Egger's Model Research Articles

Preliminary evaluation of ecological effects of silver and bighead carps to control cyanobacterial blooms in the early eutrophication lakes

放养鲢（Hypophthalmichthys molitrix）、鳙（Aristichthys mobilis）控制富营养化湖泊蓝藻水华暴发是当前最有效的手段之一.为评估富营养化初期湖泊鲢、鳙控藻的生态效果，2016年在洱海红山湾开展原位围栏鲢、鳙控藻实验，对围栏内外的浮游生物群落结构及水环境因子的变化进行对比分析，同时测定了围栏内鲢、鳙的生长及摄食节律.结果表明：围栏内鲢、鳙呈现匀速生长，围栏生存环境适宜.根据Egger's模型估算鲢、鳙的日摄食量分别为24.96%和18.18%，鲢的日粮高于鳙；滤食率结果表明，鲢对浮游植物的摄食率高于鳙（分别为3.01和2.19 L/（g·h），而鳙对浮游动物的滤食率高于鲢（分别为18.61和13.54 L/（g·h））.研究期间，围栏内外水体理化因子无显著差异；但围栏内外微囊藻生物量差异明显，并且在7月达到生物量峰值（围栏内为1.7 mg/L，围栏外为2.4 mg/L）.鲢、鳙对浮游植物的优势种类——微囊藻和隐藻有明显的削减效果，6-8月逐渐上升并在8月达到最高（64%）；当浮游植物优势种由微囊藻替换为硅藻门和绿藻门的种类时，鲢、鳙的削减效率不明显（10-11月为负值）.此外，鲢、鳙放养显著降低了浮游甲壳动物的总生物量和枝角类生物量.因此，结合实验结果得出，鲢具有更高的控藻能力，尤其对微囊藻水华，但同时具备了较高对浮游甲壳动物的削减能力，需要进一步分析富营养化初期湖泊——洱海中实施非经典生物操纵的适宜性.;It is one of the most effective ways to control the outbreak of cyanobacteria blooms in eutrophic lakes by stocking silver and bighead carps. In order to evaluate the ecological effects of controlling algae by silver and bighead carps in early eutrophication lakes. In 2016, a little biomanipulation in-situ pen with the stock of silver and bighead carps was built to control cyanobacterial blooms in Hongshan Bay of Lake Erhai. The changes of plankton community structure and water environmental factors were compared and analyzed within and outside the pen. Meanwhile, the growth and feeding rhythm of silver and bighead carps were measured. The pen-cultured silver and bighead carp all displayed normal growth, the survival environment of the pen is suitable. Daily rations of silver and bighead carp were estimated by Egger's model in the main growing season. Filtration rate was calculated from the daily ration and the density plankton in the lake. Daily rations of silver and bighead carp was 24.96% and 18.18%. The daily rations silver carp is higher than that of bighead carp. Filtration rates of silver and bighead carp for phytoplankton were 3.01 L/(g·h) and 2.19 L/(g·h), respectively, and filtration rates for zooplankton were 13.54 L/(g·h) and 18.61 L/(g·h), respectively. Silver carp had a stronger ability of eliminating phytoplankton than bighead carp. Bighead carp had a stronger ability of eliminating zooplankton than silver carp. During the study, there was no significant difference in the environmental parameters within and outside the pen. The biomass of Microcystis reached its peak in July (1.7 mg/L in the fish pen and 2.4 mg/L in the surrounding lake water). The Microcystis biomass was significantly lower in the pen. The present stocking density of silver and bighead carp(about 20 g/m³ in June)was effective to control Microcystis. From June to August, the reduction rate of the phytoplankton in the silver and bighead carp gradually increased, and the rate of reduction was up to 64% in August. When phytoplankton's dominant species Chlorophyta and diatom replace Microcystis, the rate of reduction decreased gradually, with negative values in October and November. Furthermore, the biomass of crustacean zooplankton biomass and cladocerans biomass were significantly lower in the pen. Therefore, in combination with several experimental results, silver carp had a stronger ability of eliminating phytoplankton than bighead carp. Especially for Microcystis blooms, silver carp at the same time have the higher on the reduction ability of crustacean zooplankton. We need to further analyze the suitability of non-traditional biological manipulation in the early stage of eutrophication Lake Erhai.

The influence of particle size of dietary prey on food consumption and ecological conversion efficiency of young-of-the-year sand lance, Ammodytes personatus

Abstract The Eggers model was used to study the influence of two particle sizes of dietary prey on food consumption and ecological conversion efficiency of young-of-the-year sand lance, Ammodytes personatus, in continuous flow-through seawater in 2.5-m3 tanks in the laboratory. The sand lances (average body weight 0.85 ± 0.21 g) were fed larval (average body length 0.56 ± 0.08 mm) or adult (average body length 10.12 ± 1.61 mm) Artemia salina. The gastric evacuation rate of the fish feeding on larval Artemia was 0.214, higher than that of those feeding on adult Artemia (0.189). The daily food consumption of the fish feeding on larval Artemia was 60.14 kJ/100 g in terms of energy content, higher than that of the fish feeding on adult Artemia (51.69 kJ/100 g), but the daily growth rate of fish feeding on larval Artemia was 14.86 kJ/100 g, significantly lower than that of the fish feeding on adult Artemia (19.50 kJ/100 g), indicating that less energy was used for growth when the food particles were smaller. Slow growth of sand lances preying on larval Artemia was probably due to the high energy consumption during predation, consistent with the basic suppositions of optimal foraging theory.

In situ study on the control of toxic Microcystis blooms using phytoplanktivorous fish in the subtropical Lake Taihu of China: A large fish pen experiment

Three large fish pens (0.36 km 2 of each) stocked with silver and bighead carp were set up in Meiliang Bay for controlling toxic Microcystis blooms. The responses of plankton communities and food consumption of silver and bighead carp were studied. Crustacean zooplankton were significantly suppressed in the fish pens. Total phytoplankton biomass, Microcystis biomass and microcystin concentration were lower in the fish pens than in the surrounding lake water, but the difference was not statistically significant. The present stocking density of silver plus bighead carp (about 40 g/m 3 in July) was likely too low to achieve an adequate control of Microcystis. Silver carp fed mainly on phytoplankton but bighead carp mainly on zooplankton: mean zooplankton contribution in the gut was 31.5% for silver carp and 64.7% for bighead carp. Compared with previous studies, both carp species preyed upon more zooplankton because of the abundant food resource. Daily rations of silver and bighead carp were estimated by Egger's model in the main growing season. Filtration rate was calculated from the daily ration and the density of plankton in the lake. During May–October, filtration rates of silver and bighead carp for phytoplankton were 0.22–1.53 L g − 1 h − 1 and 0.02–0.68 L g − 1 h − 1 , respectively, and filtration rates for zooplankton were 0.24–0.44 L g − 1 h − 1 and 0.08–1.41 L g − 1 h − 1 , respectively. Silver carp had a stronger ability of eliminating phytoplankton than bighead carp. To achieve a successful biomanipulation with a minimum effect of ichthyoeutrophication, the stocking proportion of bighead carp should be controlled in the future practice.

A dieta e o consumo diário de alimento de Cichla monoculus na Amazônia Central

Avaliar a dieta, o ritmo alimentar e a taxa de consumo diária de alimento dos peixes pode permitir estimar a relação entre a alimentação e o crescimento, a pressão de predação sobre espécies de presas, a limitação alimentar durante estações do ano e a competição intra e inter-específica. Estas informações são desconhecidas para C.monoculus na Amazônia Central e aqui são apresentados dados sobre a ecologia trófica desta espécie durante quatro estações hidrológicas. A área de estudo incluía três lagos de várzea na Amazônia Central, durante os períodos de agosto de 1997 a julho de 1998. Os estudos da dieta e do ritmo alimentar foram feitos através das análises dos conteúdos estomacais. A taxa de evacuação gástrica foi estimada experimentalmente. O consumo diário de alimento foi calculado a partir dos modelos de Elliot & Persson e de Eggers. A intensidade de alimentação da espécie foi baixa durante a seca. A dieta do C. monoculus foi basicamente piscívora e composta de nove famílias de peixes e uma de camarão, apresentando variações no decorrer das estações hidrológicas e com o tamanho do peixe. A taxa de evacuação gástrica foi 16,9% h-1. O consumo diário de alimento, que não foi diferente nas quatro estações hidrológicas, teve média igual a 2,23% do peso corporal. Este valor é baixo comparado a outros estudos estimados para peixes tropicais. Indicando que esta espécie come relativamente pouco.

An in situ estimate of food consumption of five cyprinid species in Lake Balaton

Daily rations of five cyprinid species, bream Abramis brama, silver bream Blicca bjoerkna, roach Rutilus rutilus, gibel Carassius auratus gibelio and carp Cyprinus carpio, in Lake Balaton, a large shallow lake, estimated by the Eggers model differed from that of the Elliott – Persson model by only − 4.3 to +7.3% (the differences were insignificant). Daily rations varied within the range of 0.23–0.69 in bream, 0.55–3.61 in silver bream, 0.69–4.65 in roach, 0.38–3.16 in gibel and 0.50–9.74 g dry 100 g wet fish mass−1 day −1 in carp at temperatures ranging from 8.7–25.8% C. Daily ration was related exponentially with temperature in silver bream, roach, gibel and carp. For bream, a significant relationship was obtained only when a daily ration value was excluded from the analysis. Annual rations were assessed using the relationships between the daily ration estimates from the Elliott—Persson model and water temperature, and the long-term averages of the monthly water temperature data. From these estimates the bream population consumed 104%, silver bream 424%, roach 487%, gibel 363% and carp 913% dry mass of food of its wet biomass annually.

An in situ estimate of food consumption of five cyprinid species in Lake Balaton

Daily rations of five cyprinid species, bream Abramis brama, silver bream Blicca bjoerkna, roach Rutilus rutilus, gibel Carassius auratus gibelio and carp Cyprinus carpio, in Lake Balaton, a large shallow lake, estimated by the Eggers model differed from that of the Elliott – Persson model by only − 4.3 to +7.3% (the differences were insignificant). Daily rations varied within the range of 0.23–0.69 in bream, 0.55–3.61 in silver bream, 0.69–4.65 in roach, 0.38–3.16 in gibel and 0.50–9.74 g dry 100 g wet fish mass−1 day −1 in carp at temperatures ranging from 8.7–25.8% C. Daily ration was related exponentially with temperature in silver bream, roach, gibel and carp. For bream, a significant relationship was obtained only when a daily ration value was excluded from the analysis. Annual rations were assessed using the relationships between the daily ration estimates from the Elliott—Persson model and water temperature, and the long‐term averages of the monthly water temperature data. From these estimates the bream population consumed 104%, silver bream 424%, roach 487%, gibel 363% and carp 913% dry mass of food of its wet biomass annually.

Variability in Daily Ration Estimates of Age-0 Striped Bass in the Chesapeake Bay

Abstract Previous studies have developed and applied bioenergetics models to estimate trophic demand for prey by striped bass Morone saxatilis in Chesapeake Bay. Although these models were validated with laboratory studies, no field estimates of daily ration of striped bass were available in Chesapeake Bay for comparison with bioenergetics model estimates. This study estimated growth and daily ration of age-0 striped bass in the upper Chesapeake Bay for two dates (6 and 19 October 1993) using the Eggers model. Experiments on the gastric evacuation rate of captive striped bass at 17°C found that stomach contents were evacuated at a rate of e −0.12h , where h is time in hours since feeding. Daily ration estimates only 14 d apart varied by 66% (0.0326 g · g−1 · d−1 on 6 October and 0.0542 g · g−1 · d−1 on 19 October). Bioenergetics model estimates of consumption over this period averaged 0.0559 g · g−1 · d−1. Based on the variability in Eggers estimates, it would require more than two estimates (2.4) of dail...

The Guts to Estimate Fish Daily Ration

We compared daily ration values estimated using the Elliott and Persson and the Eggers models implemented with field-derived variations in stomach and complete digestive tract (CDT) contents of fish. Stomach evacuation rate (0.31∙h−1) was 2.8 times greater than that of CDT (0.11∙h−1). Daily rations obtained using both models and sections of the digestive tract estimated at 2-h intervals averaged 0.84 (Trial 1), 2.56 (Trial 2), and 2.41 g dryl∙100 g wet−1∙d−1 (Trial 3) and never differed by more than 23.6% within trials (average = 11.4%). Variances in daily ration values from the Elliott and Persson model were, on average, 3.4 times larger than variances derived using Eggers model. Variances associated with daily rations on stomach contents were, on average, 5.9 times larger than variances based on CDT contents. Sampling frequencies (from 2- to 4-, 6-, 8-, and 12-h intervals) had no significant influence on mean daily ration values but, on average, caused a 3.6-fold increase in variances. The precision and robustness of daily ration values appeared more directly influenced by the section of digestive tract used than by the estimation model chosen; the Eggers model implemented with CDT contents appeared to be the most efficient combination.

Bias Associated with Using the Eggers Model for Estimating Fish Daily Ration

Estimates of yellow perch (Perca flavescens) daily ration derived from Eggers' model were compared with those based on the Elliott–Persson model and a 3-h within-day sampling interval. Correcting for the bias in Eggers estimates associated with food weight differences at the start and finish of estimation periods significantly reduced discrepancies between the two when Eggers estimates were also based on a 3-h sampling interval. As sampling interval was increased to 6 and 12 h for Eggers estimates, a positive bias related to variability about [Formula: see text] emerged and inflated exponentially with increasing ration levels. A third bias (typically positive) may be introduced when [Formula: see text] in Eggers' model is computed without regard to the skewness that often exits in distribution of food weights among fishes within a single collection. Use of the median or a normalizing transformation will avert this. While each bias alone can have an important effect on daily ration estimates, the possibility of accentuated bias from multiple sources also exists. Two of the potential biases are easily managed, but caution is advised when Eggers' approach is used to estimate daily rations based on expanded sampling intervals.

An In Situ Experimental Evaluation of the Elliott and Persson and the Eggers Models for Estimating Fish Daily Ration

We compared estimates of daily ration developed using the theoretically rigorous and logistically demanding Elliott and Persson model and the more easily applied Eggers model which is infrequently used because of its assumptions about rigid fish feeding periodicity. Comparisons were based on ten 24-h samplings of six different yellow perch (Perca flavescens) populations. Daily ration estimates from the two models did not differ significantly. This consistency occurred in spite of the fact that in some cases the observed feeding periodicity violated the assumptions of the Eggers model. A simulation model demonstrated that 95% confidence intervals were smallest for the Eggers estimates and that the Eggers model was more robust than the Elliott and Persson model to changes in both sampling frequency and number offish sacrificed at each sampling event. The latter proved particularly sensitive to changes in sampling frequency. We concluded that the two models provide estimates of daily ration comparable in magnitude and accuracy and consequently that the restriction of the Eggers model to fish with rigid feeding periodicity is not justified. Furthermore, the Eggers model, because of its robustness, reduces the sampling requirements to determine daily ration, and hence, permits its estimation on a more frequent basis.