Acta Limnologica Brasiliensia

Published by SciELO
Online ISSN: 2179-975X
Print ISSN: 0102-6712
Publications
Geographic location of Biguás Lake on the southern coastal plain of Brazil (32°04’43” S and 52°10’ 03” W) (Photo source: Google Earth  ). 
Total variation on abiotic variables during sampling period, between October 2000 and November 2013 at Biguás Lake. a = dissolved oxygen (DO- mg.L –1 ) and water temperature (°C); b = electrical conductivity (μS.cm –1 ) and pH; S = summer period; W = winter period. 
Mean values (±SD) of total phosphorous (a-TP, mg.L –1 ), total nitrogen (b-TN, mg.L –1 ), suspended material (c-SM, mg.L –1 ) and chlorophyll- a (d-Ch, mg.L –1 ) from October 2000 to November 2013 at Biguás Lake. MD = pe- riods with macrophyte dominance; PD = periods with phytoplankton dominance. 
Variation of total nitrogen (TN) and total phosphorous (TP) (mg.L –1 ) and coverage of surface lake area (%) of a: Pistia stratiotes (January to August 2003) and b: Salvinia herzogii (March to November 2013) at Biguás Lake. 
OBJETIVO: O principal objetivo foi descrever as mudanças nas características de um lago raso subtropical em períodos com e sem crescimento de macrófitas, relacionando com estado de águas claras-dominância de macrófitas, e águas túrbidas, com dominância de fitoplâncton. MÉTODOS: O estudo foi realizado no lago dos Biguás, planície costeira sul do Brasil (32° 04' 43"' S e 52° 10' 03" W). Foram feitas amostras mensais de Outubro de 2000 a Novembro de 2013. As variáveis limnológicas medidas na coluna d'água foram oxigênio dissolvido, temperatura, pH, condutividade elétrica, clorofila-a, nitrogênio total, fósforo total e material em suspensão. Os dados foram agrupados em períodos com dominância de macrófitas (MD) e dominância de fitoplâncton (PD), e foram comparados por teste-t as concentrações de nutrientes, clorofila-a e material em suspensão entre os períodos. Durante o crescimento de macrófitas foram estimadas a cobertura (%) e variação de biomassa. RESULTADOS: Durante os 13 anos avaliados, o lago mostrou-se bem oxigenado, alcalino, e a temperatura variou conforme a sazonalidade subtropical. Os menores valores das variáveis analisadas foram verificados nos períodos com dominância de macrófitas, caracterizando os períodos de águas claras e túrbidas. CONCLUSÕES: Foi verificada a influência das macrófitas aquáticas sobre a qualidade de água neste lago raso durante o período estudado, através da redução da concentração de nutrientes, clorofila-a e material em suspensão, favorecendo a manutenção de águas claras.
 
Location of the Sítios Novos reservoir in Ceará, Brazil, showing the four sampling locations in bold (180C, 300C, LIMN1 and LIMN2). Source of Ceará map: Mapeamento dos Espelhos d'Água do Brasil, modified of FUNCEME (2011a); figure produced with Surfer 11 (Golden Software, 2013).  
Rainfall (white bars) between October 2010 and July 2011 (except January and May) and standard deviation (lines) in the region where the Sítios Novos reservoir is located. Black bars indicate historical (last 30 years) mean rainfall for the same months. Hatched bars represent the volume of the expected annual quota of water in the reservoir at each month (Data source: FUNCEME, 2011b).  
Sitios Novos reservoir (Ceará, Brazil).
Cover photo of Vol 26, N1 
Acta Limnologia Brasiliensia
Fish farm in the background under sunlight
<i>Oreochromis niloticus<i>
AIM: There is currently no consensus regarding the physical and chemical variability of tropical reservoirs. In semiarid Northeastern Brazil, reservoirs are among other things used for human consumption, industrial water supply and intensive fish farming, all of which can impact water quality. The objective of this study was to evaluate the physical and chemical variability of the water in Sítios Novos, a reservoir in semiarid Northeastern Brazil, comparing samples collected in areas of intensive tilapia (Oreochromis niloticus) farming to samples from areas not directly impacted by aquaculture, in both the dry and the rainy season. METHODS: Between October 2010 and July 2011, data were collected on temperature, conductivity, pH, turbidity, salinity, chlorophyll a, dissolved oxygen, oxygen demand, total phosphorus and total nitrogen levels in the water column using a multiparametric probe at four different sampling locations. Physical and chemical differences between the four locations were evaluated with the Kruskal-Wallis (KW) test and Dunn's post test, while the t test, followed by Welchʼs correction, was used to compare samples collected in different seasons. RESULTS: No influence of intensive aquaculture was detected when comparing sampling locations near fish farms (180C and 300C) to locations not directly impacted by aquaculture (LIMN1, near the dam, and LIMN2, near the debouch of the São Gonçalo river). However, the sampling locations differed significantly (p
 
Diurnal variations in the forms of inorganic carbon. DIC values are highly influenced by fraction CO 2 , (a), however fraction HCO 3-prevails in the period between 12:00 PM and 6:00 PM.
Diurnal variation in the concentrations of dissolved gases, their theoretical equilibrium value and respective flows in the interface water/atmosphere.
Diurnal pH and underwater radiation variations.
Natural waters may play the role of sinks or carbon dioxide (CO2) emitters, depending on the physicochemical characteristics of the system (diffusion and reaction of this gas into water) as well as on the pH, and the primary production of micro-organisms as a result of the consumption of such compounds. Evidence suggests that the CO2 concentrations in ponds are mainly governed by the aquatic metabolism, i.e. by the balance between respiration and photosynthesis; AIM: The purpose of this study was to describe aspects of the metabolism of tilapia cultivation based on the dynamic and balance of the oxygen concentrations (DO) and forms of dissolved inorganic carbon (DIC): carbon dioxide (CO2) and bicarbonate (HCO3-). Other variables analyzed are: total phosphorus, water transparency, total alkalinity, water temperature, pH, underwater radiation and quantitative analysis of phytoplankton community; METHODS: Sampling was collected infor 5 consecutive days from 6:00 AM to 8:00 PM (December/2006) every 2 hours; RESULTS: During the test it was observed periodicity in the fluctuations of the DIC concentrations, being CO2 and HCO3- the predominant fractions. The values of DIC were strongly influenced by the fraction of CO2 and it was observed a predominance of the fraction HCO3- in the afternoon. CO2 concentrations ranged from 0.48 µM through 138.94 µM, reaching a daily average of 18.04 µM. The flow of CO2 in the interface atmosphere/water showed variations during the day. In the afternoon (from 12:00 PM until 6:00 PM) the variation pointed to the flow atmosphere/fish pond; however, the balance was 577 µmol.m-2.h-1 in the flow fish pond/atmosphere; CONCLUSIONS: The observed dynamics indicated that under the conditions of this study, the metabolism of aquatic organisms was the main driving force of this system, a fact corroborated by the intense process of euthrophication in the pond.
 
Study area highlighting the location of the Parnaiba River Delta Estuary.
Mean (±std. dev.) of the Total weight and Total length of Elops saurus juvenile on the Parnaiba Delta River in the period between July (2016) to May (2017).
Food items of juvenile Elops saurus in Delta do Rio Parnaíba (PI) between July 2016 and April 2017. Frequency of occurrence (FO), Frequency numerical (FN), Frequency Gravimetric (FW) e Relative Importance Index (IRI).
Frequency numerical (FN) and Gravimetric (FW) on diet of juvenile Elops saurus in the Parnaiba Delta River in the period between July (2016) to May (2017).
Seasonal analysis for Frequency of occurrence (FO%), Frequency numerical (FN%), Frequency Gravimetric (FW%) e Relative Importance Index (%IRI) on diet of Elops saurus in Delta do Rio Parnaíba (PI) between July 2016 and April 2017.
Aim Identify seasonal variations in the diet of juvenile living in the estuary of the Parnaíba River Delta. Methods Food items were identified through analysis of stomach contents, and later submitted to analysis by regular methods for Frequency of Occurrence (FO), Frequency Numerical (FN), Gravimetric Frequency (FW) and Relative Importance Index (IRI). Results Juvenile diet of Elops saurus that inhabit the lagoons in the Parnaíba delta was composed in order decreasing of importance by Osteichthyes (Teleostei), Insecta and Crustacea in addition to Polychaeta and Nematoda. It was also observed a high frequency of occurrence of fragments of plastics in the diet. In the rainy season, 17 items were recorded in the diet, whereas in the dry season only 7 items were present. Relative Importance Index showed high presence of the Teleostei fish (69.93%) on diet of E. saurus during the rainy season, whereas during the dry period the insects of the families Corixidae (43.25%) and Dysticidae (39.16%). Conclusions With the study it was possible to identify that juvenile are piscivorous in the rainy season when there is a higher availability of prey in the environment and insectivores in the dry season when it reduces the supply of food, indicating feeding flexibility to environmental alterations.
 
Aim In the present study has analyzed several aspects of the life history traits of Melanoides tuberculata, an exotic species, under laboratory conditions, and its response to some stressors has also been applied. Methods Sensitivity to two toxic substances was tested. The mollusks were collected and cultured in the laboratory under controlled conditions of temperature of 25 ± 1 °C and ad libitum food regime. Growth rates and biomass were experimentally obtained and the individual growth curve obtained. Results The experiment lasted 287 days and the maximum shell lengths registered was 11.67 mm. The growth curve indicated a rate of 3.98 year⁻¹ and a maximum theoretical length of 10.61 mm. The mean post-embrionary development time until first reproduction was 275 days and the size of the primipara was 10.13 mm. An accelerated growth of juveniles was observed with fast increase in the shell length until sexual maturity, but growth rate decreased afterwards as more energy was devoted to reproduction. Under the combination of 25 °C and fed on alternate days, M. tuberculata had a slow growth and a long-life expectancy under laboratory conditions. The tolerance of this mollusk to temperature as a stressor ranged between 16 °C and 37 °C, being the optimum temperature situated between 29 °C and 34 °C. The LC(I)50-24h for reference substances were: 0.70 g L⁻¹ for KCl and 9.05 g L⁻¹ for NaCl. Conclusion Based on these results, we can conclude that M. tuberculata is a species tolerant to temperature and salinity, what partially explains to accordance to its wide and rapid dispersion throughout tropical waters.
 
Aim: In order to understand the factors which influence the predatory activity of the Hoplias aff. malabaricus, the present study evaluated feeding habits of this species and its relation to prey availability, in addition to environmental variables. Methods: Six samplings were conducted in the Taperoá II reservoir, semi-arid of Paraíba state, Brazil, between October 2005 and October 2006. Measures were taken: rainfall, the reservoir volume, transparency, dissolved oxygen, pH, temperature, nitrate, nitrite, ammonia and phosphate. The activity, diet and feeding habits of H. aff. Malabaricus, from the method of frequency of occurrence of food items and point methods, conjugates in IAI (Alimentary Index). Spearman correlation analysis, a glm and CCA were performed between biotic and abiotic variables, and we used the CPUE as a measure of fish abundance. Results: Eleven taxa of fish were recorded, four of which were predated by adult "trahira". Insects and other items were also common in the stomachs of juveniles. According to statistical analysis, it was observed that the highest consumption of cichlids was correlated with its increase in CPUE in the environment, while no relationship was observed for A. bimaculatus, C. bimaculatum and S. notonota abundances. The environmental factors as nutrients, transparency and water volumn were related to selection of species by trahira. Conclusions: Intrinsic characteristics of preys as swimming speed, food habit and the food preference of the predator possibly be the main factors to selection of species. Other mechanisms as heterogeneity of habitat and environmental factors can also influence the consumption of prey by trahira.
 
AIM: The aim of this work was to study the relationships between temporal variability of Erodona mactroides and abiotic parameters of the water column and the substrate in a shallow embayment of the Patos Lagoon estuarine region in southern Brazil; METHODS: Samples were taken with a PVC corer (10 cm diameter) buried 10 cm into the sediment between October 2002 and December 2004. Each month 18 biologic samples were taken, six substrate samples were analyzed for sediment grain size and organic matter content and sediment deposition rates were determined by 12 sediment traps every two weeks. Salinity, water temperature, water level and estuarine freshwater discharge were measured daily. Abiotic parameters and bivalve densities were tested among months with registered mortality events by ANOVA (One-way, p = 0.05), being the E.mactroides seasonal variability tested by Kruskal-Wallis (p = 0.05). Regression analyses among abiotic parameters and Spearman's "R" correlation analyses between biological and environmental data were both performed; RESULTS: Two periods were identified with distinct features: one at the beginning of the study when observed limnetic conditions in the estuarine region were caused by the ENSO - El Niño 2002/2003 phenomenon when an absence of E. mactroides was registered as well as a higher percentages of fine sediments and lower percentages of organic matter. The second period was characterized by a decreasing influence of the El Niño and predominance of mixohaline conditions, recruitments and increasing densities of E. mactroides with a successive decrease of mean densities due to three mortality events, lower percentages of fine sediments and higher percentages of organic matter; CONCLUSIONS: The present study provides evidences that the occurrence of E. mactroides in the southern estuarine region depends on the water flow regime from the drainage basin, which characterizes species recruitment as temporally unpredictable and affects its persistence through time due to adverse conditions that influence species development like events of fine sediment deposition.
 
Scheme of Fattening Sector of the Frog Culture, Aquaculture Center at Unesp. The six ponds are composed of pool (P), shelters (S), vibrating trough for the feeding (VT), inlet (I) and outlet (O) water in continuous flow, arranged in a linear fashion. The effluent is taken out of the system according to the arrows which flows for an external receiver box (B).
Comparison of limnological characteristics of the effluents from frog, shrimp and fish cultures. 
AIM: Current analysis characterizes the effluent from bullfrog-rearing ponds during the grow-out phase; METHODS: Temperature, pH, dissolved oxygen, electric conductivity, turbidity, total phosphorus, N-NH3, N-NO3, BOD5 and COD and the number of thermotolerant coliforms (Escherichia coli) of the inlet and outlet water of the ponds were analyzed twice a week. Assay consisted of a completely randomized experimental design with two treatments (inlet and outlet water) and six repetitions in a split-plot, coupled to collection over time as subplot; RESULTS: All variables were significantly different (p < 0.05) between treatments and over time (p < 0.05). Average rates of temperature, pH and dissolved oxygen levels of the supply water were higher when compared to those of the effluent. The other variables such as conductivity, turbidity, total phosphorus, ammonia, nitrate, biological oxygen demand, chemical oxygen demand and E. coli were higher in the effluent when compared to rates in the supply water; CONCLUSIONS: The management during grow-out phase caused the deterioration of the water quality, with increasing levels of dissolved nutrients and the number of thermotolerant coliform. Ammonia and phosphorus levels in the effluent, caused by waste food, skin and feces, accelerate the eutrophication process of the receiving water body. Further studies on effluent treatment are required.
 
AIM: The genus Astyanax is one of the richest in number of species and has one of the widest geographical distributions in Argentina, being possible to find in nine ichthyogeographic ecoregions. The aim of the present work was to analyze the population structure of Astyanax fasciatus in the Garupá Stream, Province of Misiones, Argentina, considering its distribution by size, standard length-total weight relationship and aspects of its reproductive and feeding biology; METHODS: A total of eight experimental fishing campaigns were carried out between September 2002 and May 2004, in agreement with the seasons of the year, using a set of gillnets; RESULTS: We captured a total of 386individuals, 70% of which in the Middle Basin in autumn and winter. The following gonad stages were identified in both males and females: resting, maturing, mature and spawning. The highest gonadal activity corresponded to the autumn-winter period. The Middle Basin showed the highest capture of individuals in reproductive activity, thus reflecting the seasonality of spawning. The average fecundity was of 4000 oocytes, being 1100 µm the largest oocyte diameter. The mean standard length of the total catch was 99.3 mm and females reached larger sizes than males (P < 0.05). The standard length varied according to the seasons of the year. Both sexes presented an isometric growth (b =3). Females presented the highest values of K in spring and summer, whereas males did so in spring. The K-GSI relationship reflected that the highest K values corresponded to the lowest GSI ones. We found that A. fasciatus feeds on a wide variety of foods of both plant and animal origin. The food items of plant origin presented the highest index of occurrence; CONCLUSIONS: The long spawning seasons and the recruitment along all four seasons of the year allow characterizing A. fasciatus as a foraging species that is very well adapted to the environment studied in this work.
 
Location of the study site in Brazil, Rio Grande do Sul state, Caí River basin. Sites Ca245, Ca136, Ca092 and Ca070.
Survival comparison, mean and standard deviation in Daphnia magna exposed to Caí River sediment samples, control group and expected survival from Mar./2005 to June/2009.
Mean number of neonates per Daphnia magna brood exposed to sediment samples from each site.
Mean number of neonates and standard deviation per point, considering the total number of births.
Mean number of neonates and comparison of the results between the sites using the Duncan Test. Same letter did not differ significantly by the LSD test (p ≤ 0.01).
AIM: The Caí River is one of the five that form the Guaiba Lake Hydrographic Basin. It is used for public water supply in the capital of Rio Grande do Sul; METHODS: Sediment samples for toxicity test (21 days) with Daphnia magna were taken from four sites between the middle and upper reaches in this river from Mar./05 to June/09. Their quality is described based on the survival and reproduction responses of 440 test-organisms from the beginning of their lives (2-26 hours). Percentage survival, mean and total reproduction were calculated for this evaluation. Spearman correlation and Duncan Test were used to compare reproduction between sites and variation of this parameter statistically over time. Bacteriological, physical and chemical parameters in water samples collected during the period of the study were considered; RESULTS: Acute toxicity was observed in 18% of the samples and chronic toxicity in 95%, indicating the presence of small doses of environmental aggressors. Mortality and reproduction did not always follow the same trend, and it became clear that the reproductive activity was more sensitive when compared using contaminated samples. Duncan Test showed up to four clusters at sites Ca070, Ca092 and Ca245, indicating reproduction variation. A pattern of monthly rainfall distribution was not observed, nor was there a correlation between survival, reproduction and rainfall; CONCLUSIONS: Presence of low concentrations of xenobiotics was confirmed by physical, chemical, bacteriological and metal responses in water samples, besides a small effect on survival and constant change in reproductive activity in the organisms exposed to sediment samples. Long duration assays are more appropriate to evaluate environmental samples, since usually changes in ecosystem quality are tenuous and not detected by short tests. Caí River quality has improved, but further studies are needed to confirm this trend, and to follow the history of the area with a more detailed definition of the course characteristics and the most fragile sites in the region.OBJETIVO: O rio Caí integra a Bacia Hidrográfica do Lago Guaíba que é utilizado para o abastecimento público de água da capital do Rio Grande do Sul; MÉTODOS: Entre Mar./05 e Jun./09 foram amostrados quatro locais deste rio para avaliação da toxicidade do sedimento entre as regiões média e superior, utilizando Daphnia magna, em testes de 21 dias. A qualidade foi descrita a partir da sobrevivência e reprodução, observadas em 440 organismos-teste, desde o início de suas vidas (2-26 horas). Para tanto foram calculadas a porcentagem de sobrevivência, média reprodutiva e reprodução total. Visando comparar estatisticamente a reprodução entre os locais e a variação deste parâmetro no tempo, foram utilizados Teste de Duncan e Correlação de Spearman. Também foram considerados os parâmetros bacteriológicos, físicos e químicos em amostras de água realizadas no período de estudo; RESULTADOS: Foi observada toxicidade aguda em 18% das amostras e toxicidade crônica em 95%, indicando agressores ambientais em pequenas doses. Mortalidade e reprodução nem sempre seguiram a mesma tendência, ficando evidente a maior sensibilidade da atividade reprodutiva frente a contaminantes. O Teste de Duncan mostrou até quatro agrupamentos nos locais Ca070, Ca092 e Ca245, indicando variação na reprodução. Não foi observado padrão de distribuição para precipitação pluviométrica mensal nem correlação entre sobrevivência, reprodução e precipitação pluviométrica; CONCLUSÕES: Foi confirmada a presença de xenobióticos em baixas concentrações através de análises físicas, químicas, bacteriológicas e de metais em amostras de água, além de pequena ação na sobrevivência e constante alteração na atividade reprodutiva nos organismos expostos às amostras de sedimento. Ensaios de longa duração são mais apropriados para avaliar amostras ambientais, pois normalmente as alterações são tênues nestes ambientes e testes curtos não as detectam. Tem se observado recuperação na qualidade deste rio, no entanto estudos subseqüentes são necessários para confirmar esta tendência e traçar o histórico da área, definindo mais detalhadamente as características do curso e os locais mais frágeis da região.
 
AIM: The Sinos River, a tributary of Guaíba Lake, is 200 km long from the headwaters to the mouth and is influenced by several sources of pollution. A study to learn more about conditions in this river was performed in the middle and lower reaches. The study evaluated the effects of sediment contamination by xenobiotics on the survival and reproduction of Daphnia magna. METHODS: Eight sediment samples were collected per site from Dec/2007 to Aug/2009, as a substrate for 480 young cladocera (2-26 h old at the beginning of the trials) in chronic toxicity tests (21 days). For this purpose, D. magna individuals were exposed to sediment and M4 culture medium, at a proportion of 1:4 (v:v) using 50 mL beakers, kept at 20 ºC ± 2 ºC in 16h light:8h dark cycles. The test organisms came from lots with LC50-24h = 1.04 mgK2Cr2O7 ± 0.11 mg. Percentage survival and reproduction were considered to define acute and/or chronic responses. Duncan (p
 
AIM: The Taquari River, a tributary of Guaíba Lake, is a major economic and environmental source for Rio Grande do Sul, a state located in the far south of Brazil; METHODS: This study evaluated the interference of sediment from this river in the reproduction and survival of 320 microcrustaceans (80 organisms per site) of the Daphnia magna species. Four sites between the middle course and the river mouth were monitored using eight samples from each site, between June/06 and April/10. Mortality higher than 20% suggested the acute action of the sample on the daphniids, while low reproduction indicated the presence of chronic toxicity. Sometimes an effect on survival was noted, but the number of individuals generated was always low. Semi-static chronic assays (21 day) were developed in 50 mL beakers using sediment and M4 culture medium at a ratio of 1:4 (v:v). Each beakers received a microcrustacean born from lots presenting LC50-24 hours = 0.98 mg K2Cr2O7 ± 0.04 mg totaling ten replicas per sample. The assays were developed under controlled light (16 hours light/day) and temperature (20 ºC ± 2 ºC) conditions; RESULTS: Duncan test showed a variation in reproduction (p < 0.05) with the presence of chronic toxicity. There was less reproductive activity in 91% of the samples, while for survival the reduction attained 9%. Spearman correlation identified the dependence between the rainfall index and reproduction in one of the samples and was absent when the rainfall index was compared to survival; CONCLUSIONS: Taquari River presented episodes of toxicity, and it is necessary to continue studies in the area and to inspect local sources of pollution, as already has been done. Chronic bioassays should be maintained when the purpose is to evaluate environmental quality, since reproduction proved more sensitive than survival.
 
Survival of Daphnia magna exposed to Gravataí River sediment samples, control group and expected survival from January/2006 to May/2009. 
Mean reproduction of Daphnia magna exposed to Gravataí River sediment samples, control group and expected mean, from January/2006 to May/2009. 
Difference in births between the control group and the samples. 
Comparison of births at each point during the period sampled, applying the Duncan Test. Months with the same letter were not significantly different according to the LSD test (p ≤ 0.05). 
AIM: Persistent pollutants released to riverbeds return to the trophic system, damaging living organisms thereof. Ecotoxicological assays express the effect of environmental interactions with organisms found there. Assays were performed with microcrustacean Daphnia magna (Straus, 1820) in sediment samples, from the headwaters to the mouth, in order to evaluate the Gravataí River quality; METHODS: Bottom sediment was used to evaluate the responses of cladocerans to environmental changes in 15 samples collected between Jan./06 and May/09. The microcrustaceans were submitted to stress for 21 days from birth (2-26 hours old). Duncan Test, percentage survival, reproduction and Spearman Correlation were used to evaluate the quality of the sites; RESULTS: Duncan Test showed a significant difference (p < 0.05) in reproduction in 14 of the 15 samplings, and chronic action was more constant (88%) than the acute one (23%). Changes in survival and reproduction related to season or rainfall regime were only observed on a few occasions. The two sites located close to the mouth presented a Spearman Correlation (p < 0.01) for survival and reproduction. There were changes in some samplings in the headwaters as a result of sewage discharges in the area; CONCLUSIONS: Fluctuating responses were observed in this river due to anthropic contaminants, slow flux and current reflux.
 
The study area showing the Ilha Solteira Reservoir, with sampled areas in the Grande River, São Paulo, Brazil. Source: Kliemann et al. (2018).
Food items consumed by Rhaphiodon vulpinus in the Ilha Solteira Reservoir, Upper Paraná River basin, Brazil. Values are based on percentages of the weight of food items.
Relative numeric abundance and medians for total weight and standard length ± interquartile deviation of Rhaphiodon vulpinus in the Ilha Solteira Reservoir, Upper Paraná River basin, Brazil.
Prevalence, mean intensity of infection and mean abundance of parasites (mean ± standard error) of Rhaphiodon vulpinus in the Ilha Solteira Reservoir, Upper Paraná River basin, Brazil.
Aim To assess the dietary, populational and parasitological aspects of the non-native wild species Rhaphiodon vulpinus in an area under the influence of cage fish farm, in the Ilha Solteira Reservoir, São Paulo State. Methods Fifty-one specimens of R. vulpinus were captured bimonthly, from September 2014 to August 2016, with gill nets with different mesh sizes, in area surrounding a cage fish farm and area not influenced by this activity. The specimens were quantified and their mass (g) and standard length (cm) measured. The stomachs were analyzed with a stereomicroscope and the food items were quantified using the gravimetric method. The parasites were collected during necropsy and their prevalence, mean intensity of infection and mean abundance were subsequently calculated. Results There were changes in feeding activity regarding the area, with greater numbers of individuals with stomach contents in the areas under the influence of fish farm. However, diet composition did not change between the areas analyzed, with prey represented by small fish, such as Geophagus sveni, and shrimps. In the fish farm area there was also a decrease in abundance and an increase in the total mass of the individuals, while there was no difference in standard length between the areas. In terms of parasitological aspects, low parasitic indexes and the absence of differences between the areas were observed. The first report of the monogenean Notozothecium lamotheargumedoi in the Ilha Solteira reservoir is also presented. Conclusions The cage fish farm affected some aspects of the population and the food intake of R. vulpinus. Furthermore, the parasite-host relationship demonstrated that phylogenetic specificities had a greater effect than aquaculture activity on R. vulpinus in the fish farm area.
 
Geographical location of edge, forest, and pasture stretches sampled in three low-order streams of the Catuaba Experimental Reserve, municipality of Senador Guiomard, Acre, Brazil.
Composition of stomach contents of Apistogramma agassizii individuals from the forest, edge, and pasture areas.
Aims To evaluate the effects of replacing riparian vegetation with pasture in the diet of Apistogramma agassizii and Aequidens tetramerus. Methods The study was carried out in the municipality of Senador Guiomar, Acre. We sampled three streams divided into three stretches each (100 m), bordered by forest, pasture, and both forest and pasture (edge). Quarterly collections using fishnets were performed between January and October 2008. Results The species A. agassizii had a diet based on the consumption of adult insects in stretches of forest, different from the pasture environment, in which the consumption of insect larvae was higher. In the diet of A. tetramerus, the most important item was insect larvae in all environments, mainly in the pasture. We found low amplitude of trophic niche for A. agassizii in the forest environment, due to the consumption of adult insects, and for A. tetramerus in the pasture, due to the consumption of insect larvae. In the pasture areas, we found no difference between the items consumed by the species, which showed a high trophic niche overlap, influenced by the consumption of Diptera larvae. Conclusion Thus, we show that allochthonous items, such as adult insects, are food resources indicative of riparian vegetation conservation and are important for both species, mainly A. agassizii. However, this item has been replaced by autochthonous items, such as Diptera larvae, in the A. agassizii diet and become predominant in the A. tetramerus diet as the riparian vegetation deteriorates.
 
Location of the study area (Middle Uruguay River) and the sampling site.
Aim This study provides the first direct evidence about the location of a spawning site of Brycon orbignyanus (Valenciennes, 1850) in the Middle Uruguay River. Methods Sampling was carried out with a plankton net (500 µm) in November 2017 in the Uruguay River near the confluence with the Piratinim River, southern Brazil. Eggs were sorted in the field, and to confirm species identity we used the live ichthyoplankton technique. Results We captured 47 eggs of B. orbignyanus in the channel of the Uruguay River, characterized by fast flow, shallow depth (approximately 3 m) and rocky bottom, located a few kilometers upstream from its confluence with the Piratinim River. Eggs are spherical, well hydrated, semi-dense, transparent and non-adhesive, with a single membrane and large perivitelline space. Total diameter varied between 3,500 and 4,000 µm. Eggs were in early stages of embryonic development, and cells showed 8, 16 or 32 blastomeres. A total of 16 eggs hatched into larvae in the plastic bags. Larvae hatched approximately 18 hours after incubation, and took 14 days to become juvenile. Conclusion This seems to be the first record of a spawning site of B. orbignyanus in the La Plata River Basin, and points to the relevance of the Middle Uruguay River as a recruitment area for this endangered species.
 
Limnoperna fortunei (Dunker, 1857), is an asiatic mussel that arrived in South America in 1991. Since 2004, we have noticed that the advance of this species in the lower Paranaíba River, a tributary of the Upper Paraná River, is slow when compared to the average speed of 240 km/year in the Paraná River (middle and lower course). AIM: The goal of this work is to understand what factors are limiting the spread of L. fortunei in this stretch of the Paranaíba River. METHODS: Its occurrence and dispersion were sampled twelve times between March 2006 and November 2007 in the Paranaíba River, including the São Simão hydroelectric reservoir. Physicochemical characteristics of the water were analysed, and a Stream Length-Gradient Index calculated for the study area. RESULTS: Adult mussels were easily found attached to the hulls of barges that travel on this stretch of the Paraná-Tietê waterway and on vessels that were docked in the harbours of grain exporters located in São Simão (GO). However, no larvae or adults were found near the harbours or upstream from them at the São Simão hydroelectric reservoir. The pH and concentration of calcium and dissolved oxygen values among lotic habitats and the reservoir were similar: DO values were close to 7 mg.L-1, the average pH was near 7, average values of total Ca ranged between 4 and 6 mg.L-1 and the chlorophyll-a levels were not restrictive to the mussel. CONCLUSION: Physical and chemical water parameters show that habitats were suitable for establishment of the mussel. In addition to a low pressure of propagules, this paper proposes some hydrological variables, such as the energy of the fluvial stretches, expressed by the Stream Length-Gradient Index and changes in flow downstream of the dam as barriers to the establishment of the species, discouraging larval settlement, and decreasing survival and recruitment.
 
The different taxa, survey sites and habitats of the caddisflies found on cases of another species.case; e) Triplectides egleri Manaus in Amazonatolica ham- adae case; f ) Marilia sp. from Ponte
Triplectides egleri from Manaus in a part of a shrimp leg. The head and torax of the larva are visible in the middle portion of the structure, marked by the arrow. 
AIM: Larvae of Triplectidesspp. and Mariliasp. occupying cases of other species are recorded and photographed; METHODS: The material was collected in different sites and dates in Atlantic Forest and Central Amazon regions; RESULTS: The Triplectides larvae seem to have an opportunistic behavior, occupying a great variety of cases, which reflects their common habit of enter in hollow twigs instead of build complex cases. However, this behavior is not frequently recorded in Marilia larvae, and we believe that the difference on the roughness of the interior walls, as well as the difference of the color of the material of the cases limit the opportunistic behavior in this genus; CONCLUSIONS: Experimental studies with different species can help the understanding of this behavior in the light of adaptive values.
 
Miranda dam (arrow indicates sampling location) (adapted from Vono et al., 2002).
Frequency of individuals and sex ratio by size class in a population of Macrobrachium amazonicum in Miranda dam (MG) between april/2012 and may/2013. A: frequency distribution of males and females in Carapace Length size (US -undetermined sex; M -Male; F -Female). B: sex ratio by size class. *not significant difference.
Monthly frequency of individuals in a population of Macrobrachium amazonicum in Miranda dam (MG) between april/2012 and may/2013 according to their population category and recruitment observed.
Aim The present study aimed to analyze a M. amazonicum population structure in a reservoir of the “Triângulo Mineiro”, Brazil. Methods Monthly surveys were carried out from April/2012 to May/2013 at the Miranda Hydroelectric Plant Reservoir located in Araguari river, state of Minas Gerais. A sampling section of 100 m long, 5 m wide and depth not exceeding 1 m was defined on the banks of the reservoir. Sampling consisted on two persons quickly passing a 2 mm sieves in partially submerged marginal vegetation, for one hour. The sampled specimens were identified, sexed and measured. Results A total of 2,584 specimens were analyzed, of which 64.62% were females (3.93% ovigerous, 5.94% non-ovigerous and 54.75% juveniles), 29.16% males (21.41% adults and 7.76% juveniles) and 6.22% juveniles of undetermined sex. The sex ratio (1:2.21) indicated a clear deviation for females, for the whole sampling period, monthly and for each size class. Males had an average carapace length (CL = 4.50 ± 0.71 mm) significantly lower than females (CL = 4.64 ± 1.47 mm) and the size frequency distribution revealed a unimodal pattern, with peaks occurring in 4.0 - 4.9 mm size class for males and in 3.0 - 3.9 mm size class for females. The relation between total and carapace length was significant, indicating a negative allometric growth. No males’ morphotypes were found. The population presented a continuous reproduction with a gradual increase between April and June/2012. Female sexual maturity was determined for 6.3 mm of CL, while for males was estimated for 4.0 mm. Conclusion The Miranda reservoir population had a body size variation similar to the continental populations of Pantanal. The sexual dimorphism observed may be related to the absence of male morphotypes and to the “pure search” reproduction strategy. The deviated sex ratio for females may increase the chance of fertilization and the reproductive success. The presence of juveniles and ovigerous females throughout the year indicates a continuous reproduction pattern of the population.
 
Map of the sampling sites. CV (riparian vegetation) and CSV (agriculture land use) at Campo River sub- Basin. CrV (riparian vegetation) and CrSV (agriculture land use) at Cravo River sub-Basin. Based on the protocol described by Callisto et al. (2002) CV and CrV are natural environments (80 and 85 points, respectively); CS are altered and CrSV are impacted environments (47 and 40 points, respectively). 
Aim: We compare catalase activity in SmicrideaMcLachlan, 1871 (Insecta, Trichoptera) collected in natural and agricultural streams and correlates the enzyme pattern with metal content in the water.Methods Organisms were collected in sites classified as natural (riparian vegetation in buffer zone) and altered/impacted (agricultural land use in drainage area) environments, located at Cravo River and Campo River sub-basins (RS, Brazil). Next the collected larvae were identified and used to proteins quantification and catalase activity measure. The concentration of Mg, Cr, Cu, Pb and Cd in the water was determined by atomic absorption spectrometry.ResultsCatalase activity in Smicridea ranged from 1.5 to 6 U, with mean values about 2.63 ± 0.096 U (SEM). The presence of metals was higher in the streams located at agricultural drainage area, except for Mg at the Cravo sub-basin and Cu at the Campo sub-basin. Catalase was higher in Smicridea collected in natural streams as compared to that agriculture streams and was correlated with Pb and Cd levels.Conclusions The data showed the potential of this biomarker as a useful tool for complementation of water quality biomonitoring studies using Smicridea as bioindicator.
 
Political map of Brazil highlighting (gray color) the state of São Paulo, where it entered the Chavantes reservoir in the middle Paranapanema River SP/PR. (arrow) Study site-a system of fish farming in net cages (NC) and reference site (RS). (Source: Satellite image of GoogleEarth-DigitalGlobe; IBGE).
Alimentary Index (AI) of A. affinis in NC (a) and RS (b), collected in Chavantes reservoir, Paranapanema River SP/PR. Table 1. Relationship weight-length in the species A. affinis in sites (NC) = Net Cage and (RS) = Reference Site in the Chavantes' reservoir, Paranapanema River SP/PR, where: (n) = number of analyzed specimens, (φ) = condition factor, (θ) = growth type, (r 2 ) = determination coefficient, (p) = significance level, *values statistically different p = <0.0001.
"Mean-Plot"-Individual condition factor of A. affinis for net cage site (1) and reference site (2) where: a) populations considering the total weight, b) carcass weight and c) gonad weight in Chavantes reservoir, Paranapanema River SP/PR (values significantly different Mann-Whitney test (U Test; p < 0.0001).
OBJETIVO: O objetivo deste estudo foi avaliar a influência de uma piscicultura em tanques-rede na dieta e nos atributos biológicos da espécie Apareiodon affinis na represa de Chavantes. MÉTODOS: Foram coletadas amostras da população ao redor dos tanques-rede (TR) e comparada com uma área sem esta influência, denominada controle (CT). As amostragens foram realizadas mensalmente de mar/2008 até fev/2009. Os peixes foram capturados utilizando-se de rede de espera com esforço padronizado, expostas por 14 horas. Todos os peixes foram medidos (comprimento padrão) e pesados (peso total, peso da carcaça, peso corporal sem as gônadas). Para determinar a composição da dieta, foi calculado o índice alimentar (IAi). Também foram calculados a relação peso comprimento, fator de condição, índice gonodossomático (IGS) e o potencial reprodutivo. RESULTADOS: Um total de 3050 indivíduos foi capturado. Os resultados do (IAi) revelou que o item detrito, foi o principal alimento utilizado pelas populações de A. affinis nas duas áreas estudas (TR = 73,1% e CT = 95,7%). A utilização da ração na dieta de A. affinis foi registrada para as populações do TR somando (20,5%) do total de itens consumidos pelas populações. As populações residentes ao redor dos tanques-rede apresentaram maiores valores de fator de condição e período reprodutivo. CONCLUSÃO: Os resultados mostram a habilidade da espécie em se beneficiar da entrada de matéria orgânica proveniente das atividades da piscicultura, inserindo um novo item em sua dieta (ração). Este trabalho indica que a espécie A. affinis conseguiu se estabelecer ao redor dos tanques-rede, alocando energia suficiente para aumentar o seu período reprodutivo e manter suas populações viáveis ao redor dos tanques-rede, comprovado pela elevada abundancia. Este estudo sugere que os sistemas de pisciculturas em tanques-rede influenciam a dieta e os atributos biológicos da espécie A. affinis residentes na represa de Chavantes, Brasil.
 
Localization of Lagoon Bonita showing the sampling stations. 
Monthly rainfall data over the study period (EMBRAPA-CPAC). 
Biovolume (ind.mL-1 ) of the phytoplankton community and relative biovolume (%) of Peridinium umbonatum at littoral zone (stations 1 and 3) and pelagic zone (station 2) of Lagoon Bonita from April/2005 to March/2006. 
AIM: The main goal of this study was to investigate the temporal and spatial distribution of Peridinium umbonatum and its relationship with the physical and chemical water variables of the pelagic and littoral zones of Lagoon Bonita, located in Brasília, Distrito Federal; METHODS: Samples were collected at three stations: two in the littoral zone and one in the pelagic zone, every 15 days from April 2005 through March 2006; RESULTS: P. umbonatum was the only member of class Dinophyceae recorded during the entire seasonal cycle, with few exceptions, in both the littoral and pelagic zones of Lagoon Bonita. The highest biovolume (7.5 mm³.L-1) of this alga occurred near shore at the beginning of the rainy season, in November 2005. Smaller values of P. umbonatum biovolume were recorded in May and June 2005, typical dry months; CONCLUSIONS: P. umbonatum and the phytoplankton community as a whole had higher biovolumes in the two littoral zone sites, at the end of the dry season and the beginning of the rains. Both, the temporal and spatial scales were relevant in the presence of P. umbonatum, and the spatial heterogeneity was the dominant factor along the study period. The plant community structure, mainly submersed macrophytes, has affected the P. umbonatum population dynamics that took place at shallow, nutrient-poor conditions, small-size lake, which matches with habitat template described to Lo functional classification established by Reynolds et al. (2002).
 
Localization of Lagoon Bonita showing the sampling stations. 
Monthly rainfall data over the study period (EMBRAPA-CPAC). 
Biovolume (ind.mL-1 ) of the phytoplankton community and relative biovolume (%) of Peridinium umbonatum at littoral zone (stations 1 and 3) and pelagic zone (station 2) of Lagoon Bonita from April/2005 to March/2006. 
AIM: The main goal of this study was to investigate the temporal and spatial distribution of Peridinium umbonatum and its relationship with the physical and chemical water variables of the pelagic and littoral zones of Lagoon Bonita, located in Brasília, Distrito Federal; METHODS: Samples were collected at three stations: two in the littoral zone and one in the pelagic zone, every 15 days from April 2005 through March2006; RESULTS:P. umbonatum was the only member of class Dinophyceae recorded during the entire seasonal cycle, with few exceptions, in both the littoral and pelagic zones of Lagoon Bonita. The highest biovolume (7.5 mm3.L-1) of this alga occurred near shore at the beginning of the rainy season, in November 2005. Smaller values of P. umbonatum biovolume were recorded in May and June 2005, typical dry months; CONCLUSIONS: P.umbonatum and the phytoplankton community as a whole had higher biovolumes in the two littoral zone sites, at the end of the dry season and the beginning of the rains. Both, the temporal and spatial scales were relevant in the presence of P. umbonatum, and the spatial heterogeneity was the dominant factor along the study period. The plant community structure, mainly submersed macrophytes, has affected the P. umbonatum population dynamics that took place at shallow, nutrient-poor conditions, small-size lake, which matches with habitat template described to Lo functional classification established by Reynolds et al. (2002).
 
Mean ± SE growth rates of three cladoceran species (Moina minuta, Ceriodaphnia cornuta and Diaphanosoma spinulosum) at three experimental treatments following a trophic gradient (oligotrophic, mesotrophic and eutrophic).  
AIM: Aquatic environments of semi-arid regions are subject to changes in water quality and volume due to short and irregular rain seasons. Consequently, zooplankton composition changes in association to fluctuations in the trophic degree. To comprehend these processes, this study analyzed the influence of nutrient concentrations (N and P) on the population dynamics of three species of Cladocera - Moina minuta, Ceriodaphnia cornuta, and Diapahnosoma spinulosum - from the Taperoá II Dam, Paraíba, Brazil; METHODS: Animals were experimentally submitted to different nutrient concentrations as a means to reproduce specific trophic conditions from natural environments. Zooplankton densities were evaluated once every three days, with food (i.e. algal cultures) being supplied in alternate days. To compare population growth, an ANOVA was performed, followed by Tukey's HSD post-hoc test; RESULTS: The population growth of the three species differed significantly both among species and among treatments. Moina minuta populations showed higher growth rates under higher nutrient concentrations, whereas Ceriodaphnia cornuta growed more efficiently in intermediate concentrations, and Diaphanosoma spinulosum showed a better development in low nutrient concentrations; CONCLUSIONS: The results from the experimental approach, presented here, are similar to what is observed in the field, based on previous studies carried out in the Taperoá II Dam. Therefore, these results suggest that the hydrological cycle seems to be the major determinant of zooplankton population dynamics in aquatic semi-arid environments
 
Location of the analyzed area and Espinhaço Range Biosphere Reserve (ERBR) in Southeast Region, Brazil.
Areas with potential for good quality watercourses (PQW) at the Espinhaço Range Biosphere Reserve.
Satellite image of PQW Area 05 with the mining site on the east side.
Satellite image of PQW Area 06 with environmental degradation by mining.
Percent and accumulative eigenvalues.
Aim This paper aims to make inferences about the quality of watercourses, and its conservation, through the habitat suitability model of Campylocia burmeisteri. Methods The modelling demanded twenty-five occurrence records, twelve as training data and thirteen as test data. The study area consisted of a 300 kilometers buffer zone applied over the occurrence records. We used a set of twenty-two environmental layers as ambient data, as follows: 19 bioclimatic variables available on Worldclim; altitude from Worldclim; slope, obtained through geoprocessing in ArcGis v10.3 with altitude variable; and drainage density provide by Ambdata. These layers were transformed by the use of fuzzy logic to represent a continuous variation, and thus the most significant data was select after a PCA. To indicated to new surveys areas, we define locations with significant occurrence probability and distant from occurrence points. And, lastly, we observed the environmental integrity to analyze the potential watercourse quality, by using satellite images, in a buffer zone of ten kilometers from Espinhaço Range Biosphere Reserve. Results The chosen regions with the highest occurrence probability, which account for 9 new survey areas, are concentrated in interfluvial areas and near conservation units. We performed an analysis focused on the region of the Espinhaço Range Biosphere Reserve and delimited seven areas that presented good habitat suitability. The region was observed using satellite images, and five of the areas presented high ecological integrity. Two areas showed impacts from mining activity. Conclusions The distribution pattern corroborates the features of the species as a bioindicator of good water quality. It is estimated that this methodology can be adapted and applied to other bioindicators. The areas where headwaters and low-order tributaries are present must be conserved, because they are fundamental for maintaining the quality within the respective watershed.
 
Aim Characterize habitats and determine the reproductive parameters of the prawn Desmocaris trispinosa (Aurivillius, 1898) from Banco stream, a periurban stream of Abidjan (Côte d'Ivoire, West Africa). Methods Sampling was conducted monthly, from July 2020 to June 2021 at four stations. Environmental characteristics were measured before prawn sampling. The sampling was made with a dipnet during five-minute active fishing conducted by a single operator at each station. Results According to environmental variables, sampling stations were divided into three groups: almost undamaged (B4), slightly disturbed (B1) and disturbed (B2 and B3). In total, 467 specimens of D. trispinosa were captured in which 127 males, 275 females and 65 juveniles. Overall, the sex ratio (1:2.1) was in favour of females. Considering stations, the sex ratio was also in favour of females. But, only in the almost undamaged station (B4), the difference was significant (χ2 = 70.20; P<0.001). At this station, a variation of sex-ratio was observed in two seasons. In total, 116 ovigerous females were analysed on all stations. Fecundity varies from 5 to 16 oocytes with an average of 11.03 ± 2.18. First maturity size was estimated at 4.82 mm carapace length for the combined data. Females from the station free from human activities (B4) reached sexual maturity (4.23 mm) before those of the other stations (4.97 in B1 and 5.70 mm in B2). D. trispinosa from Banco stream reproduces continuously year-round with two peaks in the rainy season. The oocyte volume was negatively influenced by temperature and positively by dissolved oxygen. Conclusions D. trispinosa reproduces year-round in undisturbed stations and reaches sexual maturity faster at these stations compared to disturbed stations. The sex ratio was in favour of females. Consequently, this species would be naturally polygamous.
 
Growth of Ceriodaphnia silvestrii, in laboratory, at 25ºC and fed with Monoraphidium dybowski 10 5 cellsmL-1 and 12:12 h light-dark photoperiod.
Population growth curve of Ceriodaphnia silvestrii cultured at 25ºC and fed with Monoraphidium dybowski 10 5 cellsmL-1 and 12:12 h light-dark photoperiod in the laboratory.
Relationship between fecundity and longevity of Ceriodaphnia silvestrii cultured at 25ºC and fed with Monoraphidium dybowski 10 5 cellsmL-1 and 12:12 h light-dark photoperiod in the laboratory.
shows the relationship between fecundity and longevity. The highest fecundity was 15 eggs per female, reached at an age of 19 days. In order to determine if the culture conditions were adequate, the main physical and chemical variables were monitored along the experiments. The values for the concentrations of the main ions and other characteristics of the water culture indicate that the water used as medium had moderate hardness (143mgL-1 CaCO 3 ), nearly neutral pH (7.2), high conductivity (172 µScm-1 ) and low ammonium nitrogen (0.28 mgL-1 ), sulphate (9.17 µgL-1 ) and potassium (7.36 µgL-1 ) concentrations, throughout the experimental period.
The life-cycle of Ceriodaphnia silvestrii Daday, 1902, a Neotropical endemic species (Crustacea, Cladocera, Daphnidae). Considering the scarcity of detailed information on the life cycle of Neotropical cladocerans, a study was conducted to get the necessary information to maintain cultures of Ceriodaphnia silvestrii in laboratory, aiming its use as a standard test-organism in ecotoxicological tests. Additionally, the life history information may help to understand the functional role of the species in natural communities, since it has a wide geographical distribution and sometimes occurs in high densities. The cladoceran culture was kept under constant conditions (Monoraphidium dybowskii at 10 5 cells.mL -1 , photoperiod 12h light : 12h dark and water temperature of 25 ± 2 0 C). The parameters observed were: individual growth, population growth, biomass, fecundity and longevity. The following results were obtained: final body length of 1.0mm; intrinsic natural rate of increase (r) of 0.34 d -1 ; fecundity of 9.46 ± 4.17 eggs per female; longevity of 29.8 ± 5.89 days; size at maturity was 0.57 ± 0.04mm, and dry weights for neonates and primipara were 3.8 ± 1.69 and 9.7 ± 3.3 mg, respectively. This species can be readily cultured in the laboratory, and had excellent performance in the conditions tested. It can therefore be used for ecotoxicological tests. RESUMO: Ciclo de vida de Ceriodaphnia silvestrii, Daday, 1902, espécie endêmica Neotropical (Crustacea, Cladocera, Daphnidae). Considerando a escassez de informações sobre o ciclo de vida de cladóceros da região Neotropical, o presente estudo foi realizado com a espécie Ceriodaphnia silvestrii Daday,1902, com objetivo de manter o cultivo desta espécie em laboratório, visando a sua padronização como organismo-teste nos ensaios ecotoxicológicos. Além disso, visou contribuir com informações relevantes sobre seu ciclo de vida que sirvam de subsídio para a avaliação do seu papel funcional nos ecossistemas em que ocorre, visto que é uma espécie de ampla distribuição geográfica. As culturas de Ceriodaphnia silvestrii foram mantidas sob condições constantes: concen-tração alimentar de 10 5 céls.mL -1 , da alga clorofícea Monoraphidium dybowskii, fotoperíodo de 12 : 12h claro/escuro e temperatura de 25 ± 2 0 C. Os parâmetros do ciclo de vida quantificados foram: crescimento individual, crescimento populacional, biomassa, fecundidade e longevidade. O comprimento máximo do corpo foi de cerca de 1,0mm, 0,34 d -1 para taxa intrínseca de aumento natural (r), fecundidade de 9,46 ± 4,17 ovos/ fêmeas, longevidade de 29,8 ± 5,89 dias, comprimento de primeira maturação de 0,57 ± 0.04mm, e peso seco individual para neonatas e primíparas foi de 3,8 ± 1.69 e 9,7 ± 3,3 mg, respectivamente. Esta espécie é de fácil cultivo em laboratório, e tem excelente desempenho nas condições testadas, podendo portanto ser utilizada em en-saios ecotoxicológicos. Palavras-chave: Zooplâncton, Ciclo de vida, cultivo de Cladocera, Ceriodaphnia silvestrii.
 
Map of the seven lakes studied in the Médio Rio Doce. The contour line delimits in the Parque Estadual do Rio Doce (Médio Rio Doce), containing in its interior Lakes Carioca (CA -19° 45' 26,0'' S and 042° 37' 06,2' 'W) Gambazinho (GN -19° 47' 07,7'' S and 042° 34' 45,5'' W) and Dom Helvécio (DH -19° 46' 55,7'' S and 042º 35' 28,9'' W), and in its surrounding Lakes Jacaré (JA -19° 48' 37,8'' S and 042° 38' 57,0'' W), Palmeirinha (PA -19° 49' 41,8'' S and 042° 36' 25,4'' W), Águas Claras (AC -19° 49' 06,9'' S and 042° 35' 42,5'' W) and Amarela (AM -19° 49' 23,1'' S and 042° 34' 28,7'' W).  
The presence of the two exotic zooplankton species (Kellicottia bostoniensis and Mesocyclops ogunnus) in lakes of the Middle River Doce is discussed in the present work. K. bostoniensis was registered in Lakes Jacaré, Carioca and Águas Claras while M. ogunnus was restricted to the littoral zone of Lake Dom Helvécio. These zooplankton species may have been introduced in these environments by human action. Despite the low densities registered for both species, the monitoring of the invasion process is necessary to evaluate possible impacts on the zooplankton community structure in the lakes of Middle River Doce.
 
Sampling site location (star) in the Ibicuí River, city of Cacequi, Rio Grande do Sul state, southern Brazil.
Graphical representations following the method proposed by Costello (1990) modified by Amundsen et al. (1996) showing the proportion of food categories found in the diet of three standard length classes (SLC) of Piabarchus stramineus from the Ibicuí River, southern Brazil, between April 2001 and February 2002. a = SLC1; b = SLC2; c = SLC3. ALI = allochthonous insects; AUI = autochthonous insects; VM = vegetal matter; Sed = sediment; Cru = Crustacea; Sca = fish scales; Fis = Fish; Arac = Arachnida; Col = Collembola.
Graphical representation of the two first NMDS axis showing seasonal variation in the diet of Piabarchus stramineus in the Ibicuí River, southern Brazil, between April 2001 and February 2002. Aut = autumn; Win = winter; Spr = spring; Sum = summer.
Aim In the present work we describe and analyze the diet of a small characin species, Piabarchus stramineus, from the Ibicuí River, Uruguay River Basin, southern Brazil. Methods Samples were collected monthly from April 2001 to March 2002 with seine net. All fish were measured, weighed, and had its stomach extruded for gut content analysis. Months were grouped in seasons and fish were classified within three standard length classes (SLC). We tested for possible alimentary differences between the different seasons of the year and standard length classes. Results The analysis of the content in 301 stomachs identified 27 food items and low to intermediary niche breadth. The main food item/category was allochthonous insects, regardless of the seasons, and P. stramineus can be classified as an insectivorous species. We observed no food overlap between smaller and larger fish (SLC1 and SLC3). On the other hand, we observed food overlap between small and intermediary fish (SLC1 and SLC2) and between intermediary and large fish (SLC2 and SLC3), evidencing a transition in food consumption along size classes. A temporal variation in diet composition was also observed among size classes. Thus, different sized fish differed in their diets, with smaller fish feeding mainly on cladocerans (SLC1 and SLC2) and larger fish (SLC3) feeding mainly on allochthonous Diptera and Hymenoptera. Conclusions The species diet varies in time (seasons) and such variation is different in each size class. Allochthonous food items were important in the diet of the species in the different developmental phases, especially for larger fish, with autochthonous items also important, especially for smaller fish. The allochthonous food items are strongly related to the ciliary forest; thus, we emphasize the importance of the conservation of such environments.
 
Map of the seven lakes studied in the Médio Rio Doce. The contour line delimits in the Parque Estadual do Rio Doce (Médio Rio Doce), containing in its interior Lakes Carioca (CA-19° 45' 26,0'' S and 042° 37' 06,2' 'W) Gambazinho (GN-19° 47' 07,7'' S and 042° 34' 45,5'' W) and Dom Helvécio (DH-19° 46' 55,7'' S and 042º 35' 28,9'' W), and in its surrounding Lakes Jacaré (JA-19° 48' 37,8'' S and 042° 38' 57,0'' W), Palmeirinha (PA-19° 49' 41,8'' S and 042° 36' 25,4'' W), Águas Claras (AC-19° 49' 06,9'' S and 042° 35' 42,5'' W) and Amarela (AM-19° 49' 23,1'' S and 042° 34' 28,7'' W).
The presence of the two exotic zooplankton species (Kellicottia bostoniensis and Mesocyclops ogunnus) in lakes of the Middle River Doce is discussed in the present work. K. bostoniensis was registered in Lakes Jacaré, Carioca and Águas Claras while M.ogunnus was restricted to the littoral zone of Lake Dom Helvécio. These zooplankton species may have been introduced in these environments by human action. Despite the low densities registered for both species, the monitoring of the invasion process is necessary to evaluate possible impacts on the zooplankton community structure in the lakes of Middle River Doce.
 
Aim The order Ephemeroptera, together with Trichoptera and Plecoptera, has been considered as sensitive in environmental quality assessment. However, the species Campsurus truncatus Ulmer 1920 (Polymitarcyidae) has been sampled in anthropically altered sites. In this paper, data on the occurrence of that species in the water quality monitoring network of the Environmental Agency of São Paulo State (CETESB) were gathered to review its position in the environmental gradient and in the quality assessment of rivers and reservoirs. Methods For this, a compilation of the occurrences and densities of Campsurus obtained in rivers and reservoirs of São Paulo state between 2001 and 2018, with grab samplers, was carried. Environmental factors, the Trophic State Index (TSI) and the Benthic Community Index (BCI) were related to the species densities to define its environmental requirements. Results The sublittoral zone of reservoirs was the most common habitat to C. truncatus, occurring more frequently at mesotrophic sites with fair ecological quality. Higher mean densities were recorded at eutrophic sites with good ecological quality conditions. The statistical analysis did not show linear correlation between C. truncatus densities and any of the analyzed environmental variable such as grain size, organic matter content, DO and light penetration, although there was a tendency for higher species densities occur in muddy, dark sediments and with intermediate levels of organic matter. As described in literature the presence of aquatic plants can actually benefit that population once the highest densities were observed in sites with many macrophytes, as Salto Grande reservoir, but it may be confusing the relationship between population density and environmental factors. Conclusions The high occurrence and densities of C. truncatus obtained in eutrophic environments suggest that the species should not be considered as a sensitive taxon in qualitative indexes, such as the BCI for rivers and the sublittoral region of reservoirs. Moreover, its exclusion from the richness of sensitive groups had low impact on the diagnoses already performed at the CETESB monitoring network.
 
AIM: The present study investigated population structure, weight-length relationships, sex ratio and associations between feeding activity and reproductive period, diet and alimentary regime of Steindachnerina notonota at Taperoá II dam, semi-arid region of Paraíba State. METHODS: The region has the lowest pluviometric rates of Brazil. Fishes were collected during six sampling periods (October and December/2005, and March, June, August and October of 2006) encompassing two dry periods, and one rainy period. Cast, seine and gill nets were used to collect the individuals. RESULTS: Throughout the study period 120 individuals were collected, with total length ranging between 2.2 and 10.7 cm and weight between 0.31 and 43.1 g. A recruitment period, identified due to a higher abundance of small individuals in the population, was observed in the beginning of the rainy period of 2006, lasting until the beginning of the dry season. S. notonota showed a negative allometric growth type, i.e., individuals 'elongate' during their development. A significantly higher proportion of females were observed throughout the study period. The relationship between feeding and reproductive activities were not significant, given that individuals showed high feeding rates regardless of the intensity of their reproductive activities. Although the diet of S. notonota comprised several items such as plant debris, eggs, organic matter, phytoplankton, zooplankton, Nematoda, Ostracada, Conchostraca, among others, the most important feeding item was detritus, suggesting a predominant detritivirous feeding habit. CONCLUSIONS: Biological aspects of S. notonota observed in the present study suggest that this species has potential to attain great population sizes, as consequence of both diet and feeding dynamics, as well as its reproductive characteristics and growth type.
 
This article discusses the purpose and effects of Law 3824/1960, which makes mandatory the removal of vegetation and consequent cleaning of land sites subject to flooding by the construction of artificial reservoirs. The importance of this reflection is to avoid having a law that is considered effective, though if questioned, may prove contrary to the objectives for which it was created. Thus, this article aims to awaken decision makers to the possibility that this law is considered inapplicable to the current reality, according to the social, scientific, legal and environmental advances achieved in recent years. As a specific objective, based on the findings obtained, we aim to stimulate authorities to act in favor of the elaboration of a law that will meet these advances.
 
Examples of Apistogrammoides pucallpaensis. (A) Living example; (B) Living example in stress situation; (C) Alcohol example. Standard length 40 mm.
Geographical records of Apistogrammoides pucallpaensis. (A) Known geographical distribution; (B) Two new records in Amazonian lakes of Brazil.
Aim The objective of this work is to record the occurrence of Apistogrammoides pucallpaensis in Brazilian territory, since so far its distribution is restricted to Peru and Colombia. Methods The collections were carried out in the year of 2013, during the research of ichthyofauna of the region of Auati-Paraná, located in the Mamirauá Reserve in the state of Amazonas. In the floating aquatic vegetation was used net and on the coastal region rapichés. Apistogrammoides is the only one among Geophaginae that has 6-9 spines in the anal fin, while Apistogramma has 3-4. Results Note the presence of three evident mark on the caudal fin and presence of a black stripe on the side of the body that follows from the eye to the caudal peduncle feature thet differentiate the genre. Conclusions This work extends the distribution of A. pucallpaensis being the first record of the species for Brazil.
 
Location Map of the Hydrographical Basin of Pardo River, RS, Brazil. 
Location of the Sampling Stations over the Hydrographical Basin of Pardo River, RS, Brazil. 
Environmental monitoring studies in the Hydrographical Basin of Pardo River, RS, Brazil, in the time series from 2007 to 2009, showed no agreement between the water quality evaluation obtained through the Water Quality Index (WQI - NSF), which ranged from "regular" to "good", and the Environment National Council (CONAMA) Resolution 357/2005, which was bad ("class 4"), highlighting as critical variables for this classification the thermotolerant coliforms and the phosphate concentration, indicating process of water eutrophication, related to the large amount of nutrients and organic load from domestic sewage and excess fertilizers used in agriculture. AIM: This research aimed to calibrate the WQI - NSF for the Pardo River Basin, based on the CONAMA Resolution 357/2005. METHODS: Using the database (2007 a 2009) from the Laboratory of Limnology of the University of Santa Cruz do Sul (UNISC), RS, corresponding to the environmental monitoring studies realized in the Hydrographical Basin of Pardo River new weights of the relative importance of the variables used to calculate the WQI were attributed, by means of principal component analysis. RESULTS: There was a significant agreement between the results of the assessment of water quality using the CONAMA Resolution 357/2005 and the new WQI calibrated. CONCLUSION: The results certify the use of the calibrated WQI in environmental monitoring programs in lotic systems belonging to Guaíba Hydrographical Basin, RS.
 
Aim: To analyze temporal distribution of larvae and juveniles and the early development and of Moenkhausia cf. gracilima. Methods Samples were taken quarterly in twenty-five sites in the upper Paraná River floodplain between August 2013 and May 2015. The samples were taken under the water surface at night using 0.5 mm mesh plankton nets. In the laboratory, samples were sorted, identified and separated into larval (preflexion, flexion and postflexion) and juvenile periods. Results A total of 248 individuals was collected, mainly in the Saraiva Lagoon, suggesting that the entire life cycle of this species occurs in this environment. The reproductive period takes place between December and April, since the postflexion larvae were found until May. However, the occurrence of juveniles between February and May indicates probable batch spawning. Among the 95 individuals used for ontogenic description, 82 were larvae and 13 juveniles. Larvae may be characterized by irregular pigmentation in the upper region of the head, mouth, and body, increasing throughout development; upper lobe of the caudal fin more pigmented than the lower lobe, only visible in postflexion larvae; terminal mouth; anal opening located anterior to the median region of the body and total number of myomers ranging from 34 to 40 (15 to 20 pre and 16 to 23 postanal), while juveniles have characteristics similar to adults. The total number of fin rays is: P. 11-16, V. 7-11, D, 9-11 and A. 21-23. Conclusions According to the distribution of developmental periods it is possible to conclude that this species reproduces in the summer, preferably in lagoons. Growth analysis indicated important alterations in larval morphology (metamorphosis) that may be associated with the ecomorphological characteristics of the species. The morphological separation of larvae of M. cf. gracilima from other larvae of small characids, especially at preflexion and flexion stages may be complicated by the overlap of traits, suggesting the use of other variables, mainly morphometric, for the separation of the species.
 
Location of the Cascalho Lagoon in the Upper Paraná River floodplain, MS, Brazil. 
Dispersion of scores of first two axes of Principal Component Analysis (PCA) in the rainy (solid circle) and dry (open circle) periods. Temp = temperature and DO = dissolved oxygen. 
AIM: We evaluated the composition and community attributes of invertebrates associated to Eichhorniaazurea at Cascalho Lagoon, Upper Paraná River, Mato Grosso do Sul State, Brazil, over a hydrological cycle, as well the possible influence of abiotic factors upon these attributes. METHODS: The samplings were conducted during 2010 in the rainy and dry periods at stands of E.azurea. The attributes evaluated were abundance, richness, diversity, evenness and dominance. The abiotic factors, temperature, dissolved oxygen, pH and turbidity were summarized by a Principal Component Analysis (PCA). In order to verify possible differences between the mean values of the community attributes and the scores of the PCA axis in different periods, we employed null models analysis of variance. The influence of abiotic factors on each attribute was evaluated through Pearson correlations. RESULTS: We captured 3,052 individuals, distributed into 32taxa, belonging to the phyllum Mollusca, Annelida, Nematoda and Arthropoda. Among the assessed attributes, only abundance and richness varied significantly between periods, with higher values during the rainy period. Chironomidade was dominant in both periods, whereas Notonectidae and Cyclopoida were rare in the rainy, and Bivalve, Decapoda, Haliplidae, Trichoptera and Pyralidae, in the dry period. A temporal distinction was evident only for the PCA axis 1, which represented gradients in temperature, dissolved oxygen and pH. Among the community attributes, only abundance was significant and negatively correlated with this axis. CONCLUSION: We attested that: i)the rainy period should add favorable conditions for invertebrates' higher richness and abundance in this macrophyte; ii)only the later attribute was influenced by limnological gradients.
 
Aim Phytotelm plays an important role in plant growth and ecosystem functioning, but this natural aquatic microcosm is poorly known. We evaluated the seasonal (dry and rainy seasons) and spatial variations (forest trail and stream sites) of the phytotelm in Nidularium longiflorum, bromeliad that occurs in the Atlantic Forest. Methods Abiotic and biotic variables were measured in tank-bromeliad phytotelms. The biomass was analyzed by ash-free dry mass and chlorophyll-a concentration. Results Abiotic variables measured in the phytotelmic environment of bromeliads varied between sampling sites and seasons. Temperature, electrical conductivity and total nitrogen values were significantly different between seasons and sites. Chlorophyll-a and ash-free dry mass (organic matter) in phytotelm were significantly different between sampling sites. Eleven genera of algae in the phytotelm were identified. PCA axis 1 ordination evidenced the seasonal variation of environmental conditions. Conclusions Our findings suggest that environmental and micro-environmental conditions do not favor the development of algal community in the phytotelm. Biomass and abiotic variables in phytotelm of Nidularium longiflorum change seasonally, however biomass accumulation was strongly influenced by site characteristics.
 
Map of geographic location of study areas (Itacorubi and Ratones mangroves) in the municipal of Florianópolis/SC, Brazil. 
Sample design showing the replicas (4), in the times (7, 15, 30, 60, 90 and 120 days), seasons (winter and summer), senescent leaves (A. schaueriana and R. mangle) and local studies (Itacorubi and Ratones mangroves). 
Averages values and standard error (vertical bars) of senescent leaves mass loss for A. schaueriana (A and C) and R. mangle (B and D) in the winter (A and B) and summer (C and D) in the studied mangroves. 
Regression Tree with replicate values (n), significant parameter average (m) and parameter complexity at each knot (CP) divided by the values of water temperature, electrical conductivity, pH and dissolved oxygen in function of the percent of remaining mass of leaf detritus in the mangroves of Ratones and Itacorubi during the winter (A) and summer (B) seasons. 
Localization, decomposition rates (k), condition of experiment and authors of studies on mangroves with detritus of A. schaueriana (A) and R. mangle (B). 
Aim: The objective of this study was to determine the rate of decomposition of two dominant arboreal species (Rhizophora mangle and Avicennia schaueriana) in two Brazilian subtropical mangroves (Ratones and Itacorubi) and their relationship with abiotic factors during two periods of the year (winter and summer). Methods: Senescent leaves (4 ± 0.1 g dry weight) were placed into litter bags (20 × 25 cm with 1 cm mesh size) and submersed in mangrove forests during a winter and a summer sampling period. Replicates (n = 4) of each detritus sample were obtained from the mangroves after 7, 15, 30, 60, 90 and 120 days of incubation during both time periods. During each period, in situ measurements were taken to obtain the temperature, electrical conductivity, pH, and dissolved oxygen in the water column. Results: The species R. mangle and A. schaueriana exhibited slow rates of decomposition at Itacorubi and intermediate rates at Ratones during the winter, while quick rates were observed at both sites during the summer; this result suggested that water temperature is an influential factor. There was no difference in the loss of mass between the sites during the winter, but in the summer, the highest values were observed for R. mangle in Ratones site. The highest summer temperatures were negatively associated with mass loss, suggesting that the temperature is an influential factor. During the winter, remaining mass was associated negatively with electrical conductivity, possibly because of a greater resource available to decomposing communities, and it was also positively associated with oxygen, revealing a pattern opposite to that observed in the literature. Conclusions: Our results showed that decomposition accelerated with higher temperatures and that electrical conductivity decelerated with increased dissolved oxygen, confirming the effects of abiotic factors on both detritus decomposition and mangrove functioning.
 
Diagram of the fish pond: Inset A: shaded area indicates southeastern Brazil (State of São Paulo). Inset B: aquaculture farm of the Universidade Estadual Paulista. Inset C: fish pond studied with the sampling sites: IW1 and IW2 = water inlets; FP = deep water site; WO = water outlet and ■ = frog culture sector.
Monthly variation of air temperature (line -°C) and precipitation (bars -mm) during analysis, indicating the rainy and dry seasons.
Aim Limnological conditions, phytoplankton and zooplankton communities in a fishpond highly affected by management during the dry and rainy seasons are investigated. Methods Water samples were analyzed for physicochemical parameters; soil samples were analyzed for macro- and micro-nutrients, phytoplankton and zooplankton communities, at four sites, during eight months in the rainy and dry seasons. Distance-based linear model (DISTLM) was applied with Akaike Information Criterion (AIC), where the influence of environmental variables in the variation of phytoplankton and zooplankton composition could be assessed and the best model could be selected. Results The multiparameter test revealed that variables pH, TSS and TP better explain the composition of the biotic community (AICc = 45.6; R2 = 0.80). Chlorophyceae was the dominant group with 32 taxa, or rather, 75-85% of total phytoplankton, with high density at 2,365-4,180 ind.L⁻¹ during the sampling period. Rotifera was the most abundant group in the zooplankton community during the two seasons, except at IW2 during the dry season, when Copepoda had a higher density, namely, 52% of total zooplankton community at this site. Conclusions The contribution of allochthonous material to the fishpond during the two seasons mainly consists of macro- and micro-nutrients and thermotolerant coliforms that influenced the plankton community and enhanced high Cyanobacteria density in the rainy season. Plankton community in the studied pond was characteristic of small water bodies. Management protocol in places with continuous water flow according to the region may be an important tool to optimize and to avoid risks in fish production.
 
Objective The objective of this study is to evaluate whether the distribution of structural attributes of rotifers in reservoirs in the semiarid region is more strongly influenced by abiotic or biotic environmental factors (density of cyanobacteria).Method Sampling occurred in two reservoirs in the Paraíba Basin, northeastern Brazil (Poções and Camalaú) during April and June 2012. Eight sampling points were distributed at two stations in each reservoir: the region near the entrance of the main tributary and region of the dam and collections were made in the limnetic and littoral zone in every season. To assess the abiotic influence and density of cyanobacteria in the distribution of the structural attributes of rotifers, environmental variables bivariate correlation was conducted in series.ResultsIn Poções reservoir, the distribution of rotifer biomass was negatively related to the density of cyanobacteria; among the environmental variables, chlorophyll-a and total nitrogen were negatively related to all of the tested structural attributes, while the concentrations of total phosphorus were strongly related to the abundance of rotifers. In the Camalaú reservoir, the biomass was a structural attribute with a stronger correlation to the density of cyanobacteria; between the environmental variables and Egeria densa, nitrate was negatively related to all of the attributes tested, while transparency was moderately related to the abundance, biomass and richness as well as Chara sp. with abundance.Conclusions Assemblages of rotifers are more clearly related to environmental conditions, especially those indicative of trophic conditions, despite the density of cyanobacteria having been a factor that was positively related to the structural characteristics of rotifers and thus indicative of such structural assemblies. This can be used for analysis of local environmental condition factors.
 
Scheme showing the emergent aquatic macrophyte Crinum americanum forming rosettes.  
Scheme showing the emergent aquatic macrophyte S. alterniflora forming stems.  
Simple linear regression between the individual aboveground area and aboveground dry mass (A), simple linear regression between the individual height and aboveground dry mass (B) of Crinum americanum, and linear equation and coefficient of determination (R 2 ).  
Simple linear regression between the individual aboveground area and aboveground dry mass (A), simple linear regression between individual height and aboveground dry mass (B) of Spartina alterniflora, and linear equation and coefficient of determination (R 2 ).  
Aim Non-destructive methods for estimating aquatic macrophytes biomass may be employed by using indirect measurements, especially in experimental studies, thus enabling the conservation of plant samples. It is possible to estimate macrophyte biomass by developing mathematical equations that relate the plants’ dry mass to their morphological variables. The aim of this study was to evaluate the relationship between different morphological variables and biomass in order to determine which variable is easier to be obtained for the emergent aquatic macrophytes Crinum americanum and Spartina alterniflora. Methods We obtained the aboveground area and height of individuals of both species, with different sizes and distinct developmental stages. The samples were collected in the Itanhaém River Estuary (SP, Brazil). The plants were dried in a laboratory oven and weighed so as to obtain their dry mass. Simple linear regression analyses were applied to the morphological variables and the individual dry mass to obtain equations. Results For the both species, the relationship between area and biomass, and the relationship between individual height and biomass presented significant coefficients of determination (p < 0.0001). For the elaboration of models involving the individual height, we used only one morphological measure for each individual, whereas for models involving the individual area it was necessary to obtain more than one hundred morphological measurements per individual. Conclusions The morphological variables chosen are good attributes for estimating the aboveground biomass of C. americanum and S. alterniflora. Considering the models’ adjustment and the consumed time to obtain the measurements, we conclude that the individual height measurement is better for biomass estimation for both species.
 
Barra Bonita hydroelectric reservoir and its location in Brazil and São Paulo State (highlighted) (a); cascade system in Tietê River (b); and sampling stations (c).
Ternary plots show the contribution of each optically significant constituent for a at 440, 620 and 665 nm collected in May (a) and October (b). 
a* φ spectra measured in May (a) and October (b) 2014. 
Normalized a* φ spectra for 440 nm collected at sampling stations: 3 (a), 5 (b), 14 (c) and 20 (d).
Aim: In this research, we investigated the spectral variability of the specific phytoplankton absorption coefficient, a*φ, measured in a tropical meso-to-hypertrophic reservoir, aiming to find spectral features associated with the chlorophyll-a (chla) and other accessory pigments present in different phytoplankton species. Methods To accomplish this research, two fieldworks were carried out in different seasons in order to report a high bio-optical variation. Phytoplankton absorption coefficient, aφ, and chla concentration were measured in laboratory to estimate a*φ. Results The outcomes have indicated that there is a remarkable phytoplankton community dynamic as spatially as seasonally. Chla absorption features were well-defined at 440 nm and 675 nm. Conclusions All the a*φ spectra exhibited the absorption peak around 630 nm associated with phycocyanin pigment present in cyanobacteria. Some spectra have shown a peak at about 460 nm, which is related to chlorophyll b and chlorophyll c (chlb and chlc, respectively) found in different phytoplankton species. In turn, absorption features of carotenoids around 490 nm also were identified, however, well defined just in curves measured in austral autumn. Such spectral features are found in phytoplankton groups already identified in the study area such as Chlorophyceae, Bacillariophyceae, Cyanophyceae, Conjugatophyceae, Chrysophyceae, among others. We expect that the results are useful in researches about remote sensing of phytoplankton and eutrophication in reservoirs.
 
Top-cited authors
Elvio S. F. Medeiros
  • Universidade Estadual da Paraíba
Maria Cristina Crispim
  • Universidade Federal da Paraíba
Jandeson Brasil
  • Federal University of Rio de Janeiro
Raquel Da Silva Cordeiro
  • Instituto Federal de Educação, Ciência e Tecnologia do Ceará
Marina Satika Suzuki
  • Universidade Estadual do Norte Fluminense