Net Growth Efficiency Research Articles

Photosynthetic metabolism and growth of pineapple (Ananas comosus L. Merr.) cultivated ex vitro

Pineapple (Ananas comosus L.) is a bromeliad with constitutive CAM metabolism. However, facultative C3/CAM metabolism in the first 2 months of growth is a characteristic of this species. Thus, young pineapple plants can exhibit C3 photosynthesis when the environmental conditions, such as the diurnal temperature range and water supply, are favorable to growth. However, high temperature diurnal amplitude, soil/air moisture alterations and changes in light intensity in association with air humidity have caused facultative C3/CAM metabolism. The objective of the study was to assess the physiology and growth of ex vitro ‘Vitoria’ and ‘IAC Fantastico’ pineapple genotypes during acclimatization from the in vitro environment. The research was carried out in a greenhouse using the split plot design used in the in vitro culture (Couto et al, Rev Bras Frutic 36(2):459–466, 2014). The explants were planted in trays with Vivatto® substrate. The net photosynthesis rate, growth and photochemical efficiency were measured at 60 and 75 days of acclimatization (DA). The greater growth (canopy diameter and height, shoot dry mass, total dry mass and leaf area) of ‘IAC Fantastico’ was associated with CAM metabolism. CAM metabolism was likely induced by the stressful environmental micrometeorological variables inside the greenhouse. In contrast, ‘Vitoria’ exhibited C3 metabolism and reduced growth at 60 and 75 DA. ‘Vitoria’ had greater photosynthate partitioning to the root system and high photochemical efficiency 75 DA. We conclude that the stress imposed by the environmental conditions induced CAM metabolism in ‘IAC Fantastico’ and increased growth gain characteristics at 60–70 DA.

Effects of LED light quality on the growth, metabolism, and energy budgets of Haliotis discus discus

In this study, a bioenergetics approach was used to examine the effects of different LED light qualities (red, orange, blue, green light, natural light and a dark setting) on the growth and survival of the abalone Haliotis discus discus, and its physiological response mechanism under different light qualities. The results suggest that under blue or green light, the survival rate, specific growth rate, food intake, and food conversion efficiency of H. d. discus were significantly lower than in those groups under red or orange light (P<0.05). Under red or orange light, pepsin, amylase and cellulose activity was significantly higher than those in any other light quality group (P<0.05), whereas lipase activity exhibited no significant difference among the light quality groups (P>0.05). Under blue or green light, lactate dehydrogenase activity and lactic acid content were higher (P<0.05), suggesting enhanced anaerobic metabolism. Under blue or green light, H. d. discus lost more energy via excretion, feces and respiration than was acquired from its food. Under red or orange light, H. d. discus acquired more energy from its food and lost less energy via excretion and feces; as a result, its assimilation efficiency (K1) and net growth efficiency (K2) were significantly higher than those of any other group (P<0.05). Therefore, we suggest that red or orange light should be used as a light source for the aquaculture of H. d. discus.

Nitrogen sources and net growth efficiency of zooplankton in three A mazon River plume food webs

The plasticity of nitrogen specific net growth efficiency (NGE) in marine mesozooplankton is currently unresolved, with discordant lines of evidence suggesting that NGE is constant, or that it varies with nitrogen source, food availability, and food quality in marine ecosystems. Specifically, the fate of nitrogen from nitrogen fixation is poorly known. We use 15N : 14N ratios in plankton in combination with hydrological data, nutrient profiles, and nitrogen fixation rate measurements to investigate the relationship between new nitrogen sources and the nitrogen specific NGE in three plankton communities along the outer Amazon River plume. The NGE of small (200–500 μm) mesozooplankton was estimated from the δ15N differences between particulate nitrogen and zooplankton using an open system Rayleigh fractionation model. The transfer efficiency of nitrogen among larger (> 500 μm) mesozooplankton was estimated from the change in δ15N as a function of zooplankton size. The Amazon River was not a significant source of bioavailable nitrogen anywhere in our study region, and subsurface nitrate was the primary new nitrogen source for the outer shelf community, which was dominated by diatoms. N2 fixation was the principal new nitrogen source at sites of high diatom diazotroph association abundance and at oceanic sites dominated by Trichodesmium spp. and Synechococcus spp. Although we found clear spatial differences in food quantity, food quality, and diazotroph inputs into mesozooplankton, our data show no significant differences in mesozooplankton nitrogen transfer efficiency and NGE (for latter, mean ± SD: 59 ± 10%) among sites.

Effects of temperature and body size on the physiological energetics of the stalked sea squirt Styela clava

An assessment of the patterns of thermal acclimation of physiological processes of the stalked sea squirt Styela clava is needed to further understand growth patterns associated with large seasonal fluctuations in ambient temperature. The effects of different exposure temperatures on physiological processes of S. clava were measured at 5, 10, 15, 20, and 25°C. The impact of temperature on energy balance at a whole organism level was then assessed by scope for growth (SFG) and net growth efficiency (K2) measures. Physiological rates of S. clava were well correlated with its dry tissue weight (DW). Positive allometry with DW indicated that all physiological rates investigated were generally higher in the larger individuals regardless of temperature. Some allometric equations (e.g., feces production rate vs. DW and respiration rate vs. DW) exhibited identical estimates of exponents, enabling accurate comparisons of the rates across temperatures. In contrast, disparities across temperatures of the values for the weight exponent were detected in other allometric equations, revealing that thermal effects on these rates have different degrees for large and small individuals. The SFG value in S. clava of different sizes was similar at lower temperatures (5–10°C), peaking at 15°C. The SFG was positive with a relatively constant K2 in this temperature range. This positive energy balance reflects the reduction in metabolic costs at lower temperatures. In contrast, increased metabolic costs at higher temperatures (20–25°C) resulted in lowered SFG and K2 values, indicating that the feeding rate did not increase as greatly in compensation for the increased metabolic costs at higher temperatures. The lowered absorption at 25°C (compared with 20°C) resulted in negative SFG and K2 values. Finally, our results confirm that the absence of compensatory adjustment to warmer conditions leads to energetic disruption at a whole organism level at such temperatures.

Effects of Ca and Mg concentrations in seawater on the growth and energy budget of juvenileParalichthys olivaceus(Temminck &amp; Schlegel, 1846)

Summary Effects of seawater calcium (Ca) and magnesium (Mg) concentrations on the growth and energy budget of juvenile Paralichthys olivaceus (Temminck & Schlegel, 1846) were investigated at 20°C and a salinity of 30 psu. The Ca/Mg ratio (Ca : Mg = 1 : 3) in the experimental water was kept constant. Five treatments were set: C1, C2, C3, C4, and C5, and the Ca and Mg concentrations were 700, 1100, 1600, 2200, and 2800 (mg L−1), respectively. After a 60-day feeding trial the P. olivaceus survival rates were not affected significantly by Ca or Mg concentrations in the range of 700–2800 mg L−1. However, the specific growth rates (SGR) and weight gain (WG) of all treatments decreased with ascending Ca and Mg concentrations. The Ca and Mg concentrations had a strong influence on various energy parameters, namely, energy deposited for growth (G), energy lost for respiration (R), and energy lost in excretion (U), but had little influence on energy lost in feces (F). This indicated that the growth rate differences under different concentrations of Ca and Mg mainly resulted from differences of assimilation efficiency and energy channeled into respiration. The highest net growth efficiency was attained at the lowest concentration of Ca and Mg in seawater, and the higher concentrations of Ca and Mg increased the energy channeled to respiration and excretion, which led to significant reduction in growth. Therefore, the optimal growth of P. olivaceus could be obtained by regulating the concentration of Ca and Mg at 700 mg L−1, where the average energy budget was: 100C (100% energy consumed in food) = 47.21 (±0.63) G + 32.89 (±0.42) R + 16.71 (±0.56) F + 3.19 (±0.05) U.

Comparative Bioenergetics of Diploid and Triploid Pacific Oysters Crassostreas gigas at Different Temperatures

The energy budgets, assimilation and conversion efficiency of 1-year-old-triploid Pacific oysters Crassostreagigas, were compared with those of sibling diploids to clarify the mechanism of energy metabolism. No significant difference was found between diploids and triploids in oxygen consumption. The net growth efficiencies of triploids and diploids were 37.4% and 33.9% respectively, and the gross growth efficiencies of them were 28.8% and 22.7%. The influence of ploidy and temperature on K1 was significant, but the variation of K2 may be attributable to ambient temperature. The ratio of gonad dry weight and dry tissue of triploids was 5%on average, and diploids about 25.6%. Our results showed that triploids, which do not reproduce and only have limited gonadal development, spend more energy for growth and more efficient in using energy than diploids do.

물렁가시붉은새우(Pandalopsis japonica)의 유생 단계에 따른 에너지수지

【The energy budget of the larvae of pandalid shrimp, Pandalopsis japonica, reared in the laboratory from zoea to post-larva was investigated. Energy used during the growth of the shrimp larvae was calculated daily for feeding, growth, molting, and metabolism. The total energy used was 16.2 J for the entire larval stage. Molting energy loss was estimated at a total 1.03 J. Energy used for respiration was estimated at a total of 1.85 J. The intake energy by feeding reached a total of 77.69 J. The total sum of energies used by excretion and egestion was 58.61 J. Larvae assimilated 24.57% of ingested food and used 84.91% for somatic growth. The gross growth efficiency ( $K_1$ ) was 22.19% for the entire larval stage, and the net growth efficiency ( $K_2$ ) was 90.31%. Maintenance costs were estimated at 9.69% of assimilated energy for the entire larval stage.】

Effects of salinity on growth, molt and energy utilization of juvenile swimming crab Portunus trituberculatus

We evaluated the effects of salinity on the growth,molt,and energy utilization of juvenile Portunus trituberculatus.The crabs were held at five salinities(15,20,25,30,and 35) and cultured in rectangular aquari-ums.Each treatment group was quadruplicated,with each replicate consisting of 3 stages(7 juveniles/stage).During the 50-day experiment,mortalities and incidence of "molt death syndrome" were recorded daily,while the intermolt period,carapace length,carapace width,and wet weight were measured at each molt.Salinity had a sig-nificant effect on growth and energy utilization.At salinities of 20,25,and 30,food intake(FId) was lower and food conversion efficiency(FCEd) was higher than in the control.At 30,FCEd was significantly higher than in crabs held at 15 and 35,but not different from those held at 20 and 25.The assimilation efficiency(K1) and net growth efficiency(K2) of crabs held at 20,25,and 30 were significantly higher than in the remaining groups.At the end of the experiment,crabs held at 25 and 30 had a higher wet body weight,relative body weight gain,and SGR.The difference was significant when compared to crabs held at 15 and 35 ppt,but not 20 and 25 ppt.Re-gression analysis suggested that maximum SGRd would occur at salinity 26.3.The molt recycle(MC) between instars VII–X ranged from 18.9 to 23.5 d,and was not different among the groups.Nevertheless,MC was 3.1-4.6 d shorter in crabs held at 30 than the remaining groups.MDS was observed at 15,suggesting that the lower salin-ity plays a role in inhabiting the molt of P.Trituberculatus.Conversely,new shell hardening was inhibited by higher salinity.Our results indicate that the culture water should be maintained at about 25 salinity to improve growth and molt success.

쥐노래미(Hexagrammos otakii)자치어의 먹이와 수온에 따른 성장 및 에너지 수지

The growth, respiration, ingestion, and ecological efficiencies of Hexagrammos otakii larvae and juveniles reared on different diets and temperatures were estimated. A factorial experiment using two diets [non-enriched hatched Artemia nauplii (NEA) and enriched Artemia nauplii (EA)] crossed with two temperatures [natural seawater temperature (NT, ) and heated seawater (HT, )] was conducted to investigate growth and energy budgets of Hexagrammos otakii larvae and juveniles. The energy used by larvae and juveniles for 6 weeks was calculated using data on ingestion, growth, respiration, excretion, and egestion. In the NT trials, the energy used for growth by larvae and juveniles was 0.121 and 0.129 Kcal in the NEA and EA treatments, respectively. Assimilation efficiency at NT were 78.0% and 80.2% in the NEA and EA trials, respectively. Gross growth efficiency () were 60.5% and 62.3% and net growth efficiency () was 77.56% and 77.71% in the NEA and EA trials, respectively. In the HT trials, the energy used for growth by juveniles was 0.189 and 0.212 Kcal in the NEA and EA trials, respectively. Assimilation efficiency at HT was 86.4% and 95.1% in the NEA and EA trials, respectively. Values of and at HT were 69.5% and 80.43%, respectively, in the NEA trials, and 73.9% and 77.66%, respectively, in the EA trials. These results suggest that enriched Artemia nauplii and higher temperatures () are effective for rearing larvae and juveniles of H. otakii.

Growth energetics of juvenile herring, Clupea harengus L.: food conversion efficiency and temperature dependency of metabolic rate

Summary The relationship between rates of food consumption (C) and somatic growth (G) and the effect of temperature (T) on rates of mass lost during food deprivation were examined in 9–10 cm total length (TL) [1.0–1.5 g dry mass (DM)] juvenile Atlantic herring (Clupea harengus L.) in the laboratory. One feeding-growth trial was conducted at 16°C using groups of herring feeding on known rations of brine shrimp (Artemia spp.) nauplii to quantify gross and net growth efficiency. Rates of mass lost by groups of herring (a proxy for metabolic rate, M) were measured in trials conducted at 9.7, 14.2 and 17.9°C. Gross growth efficiency (GGE = 100*G*C−1) at 16°C was 25% at the highest rations (5.8–6.6% DM). The maintenance ration (Cmain = C at zero G) was equal to 432 J*fish−1*d−1 or 2.0% DM*d−1. At 16°C, net growth efficiency (100*G*(C−Cmain)−1) was 42%. The nucleic acid content (RNA-DNA ratio, RD) in herring muscle tissue was strongly related to somatic growth (G, % DM*d−1 = −0.36*RD2 + 3.21*RD −3.92, r2 = 0.90, P < 0.05, n = 8 groups). The effect of T (9.7–17.9°C) on M was described by a second order polynomial equation M = −1.24*T + 38.2*T − 218 (J*g DM−1*d−1) and M = −10*T + 310*T − 1815 (J*fish−1*d−1). This was the first study to investigate the influence of temperature on the metabolic rate of juvenile Atlantic herring under stress-free conditions in the laboratory and provides the first estimates of gross and net growth efficiency for this species feeding on live prey.

Comparison of the physiological energetics betweenMytilus chilensis,Mytilus galloprovincialisand their hybrids, under laboratory conditions

Laboratory-produced juvenile individuals of the species Mytilus chilensis, M. galloprovincialis and their hybrids were subjected to physiological measurements under an experimental diet of Isochrysis galbana (30 × 106 cells L−1), 13°C temperature and a salinity of 30 psu. Pure species individuals showed a higher clearance rate (CR). Mytilus chilensis had a CR of 1.13 L h−1, while M. galloprovincialis registered only 0.78 L h−1. Also, pure taxa registered higher values (above 70%) of absorption efficiency when compared with hybrid individuals. Ammonia excretion in M. chilensis and M. galloprovincialis was 1.5% and 0.4%, respectively, while hybrids registered significantly lower values. Under these experimental conditions, M. chilensis registered the highest scope for growth (P < 0.05), compared with M. galloprovincialis and their hybrids. However, the net growth efficiency index (K 2) in hybridization type I (♀Mg × ♂Mc) was higher (P < 0.05) than other experimental groups. The invasive mytilid M. galloprovincialis showed values that are very similar to those obtained with the hybridization I group (♀Mg × ♂Mc). Finally, we discuss that water temperature is an important factor in the biogeographic separation of both species and the potential effects that the settlement of the invasive species may have for Chilean mussel production.

멍게(Halocynthia roretzi)의 계절별 생리적 변화 및 에너지 수지

The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average <TEX>$25^{\circ}C$</TEX>). Net growth efficiency(<TEX>$K_2$</TEX>) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.

수온과 먹이에 따른 도루묵 (Arctoscopus japonicus) 치어의 에너지수지

In this study, energy budget was estimated to produce an efficient artificial seed. And it needs to enhance fisheries productivity of sandfish, A. japonicus. In order to estimate energy budget of the sandfish, A. japonicus juvenile fed on nonriched Artemia nauplii (NA) and the enriched Artemia nauplii (EA), of sandfish were reared at constant condition of seawater temperature of natural temperature (NT) and heated temperature (HT). During the reared period, energy used by the reared juveniles were calculated from estimates of data on ingestion, growth, oxygen consumption, nitrogen excretion and energy content. Energy budget of NT-NA, NT-EA, HT-NA and HT-EA were represented as 100C=66.49G+21.28M+0.78F+1.44U, 100C=67.54G+21.40M+9.39F+1.67U, 100C=66.86G+22.66M+8.01F+2.47U and 100C=67.06G+22.96M+7.70F+2.28U. The assimilation efficiency estimated NT-NA, NT-EA, HT-NA and HTEA were represented as 87.78%, 88.94%, 89.52% and 90.02%. Gross growth efficiency estimated NT-NA, NT-EA, HT-NA and HT-EA were represented as 66.49%, 67.54%, 66.86% and 67.06%. Net growth efficiency estimated NT-NA, NT-EA, HT-NA and HT-EA were represented as 75.75%, 75.94%, 74.68% and 74.49%. In this results, two ways could be considered to produce an efficient artificial seed of sandfish. To hasten the growth of sandfish juvenile, heated seawater (HT) and enriched Artemia nauplii (EA) should be inputted to reared condition. And to increase the energy efficiency, natural seawater (NT) and enriched Artemia nauplii (EA) should be inputted to reared condition.

Metabolic rates and carbon budget of early developmental stages of the marine cyclopoid copepod Oithona davisae

The genus Oithona has been considered the most abundant and ubiquitous copepod in the world's oceans. However, despite its importance, the metabolism of its developmental stages (nauplii and copepodites), crucial to explain their evolutionary success, is almost unknown. We determined respiration rates, ammonium and phosphate excretion rates, and the net growth efficiencies of early developmental stages of Oithona davisae as related to stage, body weight, temperature, and food availability. Respiration and excretion rates increased with increasing body weight and were positively related to temperature and food. Specific respiration rates of nauplii and copepodites varied from 0.11 to 0.55 d−1 depending on stage, body weight, temperature, and food availability. Metabolic C:N ratios were higher than 14, indicating lipid‐oriented metabolism. Assimilation efficiencies and net growth efficiencies ranged from 65% to 86% and from 23% to 32%, respectively, depending on body weight, stage, and temperature. Assimilation efficiencies and net growth efficiencies estimated using the respiration rates of nauplii with food were 1.7 times higher and 0.6 times lower, respectively, than those calculated using respiration rates of nauplii without food. Therefore, the use of respiration rates measured in filtered seawater led to substantial bias on the estimations of zooplankton carbon budget. O. davisae developmental stages exhibited similar assimilation and growth efficiencies but lower carbon‐specific respiratory losses than calanoid copepods. Hence, the low metabolic costs of Oithona compared with calanoids may be one reason for their success in marine ecosystems.

Trophic role and carbon budget of metazoan microplankton in northwest Mediterranean coastal waters

We determined the feeding rates, trophic effect, and growth efficiencies of natural assemblages of metazoan microplankton from a coastal site in the northwest (NW) Mediterranean over a seasonal cycle in laboratory incubations. Micrometazoans, i.e., multicellular heterotrophic plankters between 20 and 200 µm, were mainly constituted by invertebrate larval stages. Copepod nauplii and copepodites dominated the community, except in April, when polychaete larvae dominated. We analyzed the grazing pressure of micrometazoans on chlorophyll a (Chl a; total and &gt; 10 µm), nanoflagellates, phototrophic nanoflagellates, dinoflagellates, diatoms, and ciliates. Micrometazoans grazed on all the prey groups, with carbon‐specific ingestion rates ranging from 0.31 to 1.24 d−1. The gross growth efficiencies for the entire metazoan microplankton community, calculated as the slope of the linear regression relating specific growth rates vs. specific ingestion rates, varied between 0.27 and 0.39. The respiratory carbon losses of micrometazoans depended on temperature and ranged from 0.16 to 0.36 d−1, with a Q10 = 2. The average net growth efficiency, 0.41, was independent of temperature and food availability. Overall micrometazoans have higher specific growth rates than, but similar food conversion efficiencies to, mesozooplankton. The grazing effect on the standing stock of the different prey was &lt; 1% d−1 for Chl a (total and &gt; 10 µm) and &lt; 2.5% d−1 for the other studied prey, which seems insufficient to exert relevant control on phytoplankton and protozoan dynamics. The inclusion of micrometazoans did not change appreciably our current view of the role of metazooplankton in marine trophic webs of NW Mediterranean coastal waters.

Allometric Scaling of Metabolism, Growth, and Activity in Whole Colonies of the Seed‐Harvester AntPogonomyrmex californicus

The negative allometric scaling of metabolic rate with body size is among the most striking patterns in biology. We investigated whether this pattern extends to physically independent eusocial systems by measuring the metabolic rates of whole functioning colonies of the seed-harvester ant Pogonomyrmex californicus. These intraspecific scaling data were compared to the predictions of an additive model developed to estimate collective metabolic rates. Contrary to the prediction of the additive model, colony metabolic rate allometry resembled the pattern commonly observed interspecifically for individual organisms, scaling with colony mass(0.75). Among the same-aged colonies, net growth rate varied by up to sevenfold, with larger colonies exhibiting higher net growth efficiency than smaller colonies. Isolated worker groups exhibited isometric metabolic rate scaling, suggesting that the social environment of the colony is critical to regulating individual patterns of work output. Within the social environment, individual worker locomotor velocities exhibited power-law distributions that scaled with colony size so that larger colonies exhibited a greater disparity between active and inactive ants than did smaller colonies. These results demonstrate that behavioral organization within colonies may have a major influence on colony-level metabolism and in generating intraspecific variation in growth trajectories.

Using energy budget data to assess the most damaging life-stage of an agricultural pest Mocis latipes (Guenèe, 1982) (Lepidoptera - Noctuidae)

There is much evidence to support that Mocis latipes larvae (Guenèe, 1852) are the most dangerous pasture pest and usually cause large environmental losses. However, no studies have been carried out to identify the instars during which this moth causes the most damage to the environment. Here we calculate M. latipes larval energy budget to assess its consumption across all instars and estimate the consumption/amount of plant biomass required to complete its larval development. Assimilation, respiration, consumption, excretion, gross growth efficiency and net growth efficiency were calculated. Pearson correlations were used to identify the best predictors that influenced larval growth and weight. Across all instars consumption increased exponentially, especially during the last phase. M. latipes larvae consumed ca 13.8% of total food from the first to the fifth instar, whereas during the sixth instars these larvae consumed ca 72.6%. Results also show that the best gross growth and net growth efficiency were obtained when larvae reached the fifth instar. The results also show that one larva of Mocis latipes consumes 1.02 g (dry weight) of Paspalum maritimum (Trin) in 19 days. Overall, our results indentified the sixth instar as the most destructive instar of this insect. Thus, once we know the most destructive instars of this pest, measures can be taken to disable M. latipes larval development and consequently stop their increase in plant consumption, reducing ecological and economic damage. This knowledge may eventually lead to reduced agricultural damage and contribute to sustainable farming strategies.

Growth and Energy Budget Models of the BivalveArctica islandicaat Six Different Sites in the Northeast Atlantic Realm

We compared lifetime and population energy budgets of the extraordinary long-lived ocean quahog Arctica islandica from 6 different sites—the Norwegian coast, Kattegat, Kiel Bay, White Sea, German Bight, and off northeast Iceland—covering a temperature and salinity gradient of 4-10C (annual mean) and 25-34, respectively. Based on von Bertalanffy growth models and size-mass relationships, we computed organic matter production of body (PSB) and of shell (PSS), whereas gonad production (PG) was estimated from the seasonal cycle in mass. Respiration (R) was computed by a model driven by body mass, temperature, and site. A. islandica populations differed distinctly in maximum life span (40 y in Kiel Bay to 197 y in Iceland), but less in growth performance (f# ranged from 2.41 in the White Sea to 2.65 in Kattegat). Individual lifetime energy throughput, as approximated by assimilation, was highest in Iceland (43,730 kJ) and lowest in the White Sea (313 kJ). Net growth efficiency ranged between 0.251 and 0.348, whereas lifetime energy investment distinctly shifted from somatic to gonad production with increasing life span; PS/PG decreased from 0.362 (Kiel Bay, 40 y) to 0.031 (Iceland, 197 y). Population annual energy budgets were derived from individual budgets and estimates of population mortality rate (0.035/y in Iceland to 0.173/y in Kiel Bay). Relationships between budget ratios were similar on the population level, albeit with more emphasis on somatic production; PS/ PG ranged from 0.196 (Iceland) to 2.728 (White Sea), and P/B ranged from 0.203-0.285/y. Life span is the principal determinant of the relationship between budget parameters, whereas temperature affects net growth efficiency only. In the White Sea population, both growth performance and net growth efficiency of A. islandica were lowest. We presume that low temperature combined with low salinity represent a particularly stressful environment for this species.

Bioenergetics and growth in the ctenophore Pleurobrachia pileus

Knowledge of how energetic parameters relate to fluctuating factors in the natural habitat is necessary when evaluating the role of gelatinous zooplankton in the carbon flow of coastal waters. In laboratory experiments, we assessed feeding, respiration and growth of the ctenophore, Pleurobrachia pileus, and constructed carbon budgets. Clearance rates (F, l d−1) of laboratory-reared Acartia tonsa as prey increased as a function of ctenophore polar length (L, mm) as F = 0.17L 1.9. For ctenophores larger than about 11 mm, clearance rate was depressed in containers of 30–50 l volume. Clearance rates on field-collected prey were highest on the copepod, Centropages typicus, intermediate on the cladoceran, Evadne nordmanni and low on the copepods, Acartia clausi and Temora longicornis. Specific growth rates of 8–10 mm P. pileus increased with increasing prey concentrations to a maximum of 0.09 d−1 attained at prey carbon densities of 40 and 100 μg C l−1 of Artemia salina and A. tonsa, respectively. Weight-specific respiration rates increased hyperbolically with prey concentration. From experiments in which growth, ingestion and respiration were measured simultaneously, a carbon budget was constructed for individuals growing at maximum rates; from the measured parameters, the assimilation efficiency and net growth efficiency were estimated to be 22 and 37%, respectively. We conclude that the predation rates of P. pileus depend on ctenophore size, prey species, prey density and experimental container volume. Because the specific growth rates, respiration, assimilation and net growth efficiencies all were affected by food availability, knowledge of the ambient prey field is critical when evaluating the role of P. pileus in the carbon flow in coastal waters.

Effect of sewage cultured Lemna minor on growth of Mollinesia latipinna fed on mixed diets

Effect of sewage cultured Lemna minor on growth of Mollinesia latipinna was investigated using three different types of feeds viz.control feed (F1), raw lemna incorporated feed (F2) ,and decomposed lemna incorporated feed (F 3 ) for 20 days. The feeds were prepared by using sewage cultured L.minor .The test animals fed with decomposed lemna incorporated feed showed high production (0.205) ,Gross growth efficiency (11.08 %), Net growth efficiency (11.39 %) ,Assimilation efficiency (97.31)and Metabolism (1.61). Raw L.minor incorporated fish feed showed slightly low value of Metabolism (1.58), Assimilation (1.75) and relative growth efficiency.