Bioenergetic Growth Research Articles

Origin of relation between K and Linf and synthesis of relations among life history parameters

Four patterns occur in growth and mortality parameters across species of fish. Three of these relations, Mxm = 1.65, M = 1.50K, and L(xm) = 0.66Linf where M is natural mortality, xm is age at maturity, L(xm) is length at maturity, and Linf is asymptotic length, were previously shown to result from optimization of the age at maturity. In this study the fourth relation, that between asymptotic size and the growth coefficient, Linf = CK-h, was obtained from a bioenergetic growth equation. A numerical value of h = 0.33 was predicted, and this agrees with the observed value. The relation between the growth coefficient K and size Linf results from the limited amount of assimilated food that must be used both for growth and body functions, and the body functions are a function of body size. The four Beverton and Holt invariants, together with the net reproductive rate, relate many life history parameters to a metabolic parameter and mortality.

A Model for the Space–Time Dependence of Feeding for Pelagic Fish Populations

The time-varying spatial distribution of pelagic fish is an important factor in the development of feeding rate estimates for input into bioenergetics growth models. Key issues are the degree to which fish and prey distributions overlap, the frequency and duration of such overlaps, and the effectiveness of foraging during overlaps. A model for the space and time dependences of feeding by the pelagic planktivorous alewife Alosa pseudoharengus in the Great Lakes is presented. The model combines two submodels: (1) a diffusion–taxis model of predator and prey dispersal and (2) a foraging rate model. Both models depend on environmental variables. The diffusion–taxis model is based on directional motion and random motion on the part of the fish. Directional motion is determined from a taxis function that relies on local cues for feeding rate and encounter rate with predators. The foraging model expresses the feeding rate of a predator as a function of predator and prey sizes, prey density, light level, and temperature. The diel movements, distribution, and feeding rates of alewives were simulated with these models. The model simulations successfully represented the time-varying spatial distribution of alewives and predicted peaks in their feeding rate at dawn and dusk. The model simulations suggested a nighttime feeding rate that was less than what is known from the literature. These results suggest that many of the known features of alewife distribution can be reproduced with this class of model. Given the typically patchy distribution of predator and prey, the nonhomogeneous character of environmental conditions, and the dynamic nature of both the biological and physical components of an ecosystem, a spatiotemporal approach such as this may be necessary for modeling the feeding, growth, and production dynamics of pelagic fishes.

Productivity of outdoor algal cultures in unstable weather conditions

In the outdoor cyclic fed batch cultures of Chlorella pyrenoidosa, some typical growth kinetics patterns in unstable weather conditions were observed. On cloudy days, the biomass output rate (R) was low, but the bioenergetic growth yield (Y) was generally high. In the cloudy morning-sunny afternoon condition, the values of Y were low, especially in the afternoon. In the sunny morning-cloudy afternoon condition, both R and Y were high. A few very high short-term Y values were measured during the cloudy the cloudy afternoon.

Bioenergetic modelling of effects of fertilization, stocking density, and spawning on growth of the Nile tilapia, Oreochromis niloticus (L.)

Abstract. A bioenergetic growth model was developed to examine the integrated effects of fertilization, stocking density, and spawning on the growth of tilapia, Oreochromis niloticus (L.), in pond aquaculture. The analyses showed that growth rates increase with higher levels of organic fertilization up to 500kg/ha/week. Growth rates increased with added food rations in ponds, reaching a maximum growth of 2-07g/day at about 44–48 days after stocking. Fish growth rates decreased with increased levels of stocking density. The stocking density for optimal growth is 1fish/m2; the optimal density for total harvesting weight and fish size is 2 fish/m2. Model sensitivity analysis indicated that tilapia growth is most sensitive to catabolism (metabolism) and anabolism (synthesis) coefficients, both of which are geometrically related to the fish body weight. Food assimilation efficiency (b) and the food consumption coefficient (h) have a modest effect on fish growth. Spawning in grow-out ponds can have a major effect on fish growth.

Relation between mortality of young walleye ( Stizostedion vitreum) and recruitment with different forms of compensation

The relation between mortality of young fish and recruitment is important for assessment of the environmental effects of facilities that kill large numbers of young fish, such as electric power stations and hydropower plants. A simulation model with a bioenergetic growth component was applied to examine the relation between mortality of young and recruitment for walleye ( Stizostedion vitreum) with different forms of population regulation, including: food limited growth, food limited growth with size-dependent mortality, and food limited growth with age at maturity dependent on size. With food limited growth small increases in mortality of young reduced recruitment considerably, but the population slowly approached a new equilibrium. If mortality of young increased when growth was food limited, the population approached a new equilibrium of natality and mortality because with fewer individuals there was more food per individual, and individuals were larger in size and produced more eggs; this feedback adjusted natality to equal mortality. With either mortality or age at maturity dependent on size, large increases in mortality of young resulted in only small decreases in recruitment.

Thermodynamic Framework for Evaluating PAH Degradation in the Subsurface

AbstractA method is presented to evaluate the influence of redox conditions and pH on mineralization of polycyclic aromatic hydrocarbons (PAH) in subsurface environments. Microbial yields based on the free energy liberated from heterotrophic PAH metabolism are estimated under various environmental conditions using a simple bioenergetic growth model. The types and chemical forms of electron acceptors addressed in this paper include oxygen, nitrate, sulfate, carbon dioxide, iron (Fe+3and FeOOH), and manganese (Mn+4 and MnO2). PAHs addressed include naphthalene (2‐fused aromatic rings), anthracene (3‐fused aromatic rings), phenanthrene (3‐fused aromatic rings), and pyrene (4‐fused aromatic rings).Calculated free energy changes demonstrated that sequential utilization of electron acceptors will follow the order Mn+4, O2, NO3−1, Fe+3, MnO2, FeOOH, SO4−2, and CO2. The behavior in microbial growth yield predictions were found to mimic the change in free energy liberated with the use of different electron acceptors. Despite release of free energy under all conditions evaluated, the small energy liberated during PAH mineralization under sulfate‐reducing and methanogenic conditions suggests that heterotrophic degradation of PAH compounds under these conditions is unlikely to occur.The large microbial growth yields associated with reduction of free metal species (Mn+4, Fe+3) during PAH oxidation suggest a selective advantage for microbes that can tolerate acid conditions and/or participate in metal chelation processes.

Effect of photobioreactor inclination on the biomass productivity of an outdoor algal culture

The profiles of photon flux density incidented on a tubularloop photobioreactor in the day could be altered by inclining the bioreactor at an angle with the horizontal. The photon flux density at noon decreased with increasing angle of inclination, whereas the photon flux density in the early morning and late afternoon increased with increasing angle of inclination. The overall photosynthetic radiance received by the bioreactor inclined at 0, 25, 45, and 80 degrees was 1:0.89:0.77:0.62. Regardless of the angle of bioreactor inclination, the overall biomass output rate of a fed-batch culture over an 8-h/day period was comparable (26-36 g-biomass m(-2) bioreactor surface area day(-1)). As a bioreactor inclined at an angle occupied smaller land area, and daily biomass output rate per land area of a bioreactor inclined at 80 degrees (130 g-biomass m(-2) land) was about six times of that obtainable at horizontal position (21-g biomass m(-2) land). The bioenergetics growth yield from the absorbed photosynthetic radiance was not a constant but an inverse function of the photon flux density. The quasi-steady state chlorophyll content of the Chlorella cells varied between 36 and 63 mg g(-1) cells. Photoinhibition of the maximum photosynthetic capacity was not observed in this study.

High CO2 partial pressure depresses productivity and bioenergetic growth yield of Chlorella pyrenoidosa culture

When low-CO2 grown Chlorella pyrenoidosa (YSK strain) cells were exposed to high CO2 partial pressures (pCO2), the specific growth rate (μ) declined exponentially reaching a steady state value in about 20 h. A short interruption (up to 1 h) by temporarily lowering the pCO2 did not prevent the continuous decline in μ when high pCO2 was restored. In chemostate studies, light-limited cultures were supplied with 2 to 90 kPa of CO2. The steady state biomass production rate and bioenergetic growth yield were related inversely to pCO2 and the average energy uptake rate. The maintenance energy coefficient was, however, independent of dissolved pCO2 in the pCO2 range studied.

Simulation of the potential for life history components to regulate walleye population size

Jensen, A.L., 1989. Simulation of the potential for life history components to regulate walleye population size. Ecol. Modelling, 45: 27-41. A bioenergetic life history simulation model was applied to identify components of the walleye (Stezostedion vitrium) life history that had a potential for population regulation. The model combined a predator-prey model, a bioenergetic growth model, a relation between mortality and size, and the exponential mortality model to produce a feedback relation among abundance, food concentration, growth, and mortality. Larval mortality, juvenile mortality, and age at maturity were identified as factors with a potential for compensation. As the number of larvae increased, the number of young-of-year (roY) increased to a maximum and then decreased with further increase in the number of larvae. This occurred because as the number of larvae increased, food concentration decreased, growth rate decreased, and mortality, which was size dependent, increased. As the number of juveniles increased, the number of recruits increased to a maximum, and then with further increase in the number of juveniles the number of recruits decreased. Age at maturity increased exponentially with increase in the number of juveniles because growth decreased. Change in mortality of both adults and YOY had little potential for compensation.

Bioenergetics of growth of a cyprinid, Phoxinus phoxinm (L.): development and testing of a growth model

The development, verification and validation of a bioenergetics growth model for the European minnow, Phoxinus phoxinus, are described. Sensitivity analysis showed that the growth predicted by the model was sensitive to parameters used in the estimates of the energy and dry matter content of the fish and metabolic rate. The model gave good predictions of the form of the growth‐temperature relationship, but failed to predict the growth‐ration relationship well. Validation of the model against experimental data showed that the model underestimated growth at lower rations and overestimated growth at higher rations. Only at low ration levels did the model predict growth rates equivalent to those recorded for a natural population of minnows. Analyses of an empirical regression equation for growth rate, as well as the bioenergetics model, highlighted four areas for future research: (1) the energy content of fish in relation to environmental factors; (2) the feeding metabolism of fish in relation to environmental factors; (3) the regulatory mechanism of long‐term growth; (4) the effect of gonadal maturation on long‐term growth. The identification of these problems illustrates the advantage of a partially explanatory model, the bioenergetics model, over a descriptive empirical model.

Surfacing frequency as an index of bioenergetics components of air breathing fishes

Surfacing frequency (Sf) in obligatory air-breathing fishes is a behavioural index of O2 uptake; as both are interrelated, there is a possibility of predicting one from the other. From the point of cause and effect relationship, feeding (C) is regarded as the cause and Sf and O2 uptake as its effects. Hence, the last two are predictable from the cause. A pathway for predicting the bioenergetics components, feeding (C), metabolism (M) and growth (P) from a behavioural index of surfacing frequency has been proposed. In this model, C occupies the focal point connecting on the horizontal plane Sf on one side and P on the other side and M vertically. The developed multiple regression models predict the bioenergetics components of the fishes,Macropodus cupanus andChanna striatus of different weight classes ex-posed to different rations and temperatures; the percentage of variation accounted for by the equations is over 90. The pathway can also be followed for predicting bioenergetics components of gill-breathing fishes, if feeding rate alone is known. On application of the relevant part of the pathway toSalmo trutta, the percentage of variation accounted by the equations is 95.

Sensitivity of bioenergetic growth models of animals to changes in the energy balance parameters

Identification of mechanisms and parameters to which the system dynamics are most sensitive leads not only to a better understanding of the system but also eliminates unnecessary experimental and theoretical investigations concerning non-critical parameters. An effective approach to this identification is sensitivity analysis of a mathematical model of the system being studied. This paper examines the sensitivity of bioenergetic growth models of animals to changes in the energy balance parameters and draws a general conclusion. Bioenergetic growth models of animals are much more sensitive to changes in the instantaneous values of food consumption and food assimilation efficiency than to changes in the instantaneous value of respiration. A model of energy flow through the amictic female rotifer Brachionus rubens Ehrbg. is considered to illustrate the conclusion.