Bioenergetic Growth Research Articles

Development and application of a bioenergetics growth model for multiple early life stages of an ecologically important marine fish

Spatial and temporal variability in temperature and food availability are key drivers of growth of marine fishes. Growth during the early life stages (ELS's) is tightly coupled to survival, and in turn, can set year-class strength (i.e. annual recruitment) and overall stock productivity of populations and fished stocks. Ontogenetic changes in physiology, dietary preferences, and growth across ELS's can be accounted for within bioenergetics models, but existing models lack resolution within larval and early juvenile stages. We leveraged daily output from a coupled physical-biogeochemical model to force a highly resolved ontogenetic bioenergetics model parametrized for an ecologically important rockfish in the California Current System. Size-at-age predictions closely track empirical growth trajectories of the ELS's. Scenario testing revealed that growth performance is disproportionately driven by changes in temperature compared to food availability. We then expanded the model to incorporate spatial climatological differences in temperature and prey concentration and found that preflexion growth potential is maximized in areas of historical spawning, suggesting the timing and location of reproduction is an adaptive strategy that places larvae in habitat favorable for survival. Growth potential for late-stage larvae (postflexion) is greatest over a broad areal extent, implying that if a particle tracking algorithm was coupled to the bioenergetics model, a wide range of larval dispersal pathways would place postflexion larvae in habitat suitable for rapid growth. Finally, growth potential of pelagic juveniles is maximized over the continental shelf and shelf-break, aligning with high juvenile catch rates from a fisheries-independent survey. In summary, this study (i) serves as a proof of concept that a bioenergetics model with high ontogenetic resolution can reproduce life stage-specific growth trajectories even though the underlying physiology data for model parameterization is imperfect and (ii) can aid future studies aimed at understanding how ecosystem processes interact with ontogenetic growth and changes in year class strength of early life stages of marine fishes.

Size-Specific Growth of Filter-Feeding Marine Invertebrates

Filter-feeding invertebrates are found in almost all of the animal classes that are represented in the sea, where they are the necessary links between suspended food particles (phytoplankton and free-living bacteria) and the higher trophic levels in the food chains. Their common challenge is to grow on the dilute concentrations of food particles. In this review, we consider examples of sponges, jellyfish, bryozoans, polychaetes, copepods, bivalves, and ascideans. We examine their growth with the aid of a simple bioenergetic growth model for size-specific growth, i.e., in terms of dry weight (W), µ = (1/W) dW/dt = aWb, which is based on the power functions for rates of filtration (F ≈ Wb1) and respiration (R ≈ Wb2). Our theory is that the exponents have (during the evolution) become near equal (b1 ≈ b2), depending on the species, the stage of ontogeny, and their adaptation to the living site. Much of the compiled data support this theory and show that the size-specific rate of growth (excluding spawning and the terminal phase) may be constant (b = 0) or decreasing with size (b < 0). This corresponds to the growth rate that is exponential or a power function of time; however, with no general trend to follow a suggested 3/4 law of growth. Many features are common to filter-feeding invertebrates, but modularity applies only to bryozoans and sponges, implying exponential growth, which is probably a rather unique feature among the herein examined filter feeders, although the growth may be near exponential in the early ontogenetic stages of mussels, for example.

Actual and Model-Predicted Growth of Sponges—With a Bioenergetic Comparison to Other Filter-Feeders

Sponges are one of the earliest-evolved and simplest groups of animals, but they share basic characteristics with more advanced and later-evolved filter-feeding invertebrates, such as mussels. Sponges are abundant in many coastal regions where they filter large amounts of water for food particles and thus play an important ecological role. Therefore, a better understanding of the bioenergetics and growth of sponges compared to other filter-feeders is important. While the filtration (pumping) rates of many sponge species have been measured as a function of their size, little is known about their rate of growth. Here, we use a bioenergetic growth model for demosponges, based on the energy budget and observations of filtration (F) and respiration rates (R). Because F versus dry weight (W) can be expressed as F = a1Wb1 and the maintenance respiratory rate can be expressed as Rm = a2Wb2, we show that if b1~ b2 the growth rate can be expressed as: G = aWb1, and, consequently, the weight-specific growth rate is µ = G/W = aWb1−1 = aWb where the constant a depends on ambient sponge-available food particles (free-living bacteria and phytoplankton with diameter < ostia diameter). Because the exponent b1 is close to 1, then b ~ 0, which implies µ = a and thus exponential growth as confirmed in field growth studies. Exponential growth in sponges and in at least some bryozoans is probably unique among filter-feeding invertebrates. Finally, we show that the F/R-ratio and the derived oxygen extraction efficiency in these sponges are similar to other filter-feeding invertebrates, thus reflecting a comparable adaptation to feeding on a thin suspension of bacteria and phytoplankton.

Nutrient loading effects on fish habitat quality: Trade‐offs between enhanced production and hypoxia in Lake Erie, North America

Abstract Across diverse systems, nutrient loading from anthropogenic sources into aquatic systems has increased over the past century. Such nutrient inputs may enhance system productivity and thereby increase resource availability but may also lead to undesirable conditions such as hypoxic zones. We examined the habitat quality trade‐offs associated with increases in phosphorus in a model system (Lake Erie, North America) with a history of anthropogenic nutrient loading. Using a water quality model and a bioenergetics growth rate potential model with fine vertical and temporal resolution, we assessed how the quality of habitat for multiple species of adult and juvenile fish changed across a range of phosphorus loading scenarios and across 19 different meteorological years. Increases in phosphorus loading increased invertebrate prey biomass, but also increased the duration and extent of the mid‐summer hypoxic zone. In general, phosphorus loading caused overall habitat quality to decline and only increased peak habitat quality (i.e., spatio‐temporal locations where temperature and prey abundance were already above average), but responses were species‐ and life‐stage specific. One challenge in ascertaining the effects of nutrient loading on fish habitat quality is separating the negative effects of hypoxia from the potential positive effects of increased prey densities. Through various model scenarios, we evaluated the individual effects of hypoxia and increased prey availability on fish habitat quality, demonstrating their potentially counter‐balancing effects. That is, the negative effects of low oxygen on fish habitat quality appear more severe if the prospect that increased hypoxia is accompanied by altered prey densities is not accounted for. Despite modelled responses to altered phosphorus loads, habitat quality responded more strongly to variation in annual meteorological conditions. Annual meteorological conditions such as temperature, vertical mixing, and timing of phosphorus loading had a greater effect on habitat quality for all species and life‐stages than changes in annual amount of phosphorus loading. This limited effect of changes in phosphorus loading on habitat quality probably partially reflects our focus on short‐term (1‐year) changes in loading. Thus, nutrient abatement programmes may not lead to obvious, rapid positive habitat quality responses, as short‐term meteorological effects may overwhelm effects related to nutrient reduction and changes in prey densities may partially offset the benefits of decreased hypoxic conditions.

Fish growth trajectory tracking using Q-learning in precision aquaculture

This paper studies fish growth trajectory tracking using Q-learning under a representative bioenergetic growth model of Nile tilapia (Oreochromis niloticus). The fish growth rate varies in practice and cannot be easily estimated due to the complex aquaculture condition and variable environmental factors. Additionally, the growth trajectory tracking problem is challenging to solve by most of the model-based control approaches due to the nonlinear couplings and interactions between multi-inputs such as temperature, dissolved oxygen, un-ionized ammonia, and the model uncertainty of the fish growth system. We formulate the growth trajectory tracking problem as sampled-data optimal control using discrete state-action pairs Markov decision process on the simulated growth trajectories data to mimic the real aquaculture environment adequately. We propose two Q-learning algorithms that learn the optimal control policy from the simulated data of the fish growth trajectories beginning from the juvenile stage until the desired market weight in the aquaculture environment. The first Q-learning scheme learns the optimal feeding control policy to fish growth rate cultured in cages, while the second one online updates the optimal feeding control policy within an optimal temperature profile for the aquaculture fish growth rate in tanks. The simulation results demonstrate that both Q-learning control strategies achieve good trajectory tracking performance with lower feeding rates and help compensate for the environmental changes of the manipulated variables and the bioenergetic model uncertainties of fish growth in the aquaculture environment. The proposed Q-learning control policies achieve 1.7% and 6.6% relative trajectory tracking errors of the average total weight of fish from both tanks on land and floating cages, respectively. Furthermore, the feeding and temperature control policies reduce 11% relative feeding quantity of the food waste in tanks on land compared to the floating cages where the water temperature is maintained at the ambient temperature of 29.7°C.

Model predictive control paradigms for fish growth reference tracking in precision aquaculture

In precision aquaculture, the primary goal is to maximize biomass production while minimizing production costs. This objective can be achieved by optimizing factors that have a strong influence on fish growth, such as feeding rate, temperature, and dissolved oxygen. This paper provides a comparative study of four model predictive control (MPC) strategies for fish growth reference tracking under a representative bioenergetic growth model in precision aquaculture. We propose to evaluate four candidate MPC formulations for fish growth reference tracking based on the receding horizon. The first MPC formulation tracks a desired fish growth trajectory while penalizing the feed ration, temperature, and dissolved oxygen. The second MPC optimization strategy directly optimizes the feed conversion ratio (FCR), which is the ratio between food quantity and fish weight gain at each sampling time. This FCR-like optimization strategy minimizes the feed while maximizing the predicted growth state’s deviation from the given reference growth trajectory. The third MPC formulation includes a tradeoff between the growth rate trajectory tracking, the dynamic energy, and food cost. The last MPC formulation aims to maximize the fish growth rate while minimizing the costs. Numerical simulations that integrate a realistic bioenergetic fish growth model of Nile tilapia (Oreochromis niloticus) are illustrated to examine the comparative performance of the four proposed optimal control strategies. A sensitivity analysis is conducted to study the robustness of these MPC strategies with respect to the effect of the prediction horizon, the regularization term, and the additive input disturbances to the process. The obtained results show great potential and flexibility to meet the fish farmers’ needs depending on the type of fish, selling price, culture duration, and feed cost.

The impact of seasonal regulation of metabolism on the life history of Antarctic krill

Antarctic krill up- and down-regulate their metabolism as a strategy to cope with the strong seasonal environmental fluctuations in the Southern Ocean. In this study, we investigate the impact of this light- and temperature dependent metabolic regulation on growth, reproduction and winter survival of krill. Therefore, we advance a bioenergetic growth model of krill by adding a data-derived scaling function of krill activity. With SERBIK (SEasonally Regulated BIoenergetic Krill growth model), we conduct a numerical experiment which tests the impact of such scaling on krill life history under two different winter food conditions: In the first scenario, we simulate life history of krill when winter food availability is low; in the second scenario, winter food availability is increased within realistic ranges. The results demonstrate that the scaling of metabolism is especially important during low food winters. Reducing metabolism during winter permits individuals to grow to larger body length, reproduce successfully and release a greater number of eggs. It further significantly reduces within-year size fluctuations caused by starvation during months with low food availability. Finally, SERBIK can be used in future spatial modelling studies which include movement of krill along latitudinal gradients and thus spatio-temporal gradients in light- and temperature.

Bioenergetic growth model for the yellowtail kingfish (Seriola lalandi)

The culture of Seriola species is well established in Japan and is an emerging industry in many other temperate regions around the world. Despite many studies on the growth, physiology and nutritional requirements of yellowtail kingfish, the complex interactions between nutrition and environmental impacts are still being investigated. Here, we present a theoretical bioenergetic model for yellowtail kingfish bringing together the current knowledge of this species growth, metabolism and other aspects of its physiology. We solve the energy budget of yellowtail kingfish using existing theoretical equations to represent all energy gains and all metabolic costs and parameterising them with published data obtained when rearing yellowtail kingfish. Our model predicts growth as a function of suitable temperatures for yellowtail kingfish (18–27 °C) and estimates the rate of feed ingestion as well as the effect of diet on feed conversion ratio (FCR). Our model can be used to estimate energy and protein retention, nutrients loads into the ecosystem, and how these outputs change through diet manipulation at specified weight classes. We demonstrate how to use our model to predict improvements to FCR and include a simulation example showing results from shifting from a high protein-low fat diet for juveniles (0 to 500 g) to a low protein-high fat diet for adult fish (500–1000 g). Excretion of dissolved nitrogen and the consumption of oxygen through fish respiration are highest at the optimum temperature for growth. When fed a diet of 45% protein and 20% fat, our simulation shows that a constant biomass of 1000 kg of fish at a constant optimum temperature of 22.8 °C, excretes 153.1 kg of nitrogen year -1. For the same diet composition and temperature, oxygen consumption decreases from 19.9 to 10.2 kg day−1 for 1000 kg of fish weighing 50 g and 1.5 kg, respectively. Our model is useful to investigate complex interactions of metabolism for the culture of yellowtail kingfish in a commercial setting and allows predictions for changes that could improve production.

Soybean Cultivation Cost-effectiveness Depending on Bacterial Preparations and Growth Stimulants Use

Researches and analysis of the data obtained on the basis of the Armavir Experimental Station of the All-Russian Scientific Research Institute of Oilseeds establish the most effective bacterial preparations, growth stimulants and their combination for soybean cultivation under conditions of unstable moisture on ordinary chernozem. The soybeans yield during the seed treatment with the rhizobial preparation Nitrofix P (2 kg/t) in combination with the film former was the highest and amounted to 1.83 t/ha, which is 0.23 t/ha higher than in the control. It also obtained the maximum collection of plant protein – 0,69 t/ha. The highest yields (1.72–1.83 t/ha) and relatively low production costs allow getting quite high profits (19,472–22,191 rub/ha) with complex soybeans seed treatment with rusobial preparations containing a film former. The maximum profitability in the study of seed treatment with rhizobial preparations was obtained in the variants with the use of the preparations Nitrofiks P and Nitrofiks Zh in combination with the film-forming agent – 95–107 %, which is higher in comparison with the use of bacterial preparations by 2–15 %, and with the control by 12–24 %. The most cost-effective (107 %) was the use of rhizobial Nitrofix preparation in its powder form (2 kg/t) combining with a film former. The obtaining soybeans yield – 1.73 t/ha in the treatment of seeds combining with a rhizobial preparation in combination with a growth stimulator Nagro bioenergetic made it possible to get the highest profit – 19 668 rubles/ha. Given the cost of production and profit per hectare rate, the highest level of profitability was obtained when applying seed treatment with the rhizobial preparation Nitrofiks Zh in combination with Albit and Nagro bioenergetic growth stimulants: 91–94 %. Hence it has been established that the bacterial preparations for treating seeds in combination with a film former and growth stimulant use provides high profits and increases the soybean cultivation profitability level.

Improving pacific oyster (Crassostrea gigas, Thunberg, 1793) production in Mediterranean coastal lagoons: Validation of the growth model “ShellSIM” on traditional and novel farming methods

Bivalve farming is a major European aquaculture activity, representing 48.5% of total biomass produced. Italy is one of the largest consumers of oysters but local production does not meet the market demand. Italy has approximately 384,000 ha of shallow lagoons in its coastal area, already devoted to extensive aquaculture activities, which could also represent potential locations for Pacific oyster (Crassostrea gigas, Thunberg, 1793) farming.The aim of this study is to enhance Pacific oyster farming in shallow coastal lagoons by testing novel farming technologies and validating an existing bioenergetic growth model (ShellSIM).Commercial performance of Pacific oysters and associated environmental parameters were monitored in two Sardinian coastal lagoons (San Teodoro and Santa Gilla, Italy). Oyster growth and survival were compared during a production cycle for two rearing systems: traditional systems (floating bags or lanterns) and Ortac units. The latter has not been previously tested in coastal lagoons. Measured performances were compared with ShellSIM predictions to evaluate the model's ability to predict growth and the potential production in other coastal lagoons.Results showed that at the end of a six months cycle the oysters mean weight and Condition Index were significantly higher (p value < 0.05) in floating bags than in Ortac, (55.8 ± 0.9 g and 50.1 ± 1.3 g; 4.6 ± 0.1 and 3.9 ± 0.1 respectively). Also, the minimum commercial size (40 g) was reached by 98% and 68% of the oyster farmed in floating bags and Ortac units respectively. On the other hand, oysters reared in the Ortac showed a higher survival than in the floating bags (95.8 ± 0.9% and 82.1 ± 3.4%, respectively).ShellSIM growth predictions were highly correlated with the observed data in both lagoons. However, high values for root mean square deviation (RMSD) indicated that ShellSIM predictions were significantly validated for San Teodoro lagoon but not for Santa Gilla suggesting further tailoring to some environmental conditions to produce more realistic growth predictions.Results of this study indicate that both floating bags and Ortac system should be employed during the production cycle to maximise oysters' survival and growth performances. Furthermore, this study provides a new validated tool to farmers and stakeholders to monitor oysters’ performances and estimate productivity in local waters.

Simulation of Yesso scallop, Patinopecten yessoensis, growth with a dynamic energy budget (DEB) model in the mariculture area of Zhangzidao Island

Scallop farming is the main economic activity in the northern parts of China, with a production that has increased quickly since the 1980s. In the present study, a bioenergetics growth model to the Yesso scallop, Patinopecten yessoensis, in the mariculture area of Zhangzidao Island was applied, based on dynamic energy budget (DEB) theory which describes energy flux variation through different compartments of the scallop body. Estimates of most DEB parameters were based on available physiological data or published information, and the two parameters, i.e., detritus contribution to food (αDet) and half-saturation constant for food (XK) were calibrated using datasets in this study. The model relied on two forcing variables: water temperature and food density expressed by different food quantifiers. The sets of data used to validate the model came from a growth experiment performed on P. yessoensis for bottom-sowing culture. The DEB model developed here for P. yessoensis was allowed to simulate growth and reproduction of the scallop in the growing area of the Zhangzidao Island.

Growth-Prediction Model for Blue Mussels (Mytilus edulis) on Future Optimally Thinned Farm-Ropes in Great Belt (Denmark)

A recently developed BioEnergetic Growth (BEG) model for blue mussels (Mytilus edulis), valid for juvenile mussels, has been further developed to an ‘extended model’ and an alternative ‘ad hoc BEG model’ valid for post-metamorphic mussels, where the latter accounts for changing ambient chl a concentration. It was used to predict the growth of M. edulis on optimally thinned farm-ropes in Great Belt (Denmark), from newly settled post-metamorphic mussels of an initial shell size of 0.8 mm to marketable juvenile 30–35 mm ‘mini-mussels’. Such mussels will presumably in the near future be introduced as a new Danish, smaller-sized consumer product. Field data for actual growth (from Day 0 = 14 June 2011) showed that size of ‘mini-mussel’ was reached on Day 109 (Oct 1) and length 38 mm on Day 178 (Dec 9) while the corresponding predictions using the extended model were Day 121 (Oct 13) and Day 159 (Nov 20). Similar results were obtained by use of the ad hoc BEG model which also demonstrated the sensitivity of growth prediction to levels of chl a concentration, but less to temperature. The results suggest that it is possible (when the conditions are optimal, i.e., no intraspecific competition ensured by sufficient thinning) to produce ‘mini-mussels’ in Great Belt during one season, but not the usual marketable 45-mm mussels. We suggest that the prediction model may be used as a practical instrument to evaluate to what degree the actual growth of mussels on farm ropes due to intraspecific competition may deviate from the potential (optimal) growth under specified chl a and temperature conditions, and this implies that the effect of thinning to optimize the individual growth by eliminating intraspecific competition can be rationally evaluated.

A bioenergetic approach to manage production and control phosphorus discharges from a salmonid hatchery

The environmental effects of fish culture operations are important issues in Michigan as well as many other parts of the world. The State of Michigan Department of Natural Resources operates the Platte River State Fish Hatchery (PRSFH) located near Honor, Michigan (USA). This facility has a restrictive discharge permit that limits the input of phosphorus into the Platte River that subsequently drains into a downstream oligotrophic lake (Platte Lake). The permit has been violated on occasion in recent years. Hatchery managers and operators need to understand the cause of these violations and prevent them in the future; and at the same time meet production goals to satisfy fishery management objectives. This paper describes the development and application of models designed to quantitatively analyze these issues. First, a bioenergetic growth and consumption model is developed for juvenile coho (Oncorhynchus kisutch) and Chinook (Oncorhynchus tshawytscha) salmon to quantify the relationship between fish production and by-product phosphorus loads. Next, phosphorus mass balance equations are used to calculate the phosphorus discharge from the facility as a function of the by-product phosphorus load and the efficiency of various phosphorus removal equipment and processes. The accuracy and consistency of the energy and mass balance equations are verified using extensive measurements. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. An example of model utility is presented that analyzes the PRSFH phosphorus discharge and provides insights into why permit violations occurred in 2009 but not in 2010. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits. Statement of relevanceThe environmental effects of fish culture operations are important issues in many parts of the world. This paper describes the development and application of models designed to quantitatively analyze the relationships among fish production, by-product phosphorus loads, and the phosphorus concentration of the discharge following treatment. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits.

Geographic variation in Pacific herring growth in response to regime shifts in the North Pacific Ocean

Pacific herring populations at eight North Pacific Rim locations were simulated to compare basin-wide geographic variations in age-specific growth due to environmental influences on marine productivity and population-specific responses to regime shifts. Temperature and zooplankton abundance from a three-dimensional lower-trophic ecosystem model (NEMURO: North Pacific Ecosystem Model for Understanding Regional Oceanography) simulation from 1948 to 2002 were used as inputs to a herring bioenergetics growth model. Herring populations from California, the west coast of Vancouver Island (WCVI), Prince William Sound (PWS), Togiak Alaska, the western Bering Sea (WBS), the Sea of Okhotsk (SO), Sakhalin, and Peter the Great Bay (PGB) were examined. The half-saturation coefficients of herring feeding were calibrated to climatological conditions at each of the eight locations to reproduce averaged size-at-age data. The depth of averaging used for water temperature and zooplankton, and the maximum consumption rate parameter, were made specific to each location. Using the calibrated half-saturation coefficients, the 1948–2002 period was then simulated using daily values of water temperature and zooplankton densities interpolated from monthly model output. To detect regime shifts in simulated temperatures, zooplankton and herring growth rates, we applied sequential t-test analyses on the 54years of hindcast simulation values. The detected shifts of herring age-5 growth showed closest match (69%) to the regime shift years (1957/58, 1970/71, 1976/77, 1988/89, 1998/99). We explored relationships among locations using cluster and principal component analyses. The first principal component of water temperature showed good correspondence to the Pacific Decadal Oscillation and all zooplankton groups showed a pan-Pacific decrease after the 1976/77 regime shift. However, the first principal component of herring growth rate showed decreased growth at the SO, PWS, WCVI and California locations and increased growth at the Sakhalin, WBS and Togiak locations after 1977. The SO location belonged to the same cluster as the location in with the eastern North Pacific. The calibrated half-saturation coefficients affected the degree to which growth was sensitive to interannual variation in water temperature versus zooplankton. For example, the half-saturation values for the SO location resulted in very efficient feeding that shifted the sensitivity of herring growth from food to temperature. The model results demonstrate how geographic specificity of bioenergetics parameters, coupled with location-specific variation in temperature and food, can combine to determine local and regional responses of fish growth to climate forcing.

Re‐Estimating Temperature‐Dependent Consumption Parameters in Bioenergetics Models for Juvenile Chinook Salmon

AbstractResearchers have cautioned against the borrowing of consumption and growth parameters from other species and life stages in bioenergetics growth models. In particular, the function that dictates temperature dependence in maximum consumption (Cmax) within the Wisconsin bioenergetics model for Chinook Salmon Oncorhynchus tshawytscha produces estimates that are lower than those measured in published laboratory feeding trials. We used published and unpublished data from laboratory feeding trials with subyearling Chinook Salmon from three stocks (Snake, Nechako, and Big Qualicum rivers) to estimate and adjust the model parameters for temperature dependence in Cmax. The data included growth measures in fish ranging from 1.5 to 7.2 g that were held at temperatures from 14°C to 26°C. Parameters for temperature dependence in Cmax were estimated based on relative differences in food consumption, and bootstrapping techniques were then used to estimate the error about the parameters. We found that at temperatures between 17°C and 25°C, the current parameter values did not match the observed data, indicating that Cmax should be shifted by about 4°C relative to the current implementation under the bioenergetics model. We conclude that the adjusted parameters for Cmax should produce more accurate predictions from the bioenergetics model for subyearling Chinook Salmon.Received May 20, 2014; accepted November 5, 2014

Diets and growth potential of early stage larval yellow perch and alewife in a nearshore region of southeastern Lake Michigan

Abstract Transition from endogenous to exogenous feeding is thought to be a critical period for many fish larvae, when prey availability (type, size, and density) and ambient physical conditions (e.g., temperature, water clarity) can strongly influence survival. In Lake Michigan, two important fish species, yellow perch (Perca flavescens) and alewife (Alosa pseudoharengus), hatch and, presumably, begin exogenously feeding in the nearshore zone, an area characterized by short-term variation in environmental conditions. During 2010-2011, we examined environmental conditions and spatial and temporal distributions of larval yellow perch, larval alewife, and their potential prey in a nearshore region of southeastern Lake Michigan. To consider implications of environmental conditions on larval fish habitat quality, we quantified diet contents of young larval yellow perch and alewife and modeled bioenergetic growth rate potential (an index of habitat quality) under observed and predicted prey consumption scenarios. As expected, in this dynamic nearshore zone temperatures, light levels, zooplankton prey availability, and resulting growth rate potential were highly variable. Many larval fish digestive tracts were empty, suggesting that starvation may affect cohort survival. Among early-feeding larval fish, relatively small diet items were common, with larval alewives consuming diatoms and larval yellow perch consuming veligers of invasive dreissenid mussels. Though the mechanisms underlying such prey consumption and the consequences of ingesting these prey items remain largely unexplored, our results suggest dreissenid mussel veligers present early-feeding larvae with a relatively abundant prey source that may partially offset the apparent low consumption of other prey sources within Lake Michigan’s nearshore region.

Dwarfism of blue mussels in the low saline Baltic Sea—growth to the lower salinity limit

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 517:181-192 (2014) - DOI: https://doi.org/10.3354/meps11011 Dwarfism of blue mussels in the low saline Baltic Sea—growth to the lower salinity limit Hans Ulrik Riisgård1,*, Poul S. Larsen2, Raisa Turja3, Kim Lundgreen1 1Marine Biological Research Centre (University of Southern Denmark), Hindsholmvej 11, 5300 Kerteminde, Denmark 2DTU Mechanical Engineering, Fluid Mechanics, Technical University of Denmark, Building 403, 2800 Kgs. Lyngby, Denmark 3Finnish Environmental Institute, Marine Research Centre, PO Box 140, 00251 Helsinki, Finland *Corresponding author: hur@biology.sdu.dk ABSTRACT: Mussels within the Baltic Mytilus edulis × M. trossulus hybrid zone have adapted to the low salinities in the Baltic Sea which, however, results in slow-growing dwarfed mussels. To get a better understanding of the nature of dwarfism, we studied the ability of M. trossulus to feed and grow at low salinity (7 psu) compared with its performance at relatively high-salinity (20 psu) in controlled laboratory experiments, supplemented with field (Great Belt) growth experiments with M. trossulus and M. edulis in net-bags. Subsequently, the growth of M. trossulus transplanted in cages to various localities in the northern Baltic Sea was used to evaluate the effect of very low salinities, down to 3.4 psu. The laboratory feeding experiments with M. trossulus at 7 psu showed that the growth in shell length was negligible, whereas the body dry weight nearly doubled during the 15 d experiment, with a weight-specific growth rate of 3.7% d-1. The same parameters measured at 20 psu showed a pronounced growth in both shell length and body dry weight, with a weight-specific growth rate of 2.2% d-1. The growth rates of M. trossulus and M. edulis in suspended net-bags in the Great Belt (22 psu) were similar: 5.6 and 6.8% d-1, respectively. M. trossulus in cage experiments had positive growth rates at locations with salinities above 4.5 psu, up to 2.60% d-1, but negligible increase in the shell length, and at sites with salinities below about 4.5 psu, the somatic growth was negative, around -0.3% d-1, which indicates valve closure and respiratory weight loss. A trend line in a plot of all available growth data for both mussel species as a function of salinity indicates that the growth of mussels is steadily hampered by reduced salinities from 30 psu down to about 10 psu, below which the growth is rapidly reduced to become negative below 4.5 psu. We suggest that reduced ability to produce shell material at extremely low salinity may explain dwarfism of mussels in the Baltic Sea. Reduced bio-calcification at low salinity, however, may impede shell growth, but not somatic growth, and this may at first result in an increased condition index, as seen in the benthic Baltic Sea mussels transferred to cages suspended in the water column. KEY WORDS: Mytilus edulis · Mytilus trossulus · Filtration rate · Specific growth rate · Adaptation · Effect of salinity · Condition index · Bio Energetic Growth (BEG) model Full text in pdf format PreviousNextCite this article as: Riisgård HU, Larsen PS, Turja R, Lundgreen K (2014) Dwarfism of blue mussels in the low saline Baltic Sea—growth to the lower salinity limit. Mar Ecol Prog Ser 517:181-192. https://doi.org/10.3354/meps11011 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 517. Online publication date: December 15, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Dynamic energy budget model: a monitoring tool for growth and reproduction performance of Mytilus galloprovincialis in Bizerte Lagoon (Southwestern Mediterranean Sea).

Mussel farming is the main economic activity in Bizerte Lagoon, with a production that fluctuates depending on environmental factors. In the present study, we apply a bioenergetic growth model to the mussel Mytilus galloprovincialis, based on dynamic energy budget (DEB) theory which describes energy flux variation through the different compartments of the mussel body. Thus, the present model simulates both mussel growth and sexual cycle steps according to food availability and water temperature and also the effect of climate change on mussel behavior and reproduction. The results point to good concordance between simulations and growth parameters (metric length and weight) for mussels in the lagoon. A heat wave scenario was also simulated using the DEB model, which highlighted mussel mortality periods during a period of high temperature.

Thermal habitat quality of aquatic organisms near power plant discharges: potential exacerbating effects of climate warming

AbstractWater temperature strongly affects aquatic ectotherms, as even slight temperature changes can have dramatic effects on physiological rates. Water bodies receiving industrial thermal discharges can undergo dramatic spatial and temporal changes in water temperature. To quantify effects on aquatic ectotherms, thermal habitat quality (bioenergetic growth rate potential; GRP) for zebra mussel, Dreissena polymorpha (Pallas), rusty crayfish, Orconectes rusticus (Girard), walleye, Sander vitreus (Mitchill) and smallmouth bass, Micropterus dolomieu (Lacepède) was estimated near two power plant thermal discharges on the Ohio River, USA, from 2010 to 2012 using bioenergetics models. These results were then compared with GRP under increased base temperatures representing climate warming. Growth rate potential for all species was low near the discharges during summer and highest in winter, with increasing prey consumption minimising the negative effects of increased temperatures. In their immediate vicinity, thermal discharges had a more adverse effect on GRP than plausible climate warming but primarily affected GRP over a small spatial area, particularly within 400 m downstream from the power plants. Examining thermal habitat suitability will become increasingly important as rising energy demand and climate change collectively affect aquatic organisms and their habitats.

Somatic growth of mussels Mytilus edulis in field studies compared to predictions using BEG, DEB, and SFG models

Prediction of somatic growth of blue mussels, Mytilus edulis, based on the data from 2 field-growth studies of mussels in suspended net-bags in Danish waters was made by 3 models: the bioenergetic growth (BEG), the dynamic energy budget (DEB), and the scope for growth (SFG). Here, the standard BEG model has been expanded to include the temperature dependence of filtration rate and respiration and an ad hoc modification to ensure a smooth transition to zero ingestion as chlorophyll a (chl a) concentration approaches zero, both guided by published data. The first 21-day field study was conducted at nearly constant environmental conditions with a mean chl a concentration of C=2.7μgL−1, and the observed monotonous growth in the dry weight of soft parts was best predicted by DEB while BEG and SFG models produced lower growth. The second 165-day field study was affected by large variations in chl a and temperature, and the observed growth varied accordingly, but nevertheless, DEB and SFG predicted monotonous growth in good agreement with the mean pattern while BEG mimicked the field data in response to observed changes in chl a concentration and temperature. The general features of the models were that DEB produced the best average predictions, SFG mostly underestimated growth, whereas only BEG was sensitive to variations in chl a concentration and temperature. DEB and SFG models rely on the calibration of the half-saturation coefficient to optimize the food ingestion function term to that of observed growth, and BEG is independent of observed actual growth as its predictions solely rely on the time history of the local chl a concentration and temperature.