Eutrophication Indexes Used as Fish Production Parameters in the Itaipu Reservoir (Brazil)

Rinaldo Antonio Ribeiro Filho, Julia Myriam de Almeida Pereira, Miguel Petrere Júnior, Simone Frederigi Benassi

Divis?o de Reservatório (MARR.CD), Itaipu Binacional, Foz do Igua?u, Brazil..
Engenharia de Pesca, Universidade Estadual Paulista, Registro, Brazil&Núcleo de Estudos de Ecossistemas Aquáticos, Centro de Recursos Hídricos e Ecologia Aplicada, EESC, Universidade de S?o Paulo, S?o Carlos, Brazil.
Núcleo de Estudos de Ecossistemas Aquáticos, Centro de Recursos Hídricos e Ecologia Aplicada, EESC, Universidade de S?o Paulo, S?o Carlos, Brazil&Departamento de Engenharia de Pesca e Aquicultura, Universidade Federal de Rond?nia, Rua da Paz, Brazil.
Programa de Pós Gradua??o em Diversidade Bilógica e Conserva??o, Universidade Federal de S?o Carlos (UFSCar), Sorocaba, Brazil&Programa de Pós Gradua??o em Sustentabilidade em Ecossistemas Marinhos e Costeiros, UNISANTA, Santos, Brazil.

DOI: 10.4236/jep.2013.47A018                

Abstract

The knowledge of liminology can be applied in studies of trophic state indexes and morfoedaphic indexes as factors for determining the inference fish production in reservoirs. This work is based on the hypothesis of the trophic cascade relations, particularly related to bottom-up and top-down effect in Itaipu Reservoir (Brazil). Using the data available by Itaipu, from 1999 to 2004, analyzes of multiple regressions were accomplished to determine the relationships of the dependent and independent variables. We applied the trophic state indices (TSI) based on readings Secchi disk, total phosphorus and chlorophyll-a density for obtaining TSI medium. Morfoedaphic index was calculated based on the reading of the concentration of dissolved solids and the inference of fishing yield, from this index. The average results of the trophic state indices indicate an oligotrophic status for the entire reservoir as well as for the riverine, transition and lacustrine zones separately. The fish was yieldn Estimated by the relation with cyanobacteria concentration, and this was the best variable que explained this prediction. The use of the morfoedaphic index (MEI), with the recorded catch data, predictive models can generate que estimate the fishing yield in the Itaipu Reservoir. The relations of MEI with chlorophyll-a and water transparency que Indicate this index may be a good predicting factor for future fish captures.

Keywords

Trophic Cascade Reservoir; Limnology; Biotic Community; Fish Yield

1. Introduction

1.1. Relationship between Fish and Water Quality

Fish play an important role in the biocenosis of reservoirs when it comes to water quality. The presence or absence of certain species, together with the amount of fish in the system help to determine the composition and quantity of nutrients, zooplankton and phytoplankton in reservoirs [1].

The ichthyofauna of a reservoir is altered according to water quality owing to two factors: 1) contamination by pollutants from tributaries, what can affect various parts of the reservoir and 2) changes in how the hydrological system works [1]. The composition of species of the fauna depends largely on geographical characteristics and lakes and reservoirs are characterized by the absence of true pelagic species, and most of the reservoirs are populated by species that typically inhabit the coastal region.

1.2. Trophic Cascade Interactions in Reservoirs

The trophic cascade theory in lakes and reservoirs is based on two principles: 1) loss of energy between a trophic level and another and 2) disturbance of a trophic level with consequences in the remaining trophic levels.

The pioneer work of [2] was responsible for highlighting the effect of fish on the structure of the aquatic food chain. After a few years, research such as [3,4] contributed to the development of the food web theory in lakes, revealing the important role of fish, ignored for decades in the field of limnology.

The theory of trophic cascades [5]; see critiques from [6] and the meta-analyses of [7,8] and the bottom-up/topdown theory [9] are the two main conceptual models of work used here. Phytoplankton responds positively to nutrient enriched systems with an odd number of trophic levels (three levels: phytoplankton, zooplankton and planktivorous fish), but not in systems with an even number of trophic levels (two levels without fishes, or four levels with piscivorous fishes).

The effect of the stock of planktivorous fish on the zooplankton community has been well studied [10-12] and there is strong pressure of these fish on the biomass of algae [13,14]. The effect of piscivorous fishes in a system has a strong relationship with the stock of planktivorous fishes, causing the drastic reduction of latter [6, 15,16]. Some studies confirm that the impact of fish stocks favors the concentrations of chlorophyll through the excretion of nutrients and the predation of zooplankton [17-20]. With regard to the stock of piscivorous fishes, many studies were not successful [6,17], mainly due to the low stocking density [21]. In many studies the top-down effect was observed [4,5,13,15,25-29].

[25] suggest that knowing how the food chain works can be useful for the management of aquatic ecosystems aiming at ecology conservation. The increase of piscivorous fishes may decrease the density of planktivorous ones and, consequently, increase grazing and depletions in the concentrations of chlorophyll-a. The increase in the stock of piscivorous can be a tool for rehabilitating eutrophic lakes. The concept of trophic cascade with links between limnology and fisheries biology suggests a biological alternative for lake management.

Studies by [7] prove the theory of trophic cascade. They noted that the manipulation of fish communities can be used to control algal biomass, but these relationships are fragile. The authors mention that the control of the phytoplankton through the trophic cascade management (biomanipulation) can be successful in about 60% of the cases and that the reduction zooplanktivorous species would result in a slight reduction in phytoplankton biomass and hence a small improvement in the quality of water.

[30] mention that the top-down control of chlorophylla occurs according to the following conditions: 1) shortterm experiments, 2) shallow lakes with macrophytes and 3) deep slightly eutrophic or mesotrophic lakes. Other experiments indicate that top-down control may be unlikely in the following conditions: 4) eutrophic or hypertrophic deep lakes, unless there is severe limitation of light, and 5) for all lakes when there is extreme nutrient limitation (oligotrophic and ultra-oligotrophic lakes). Important factors that are responsible for the top-down control under the described conditions in 1) and 3) are the time scales that prevent the slow development of phytoplankton; shallow depths allow macrophytes to become dominant primary producers 2), and biomanipulation induced reduction of phosphorus (P) available to phytoplankton 3).

[31] compared the data of trophic (limnological) variables with the spatial and temporal distribution of fishes, zooplankton and phytoplankton. According to the analysis (meta-analysis), the distribution of the studied trophic levels was correlated with the temperature of water and nutrient concentration distributions.

1.3. Tropical and Subtropical Trophic Cascades

According to [32], the dams in the semi-arid Northeastern region of Brazil offer excellent opportunities for theoretical comparisons on the relative importance of the top-down and bottom-up impact structuring forces on the fish-plankton interactions in tropical environments, including comparisons between the effects of the dominance of omnivorous and low number of piscivorous species. However, most of the dams have never been studied, except for some large public ponds, especially those controlled by DNOCS-Departamento Nacional de Obras Contra a Seca (National Department of Works Against Droughts) in the states of Ceará and Paraíba. Regional reports on fishery yield, hydrochemistry and limnology (e.g. [33-41]) were rare. The author points out that to make generalizations it is more appropriate to use a comparative approach based on data from climatology, limnology and plankton communities and fish collected in the reservoir, and studies correlating all these variables are in small number [42,43]. Studies with this type of approach can provide important practical and social implications for predictive limnology [44], for the management of fishery yield [45] and/or water quality.

While studying 31 Argentinean reservoirs, [46] have shown that in environments in which the effect of piscivorous stock did not cause a depletion of zooplanktivores, the phytoplankton biomass reduced drastically. The authors emphasized that human influence can cause changes in trophic relationships in lakes and reservoirs.

[47] evaluated the top-down and bottom-up effects in a floodplain lake in Bolivia. The authors found two types of effects on the trophic cascade in experiments in mesocosms, and the effect of these relationships varied among trophic levels. The effect of planktonic fishes did not show any positive relationship with zooplankton, mainly with cladocerans, and phytoplankton showed bottom-up effect.

The objectives of this work were to evaluate the water quality of the Itaipu Reservoir (central body and arms of the left bank of the reservoir) through the analysis of physical, chemical and biological variables, given the multiple uses of the reservoir during the period from 1999 to 2004; to analyze the evolution of the trophic levels of the reservoir, including its left margin arms, and characterize the trophic webs and the relationship between the relative fish biomass, plankton and limnology of the Itaipu reservoir.

2. Materials and Methods

2.1. Characterization of the Study Area

The Paraná River is the tenth longest river in the world (4695 km), and was considered the most important hydrological system of the La Plata River Basin [48]. It is formed by the confluence of the rivers Grande and Parnaíba (center-south of Brazil), flowing into La Plata River, North of Argentina [49]. The Paraná River Basin is responsible for more than 70% of hydroelectric power production in Brazil, has the largest population density in South America and includes other major rivers, such as the rivers Grande, Tietê, Parnaíba, Paranapanema, and Iguaçu, were approximately 130 dams were constructed (Figure 1).

The Itaipu Reservoir, completed in October 1982, is located in the Brazil-Paraguay border, between latitudes 24˚05′S and 25˚33′S and between longitudes 54˚00′W and 54˚37′W (Grw). It has a surface of 1350 km² in its mean elevation of operation (220 m) and 1.460 km² when in maximum height (223 m). Of these, 625 km² are part of Brazil and 835 km² of Paraguay. It stretches over 151 km (170 km in maximum quote) and separates the cities of Guairá-Salto del Guayra and also Foz do IguaçuCiudad del Este [50].

With an average depth of 22 m, and possible depths of 170 m near the dam, the Itaipu reservoir accumulates as normal maximum volume, 29,109 m³ of water. The residence time in the main channel is 29 days and the speed of the water can reach 0.6 m/s. The average residence time is, however, 40 days. It operates with a maximum annual level variation of 0.6 m [51].

Energy production is the main use of the Itaipu reservoir, which was the primary motivation for its construction. However, other secondary uses are currently coming into scene, especially 1) navigation, facilitated by the drowning of The Sete Quedas Falls (Guaira), 2) recreation and tourism, mainly in five artificial beaches built on its banks, 3) water supply for cities and irrigation of smallholdings and 4) professional fishing [52].

Based on Carlson’s trophic state index (phosphorus and chlorophyll-a), this reservoir was classified as mesotrophic, and some eutrophic areas may be found in its arms during certain periods of the year. It presents an annual cycle of thermal stratification in its main body (spring-summer), which classifies it as a monomictic hot lake, besides daily stratification processes in its arms.

Figure 1. The Paraná River basin, with its reservoirs (Source: Itaipu Binacional, 2006).

The fish assemblage of the Itaipu reservoir and its catchment area is composed of 114 species in all environments. The dominant species vary with the type of environment, because this is a factor that contributes significantly to the structure of this assemblage (ANNUAL REPORT ITAIPU BINACIONAL).

2.2. Characterization of the Sampling Stations

To establish the location of the sampling stations we considered the compartmentalization of the Itaipu Reservoir, which is composed by three horizontal regions, along the main body of the reservoir [50,53-55]: 1) the riverine zone: located at the beginning of the reservoir, 2) the transition region: between the lotic and lentic regions, and 3) the lentic region, called “lacustrine region”, where the reservoir is usually deeper and wider.

Furthermore, the Itaipu Reservoir has a dendritic form, what means that attached to its central body there are branches on the sides called reservoir arms which present systems that are almost independent from the main body system and that have their own particular characteristics. Due to this compartmentalization, a network of water quality monitors was established, totaling twelve sampling stations (Figure 2).

Figure 2. Morphometry and sampling sites in the Itaipu Reservoir, with the riverine, transition and lacustrine zones adopted in the monitoring program.

Stations E1, E2, E3, and E7, in areas of lotic characteristics are in the riverine zone. Stations E5, E11, E12, E14 and E20 are in the lacustrine region and stations E8 and E12 are in the transition region.

2.3. Data Collection

The data analyzed in this study were provided by Itaipu Binacional. Limnological analyses, including physical and chemical water variables, phytoplankton and zooplankton were made by Instituto Ambiental do Paraná (IAP), the Environmental Institute of Paraná, based on quarterly collections, between 1999 and 2004. Information on fish stocks are from the studies conducted by Núcleo de Pesquisa em Limnologia, Ictiologia e Aquicultura (NUPELIA/UEM), the Center for Research in Limnology, Ichthyology and Aquaculture.

According to [54], samples were collected at the water surface, and the physical, chemical and biological water quality variables were monitored in all field samplings. The following variables were measured in the field: temperature, dissolved oxygen concentration and percentage of saturation, pH, electrical conductivity and water transparency. Other physical and chemical variables, such as alkalinity, total nitrogen Kjeldahl (TKN) nitrate, nitrite, ammonia and nitrogen, total solids, suspended solids, BOD, COD and total phosphorus were analyzed in the laboratory, according to [56], as well as the concentration of chlorophyll-a [57]. The analysis protocols were presented by [58].

The climatological data were obtained from weather stations in the cities of Guaira (riverine area), Entre Rios do Oeste (transition zone) and Iguazu Falls (lacustrinedownstream zone).

Data on fishes were grouped into trophic guilds, according to [55]. They presented the relative densities, calculated from numerical abundance in kilograms, corresponding to the weight of gutted fish without a head.

The relative abundance of phytoplankton, zooplankton and fish were presented according to the regions (riverine, transition and lacustrine) of the reservoir to enable the comparison of the spatial distribution patterns.

2.4. Statistical Analysis of Data

To test the trophic cascade hypothesis in the reservoir we performed linear regression analyses among the physical, chemical, biological and trophic guilds, and trophic levels were analyzed one by one, determining the interactions between them. These analyses were performed in accordance with food web models (Top down and Bottom up) [9,18,24,32]. The graphs were evaluated to determine whether the relationships were linear or not. To stabilize the variance, the neperian logarithms were taken for all limnological variables. Graphically, limnological variables were expressed according to the equation below:

(1)

where var is the original value of the limnological variable lnvar is the transformed the value of var.

For biotic variables, in order to minimize null values, the transformation was performed according to the following equation, based on absolute numerical abundance:

(2)

where bio is the original value of the biotic variable + 1, ln bio is the transformed value of bio.

In the analysis of residues, assumptions of linearity, normality and homoscedasticity were confirmed.

To test the effect of limnological and fish biomass on chlorophyll-a and cyanobacteria we carried out multiple regression analyses following the stepwise procedure, in which all variables were tested, and as they did not produce any significant results, they were one by one discarded from the model.

To test the hypothesis that the chlorophyll-a, and therefore the productivity of the reservoir, depends on the concentration of nutrients, a multiple regression analysis was performed. The concentration of chlorophyll-a was considered a dependent variable, and was plotted with the forms of nutrients (independent variable), and only those that showed significant results remain present in the final model.

In order to detect possible relationships between the biotic and abiotic variables we carried out multiple regression analyses. These used the densities of cyanobacteria, the concentration of total phosphorus and biomass of fishes (omnivores and detritivores) as dependent variables, what turned out to be of relevance in the linear regression analyses performed. The analyses follow the same protocol of the abiotic variables analyses.

2.5. Trophic State Index (TSI)

In order to assess the trophic state of the Itaipu Reservoir, we used the trophic state index proposed by Carlson and modified by [59], as described below:

(3)

(4)

To determine TSI (mean), the calculation of the index was done using the weighted average by assigning a lower weight to the transparency of water, as suggested by [59]. Thus, to calculate the TSI (mean), we used the following formula:

(5)

(6)

2.6. Estimate of Fishing Yield

Through Morfoedaphic Index (MEI) of [60], we estimated fishing yield and the MEI was expressed by the following equation:

(7)

or

(8)

where TDS = concentration of dissolved solids (mg/L) and Zm = average depth (m).

2.7. Inference of Fishing Yield

In order to estimate the fishing yield of the Itaipu reservoir and verify if the predicted index values were significant we used the equation proposed by [61], with the model derived from a capture data regression analysis and MEI (morfoedaphic index):

(9)

The index below (MEI) is a relationship between the concentration of dissolved solids in water divided by the mean depth of the lake or reservoir, and was first used by [60] to estimate the fishing yield of African lakes. [62] found that a better fit could be obtained for MEI expressed as the relation between conductivity and the average depth:

(10)

3. Results

3.1. Relationships between the Limnological Variables

The analysis shows that the TKN and total phosphorus

acted positively to the development of chlorophyll-a concentrations, and the variables ammonia nitrogen and nitrate showed negative relationships with the variable. These results demonstrate the importance of nutrients in concentrations of chlorophyll-a in the reservoir. The model predicts 28% of the relationship of independent variables on chlorophyll-a (R = 0.527, R² = 0.278, N = 278, F = 26.254) (Table 1), according to the following model:

(11)

Analysis for testing the relationship between water transparency and other forms of nutrients which help to increase the concentration of chlorophyll-a was of the stepwise type, where the variables that show p > 0.05 are successively discarded from the model (Table 2). The final multiple regression model explains 30% of the variability of chlorophyll-a (R = 0.550, R² = 0.302, F = 39.586, N = 278, P ≤ 0.05), being expressed by the model below. According to this analysis, the concentration of chlorophyll-a (dependent variable) can be explained by a linear combination of independent variables, indicating that all the variables tested contributed to the development of phytoplankton, while the only negative effect was the variable water transparency.

In order to establish which other variables contributed to the development of phytoplankton (through chlorophyll-a concentration), another multiple regression analysis was performed (Table 3). The results show that besides TKN, the independent variables BOD and COD were significantly correlated with chlorophyll (Table 4). The final accepted model explains 35% (R = 0.589, R² = 0.347, F = 36.270, N = 278, P ≤ 0.05) the ratio of chlorophyll-a over the other variables:

(12)

To prove the effects of water transparency on the productivity of the reservoir, a multiple regression analysis was performed to identify independent variables that are significantly correlated with water transparency (Table 5). The result of this analysis demonstrates the importance of independent variables tested on water transparency. These responses explain 61% of the relationship significantly correlated with the tested independent variables (R = 0.783, R² = 0.613, F = 61,019, N = 278, P ≤ 0.05), having chlorophyll, turbidity and suspended solids influenced the model negatively, and ammonia nitrogen, TKN and BOD positively. The model generated in this analysis was:

(13)

3.2. Trophic State Index

Figure 3 shows the values of the weighted average (Secchi disk, chlorophyll-a and total phosphorous) of Trophic State Index. The transition zone showed the highest average (49.44), with the highest value (69.67) in August 2001. The riverine zone presented an average of 52.19, with the lowest value (34.08) in November 2003. The lacustrine zone had the lowest average among the zones of the reservoir, with an average of 36.02.

The calculation of TSI average for the entire reservoir was 45.40, what can be classified as mesotrophic. This value, however, is near the threshold value of the oligotrophic waters classification (≥44).

3.3. Density and Relative Abundance of Phytoplankton

Figure 4 shows the relative abundance of phytoplankton in the Itaipu Reservoir. Cyanobacteria were abundant in the whole system, comprising 76% of the total. In the transition zone relative abundance was 90% whereas in the riverine zone it was 65%. The diatoms corresponded to the second most abundant group, with 14% of the total. In the riverine zone we obtained the greatest concentration (23%) and the smallest contribution was in the transition zone (7%). Chlorophyceae accounted for 5%, being more abundant in the riverine zone (9%) and less abundant in the transition zone (2%). The same pattern

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	G. M. Straskraba and J. G. Tundisi, “Diretrizes Para o Gerenciamento de Lagos,” IIE-Instituto Internacional de Ecologia, 2000.
[2]	J. Hrbácek, M. Dvoráková, V. Korínek and L. Procházková, “Demonstration of the Effect of the Fish Stock on the Species Composition of Zooplankton and the Intensity of the Whole Plankton Association,” Verhandlungen des Internationalen Verein Limnologie, Vol. 14, 1961, pp. 192-195.
[3]	J. L. Brooks and S. I. Dodson, “Predation, Body Size and Composition of Plankton,” Science, Vol. 150, No. 3692, 1965, pp. 28-35. doi:10.1126/science.150.3692.28
[4]	J. Shapiro, V. Lamarra and M. Lynch, “Biomanipulation, an Ecosystem Approach to Lake Restoration,” In: P. Brezonik and L. Fox, Eds., Proceedings of a Symposium on Water Quality Management Through Biological Control, University Press of Florida, Gainesville, 1975, pp. 85-96.
[5]	S. R. Carpenter and J. F. Kitchell, “The Trophic Cascade in Lakes,” Cambridge University Press, Cambridge, 1993.
[6]	R. DeMelo, R. France and J. D. McQueen, “Biomanipulation: Hit or Myth?” Limnology and Oceanography, Vol. 37, No. 1, 1992, pp. 192-207.
[7]	M. T. Brett and C. R. Goldman, “A Meta-Analysis of the Freshwater Trophic Cascade,” Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, No. 15, 1996, pp. 7723-7726. doi:10.1073/pnas.93.15.7723
[8]	M. T. Brett and C. R. Goldman, “Consumer versus Resource Control in Freshwater Pelagic Food Webs,” Science, Vol. 275, 1997, pp. 354-386.
[9]	J. D. McQueen, J. R. Post and E. L. Mills, “Trophic Relationships in Freshwater Pelagic Ecosystems,” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 43, No. 8, 1986, pp. 1571-1581. doi:10.1139/f86-195
[10]	M. S. Arcifa, T. G. Northcote and O. Froehlich, “Fish-Zooplankton Interactions and Their Effects on Water Quality of a Tropical Brazilian Reservoir,” Hydrobiologia, Vol. 139, No. 1, 1986, pp. 49-58. doi:10.1007/BF00770241
[11]	X. T. Lazzaro, “A Review of Plankitivorous Fishes: Their Evolution, Feeding Behavior, Selectivity, and Impacts,” Hydrobiologia, Vol. 146, No. 2, 1987, pp. 97-167. doi:10.1007/BF00008764
[12]	X. T. Lazzaro, “Feeding Convergence in South American and African Zooplaktivorous Cichlids Geophagus Brasiliensis and Tilapia Rendalli,” Environmental Biology of Fishes, Vol. 31, No.3, 1991, pp. 283-293. doi:10.1007/BF00000693
[13]	J. Pijanowska and A. Prejs, “Food-Web Manipulation in Shallow, Eutrophic Lakes: Bridging the Gap between the Role-Lake Approach and Behavioral and Demographic Studies,” Hydrobiologia, Vol. 342-343, 1997, pp. 305-310. doi:10.1023/A:1017072332572
[14]	E. Jeppensen, J. P. Jensen, M. Sondergaard, T. Lauridsen, L. J. Pedersen and L. Jensen, “Top-Down Control in Freshwater Lakes: The Role of Nutrient State, Submerged Macrophytes and Water Depth,” Hydrobiologia, Vol. 342-343, 1997, pp. 151-164. doi:10.1023/A:1017046130329
[15]	J. D. McQueen, “Manipulating Lake Community Structure: Where Do We Go from Here?” Freshwater Biology, Vol. 23, No. 3, 1990, pp. 613-620. doi:10.1111/j.1365-2427.1990.tb00299.x
[16]	K. D. Hambright, “Morphological Constraints in the Piscivore-Planktivore Interaction: Implications for the Trophic Cascade Hypothesis,” Limnology and Oceanography, Vol. 39, No. 4, 1994, pp. 897-912. doi:10.4319/lo.1994.39.4.0897
[17]	D. J. McQueen, R. France and C. Kraft, “Confounded Impacts of Planktivorus Fish on Freshwater Biomanipulations,” Archiv für Hydrobiologie, Vol. 125, No. 1, 1992, pp. 1-24.
[18]	X. T. Lazzaro, “Do the Trophic Cascade Hypothesis and Classical Biomanipulation Approaches Apply to Tropical Lakes/Reservoirs?” Verhandlungen des Internationalen Verein Limnologie, Vol. 26, 1997, pp. 719-730.
[19]	R. W. Drenner, K. L. Gallo, R. M. Baca and J. D. Smith, “Synergistic Effects of Nutrients Loading and Omnivorus Fish on Phytoplankton Biomass,” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 55, No. 9, 1998, pp. 2287-2296. doi:10.1139/f98-095
[20]	F. L. M. Starling, “Development of Biomanipulation Strategies for the Remediation of Eutrophication Problem in a Urban Reservoir-Lago Paranoá,” PhD Thesis, University of Stirling, Scotland, 1998.
[21]	M. Perrow, M. L. Meijer, P. Dawidowicz and H. Coops, “Biomanipulation in Shallow Lakes: State of the Art,” Hydrobiologia, Vol. 342-343, 1997, pp. 355-365. doi:10.1023/A:1017092802529
[22]	J. Shapiro and J. Wright, “Lake Restoration by Biomanipulation: Round Lake, Minnesota, the First 2 years,” Freshwater Biology, Vol. 14, No. 4, 1984, pp. 371-383.
[23]	S. R. Carpenter, J. F. Kitchell and J. R. Hodgson, “Cascading Trophic Interactions and Lake Productivity Fish Predation and Herbivory Can Regulate Ecosystems”, BioScince, Vol. 35, No. 10, 1985, pp. 634-639. doi:10.2307/1309989
[24]	L. Persson, G. Andersson, S. F. Hamirin and L. Johansson, “Predator Regulation and Primary Production along the Productive Gradient of Temperate Lake Ecosystems,” In: S. R. Carpenter, Ed., Complex Interactions in Lake Communities, Springer, New York, 1988, pp. 53-59.
[25]	B. A. Faafeng and A. Brabrand, “Biomanipulation of a Small, Urban Lake: Removal of Fish Exclude Bluegreen Blooms,” Verhandlungen des Internationalen Verein Limnologie, Vol. 24, 1990, pp. 597-602.
[26]	M. Sondergaard, E. Jeppesen and S. Berg, “Pike (Esox lucius) Stocking as a Biomanipulation Tool 2. Effects on Lower Trophic Levels in Lake Lyng, Denmark,” Hydrobiologia, Vol. 342-343, 1997, pp. 319-325. doi:10.1023/A:1017084600712
[27]	A. Prejs, J. Pijanowska, P. Koperski, A. Martyniak, S. Borón and P. Hliwa, “Food-Web Manipulation in a Small, Eutrophic Lake Wirbel. Poland: Long-Term Changes in Fish Biomass and Basic Measures of Water Quality. A Case Study,” Hydrobiologia, Vol. 342-343, 1997, pp. 383-386. doi:10.1023/A:1017047625303
[28]	M. L. Meijer, I. DeBoois, M. Scheffer, R. Portielje and H. Hosper, “Biomanipulation in Shallow Lakes in The Netherlands: An Evaluation of 18 Case Studies,” Hydrobiologia, Vol. 408-409, 1999, pp. 13-30. doi:10.1023/A:1017045518813
[29]	J. Benndorf, W. Boing, J. Koop and I. Neubauer, “Top-Down Control of Phytoplankton: the Role of Time Scale, Lake Depth and Trophic State,” Freshwater Biology, Vol. 47, 2002, pp. 2282-2295. doi:10.1046/j.1365-2427.2002.00989.x
[30]	T. Mehner, F. Holker and P. Kasprzak, “Spatial and Temporal Heterogeneity of Trophic Variables in a Deep Lake as Reflected by Repeated Singular Samplings,” OIKOS, Vol. 108, 2005, pp. 401-409. doi:10.1111/j.0030-1299.2005.13338.x
[31]	X. T. Lazzaro, M. Bouvy, R. A. Ribeiro-Filho, V. S. Oliveira, L. T. Sales, A. R. M. Vasconcelos and M.R. Mata, “Do Fish Regulate Phytoplankton in Shallow Eutrophic Northeast Brazilian Reservoirs?” Freshwater Biology, Vol. 48, 2003, pp. 649-668. doi:10.1046/j.1365-2427.2003.01037.x
[32]	W. D. Davies, “Progress Report n Fisheries Development in Northeastern. II Reservoir Fisheries on Northeastern Brazil,” International Center for Aquaculture Research and Development, Vol. 2, 1972, pp. 1-17.
[33]	G. C. V. Gesteira, “Aspectos Biológicos Ligados à Produtividade de Pesca Nos Acudes púBlicos da áRea do ‘Polígono das Secas’-Nordeste do Brasil,” Dissertacao (Mestrado) UFRJ, 1978, 143 p.
[34]	J. W. B. Silva, “Recursos Pesqueiros de águas Interiores do Brasil, Especialmente do Nordeste,” DNOCS, Diretoria de Pesca e Piscicultura, Fortaleza, Ceará, Brasil, 1981, 98 p.
[35]	S. Wright, “Alguns Dados da fíSica e da Química das águas dos Acudes Nordestinocas,” Bol. Tec. DNOCS, Fortaleza, 39, 1981, pp. 21-32.
[36]	DNOCS, “Dados Sobre a Administracao da Pesca em Acudes Públicos Relativos ao Período de 1948 a 1990,” DNOCS, Diretoria de Pesca e Piscicultura, Fortaleza, Ceará, 1990.
[37]	F. Molle, “Caractéristiques et Potentialités des ‘Acudes’ du Nordeste Brésilien,” Doctoral Dissetation, Université Montpelier II, 1991, 380 p.
[38]	J. J. S. Gurgel and C. H. Fernando, “Fisheries in the Semi-Arid Northeast Brazil with Special Reference to the Role of Tilapias,” International Review of Hydrobiology, Vol. 79, 1994, pp. 77-94.
[39]	M. P. Paiva, M. Petrere, A. J. Petenate, F. H. Nepomuceno and E. A. Vasconcelos, “Relationship between the Number of Predatory Fish Species and Fish Yield,” In: Large Northeastern Brazilian Reservoirs, Rehabilitation of Freshwater Fisheries, 1994, pp. 120-129.
[40]	M. Bouvy, L. B. Franca and J. P. Carmouze, “Compartimento Microbiano no Meio Pelágico de Sete Acudes do Estado de Pernambuco (Brasil),” Acta Limnologica Brasiliensia, Vol. 10, 1998, pp. 93-101.
[41]	H. A. Regier and F. Henderson, “Comparative Studies on Freshwater Fisheries. FAO (Food and Agriculture Organization of the United Nations),” Fisheries Technical Paper, 1980, 46 p.
[42]	R. Quiros, “Predictors of Relative Fish Biomass in Lakes and Reservoirs of Argentina,” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 47, 1990, pp. 928-939. doi:10.1139/f90-107
[43]	R. H. Peters, “The Role of Prediction Limnology,” Limnol. Oceanogr. Vol. 31, 1986, pp. 1143-1159. doi:10.4319/lo.1986.31.5.1143
[44]	D. A. Schlesinger and H. A. Regier, “Climatic and Morphoedaphic Indices of Fish Yields from Natural Lakes,” Transactions of the American Fisheries Society. Vol. 111, 1982, pp. 1-150. doi:10.1577/1548-8659(1982)111<141:CAMIOF>2.0.CO;2
[45]	R. Quirós and M. B. Boveri, “Fish Effects on Reservoir Trophic Relationships,” In: J. G. Tundisi and M. Straskraba, Eds., Theoretical Reservoir Ecology and its Applications, IIE, BAC, Backuysv Publishers, 1999, pp. 529-546, 592 p.
[46]	D. Rejas, L. Clerck, J. Auwerkerken, P. Tak and L. Meester, “Plankton Dynamics in a Tropical Floodplain Lake: Fish, Nutrients, and the Relative Importance of Bottom-Up and Top-Down Control,” Freshwater Biology, Vol. 50, 2005, pp. 52-69. doi:10.1111/j.1365-2427.2004.01306.x
[47]	J. R. Borghetti, A. A. Agostinho and K. Nakatani, “Administracao Pesqueira no Reservatório de Itaipu,” In: J. G. Tundisi, Ed., Limnologia e Manejo de Represas, Série: Monografias em Limnologia, 1988.
[48]	A. A. Agostinho and L. C. Gomes, “O manejo da pesca em Reservatórios da Bacia do Alto Rio Paraná: Avaliacao e Perspectives,” In: M. G. Nogueira, R. Henry and A. Jorcin, Eds., Ecologia de Reservatórios, Rima. Sao Carlos, 2005, 459 p.
[49]	A. A. Agostinho, E. K. Okada and J. Gregoris, “A Pesca no Reservatório de Itaipu: Aspectos Sócio-Economicos e Impactos do represamento,” In: R. Henry, Ed., Ecologia de Reservatórios: Estrutura, Funcao e Aspectos Sociais, FUNDIBIO/FAPESP, 1999, 800 p. Itaipu Binacional, www.itaipu.gov.br
[50]	A. A Agostinho, V. S. Ferreira, H. F. Júlio Jr., C. V. Minte-Vera, E. F. Oliveira, E. K. Okada, T. A. Pagioro, M. C. Roberto, H. I. Suzuki, S. M. Thomaz and F. Abujanra, “Variacoes Espaco-Temporais na Ictiofauna e Suas Relacoes com as Condicoes Limnológicas No Reservatório de Itaipu,” Relatório Annual, Maringá, 1997, 330 p.
[51]	A. A. Agostinho, H. F. Júlio Jr., L. C. Gomes, L. M. Bini and C. S. Agostinho, “Composicao, Abundancia e Distribuicao Espaco-Temporal da Ictiofauna,” In: A. E. A. M. Vazzoler, A. A. Agostinho and N. S. Hahn., Eds., A Planície de Inundacao do Alto Rio Paraná: Aspectos Físicos, Biológicos e Socioeconomicos, EDUEM, Maringá, 1997, pp. 179-208.
[52]	IAP, “Estudos Limnológicos do Reservatório de Itaipu. Relatório Annual,” Contrato Itaipu Binacional/Instituto Ambiental do Paraná, Curitiba, 2003, 107 p.
[53]	E. F. Oliveira, C. V. Minte-Vera and E. Goulart, “Structure of Fish Assemblages along Spatial Gradients in a Deep Subtropical Reservoir (Itaipu Reservoir, Brazil-Paraguay border),” Environmental Biology of Fishes, Vol. 72, 2005, pp. 283-304. doi:10.1007/s10641-004-2582-5
[54]	APHA (Americam Public Health Association), “Standard Methods for the Examination of Water and Wastewater,” 16th Edition, Washington DC, APHA, 1985, 1134 p.
[55]	E. A. Nusch, “Comparision of Different Methods for Chlorophyll and Pheopigment Determination,” Archiv für Hydrobiologie—Beiheft Ergebnisse der Limnologie, Vol. 14, No. 1, 1980, pp. 14-36.
[56]	R. A. Ribeiro-Filho, “Relacoes Tróficas e Limnológicas no Reservatório de Itaipu: Uma Análise do Impacto da Biomassa Pesqueira Nas Comunidades Planctonicas,” Ph.D. Thesis, CRHEA/USP, Sao Carlos, 2006.
[57]	A. P. Toledo Jr., M. Talartico, S. J. Chinez and E. G. Agudo, “A Aplicacao de Modelos Simplificados para a Avaliacao do Processo de Eutrofizacao em Lagos e Reservatórios Tropicais,” In: Congresso Brasileiro de Engenharia Sanitária e Ambiental, 12, Comburiu, 1983, p. 34.
[58]	R. A. Ryder, “A Method for Estimating the Potential Fish Production of Northtemperate Lakes,” Transactions of the American Fisheries Society, Vol. 94, 1965, pp. 214-218. doi:10.1577/1548-8659(1965)94[214:AMFETP]2.0.CO;2
[59]	J. M. Meleck, “Primary Productivity and Fish Yields in Tropical Lakes,” Transactions of the American Fisheries Society, Vol. 105, 1976, pp. 575-580. doi:10.1577/1548-8659(1976)105<575:PPAFYI>2.0.CO;2
[60]	R. T. Oglesby, “Relationships of Fish Yield to Lake Phytoplankton Standing Crop, Production and Morphoedaphic Factors,” Journal of Fisheries Research Board of Canada, Vol. 34, No. 12, 1977, pp. 2271-2279. doi:10.1139/f77-305
[61]	J. G. Tundisi, “Distribuicao Espacial, Sequência Temporal e Ciclo Sazonal do Fitoplancton em Represas: Fatores Limitantes e Controladores,” Revista Brasileira de Biologia, Vol. 50, No. 4, 1990, pp. 937-955.
[62]	K. W. Thornton, “Perspectives on Reservoir Limnology,” In: K. W. Thornton, B. L. Kimmel, F. E. Payne, Eds., Reservoir Limnology: Ecological Perspectives, A Wiley-Interscience, New York, 1990, pp. 1-13.
[63]	S. S. Stivari, A. P. Oliveira and J. Soares, “On the Climate Impact of the Local Circulation in the Itaipu Lake Area,” Climatic Change, Vol. 72, 2005, pp. 103-121. doi:10.1007/s10584-005-5923-2
[64]	C. E. M. Tucci, “Escoamento Superficial,” In: C. E. M. Tucci, Ed., Hidrologia: Ciência e Aplicacao, 3a edicao, Editora da UFRGS/ ABRH, Porto Alegre, RS, 2002.
[65]	M. F. F. Ferrareze, M. G. Nogueira and N. C. Vianna, “Transporte de Nutrientes e Sedimentos no rio Paranapanema (SP/PR) e Seus Principais Tributários nas Estacoes seca e Chuvosa,” In: M. G. Nogueira, R. Henry and A. Jorcin, Eds., Ecologia de Reservatórios, Rima, Sao Carlos, 2005, 459 p.
[66]	R. M. Pinto-Coelho, L. M. A. Azevedo, P. E. V. Rizzi, J. F. Bezerra-Neto and M. E. Rolla, “Origens e Efeitos do Aporte Externo de Nutrientes em um Reservatório Tropical de Grande Porte: Reservatório de Sao Simao (MG/ GO),” In: M. G. Nogueira, R. Henry and A. Jorcin, Eds., Ecologia de Reservatórios, Rima, Sao Carlos, 2005, 459 p.
[67]	M. G. Nogueira, A. Jorcin, N. C. Vianna and Y. C. T. De Britto, “Reservatório em Cascata e os efeitos na Limnologia e Organizacao das Comunidades Bióticas (Fitoplancton, Zooplancton e Zoobentos)—Um Estudo de Caso no Rio Paranapanema (SP/PR),” In: M. G. Nogueira, R. Henry and A. Jorcin, Eds., Ecologia de Reservatórios, Rima, Sao Carlos, 2005, 459 p.
[68]	F. A. Esteves, “Fundamentos de Limnologia,” Editora Interciência/FINEP, Rio de Janeiro, 1988, 575 p.
[69]	B. Jezierska, “Fish metabolism,” Polish Ecological Studies, Vol. 5, No. 3, 1979, pp. 43-51.
[70]	T. Iwakuma, H. Hayashi, I. Yasuda, T. Hanazato and K. Takada, “Impact of Whitefish on am Enclosure Ecosystem in a Shallow Eutrophic Lake: Changes in Nutrients Concentrations, Phytoplankton and Zoobenthos,” Hydrobiologia, Vol. 200-201, 1990, pp. 141-152. doi:10.1007/BF02530335
[71]	G. Anderson, W. Granéli and J. Stenson, “The Influence of Animals on Phosphorus Cycling in Lake Ecosystems,” Hydrobiologia, Vol. 170, 1988, pp. 267-284. doi:10.1007/BF00024909
[72]	A. Persson, “Phosphorus Release by Fish in Relation to External and Internal Load in a Eutrophic Lake,” Limnology and Oceanography, Vol. 42. No. 3, 1997, pp. 577-583. doi:10.4319/lo.1997.42.3.0577
[73]	L. F. Andrade, R. F. Brunkow, C. F. Xavier and L. L. Domingues, “Fitoplancton e Características Físico-Químicas do Reservatório de Itaipu,” In: Tundisi J. G. Ed., Limnologia e Manejo de Represas, Monografias em Limnologia, Série, 1988.
[74]	T. A. Pagioro, M. C. Roberto, S. M. Thomaz, A. S. Pierini and M. Taka, “Zonacao Longitudinal das Variáveis Limnológicas Abióticas em Reservatórios,” In: L. Rodrigues, S. M. Thomaz, A. A. Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes espaciais e temporais, Rima Editora, Sao Carlos, 2005.
[75]	R. G. Wetzel, “Reservoir Ecosystems: Conclusions and Speculations,” In: K. W. Thornton, B. L. Kimmel and F. E. Payne, Eds., Reservoir Limnology: Ecological Perspectives, A Wiley-Interscience, New York, 1990, pp. 227-238.
[76]	R. Henry, “Amonia ou Fosfato Como Agente Estimulador do Crescimento do Fitoplancton na Represa de Jurumurim (Rio Paranapanema, SP)?” Revista Brasileira de Biologia, Vol. 50, No. 4, 1990, pp. 883-892.
[77]	D. J. McQueen, M. R. S. Johannes, J. R. Post, T. J. Stewart and D. R. S. Lean, “Biomanipulation and Community Structure at Lake St. George, Ontario. Canada,” Verhandlungen des Internationalen Verein Limnologie, Vol. 24, 1990, pp. 335-338.
[78]	R. W. Drenner, J. D. Smith and S. T. Threlkeld, “Lake Trophic State and the Limnological Effects of Omnivorus Fish,” Hydrobiologia, Vol. 319, 1996, pp. 213-223. doi:10.1007/BF00013734
[79]	M. C. Calijuri and J. G. Tundisi, “Limnologia Comparada das Represas do Lobo (Broa) e Barra Bonita—Estado de Sao Paulo: Mecanismos de Funcionamento e Bases para o Gerenciamento,” Revista Brasileira de Biologia, Vol. 50, No. 4, 1990, pp. 893-913.
[80]	E. E. Souza-Filho and J. C. Stevaux, “Geologia e Geomorfologia do Complexo do rio Baía, Curutuba, Ivinheima,” In: A. E. A. M. Vazzoler, A. A. Agostinho and N. S. Hahn, Eds., A Planície de Inundacao do Alto Rio Paraná: Aspectos Físicos, Biológicos e Socioeconomicos, EDUEM, Maringá, 1997, pp. 179-208.
[81]	R. G. Wetzel, “Limnology: Lakes and River Ecosystems,” Academic Press, San Diego, 2001.
[82]	L. H. Zanata, “Heterogeneidade Ambiental no Reservatório de Salto Grande (Americana-SP) Com ênfase na Distribuicao das Populacoes de Cladocera,” Master Thesis, CRHEA/EESC/USP, Sao Carlos, 1999, 218 p.
[83]	R. A. Ribeiro Filho, “Caracterizacao de Dietas Alimentares de Peixes Predadores em Acudes de Pernambuco e no Lago Paranoá (Brasília-DF),” Monografia Universidade Federal Rural de Pernambuco, Recife, 1999, 52 p.
[84]	F. Pedro, “Alimentacao e Comportamento Predatório do tucunaré Cichla ocellaris, Bloch & Schneider, 1801 (Osteichihyes: Cichlidae),” Master Thesis, UFPB, Joao Pessoa, 1995, 132 p.
[85]	R. A. Vollenweider, “A Manual on Methods for Measuring Primary Production in Aquatic Environments,” 2nd Edition, Blackwell Scientific Publications (IBP Handbook, 12), London, 1974, 225 p.
[86]	J. J. R. Ramirez, “Variacao Especial Vertical e Nictimeral da Estrutura da Comunidade Fitoplanctonica e Variáveis Ambientais em Quatro Dias de Amostragem de Diferentes épocas do ano na Lagoa das Garcas, Sao Paulo,” PhD. Thesis, USP, Sao Paulo, 1996, 300 p.
[87]	F. L. M. Starling and A. J. A. Rocha, “Experimental Study of Planktivorous Fishes on Plankton Community and Eutrophication of a Tropical Brazilian Reservoir,” Hydrobiologia, Vol. 200-201, 1990, pp. 5081-5591. doi:10.1007/BF02530375
[88]	C. C. Figueredo, “Efeitos da Tilápia (Oreochomis Niloticus) Nas Características fíSicas e Químicas e Estrutura da Comunidade Fitoplanctonica do Reservatório da Usina Hidroelétrica de Furnas (MG),” Master Thesis, UFMG, Belo Horizonte, 2000, 150 p.
[89]	R. A. Ribeiro Filho, “Estudo Experimental de Biomanipulacao: Análise dos Impactos Ambientais de Duas Espécies de Predadores no Controle de Tilápia no Lago Paranoá (Brasília-DF),” Master Thesis, CRHEA/EESC/ USP, Sao Carlos, 2002.
[90]	A. Minillo, “Análise da Distribuicao, Densidade e Toxici-Dade de Floracoes de Cianobactérias e Suas Toxinas nos Reservatórios do Médio e Baixo rio Tietê (SP) e Relacao com as Características Limnológicas do Sistema,” Ph.D. Thesis, CRHEA/EESC/USP, Sao Carlos, 2005, 394 p.
[91]	S. A Townsend, “The Seasonal Pattern of Dissolved Oxygen an Hypolimnetic Deoxygenation, in Two Tropical Australian Reservoir,” Lakes & Reservoir: Research and Management, Vol. 4, No. 1, 1999, pp. 41-53.
[92]	CETESB, “Parametros Para Análise da Qualidade de água,” 2006. http://www.cetesb.sp.gov.br/Agua/rios/variáveis.asp
[93]	J. D. McQueen, “Freshwater Food Web Biomanipulation: A Powerful Tool for Water Quality Improvement, but Maintenance Is Required,” Lakes & Reservoirs: Research and Management, Vol. 3, 1998, pp. 83-94. doi:10.1111/j.1440-1770.1998.tb00035.x
[94]	J. M. Hanson and W. C. Legget, “Empirical Prediction of Fish Biomass and Weight,” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 39, 1982, pp. 257-263. doi:10.1139/f82-036
[95]	E. Jeppensen, J. P. Jensen, M. Sondergaard, T. Lauridsen and F. Landkildehus, “Trophic Structure, Species Richness and Biodiversity in Danish Lakes: Changes along a Phosphorus Gradient,” Freshwater Biology, Vol. 45, No. 2, 2000, pp. 201-218.
[96]	R. G. Wetzel, “Limnologia,” Fundacao Calouste Gulbenkian, 1993, 1011 p.
[97]	L. M. Bini, “Monitoramento da Qualidade da água no Reservatório de Itaipu,” Relatório Final-AS CT/0044/2002Itaipu Bionacional, Junho 2003, 34 p.
[98]	C. S. Reynolds, “The Ecology of Freshwater Phytoplankton—Cambrige Studies in Ecology,” Cambrige University Press, Cambrige, 1984, 384 p.
[99]	R. Kurmayer and J. Wanzenbock, “Top-Down Effects of under Yearling Fish on a Phytoplankton Community,” Frehswater Biology, Vol. 36, 1996, pp. 599-609. doi:10.1046/j.1365-2427.1996.00127.x
[100]	H. S. Karjalainen, S. Seppala and M. Walls, “Nitrogen, Phosphorus and Daphinia Grazing in Controlling Phytoplankton Biomass and Composition—An Experimental Study,” Hydrobiologia, Vol. 363, 1998, pp. 309-321.
[101]	T. A. Pagioro and S. M. Thomaz, “Longitudinal Patterns of Sedimentation in a Deep Monomitc Subtropical Reservoir Itaipu (Brazil-Paraguay),” Archiv für Hydrobiologie, Vol. 154, No. 3, 2002, pp. 515-528.
[102]	V. A. Lamarra, “Digestive Activities of Carp as a Major Contributor to the Nutrient Loading of Lakes,” Verhandlungen des Internationalen Verein Limnologie, Vol. 19, 1975, pp. 2461-2468.
[103]	J. V. Grando, “Consideracoes Sobre o Estagio Atual da Ictiofauna e Aspectos Alimentares de Quatro Espécies de Peixes do Lago Paranoá, Brasília-DF. Brasília,” Master Thesis, Universidade de Brasília, Brasília, 1989.
[104]	J. M. A. Pereira and R. A. Ribeiro Filho, “Efeitos da Excrecao de Tilápias (Tilapia rendali e Oreochromis Niloticus) em Reservatórios e Viveiros de Piscicultura,” In: E. L. G. Espíndola and E. Wendland, Eds., Bacia Hidrográfica: Diversas Abordagens em Pesquisa, Rima, Sao Carlos, 2004, 412 p. doi:10.1007/BF02538504
[105]	R. Henry and A. C. Simao “Aspectos Sazonais da Liberacao Potencial por N, P e Fe no Fitoplancton na Represa de Barra Bonita (Rio Tietê, SP),” Revista Brasileira de Biologia, Vol. 48, No. 1, 1990, pp. 1-14.
[106]	T. A. Pagioro, S. M. Thomaz and M. C. Roberto, “Caracterizacao Limnológica Abiótica dos Reservatórios,” In: L. Rodrigues, S. M. Thomaz, A. A. Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes Espaciais e Temporais, Rima Editora, Sao Carlos, 2005.
[107]	J. G. Tundisi, “Limnologia de Represas Artificiais,” Boletim de Hidráulica e Saneamento, EESC-USP, Vol. 11, No. 1, 1986, pp. 1-46.
[108]	C. S. Reynolds, “The Response of Phytoplankton Communities to Changing Lake Environments,” Schweiz Z Hydrobiologie, Vol. 49, No. 2, 1987. pp. 220-236.
[109]	T. Matsumura-Tundisi, S. Neumann-Leitao, L. S. Aguena and J. Miyahara, “Eutrofizacao da Represa de Barra Bonitas: Estrutura e Organizacao da Comunidade de Rotifera,” Revista Brasileira de Biologia, Vol. 50, No. 4, 1990, pp. 923-935.
[110]	L. F. M. Velho, F. A. Lansac-Toha and C. C. Bonecker, “Distribuicao Longitudinal da Comunidade Zooplanctonica em Reservatórios,” In: L. Rodrigues, S. M. Thomaz, S. S. Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes Espaciais e Temporais, Rima Editora, Sao Carlos, 2005.
[111]	E. L. G. Espíndola, T. Matsumura-Tundisi and A. C. Rietzler, “Heterogeneidade Espacial do Reservatório de Tucuruí (Estado do Pará, Amazonia, Brasil) e a Distribuicao das Espécies Zooplanctonicas,” Revista Brasileira de Biologia, Vol. 60, No. 2, 2000, pp. 179-194.
[112]	G. R. Marzolf, “Reservoirs as Environments for Zooplankton,” In: K. W. Thornton, B. L. Kimmel and F. E. Payne, Eds., Reservoir Limnology: Ecological Perspectives, John Wiley & Sons, New York, 1990, pp. 195-208.
[113]	F. A. Lansac-Toha, L. F. M. Velho and C. C. Bonecker, “Estrutura da Comunidade Zooplanctonica Antes e após a Formacao do Reservatório de Corumbá-GO,” In: R. Henry, Ed., Ecologia de Reservatório: Estrutura, Funcao e Aspectos, FUNDIBIO/ FAPESP, Botucatu, 1999.
[114]	F. A. Lansac-Toha, C. C. Bonecker and L. F. M. Velho, “Estrutura da Comunidade Zooplanctonica em Reservatórios,” In: L. Rodrigues, S. M. Thomaz, A. A. Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes Espaciais e Temporais, Rima Editora, Sao Carlos, 2005.
[115]	R. de Bernardi and G. Giussani, “Diretrizes para o Gerenciamento de Lagos,” Biomanipulacao Para o Gerenciamento de Lagos e Reservatórios, Vol. 7, 2001, 221 p.
[116]	O. Rocha, S. Sendacz and T. Matsumura-Tundisi, “Composition, Biomass and Productivity of Zooplankton in Natural Lakes and Reservoirs of Brazil,” In: J. G.Tundisi, C. E. M. Bicudo and T. Matsumura-Tundisi, Eds., Limnology in Brazil, ABC/SLB, Rio de Janeiro, 1995, pp. 151-165.
[117]	E. C. Blancher, “Zooplankton-Trophic Relationship in Some North and Central Florida Lakes,” Hydrobiologia, Vol. 109, 1984, pp. 251-263. doi:10.1007/BF00007743
[118]	E. K. Okada, “Gradientes Espaco-Temporais na Pesca Artesanal no Reservatório de Itaipu,” Ph.D. Thesis, UEM/ NUPELIA, Maringá, 2001.
[119]	J. R. Hodgson, X. He and J. F. Kitchell, “The Fish Populations,” In: S. R. Carpenter and J. F. Kitchell, Eds., The Trophic Cascade in Lakes, Cambridge University Press, Cambridge, 1996, 385 p.
[120]	M. E. Power, “Effects of Fish in River Food Webs,” Science, Vol. 250, 1990, pp. 811-814. doi:10.1126/science.250.4982.811
[121]	N. G. Hairston, “Does Food Web Complexity Eliminate Trophic-Level Dynamics?” American Naturalist, Vol. 149, No. 5, 1997, pp. 1001-1007. doi:10.1086/286035
[122]	R. D. Gulati, “Manipulacao das Populacoes de Peixes Visando a Recuperacao de Lagos Eutrofizados em Regioes Temperadas,” In: R. de Bernardi and G. Giussani, Biomanipulacao para o Gerenciamento de Lagos e Reservatórios, Cap, Vol. 3, 2001, pp. 33-51.
[123]	S. R. Carpenter, J. J. Cole, J. R. Hodgson, J. F. Kitchell, M. L. Pace, D. Bade, K. L. Cottingham, T. E. Essington, J. N. Houser and A. E. Schindler, “Trophic Cascades, Nutrients, and Lake Productivity: Whole-Lake Experiments,” Ecological Monographs, Vol. 71, No. 2, 2001, pp. 163-186. doi:10.1890/0012-9615(2001)071[0163:TCNALP]2.0.CO;2
[124]	R. C. Lathrop, B. M. Johnson, T. B. Johnson, M. T. Vogelsang, S. R. Carpenter, T. R. Hrabik, J. F. Kitchell, J. J. Magnuson, L. G. Rudstam and R. S. Stewart, “Stocking Piscivores to Improve Fishing and Water Clarity: A Synthesis of the Lake Mendota Biomanipulation Project,” Freshwater Biology, Vol. 47, 2002, pp. 2410-2424. doi:10.1046/j.1365-2427.2002.01011.x
[125]	T. Bell, W. E. Neill and D. Schluter, “The Effect of Temporal Scale on the Outcome of Trophic Cascade Experiments,” Oecologia, Vol. 134, 2003, pp.578-586.
[126]	L. A. Hansson, M. Gyllstroem, A. Staahl-Delbanco and S. Svensson “Responses to Fish Predation and Nutrients by Plankton at Different Levels of Taxonomic Resolution,” Freshwater Biology, Vol. 49, 2004, pp. 1538-1550. doi:10.1111/j.1365-2427.2004.01291.x
[127]	E. T. Borer, E. W. Seabloom, J. B. Shurin, K. E. Anderson, C. A. Blanchette, B. Broitman, S. D. Cooper and B. S. Halpern, “What Determines the Strength of a Trophic Cascade?” Ecology, Vol. 86, No. 2, 2005, pp. 528-537. doi:10.1890/03-0816
[128]	F. Scasso, N. Mazzeo, J. Gorga, J. Kruk, G. Lacerot, J. Clemente, D. Fabián and S. Bonilla, “Limnological Changes in a Sub-Tropical Shallow Hypertrophic Lake during Its Restoration: Two Years of a Whole-Lake Experiment,” Aquatic Conservation: Marine and Freshwater Ecosystems, Vol. 11, 2001, pp. 31-44. doi:10.1002/aqc.420
[129]	M. R. Hasan, M. A. W. Mondal, M. I. Miah and M. G. Kibria, “Water Quality Study of Some Selected Oxbow Lakes with Special Emphasis on Chlorophyll-a,” In: S. S. de Silva, Ed., Reservoir and Culture-Based Management Fisheries, Biology and Management, 2001.
[130]	E. Jeppensen, M. Sandergaard, N. Mazzeo, M. Meerhoff, C. C. Branco, V. Huscar and F. Scasso, “Lake Restoration and Biomanipulation in Temperate Lakes: Relevance for Subtropical and Tropical Lakes,” In: M. V. Reddy and B. Moss, Eds., Tropical Eutrophic Lakes: The Restoration and Management, Science Publishers, 2005.
[131]	K. D. Hambright, R. W. Drenner and S. R. McComas, “Gape-Limited Piscivores, Planktivores Size Refuges, and the Trophic Cascade Hypothesis,” Archiv für Hydrobiologie, Vol. 121, No. 4, 1991, pp. 389-404.
[132]	A. Brabrand, B. Faafeng and J. P. M. Nilssen, “Relative Importance of Phosphorus Supply to Phytoplankton Production: Fish Excretion versus External Loading,” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 47, 1990, pp. 364-372. doi:10.1139/f90-038
[133]	F. Henderson and R. L. Welcome, “The Relationship of Yield to Morpho-Edaphic Index and Number of Fishermen in African Fisheries,” Committee for Inland Fisheries of Africa, Occas, Pap. 1, FAO, Rome, 1974, 19 p.
[134]	B. E. Marshall, “Predicting Ecology and Fish Yields in African Reservoirs from Preimpoundment Physico-Chemical Data,” FAO, CIFA Technical Paper 12, 1984, 36 p.
[135]	G. G. Sass and J. F. Kitchell, “Can Growth Be Used as a Surrogate Measure of Walleye (Sunder Vitreus) Abundance Change?” Canadian Journal of Fisheries and Aquatic Sciences, Vol. 62, No. 2, 2005, pp. 2159-2168. doi:10.1139/f05-129
[136]	P. A. Piana, K. D. G Da Luz, F. M. Pelicice, R. S. Costa, L. C. Gomes and A. A. Agostinho, “Predicao e Mecanismos Reguladores da Biomassa de Peixes em Reservatórios,” In: L. Rodrigues, S. M. Thomaz, A. A. Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes Espaciais e Temporais, Rima Editora, Sao Carlos, 2005.
[137]	M. H. Marouelli, R. H. S. Emeric, C. G. B. Cavalcanti, E. Rutkowski, M. E. C. Sales, S. M. A Segundo, G. D. Forattini, R. H. Pera and I. Castro, “Bases para uma Manejo Racional de Reservatórios. Administracao Pesqueira no Reservatório de Itaipu,” In: J. G. Tundisi, Ed., Limnologia e Manejo de Represas, Monografias em Limnologia, Série, 1988.
[138]	K. F. Roche, O. Rochaand, E. L. G. Espíndola, “Impacto do Acará, Geophagus Brasiliensis (CICHLIDAE), No Plancton da Represa do Broa: Um Experimento Usando Mesocosmos,” In: K. F. Roche and O. Rocha, Eds., Ecologia Trófica de Peixes com ênfase na Planctivoria nos Ambientes Lênticos de água doce no Brasil, Rima, Sao Carlos, 2005, 136 p.
[139]	F. Abujanra and A. A. Agostinho, “Dieta de Hypophtalmus Edentatus (Spix 1829) (Osteichthyes, Hypophtalmidae) e Variacoes de seu Estoque no Reservatório de Itaipu,” Acta Scientiarum, Vol. 24, No. 2, 2002, pp. 401-410.
[140]	F. M. Pelicici, F. Abujanra, R. Fugi, J. D. Latini, L. C. Gomes and A. A. Agostinho, “A Piscivoria Controlando a Produtividade em Reservatórios: Explorando o Mecanismo Top Down,” In: L. Rodrigues, S. M. Thomaz, A. A Agostinho and L. C. Gomes, Eds., Biocenose em Reservatórios: Padroes Espaciais e Temporais, Rima Editora, Sao Carlos, 2005.
[141]	R. M. Baca and R. W. Drenner, “Do the Effects of Piscivorous Largemouth Bass Cascade to the Plankton?” Hydrobiologia, Vol. 316, No. 2, 1995, pp. 139-151. doi:10.1007/BF00016895