting that effects are occurring at multiple levels of biological organization. Our in situ bioenergetic approach to toxicity assessment provides a measurable and ecologically relevant endpoint for assessing the sublethal effects of pollutants on fish communities.

scholarly journals Examining GDP Growth and Its Volatility: An Episodic Approach

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 890
Author(s):  
Jakub Bartak ◽  
Łukasz Jabłoński ◽  
Agnieszka Jastrzębska
Keyword(s):  
Economic Growth ◽  
Genetic Algorithm ◽  
Time Series ◽  
Human Capital ◽  
Growth Rates ◽  
Structural Breaks ◽  
Negative Relationship ◽  
Gdp Per Capita ◽  
Gdp Growth ◽  
Per Capita

In this paper, we study economic growth and its volatility from an episodic perspective. We first demonstrate the ability of the genetic algorithm to detect shifts in the volatility and levels of a given time series. Having shown that it works well, we then use it to detect structural breaks that segment the GDP per capita time series into episodes characterized by different means and volatility of growth rates. We further investigate whether a volatile economy is likely to grow more slowly and analyze the determinants of high/low growth with high/low volatility patterns. The main results indicate a negative relationship between volatility and growth. Moreover, the results suggest that international trade simultaneously promotes growth and increases volatility, human capital promotes growth and stability, and financial development reduces volatility and negatively correlates with growth.

scholarly journals Managed Wetlands Can Benefit Juvenile Chinook Salmon in a Tidal Marsh

2021 ◽  
Author(s):  
Nicole M. Aha ◽  
Peter B. Moyle ◽  
Nann A. Fangue ◽  
Andrew L. Rypel ◽  
John R. Durand
Keyword(s):  
San Francisco ◽  
Growth Rates ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Nursery Habitat ◽  
San Francisco Estuary ◽  
Rice Fields ◽  
Fish Growth ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

AbstractLoss of estuarine and coastal habitats worldwide has reduced nursery habitat and function for diverse fishes, including juvenile Chinook salmon (Oncorhynchus tshawytscha). Underutilized off-channel habitats such as flooded rice fields and managed ponds present opportunities for improving rearing conditions and increasing habitat diversity along migratory corridors. While experiments in rice fields have shown enhanced growth rates of juvenile fishes, managed ponds are less studied. To evaluate the potential of these ponds as a nursery habitat, juvenile Chinook salmon (~ 2.8 g, 63 mm FL) were reared in cages in four contrasting locations within Suisun Marsh, a large wetland in the San Francisco Estuary. The locations included a natural tidal slough, a leveed tidal slough, and the inlet and outlet of a tidally muted managed pond established for waterfowl hunting. Fish growth rates differed significantly among locations, with the fastest growth occurring near the outlet in the managed pond. High zooplankton biomass at the managed pond outlet was the best correlate of salmon growth. Water temperatures in the managed pond were also cooler and less variable compared to sloughs, reducing thermal stress. The stress of low dissolved oxygen concentrations within the managed pond was likely mediated by high concentrations of zooplankton and favorable temperatures. Our findings suggest that muted tidal habitats in the San Francisco Estuary and elsewhere could be managed to promote growth and survival of juvenile salmon and other native fishes.

Retardation and Recovery of Growth in Brook Trout Fry (Salvelinus fontinalis) Exposed for Various Durations to Acidified Water

1986 ◽  
Vol 43 (10) ◽  
pp. 2048-2050 ◽  
Author(s):  
W. H. Tam ◽  
P. D. Payson ◽  
R. J. J. Roy
Keyword(s):  
Growth Inhibition ◽  
Growth Rates ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Low Ph ◽  
Fish Growth ◽  
Control Fish ◽  
Treated Fish ◽  
Test Fish ◽  
Neutral Water

Brook trout fry (Salvelinus fontinalis) were exposed to pH 4.66 for various durations up to 141 d and then returned to neutral water. Growth of test fish was in general significantly lower than that of control fish for exposures up to days 45–78. In four of six groups of acid-treated fish, growth eventually recovered and the growth rates were not different from that of control fish. The results suggested that growth inhibition was induced early in the exposure to sublethally low pH and that recovery in the latter phase of the experiment occurred whether pH remained acidic or was readjusted to neutral.

Technique d'observation de surface in situ (TOSIS) :

1996 ◽  
Vol 84 ◽  
pp. 17-22
Author(s):  
A. Ranaivoarisoa ◽  
J. M. Olive ◽  
D. Desjardins
Keyword(s):  
Aqueous Solution ◽  
Crack Initiation ◽  
Grain Boundaries ◽  
Growth Rates ◽  
Triple Junction ◽  
Crack Nucleation ◽  
Initiation Time ◽  
Mesoscopic Scale ◽  
Crack Growth Rates

An optical method named In Situ Surface Observation Technique (ISSOT) is presented in this paper. This method is used to detect crack nucleation from a flaw (here a pit) at mesoscopic scale during a triangular push-pull cycling test under the control of charge amplitude in aqueous solution ofMgCl2 at 117°C. It can be found that the crack initiation time determined by using this technique represents 2 % of that estimated from a mechanical criterion. Moreover, the follow of the crack tip evolution by the ISSOT allows to measure average local crack growth rates. It has been shown that the variations of the latter were related to the effects of barriers such as grain boundaries, twin boundaries and grain boundaries triple junction.

scholarly journals Changing trends and emissions of hydrochlorofluorocarbons and their hydrofluorocarbon replacements

2016 ◽  
Author(s):  
Peter G. Simmonds ◽  
Matthew Rigby ◽  
Archibold McCulloch ◽  
Simon O'Doherty ◽  
Dickon Young ◽  
...  
Keyword(s):  
Growth Rates ◽  
Montreal Protocol ◽  
Hfc 134A ◽  
Production And Consumption ◽  
Ozone Depleting Substances ◽  
Phase Out ◽  
Article 5 ◽  
The Impact ◽  
Global Emissions

Abstract. High frequency, in situ global observations of HCFC-22 (CHClF2), HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) and HCFC-124 (CHClFCF3) and their main HFC replacements HFC-134a (CH2FCF3), HFC-125 (CHF2CF3), HFC-143a (CH3CF3), and HFC-32 (CH2F2) have been used to determine their changing global growth rates and emissions in response to the Montreal Protocol and its recent amendments. The 2007 adjustment to the Montreal Protocol required the accelerated phase-out of HCFCs with global production and consumption capped in 2013, to mitigate their environmental impact as both ozone depleting substances and important greenhouse gases. We find that this change has coincided with a reduction in global emissions of the four HCFCs with aggregated global emissions in 2015 of 444 ± 75 Gg/yr, in CO2 equivalent units (CO2 e) 0.75 ± 0.1 Gt/yr, compared with 483 ± 70 Gg/yr (0.82 ± 0.1 Gt/yr CO2 e) in 2010. (All quoted uncertainties in this paper are 1 sigma). About 80 % of the total HCFC atmospheric burden in 2015 is HCFC-22, where global HCFC emissions appear to have been relatively constant in spite of the 2013 cap on global production and consumption. We attribute this to a probable increase in production and consumption of HCFC-22 in Montreal Protocol Article 5 (developing) countries and the continuing release of HCFC-22 from the large banks which dominate HCFC global emissions. Conversely, the four HFCs all show increasing annual growth rates with aggregated global HFCs emissions in 2015 of 329 ± 70 Gg/yr (0.65 ± 0.12 Gt/yr CO2 e) compared to 2010 with 240 ± 50 Gg/yr (0.47 ± 0.08 Gt/yr CO2 e). As HCFCs are replaced by HFCs we investigate the impact of the shift to refrigerant blends which have lower global warming potentials (GWPs). We also note that emissions of HFC-125 and HFC-32 appear to have increased more rapidly during the 2011–2015 5-yr period compared to 2006–2010.

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