Macroinvertebrates responses based on chemical and physical variables in urban streams

Abstract The Land uses and occupations around small watersheds generate negative impacts such as deterioration of water quality, environmental simplification, reduced availability of habitats for species, and loss of biodiversity. Benthic macroinvertebrates are an important aquatic community and are widely used in environmental monitoring actions in aquatic ecosystems, including urban streams, which are still little studied in Brazil. In our study, an urban headwater basin (Monjolinho River Basin) was studied on the benthic community structure, together with the physical and chemical variables of the water, as an environmental monitoring tool calculated by RHDEP, TSI, BMWP indexes and abundance-biomass curves. The results showed a gradient of environmental quality, where the best environments are a consequence of preserving the vegetation cover. These environments (Espraiado and Canchim) present groups sensitive to environmental degradation (Ephemeroptera, Plecoptera and Trichoptera), greater diversity and a better structure in the respective benthic macroinvertebrate assemblages. Among the streams sampled, one is very clean, four are moderately polluted, and one is severely polluted. Thus, considering that these streams waters are essential for public supply, actions to clean up and recover degraded environments are urgent and a priority.

Macroinvertebrates responses based on chemical and physical variables in urban streams

Abstract The Land uses and occupations around small watersheds generate negative impacts such as deterioration of water quality, environmental simplification, reduced availability of habitats for species, and loss of biodiversity. Benthic macroinvertebrates are an important aquatic community and are widely used in environmental monitoring actions in aquatic ecosystems, including urban streams, which are still little studied in Brazil. In our study, an urban headwater basin (Monjolinho River Basin) was studied on the benthic community structure, together with the physical and chemical variables of the water, as an environmental monitoring tool calculated by RHDEP, TSI, BMWP indexes and abundance-biomass curves. The results showed a gradient of environmental quality, where the best environments are a consequence of preserving the vegetation cover. These environments (Espraiado and Canchim) present groups sensitive to environmental degradation (Ephemeroptera, Plecoptera and Trichoptera), greater diversity and a better structure in the respective benthic macroinvertebrate assemblages. Among the streams sampled, one is very clean, four are moderately polluted, and one is severely polluted. Thus, considering that these streams' waters are essential for public supply, actions to clean up and recover degraded environments are urgent and a priority.

Macroinvertebrates responses based on chemical and physical variables in urban streams

The Land uses and occupations around small watersheds generate negative impacts such as deterioration of water quality, environmental simplification, reduced availability of habitats for species, and loss of biodiversity. Benthic macroinvertebrates are an important aquatic community and are widely used in environmental monitoring actions in aquatic ecosystems, including urban streams, which are still little studied in Brazil. In our study, an urban headwater basin (Monjolinho River Basin) was studied on the benthic community structure, together with the physical and chemical variables of the water, as an environmental monitoring tool calculated by RHDEP, TSI, BMWP indexes and abundance-biomass curves. The results showed a gradient of environmental quality, where the best environments are a consequence of preserving the vegetation cover. These environments (Espraiado and Canchim) present groups sensitive to environmental degradation (Ephemeroptera, Plecoptera and Trichoptera), greater diversity and a better structure in the respective benthic macroinvertebrate assemblages. Among the streams sampled, one is very clean, four are moderately polluted, and one is severely polluted. Thus, considering that these streams waters are essential for public supply, actions to clean up and recover degraded environments are urgent and a priority.(AU)

The influence of black spot disease on the relative condition factor of Astyanax paranae Eigenmann, 1914 (Characiformes: Characidae) in Brazilian subtropical streams

Environmental disturbances and their consequences require constant studies to understand how communities and their ecological relationships respond to these processes. Through analysis of the host-parasite relationships, it is observed that the effect of these disturbances is variable and can change the physiology or behavior of organisms. Black spot disease, caused by endoparasitic helminths, is a pathology observed in natural environments, however, there is not much information about the consequences of this infestation. We separated the specimens from each stream into parasitized and non-parasitized groups, which were subjected to biometric analysis. The biometrics involved cysts count and weight-length measures, which were used to analyze the average relative condition factor. Additionally, we correlate these measures with the parasitic burden of infected individuals. Finally, the parasitized individuals were submitted to histological sections to recognize the parasite. The results demonstrate a low physiological condition in the parasitized group, when compared with non-parasitized groups from the same stream and from different streams. This suggests that pollution, in addition to effects of infestation worsen the fish condition. Besides, the parasite burden was negatively correlated with the condition factor, weight and length measures. We conclude that the parasite burden negatively affects Astyanax paranae individuals´ physiological condition and that trematodes also occur in polluted environments.

The influence of black spot disease on the relative condition factor of Astyanax paranae Eigenmann, 1914 (Characiformes: Characidae) in Brazilian subtropical streams

Environmental disturbances and their consequences require constant studies to understand how communities and their ecological relationships respond to these processes. Through analysis of the host-parasite relationships, it is observed that the effect of these disturbances is variable and can change the physiology or behavior of organisms. Black spot disease, caused by endoparasitic helminths, is a pathology observed in natural environments, however, there is not much information about the consequences of this infestation. We separated the specimens from each stream into parasitized and non-parasitized groups, which were subjected to biometric analysis. The biometrics involved cysts count and weight-length measures, which were used to analyze the average relative condition factor. Additionally, we correlate these measures with the parasitic burden of infected individuals. Finally, the parasitized individuals were submitted to histological sections to recognize the parasite. The results demonstrate a low physiological condition in the parasitized group, when compared with non-parasitized groups from the same stream and from different streams. This suggests that pollution, in addition to effects of infestation worsen the fish condition. Besides, the parasite burden was negatively correlated with the condition factor, weight and length measures. We conclude that the parasite burden negatively affects Astyanax paranae individuals´ physiological condition and that trematodes also occur in polluted environments.(AU)

Synchaeta jollyae (Shiel & Koste) (Rotifera, Synchaetidae): an overlooked species or a newcomer in Neotropical freshwaters?

Populations of Synchaeta jollyae (Shiel & Koste, 1993) (Rotifera), a species recently recorded for the first time in Brazil and South America, were analyzed in reservoirs in Southeast Brazil. Sampling was carried out monthly from August 2006 to July 2007 at Furnas Reservoir in the Rio Grande basin, state of Minas Gerais, and in four cascade reservoirs in the Tietê River basin (Barra Bonita, Bariri, Ibitinga and Nova Avanhandava) state of São Paulo, in June and September 2008 and in January and May 2009. Synchaeta jollyae occurred in most samples and periods. From the results obtained it is evident that S. jollyae occurs in water bodies of varied trophic status but reaches larger populations in eutrophic water bodies and during lower temperature periods. The greatest densities of S. jollyae were found in the eutrophic Bariri Reservoir, on the Tietê River, during the winter. Mann-Whitney test confirmed the significant difference between the population densities in periods of high and low temperatures, with populations reaching higher densities at lower temperatures. It is not yet possible to tell whether S. jollyae is a widely distributed species that has been overlooked in previous plankton studies in South America. Wherever these populations of S. jollyae might have originated, it appears to be a species well established and adapted to a wide range of conditions in the Neotropics.

Populações de Synchaeta jollyae (Rotifera, Synchaetidae), uma espécie recentemente registrada pela primeira vez no Brasil e América do Sul, foram analisadas em reservatórios do Sudeste do Brasil. As amostragens foram realizadas mensalmente de agosto de 2006 a julho de 2007 no Reservatório de Furnas, bacia do rio Grande, estado de Minas Gerais e em quatro reservatórios em cascata na bacia do rio Tietê (Barra Bonita, Bariri, Ibitinga e Nova Avanhandava), estado de São Paulo, em junho e setembro de 2008, e janeiro e maio de 2009. Synchaeta jollyae ocorreu na maioria das amostras e períodos. Pelos resultados obtidos é evidenciado que S. jollyae ocorre em corpos d'água com variados graus de trofia, porém atinge maiores densidades em corpos d'água eutróficos e em períodos de temperaturas mais baixas. As maiores densidades foram registradas na bacia do rio Tietê, no reservatório eutrófico de Bariri durante o inverno. O teste de Mann-Whitney evidenciou diferença estatisticamente significante entre as densidades populacionais de S. jollyae nos períodos com temperaturas mais baixas e temperaturas altas, com as populações atingindo maiores densidades em temperaturas menores. Ainda não é possível dizer se S. jollyae é uma espécie amplamente distribuída e negligenciada em estudos anteriores na região Neotropical ou trata-se de uma espécie recém-chegada. Quaisquer que sejam as origens destas populações de S. jollyae, parece ser uma espécie bem estabelecida e adaptada a uma ampla faixa de condições nos neotrópicos.

Synchaeta jollyae (Shiel & Koste) (Rotifera, Synchaetidae): an overlooked species or a newcomer in Neotropical freshwaters?

Populations of Synchaeta jollyae (Shiel & Koste, 1993) (Rotifera), a species recently recorded for the first time in Brazil and South America, were analyzed in reservoirs in Southeast Brazil. Sampling was carried out monthly from August 2006 to July 2007 at Furnas Reservoir in the Rio Grande basin, state of Minas Gerais, and in four cascade reservoirs in the Tietê River basin (Barra Bonita, Bariri, Ibitinga and Nova Avanhandava) state of São Paulo, in June and September 2008 and in January and May 2009. Synchaeta jollyae occurred in most samples and periods. From the results obtained it is evident that S. jollyae occurs in water bodies of varied trophic status but reaches larger populations in eutrophic water bodies and during lower temperature periods. The greatest densities of S. jollyae were found in the eutrophic Bariri Reservoir, on the Tietê River, during the winter. Mann-Whitney test confirmed the significant difference between the population densities in periods of high and low temperatures, with populations reaching higher densities at lower temperatures. It is not yet possible to tell whether S. jollyae is a widely distributed species that has been overlooked in previous plankton studies in South America. Wherever these populations of S. jollyae might have originated, it appears to be a species well established and adapted to a wide range of conditions in the Neotropics.

Populações de Synchaeta jollyae (Rotifera, Synchaetidae), uma espécie recentemente registrada pela primeira vez no Brasil e América do Sul, foram analisadas em reservatórios do Sudeste do Brasil. As amostragens foram realizadas mensalmente de agosto de 2006 a julho de 2007 no Reservatório de Furnas, bacia do rio Grande, estado de Minas Gerais e em quatro reservatórios em cascata na bacia do rio Tietê (Barra Bonita, Bariri, Ibitinga e Nova Avanhandava), estado de São Paulo, em junho e setembro de 2008, e janeiro e maio de 2009. Synchaeta jollyae ocorreu na maioria das amostras e períodos. Pelos resultados obtidos é evidenciado que S. jollyae ocorre em corpos d'água com variados graus de trofia, porém atinge maiores densidades em corpos d'água eutróficos e em períodos de temperaturas mais baixas. As maiores densidades foram registradas na bacia do rio Tietê, no reservatório eutrófico de Bariri durante o inverno. O teste de Mann-Whitney evidenciou diferença estatisticamente significante entre as densidades populacionais de S. jollyae nos períodos com temperaturas mais baixas e temperaturas altas, com as populações atingindo maiores densidades em temperaturas menores. Ainda não é possível dizer se S. jollyae é uma espécie amplamente distribuída e negligenciada em estudos anteriores na região Neotropical ou trata-se de uma espécie recém-chegada. Quaisquer que sejam as origens destas populações de S. jollyae, parece ser uma espécie bem estabelecida e adaptada a uma ampla faixa de condições nos neotrópicos.

New records of Parvalona parva (Crustacea: Anomopoda: Chydoridae) from Brazil, with first description of the male

The Neotropical species Parvalona parva (Daday, 1905) was previously reported only from two localities (Northern Argentina and Lençóis Maranhenses, Brazil). In the present paper, seven new records of P. parva from Brazil are presented. The specimens were collected from small waterbodies located in the Federal District and the states of São Paulo, Pará, and Pernambuco. These new records suggest that this species is not as rare as previously believed. The male, sexual female, and the lateral head pores of parthenogenetic females are described and illustrated for the first time.

New records of Parvalona parva (Crustacea: Anomopoda: Chydoridae) from Brazil, with first description of the male

The Neotropical species Parvalona parva (Daday, 1905) was previously reported only from two localities (Northern Argentina and Lençóis Maranhenses, Brazil). In the present paper, seven new records of P. parva from Brazil are presented. The specimens were collected from small waterbodies located in the Federal District and the states of São Paulo, Pará, and Pernambuco. These new records suggest that this species is not as rare as previously believed. The male, sexual female, and the lateral head pores of parthenogenetic females are described and illustrated for the first time.

New records of Parvalona parva (Crustacea: Anomopoda: Chydoridae) from Brazil, with first description of the male

The Neotropical species Parvalona parva (Daday, 1905) was previously reported only from two localities (Northern Argentina and Lençóis Maranhenses, Brazil). In the present paper, seven new records of P. parva from Brazil are presented. The specimens were collected from small waterbodies located in the Federal District and the states of São Paulo, Pará, and Pernambuco. These new records suggest that this species is not as rare as previously believed. The male, sexual female, and the lateral head pores of parthenogenetic females are described and illustrated for the first time.

Population structure and reproductive biology of Cichla kelberi (Perciformes, Cichlidae) in Lobo Reservoir, Brazil

The structure of Cichla kelberi population was characterized regarding the sex ratio, total length composition and some reproductive characteristics. The specimens were collected in two periods, from November 2002 to November 2003 and from December 2004 to May 2006. The sex ratio was significantly different than 1:1. The total length varied from 3.4 to 40.1 cm, with individuals in the shortest length classes occurring throughout the year, but with greater incidence in the warmer periods. Females and males reached similar lengths and there was no difference between the sexes regarding the length-weight relationship. The estimated values of condition factor were near the central value of 1.0 and decreased during the cooler months, coinciding with periods of lower reproductive activity. Individuals with mature or semi-spent gonads occurred from November to April, indicating that Cichla kelberi reproduces for a long period of time. The spawning is partitioned, with an average absolute fecundity of 6072 oocytes (from 5220 to 6908 oocytes). The high relative condition factor values, long reproductive period, large output of fingerlings and high fecundity are biological conditions that indicate the species is well adapted in this reservoir.(AU)

A população de Cichla kelberi foi caracterizada quanto à proporção sexual, composição em comprimento total e algumas características reprodutivas. As coletas foram realizadas em dois períodos, de novembro de 2002 a novembro de 2003 e de dezembro de 2004 a maio de 2006. A proporção sexual foi significativamente diferente de 1:1. Os comprimentos totais variaram de 3,4 a 40,1 cm sendo que a ocorrência de indivíduos nas classes de menor comprimento se deu ao longo de todo o ano, com maior incidência nos períodos mais quentes. Fêmeas e machos atingem comprimentos similares e não houve diferença entre os sexos quanto à relação peso - comprimento. Os valores do fator de condição estimados foram próximos ao valor centralizador 1.0 e apresentaram quedas nos meses mais frios, coincidindo com períodos de menor atividade reprodutiva. Indivíduos com gônadas Maduras ou Semi Esgotadas ocorreram de setembro a abril, indicando que Cichla kelberi reproduz-se por um longo período. A desova é do tipo parcelada e apresenta, em média, uma fecundidade absoluta de 6072 ovócitos (de 5220 a 6908 ovócitos). Os altos valores de fator de condição relativo, longo período reprodutivo, grande produção de larvas e fecundidade alta são condições biológicas que indicam boa adaptação da espécie neste reservatório.(AU)

Water alkalinity influence on the growth of Nile Tilapia larvae (Oreochromis niloticus Linnaeus, 1758 Perciformes, Cichlidae) - DOI: 10.4025/actascibiolsci.v26i2.1630 / Influência da alcalinidade da água sobre o crescimento de larvas de Tilápia do Nilo (Oreochromis niloticus Linnaeus, 1758 Perciformes, Cichlidae) - DOI: 10.4025/actascibiolsci.v26i2.1630

The growth of Oreochromis niloticus larvae was studied in different levels of water alkalinity. The laboratory experiment, which was carried out over a period of 42 days in 20-liter aquariums, consisted of three treatments: A 15.55mg CaCO3/L, B 32.58mg CaCO3/L and C 56.77mg CaCO3/L, with eighteen repetitions each. Water temperature, alkalinity, hardness, calcium, pH and conductivity values were monitored. The growth in total length, dry weight and wet weight were determined, as well as the relationships between dry weight and total length and the larvae relative condition factor in the different treatments. The result indicate that the maintenance of tilápia larvae under medium value of alkalinity of 32.58±5.64mg CaCO3/L, which provided calcium concentration of 13.27±1.44mg Ca+2/L (treatment B), is recommended for promoting better growth in total length (3.14±0.21cm), dry weight (67.66±14.95mg), wet weigh (415.40±90.75mg) and relative condition factor (1.043).

O crescimento de larvas de Oreochromis niloticus foi estudado em diferentes níveis de alcalinidade da água. O experimento de laboratório, conduzido durante 42 dias em aquários de 20 litros, consistiu de três tratamentos: A 15,55mg CaCO3/L, B 32,58mg CaCO3/L e C 56,77mg CaCO3/L, com dezoito repetições cada. Foram monitorados os valores de temperatura, alcalinidade, dureza, cálcio, pH e condutividade da água. Foram determinados o crescimento em comprimento total, peso seco e peso úmido, as relações peso seco-comprimento total e o fator de condição relativo das larvas nos diferentes tratamentos. Os resultados permitem concluir que a manutenção de larvas de tilápia sob valor médio de alcalinidade de 32,58±5,64mg CaCO3/L, que proporcionou valor de cálcio de 13,27±1,44mg Ca+2/L (tratamento B), é recomendada por promover melhor crescimento em comprimento total (3,14±0,21cm), peso seco (67,66±14,95mg), peso úmido (415,40±90,75mg) e fator de condição relativo (1,043)

Influence of different levels of pond water alkalinity on the growth of Prochilodus lineatus larvae / Influência de diferentes níveis de alcalinidade da água de viveiros sobre o crescimento de larvas de Prochilodus lineatus

The relations between alkalinity and other chemical variables play an important role in the global productivity of aquatic ecosystems, due to their influence on vital chemical and physiological processes. Liming procedures, that alter water alkalinity, promote a biological reorganization, frequently resulting in favorable response of the biota in a short period of time. Thus, the growth of curimbatá (Prochilodus lineatus Valenciennes, 1836, Characiformes, Prochilodontidae) larvae and limnological variables were studied in ponds with different levels of water alkalinity. The experiment was carried out over a period of 60 days and consisted of three treatments: A - without any correction of natural alkalinity; B with weekly alkalinity correction to 30 mg CaCO3/L; C with weekly alkalinity correction to 60 mg CaCO3/L, each one with two repetitions. The following variables were monitored: maximum and minimum air and water temperature, alkalinity, hardness, calcium, pH, conductivity, dissolved oxygen, suspended solids, transparency, ammonia, nitrite, nitrate, total phosphorus, dissolved phosphate, chlorophyll a and organic fraction weight of zooplankton. The growth in total length and dry weight was determined, as well as the relation between dry weight and total length of the larvae in the different treatments. The results indicate that the maintenance of curimbatá larvae under

As relações entre a alcalinidade e outras variáveis químicas da água têm importante papel na produtividade global dos ecossistemas aquáticos, por fazerem parte de importantes processos químicos e fisiológicos. Os procedimentos de calagem, que alteram a alcalinidade da água e promovem uma reorganização biológica, resultam, frequentemente, em respostas favoráveis da biota em curto período de tempo. Assim, o crescimento de larvas de curimbatá (Prochilodus lineatus Valenciennes, 1836, Characiformes, Prochilodontidae) e variáveis limnológicas foram estudadas em viveiros com diferentes níveis de alcalinidade da água. O experimento, com duração de 60 dias, consistiu de três tratamentos: A - sem correção da alcalinidade natural; B com correção semanal da alcalinidade para 30 mg de CaCO3/L; C - com correção semanal da alcalinidade para 60 mg de CaCO3/L, com duas repetições cada um. Foram monitorados os valores de temperatura máxima e mínima do ar e da água, alcalinidade, dureza, cálcio, pH, condutividade, oxigênio dissolvido, sólidos em suspensão, transparência, amônia, nitrito, nitrato, fósforo total, fosfato dissolvido, clorofila a e peso da fração orgânica do zooplâncton. Foram determinados o crescimento em comprimento total e em peso seco e a relação peso seco-comprimento total das larvas nos diferentes tratamentos. Os resultados permitem concluir que a manutenção de larvas de cur

The effect of water alkalinity on growth and survival of curimbatá larvae, Prochilodus lineatus (Characiformes, Prochilodontidae) in laboratory / O efeito da alcalinidade da água sobre a sobrevivência das larvas do Curimbatá, Prochilodus lineatus (Characiformes, Prochilodontidae), MANTIDAS EM LABORATÓRIO

In this work it was tried to verify the influence of different water alkalinity levels on the Prochilodus lineatus larvae survival and growth. The laboratory experiment consisted of three treatments whose medium values of alkalinity were: A 15.76 mg CaCO3/L; B 32.37 mg CaCO3/L and C 55.28 mg CaCO3/L. The maximum and minimum values of temperature, alkalinity, hardness, calcium, magnesium, pH and conductivity were monitored. The experiment was carried out in the laboratory during 42 days, and was divided into 3 treatments, each one with 18 repetitions. The growth curves in total length and dry weight, the dry weight total length relationship, the relative condition factor and the larvae survival rate for each treatment were determined. The growth in total length and dry weight showed significant differences between treatments, being the treatment B, that which permitted the best performance, whereas treatments A and C were similar. The values of survival for the larvae from the three treatments were similar. Curimbatá larvae maintenance in medium values of alkalinity of 32.37±3.73 mg CaCO3/L, and calcium of 15.73±1.23 mg Ca+2/L (treatment B) are therefore recommended, for it provides better growth performance, expressed by total length and dry weight.

Neste trabalho procurou-se verificar a influência de diferentes níveis de alcalinidade da água sobre a sobrevivência e o crescimento de larvas de Prochilodus lineatus Valenciennes, 1836. O experimento de laboratório consistiu em três tratamentos, cujos valores médios de alcalinidade foram: A 15,76 mg CaCO3/L; B 32,37 mg CaCO3/L e C 55,28 mg CaCO3/L. Foram monitorados os valores de temperatura máxima e mínima do ar e da água, alcalinidade, dureza, cálcio, magnésio, pH e condutividade. O experimento, conduzido durante 42 dias, teve três tratamentos com dezoito repetições cada um. Foram determinadas as curvas de crescimento em comprimento total e em peso seco, as relações peso seco-comprimento total, o fator de condição relativo e a sobrevivência das larvas para cada tratamento. Os resultados obtidos para o crescimento em comprimento total e em peso seco evidenciam diferenças significativas entre os tratamentos, sendo o tratamento B aquele em que o melhor desempenho foi observado, e os tratamentos A e C foram semelhantes. A sobrevivência das larvas submetidas aos três tratamentos foi semelhante. A manutenção de larvas de curimbatá sob valores médios de alcalinidade de 32,37±3,73 mg CaCO3/L e de cálcio de 15,73±1,23 mg Ca+2/L (tratamento B) é recomendada, por proporcionarem melhor desempenho em crescimento, expresso em comprimento total e em peso seco.

Water alkalinity influence on the growth of Nile Tilapia larvae (Oreochromis niloticus Linnaeus, 1758 Perciformes, Cichlidae) - DOI: 10.4025/actascibiolsci.v26i2.1630 / Influência da alcalinidade da água sobre o crescimento de larvas de Tilápia do Nilo (Oreochromis niloticus Linnaeus, 1758 Perciformes, Cichlidae) - DOI: 10.4025/actascibiolsci.v26i2.1630

The growth of Oreochromis niloticus larvae was studied in different levels of water alkalinity. The laboratory experiment, which was carried out over a period of 42 days in 20-liter aquariums, consisted of three treatments: A 15.55mg CaCO3/L, B 32.58mg CaCO3/L and C 56.77mg CaCO3/L, with eighteen repetitions each. Water temperature, alkalinity, hardness, calcium, pH and conductivity values were monitored. The growth in total length, dry weight and wet weight were determined, as well as the relationships between dry weight and total length and the larvae relative condition factor in the different treatments. The result indicate that the maintenance of tilápia larvae under medium value of alkalinity of 32.58±5.64mg CaCO3/L, which provided calcium concentration of 13.27±1.44mg Ca+2/L (treatment B), is recommended for promoting better growth in total length (3.14±0.21cm), dry weight (67.66±14.95mg), wet weigh (415.40±90.75mg) and relative condition factor (1.043).

O crescimento de larvas de Oreochromis niloticus foi estudado em diferentes níveis de alcalinidade da água. O experimento de laboratório, conduzido durante 42 dias em aquários de 20 litros, consistiu de três tratamentos: A 15,55mg CaCO3/L, B 32,58mg CaCO3/L e C 56,77mg CaCO3/L, com dezoito repetições cada. Foram monitorados os valores de temperatura, alcalinidade, dureza, cálcio, pH e condutividade da água. Foram determinados o crescimento em comprimento total, peso seco e peso úmido, as relações peso seco-comprimento total e o fator de condição relativo das larvas nos diferentes tratamentos. Os resultados permitem concluir que a manutenção de larvas de tilápia sob valor médio de alcalinidade de 32,58±5,64mg CaCO3/L, que proporcionou valor de cálcio de 13,27±1,44mg Ca+2/L (tratamento B), é recomendada por promover melhor crescimento em comprimento total (3,14±0,21cm), peso seco (67,66±14,95mg), peso úmido (415,40±90,75mg) e fator de condição relativo (1,043)

The effect of water alkalinity on growth and survival of curimbatá larvae, Prochilodus lineatus (Characiformes, Prochilodontidae) in laboratory / O efeito da alcalinidade da água sobre a sobrevivência das larvas do Curimbatá, Prochilodus lineatus (Characiformes, Prochilodontidae), MANTIDAS EM LABORATÓRIO

In this work it was tried to verify the influence of different water alkalinity levels on the Prochilodus lineatus larvae survival and growth. The laboratory experiment consisted of three treatments whose medium values of alkalinity were: A 15.76 mg CaCO3/L; B 32.37 mg CaCO3/L and C 55.28 mg CaCO3/L. The maximum and minimum values of temperature, alkalinity, hardness, calcium, magnesium, pH and conductivity were monitored. The experiment was carried out in the laboratory during 42 days, and was divided into 3 treatments, each one with 18 repetitions. The growth curves in total length and dry weight, the dry weight total length relationship, the relative condition factor and the larvae survival rate for each treatment were determined. The growth in total length and dry weight showed significant differences between treatments, being the treatment B, that which permitted the best performance, whereas treatments A and C were similar. The values of survival for the larvae from the three treatments were similar. Curimbatá larvae maintenance in medium values of alkalinity of 32.37±3.73 mg CaCO3/L, and calcium of 15.73±1.23 mg Ca+2/L (treatment B) are therefore recommended, for it provides better growth performance, expressed by total length and dry weight.

Neste trabalho procurou-se verificar a influência de diferentes níveis de alcalinidade da água sobre a sobrevivência e o crescimento de larvas de Prochilodus lineatus Valenciennes, 1836. O experimento de laboratório consistiu em três tratamentos, cujos valores médios de alcalinidade foram: A 15,76 mg CaCO3/L; B 32,37 mg CaCO3/L e C 55,28 mg CaCO3/L. Foram monitorados os valores de temperatura máxima e mínima do ar e da água, alcalinidade, dureza, cálcio, magnésio, pH e condutividade. O experimento, conduzido durante 42 dias, teve três tratamentos com dezoito repetições cada um. Foram determinadas as curvas de crescimento em comprimento total e em peso seco, as relações peso seco-comprimento total, o fator de condição relativo e a sobrevivência das larvas para cada tratamento. Os resultados obtidos para o crescimento em comprimento total e em peso seco evidenciam diferenças significativas entre os tratamentos, sendo o tratamento B aquele em que o melhor desempenho foi observado, e os tratamentos A e C foram semelhantes. A sobrevivência das larvas submetidas aos três tratamentos foi semelhante. A manutenção de larvas de curimbatá sob valores médios de alcalinidade de 32,37±3,73 mg CaCO3/L e de cálcio de 15,73±1,23 mg Ca+2/L (tratamento B) é recomendada, por proporcionarem melhor desempenho em crescimento, expresso em comprimento total e em peso seco.

Influence of different levels of pond water alkalinity on the growth of Prochilodus lineatus larvae / Influência de diferentes níveis de alcalinidade da água de viveiros sobre o crescimento de larvas de Prochilodus lineatus

The relations between alkalinity and other chemical variables play an important role in the global productivity of aquatic ecosystems, due to their influence on vital chemical and physiological processes. Liming procedures, that alter water alkalinity, promote a biological reorganization, frequently resulting in favorable response of the biota in a short period of time. Thus, the growth of curimbatá (Prochilodus lineatus Valenciennes, 1836, Characiformes, Prochilodontidae) larvae and limnological variables were studied in ponds with different levels of water alkalinity. The experiment was carried out over a period of 60 days and consisted of three treatments: A - without any correction of natural alkalinity; B with weekly alkalinity correction to 30 mg CaCO3/L; C with weekly alkalinity correction to 60 mg CaCO3/L, each one with two repetitions. The following variables were monitored: maximum and minimum air and water temperature, alkalinity, hardness, calcium, pH, conductivity, dissolved oxygen, suspended solids, transparency, ammonia, nitrite, nitrate, total phosphorus, dissolved phosphate, chlorophyll a and organic fraction weight of zooplankton. The growth in total length and dry weight was determined, as well as the relation between dry weight and total length of the larvae in the different treatments. The results indicate that the maintenance of curimbatá larvae under

As relações entre a alcalinidade e outras variáveis químicas da água têm importante papel na produtividade global dos ecossistemas aquáticos, por fazerem parte de importantes processos químicos e fisiológicos. Os procedimentos de calagem, que alteram a alcalinidade da água e promovem uma reorganização biológica, resultam, frequentemente, em respostas favoráveis da biota em curto período de tempo. Assim, o crescimento de larvas de curimbatá (Prochilodus lineatus Valenciennes, 1836, Characiformes, Prochilodontidae) e variáveis limnológicas foram estudadas em viveiros com diferentes níveis de alcalinidade da água. O experimento, com duração de 60 dias, consistiu de três tratamentos: A - sem correção da alcalinidade natural; B com correção semanal da alcalinidade para 30 mg de CaCO3/L; C - com correção semanal da alcalinidade para 60 mg de CaCO3/L, com duas repetições cada um. Foram monitorados os valores de temperatura máxima e mínima do ar e da água, alcalinidade, dureza, cálcio, pH, condutividade, oxigênio dissolvido, sólidos em suspensão, transparência, amônia, nitrito, nitrato, fósforo total, fosfato dissolvido, clorofila a e peso da fração orgânica do zooplâncton. Foram determinados o crescimento em comprimento total e em peso seco e a relação peso seco-comprimento total das larvas nos diferentes tratamentos. Os resultados permitem concluir que a manutenção de larvas de cur