Temporal variation in composition, abundance and biomass of the fish fauna after impact on subtropical transitional water

Transitional waters are characterized by large variations in salinity, temperature, turbidity, among other factors, such as tidal cycle, wind action and rainfall, that are constantly changing over time. The distribution of biota in these environments is regulated by these natural variations and also by human activities, such as pollution, overexploitation of resources, acceleration of urbanization, suppression of habitats and changes in hydrological dynamics. The objective of this study was to analyze the temporal dynamics of the fish fauna of the Saco dos Limões Cove, state of Santa Catarina, Brazil, after the construction of a highway. Fish community was evaluated over five years by annual and monthly variation in species richness, abundance and biomass. A total of 17,993 individuals were collected, distributed in 33 families, 59 genera and 79 species. The evaluated years were similar to each other in species composition. Community descriptors varied over time but did not show seasonal trends. In all years, abundance was higher than biomass, indicating both the disturbance and the ecosystem function as a nursery in the studied area. This was corroborated by the large number of juveniles of dominant species (Genidens genidens, Eucinostomus gula and Eucinostomus argenteus).(AU)

Spatio-temporal variability in the Cladocera assemblage of a subtropical hypersaline lagoon / Variabilidade espaço-temporal da assembleia de Cladocera de uma lagoa hipersalina subtropical

Cladocera represent an important zooplankton group because of their seasonal prominence in terms of abundance and their contribution in controlling primary production (phytoplankton). On a global scale, there are few studies on Cladocera in hypersaline environments. The present work aims to evaluate the spatio-temporal variation of the Cladocera assemblage across a salinity gradient in the habitats of the Araruama Lagoon. Samples were collected in random months over a period of four years at 12 fixed stations in the Araruama Lagoon using a WP2 plankton net equipped with a flow meter. Our results do not reveal significant influence of the tide and seasonal variation as factors affecting the Cladocera assemblage. Five Cladocera species were found in the Araruama Lagoon, only in stations 11 and 12 where they reached an average of 1,799 ± 3,103 ind. m-³. The mean of the Shannon Diversity Index was 0.45 ± 0.2. The species that stood out in terms of frequency and abundance were: Penilia avirostris (frequency of occurrence: 71%), followed by Pseudevadne tergestina (41%). The same species also stood out in terms of relative abundance, Penilia avirostris (87%) and Pseudevadne tergestina (11%). The absence of Cladocera in the innermost parts of the lagoon suggests that their entrance to these locations is possibly inhibited by the salinity and temperature gradient of the lagoon, being the main factors influencing the dynamics of the Cladocera assemblages.

Os cladóceros representam um importante grupo de zooplâncton, devido ao seu destaque sazonal em termos de abundância e à sua contribuição no controlo da produção primária (fitoplâncton). Em escala global, há poucos estudos com Cladocera em ambientes hipersalinos. O presente trabalho tem como objetivo avaliar a variação espaço-temporal da assembleia de Cladocera em um gradiente de salinidades da Lagoa de Araruama. As amostras foram coletadas em meses aleatórios, durante um período de quatro anos, em 12 estações fixas na Lagoa de Araruama, utilizando uma rede de plâncton WP2 equipada com um fluxômetro. Os nossos resultados não revelam uma influência significativa da maré e da variação sazonal como fatores que afetam a assembleia de Cladocera. Cinco espécies de Cladocera foram encontradas na Lagoa de Araruama. A assembleia apresentou maior densidade absoluta estações 12 e 11, atingindo uma a média de 1.799 ± 3.103 inds-³. A média do Índice de Diversidade de Shannon foi de 0,45 ± 0,2. As espécies que se destacaram em termos de frequência e abundância foram: Penilia avirostris (frequência de ocorrência: 71%), seguida de Pseudevadne tergestina (41%). As mesmas espécies também se destacaram em termos de abundância relativa Penilia avirostris (87%) e Pseudevadne tergestina (11%). A ausência de Cladocera nas partes mais interiores da lagoa sugere que a sua entrada nestes locais é possivelmente inibida pela salinidade e gradiente de temperatura da lagoa, sendo os principais fatores que influenciam a dinâmica da assembleia de Cladocera.

Spatio-temporal variability in the Cladocera assemblage of a subtropical hypersaline lagoon / Variabilidade espaço-temporal da assembleia de Cladocera de uma lagoa hipersalina subtropical

Cladocera represent an important zooplankton group because of their seasonal prominence in terms of abundance and their contribution in controlling primary production (phytoplankton). On a global scale, there are few studies on Cladocera in hypersaline environments. The present work aims to evaluate the spatio-temporal variation of the Cladocera assemblage across a salinity gradient in the habitats of the Araruama Lagoon. Samples were collected in random months over a period of four years at 12 fixed stations in the Araruama Lagoon using a WP2 plankton net equipped with a flow meter. Our results do not reveal significant influence of the tide and seasonal variation as factors affecting the Cladocera assemblage. Five Cladocera species were found in the Araruama Lagoon, only in stations 11 and 12 where they reached an average of 1,799 ± 3,103 ind. m-³. The mean of the Shannon Diversity Index was 0.45 ± 0.2. The species that stood out in terms of frequency and abundance were: Penilia avirostris (frequency of occurrence: 71%), followed by Pseudevadne tergestina (41%). The same species also stood out in terms of relative abundance, Penilia avirostris (87%) and Pseudevadne tergestina (11%). The absence of Cladocera in the innermost parts of the lagoon suggests that their entrance to these locations is possibly inhibited by the salinity and temperature gradient of the lagoon, being the main factors influencing the dynamics of the Cladocera assemblages.(AU)

Os cladóceros representam um importante grupo de zooplâncton, devido ao seu destaque sazonal em termos de abundância e à sua contribuição no controlo da produção primária (fitoplâncton). Em escala global, há poucos estudos com Cladocera em ambientes hipersalinos. O presente trabalho tem como objetivo avaliar a variação espaço-temporal da assembleia de Cladocera em um gradiente de salinidades da Lagoa de Araruama. As amostras foram coletadas em meses aleatórios, durante um período de quatro anos, em 12 estações fixas na Lagoa de Araruama, utilizando uma rede de plâncton WP2 equipada com um fluxômetro. Os nossos resultados não revelam uma influência significativa da maré e da variação sazonal como fatores que afetam a assembleia de Cladocera. Cinco espécies de Cladocera foram encontradas na Lagoa de Araruama. A assembleia apresentou maior densidade absoluta estações 12 e 11, atingindo uma a média de 1.799 ± 3.103 inds-³. A média do Índice de Diversidade de Shannon foi de 0,45 ± 0,2. As espécies que se destacaram em termos de frequência e abundância foram: Penilia avirostris (frequência de ocorrência: 71%), seguida de Pseudevadne tergestina (41%). As mesmas espécies também se destacaram em termos de abundância relativa Penilia avirostris (87%) e Pseudevadne tergestina (11%). A ausência de Cladocera nas partes mais interiores da lagoa sugere que a sua entrada nestes locais é possivelmente inibida pela salinidade e gradiente de temperatura da lagoa, sendo os principais fatores que influenciam a dinâmica da assembleia de Cladocera.(AU)

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia

Abstract In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

Resumo No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis foi dominada pelo gênero Cladotanytarsus sp. Os resultados desta pesquisa gostaram da composição taxonômica das assembleias de quironomídeos com a variação dos gradientes hidromorfológicos e físico-químicos nos wadis do norte da Tunísia.

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia / Padrões de distribuição espaço-temporal de comunidades Chironomidae nos wadis do norte da Tunísia

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis foi dominada pelo gênero Cladotanytarsus sp. Os resultados desta pesquisa gostaram da composição taxonômica das assembleias de quironomídeos com a variação dos gradientes hidromorfológicos e físico-químicos nos wadis do norte da Tunísia.

Spatio-temporal variability in the Cladocera assemblage of a subtropical hypersaline lagoon / Variabilidade espaço-temporal da assembleia de Cladocera de uma lagoa hipersalina subtropical

Cladocera represent an important zooplankton group because of their seasonal prominence in terms of abundance and their contribution in controlling primary production (phytoplankton). On a global scale, there are few studies on Cladocera in hypersaline environments. The present work aims to evaluate the spatio-temporal variation of the Cladocera assemblage across a salinity gradient in the habitats of the Araruama Lagoon. Samples were collected in random months over a period of four years at 12 fixed stations in the Araruama Lagoon using a WP2 plankton net equipped with a flow meter. Our results do not reveal significant influence of the tide and seasonal variation as factors affecting the Cladocera assemblage. Five Cladocera species were found in the Araruama Lagoon, only in stations 11 and 12 where they reached an average of 1,799 ± 3,103 ind. m-3. The mean of the Shannon Diversity Index was 0.45 ± 0.2. The species that stood out in terms of frequency and abundance were: Penilia avirostris (frequency of occurrence: 71%), followed by Pseudevadne tergestina (41%). The same species also stood out in terms of relative abundance, Penilia avirostris (87%) and Pseudevadne tergestina (11%). The absence of Cladocera in the innermost parts of the lagoon suggests that their entrance to these locations is possibly inhibited by the salinity and temperature gradient of the lagoon, being the main factors influencing the dynamics of the Cladocera assemblages.

Os cladóceros representam um importante grupo de zooplâncton, devido ao seu destaque sazonal em termos de abundância e à sua contribuição no controlo da produção primária (fitoplâncton). Em escala global, há poucos estudos com Cladocera em ambientes hipersalinos. O presente trabalho tem como objetivo avaliar a variação espaço-temporal da assembleia de Cladocera em um gradiente de salinidades da Lagoa de Araruama. As amostras foram coletadas em meses aleatórios, durante um período de quatro anos, em 12 estações fixas na Lagoa de Araruama, utilizando uma rede de plâncton WP2 equipada com um fluxômetro. Os nossos resultados não revelam uma influência significativa da maré e da variação sazonal como fatores que afetam a assembleia de Cladocera. Cinco espécies de Cladocera foram encontradas na Lagoa de Araruama. A assembleia apresentou maior densidade absoluta estações 12 e 11, atingindo uma a média de 1.799 ± 3.103 inds-3. A média do Índice de Diversidade de Shannon foi de 0,45 ± 0,2. As espécies que se destacaram em termos de frequência e abundância foram: Penilia avirostris (frequência de ocorrência: 71%), seguida de Pseudevadne tergestina (41%). As mesmas espécies também se destacaram em termos de abundância relativa Penilia avirostris (87%) e Pseudevadne tergestina (11%). A ausência de Cladocera nas partes mais interiores da lagoa sugere que a sua entrada nestes locais é possivelmente inibida pela salinidade e gradiente de temperatura da lagoa, sendo os principais fatores que influenciam a dinâmica da assembleia de Cladocera.

Intra-annual colonization of Chironomidae on leaf litter in a Brazilian Cerrado stream

In low-order streams, the processing of allochthonous leaf litter is essential in the carbon/energy flow dynamics. Benthic macroinvertebrates, such as chironomids, play critical roles in the breakdown of allochthonous materials, because their larvae take part in intricate trophic networks and have varied trophic ecologies. We evaluated the effects of intra-annual variability on the input of allochthonous leaf litter, and the interactions of leaf-detritus on the succession of Chironomidae assemblages in the dry, rainy, and transition seasons (rainy-dry and dry-rainy). The study took place in a stream in the Brazilian Cerrado. Leaves were incubated in the stream to ascertain the colonization process by Chironomidae and the loss of leaf litter mass after 90 days. Functional feeding groups (FFG) were less rich and less abundant in the dry and dry-rainy seasons, than in the other seasons. The FFG composition of Chironomidae demonstrated that temporal variation between seasons was affected by the exposure time of the leaf-detritus in the stream, and there was more segregation during the dry and rainy seasons. In conclusion, the colonization of leaf-detritus by Chironomidae larvae depended on how long allochthonous plant material remained in the stream, and the variability of the organic matter dynamics input into the stream.

Spatio-temporal variability in the Cladocera assemblage of a subtropical hypersaline lagoon

Abstract Cladocera represent an important zooplankton group because of their seasonal prominence in terms of abundance and their contribution in controlling primary production (phytoplankton). On a global scale, there are few studies on Cladocera in hypersaline environments. The present work aims to evaluate the spatio-temporal variation of the Cladocera assemblage across a salinity gradient in the habitats of the Araruama Lagoon. Samples were collected in random months over a period of four years at 12 fixed stations in the Araruama Lagoon using a WP2 plankton net equipped with a flow meter. Our results do not reveal significant influence of the tide and seasonal variation as factors affecting the Cladocera assemblage. Five Cladocera species were found in the Araruama Lagoon, only in stations 11 and 12 where they reached an average of 1,799 ± 3,103 ind. m-3. The mean of the Shannon Diversity Index was 0.45 ± 0.2. The species that stood out in terms of frequency and abundance were: Penilia avirostris (frequency of occurrence: 71%), followed by Pseudevadne tergestina (41%). The same species also stood out in terms of relative abundance, Penilia avirostris (87%) and Pseudevadne tergestina (11%). The absence of Cladocera in the innermost parts of the lagoon suggests that their entrance to these locations is possibly inhibited by the salinity and temperature gradient of the lagoon, being the main factors influencing the dynamics of the Cladocera assemblages.

Resumo Os cladóceros representam um importante grupo de zooplâncton, devido ao seu destaque sazonal em termos de abundância e à sua contribuição no controlo da produção primária (fitoplâncton). Em escala global, há poucos estudos com Cladocera em ambientes hipersalinos. O presente trabalho tem como objetivo avaliar a variação espaço-temporal da assembleia de Cladocera em um gradiente de salinidades da Lagoa de Araruama. As amostras foram coletadas em meses aleatórios, durante um período de quatro anos, em 12 estações fixas na Lagoa de Araruama, utilizando uma rede de plâncton WP2 equipada com um fluxômetro. Os nossos resultados não revelam uma influência significativa da maré e da variação sazonal como fatores que afetam a assembleia de Cladocera. Cinco espécies de Cladocera foram encontradas na Lagoa de Araruama. A assembleia apresentou maior densidade absoluta estações 12 e 11, atingindo uma a média de 1.799 ± 3.103 inds-3. A média do Índice de Diversidade de Shannon foi de 0,45 ± 0,2. As espécies que se destacaram em termos de frequência e abundância foram: Penilia avirostris (frequência de ocorrência: 71%), seguida de Pseudevadne tergestina (41%). As mesmas espécies também se destacaram em termos de abundância relativa Penilia avirostris (87%) e Pseudevadne tergestina (11%). A ausência de Cladocera nas partes mais interiores da lagoa sugere que a sua entrada nestes locais é possivelmente inibida pela salinidade e gradiente de temperatura da lagoa, sendo os principais fatores que influenciam a dinâmica da assembleia de Cladocera.

Temporal genetic structure of a stock of Prochilodus lineatus (Characiformes: Prochilodontidae) in the Mogi-Guaçu River ecosystem, São Paulo, Brazil

Prochilodus lineatus is a species of migratory fish widely distributed in the Paraná River basin, found mainly in the Grande, Pardo and Mogi-Guaçu rivers located in a well-developed region of the state of São Paulo. This study analyzes the genetic diversity and population structure in shoals of P. lineatus based on temporal analysis of specimens sampled over the years 2003, 2005, 2006, 2009, 2010, and 2015 in the Mogi-Guaçu River, São Paulo, at the region of Cachoeira de Emas. Genetic analysis performed using the D-Loop and seven microsatellite marker revealed significant genetic variability in all sampled groups. Moderate levels of structuring between groups were identified with the microsatellite markers (Fst = 0.14), while the mitochondrial marker did not reveal patterns of genetic structuring (Fst = 0.01). The genetic variability fluctuated over time, characterizing patterns of structuring among the analyzed samples. The occurrence of environmental alterations resulting in increased mortality rates, as well as changes in the water level in the ecosystem, among other factors, could determine changes in the reproductive behavior of species. The lack of favorable environmental conditions for reproduction in the basin, as reflected by tests of population bottlenecks, could have resulted in the differentiation of populations of P. lineatus over time.(AU)

Prochilodus lineatus é uma espécie de peixe migratório amplamente distribuído na bacia do rio Paraná, principalmente nos rios Grande, Pardo e Mogi-Guaçu localizados em uma região bem desenvolvida do estado de São Paulo. Este estudo analisou a diversidade genética e a estrutura populacional em cardumes de P. lineatus com base na análise temporal de espécimes amostrados ao longo dos anos de 2003, 2005, 2006, 2009, 2010 e 2015 na Cachoeira de Emas no rio Mogi-Guaçu, São Paulo, Brasil. A análise genética realizada com o marcador D-Loop e sete microssatélites revelou variabilidade genética significativa em todos os grupos amostrados. Níveis moderados de estruturação entre os grupos foram identificados com os marcadores microssatélites (Fst = 0.14), enquanto o marcador mitocondrial não revelou padrões de estruturação genética (Fst = 0.01). A variabilidade genética identificada no estoque oscilou ao longo do tempo, caracterizando padrões de estruturação entre as amostras analisadas. A ocorrência de alterações ambientais resultando em aumento das taxas de mortalidade, bem como mudanças no nível de água no ecossistema, entre outros fatores, podem determinar mudanças no comportamento reprodutivo das espécies. A falta de condições ambientais favoráveis para a reprodução na bacia, pode ter resultado na diferenciação das populações de P. lineatus ao longo do tempo.(AU)

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia / Padrões de distribuição espaço-temporal de comunidades Chironomidae nos wadis do norte da Tunísia

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis [...].

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia / Padrões de distribuição espaço-temporal de comunidades Chironomidae nos wadis do norte da Tunísia

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.(AU)

No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis [...].(AU)

Environmental influences on the ichthyoplankton in hypersaline estuaries located in a Semiarid Northeastern Brazilian coast

Hypersaline estuaries are commonly found in the Semiarid Northeast Brazilian coast. However, the utilization of these estuaries by early life stages of fishes is less well documented. This study aimed to evaluate the effects of environmental factors on the ichthyoplankton, and to describe their spatial and temporal variation in two estuaries (Tubarão and Casqueira). The sampling were diurnally in four excursions carried out during two dry-season months (November and December 2017) and two rainy-season months (May and July 2018). A total of 423 larvae representing 30 species (14 families) and 2,762 eggs (five families) were collected. Although the community structures were similar in both estuaries, there was strong seasonal variation, with higher abundances observed during the dry season. Low rainfall was the primary environmental driver affecting ichthyoplankton in both estuaries. Other environmental factors, such as depth, water temperature, and channel width, were also predictor variables for the distribution of eggs and larvae. The ichthyoplankton was dominated by marine estuarine-dependent species in both estuaries, accounting for 76% of individuals. The presence of the early life stages of typically marine species suggests that hypersaline environments provide important nursery areas and play an essential role for some coastal fish species.(AU)

Os estuários hipersalinos são comumente encontrados na região semiárida da costa nordestina brasileira. No entanto, a utilização desses estuários pelos primeiros estágios de vida dos peixes é pouco documentada. O objetivo deste estudo foi avaliar os efeitos de fatores ambientais sobre o ictioplâncton e descrever sua variação espacial e temporal em dois estuários (Tubarão e Casqueira). As amostragens foram diurnas em quatro excursões realizadas em dois meses da estação seca (novembro e dezembro de 2017) e dois meses da estação chuvosa (maio e julho de 2018). Um total de 423 larvas representando 30 espécies (14 famílias) e 2.762 ovos (cinco famílias) foram coletadas. Embora as estruturas das comunidades fossem semelhantes em ambos os estuários, houve fortes diferenças de variação sazonal, com maiores abundâncias observadas durante a estação seca. A baixa precipitação foi o principal fator ambiental que afetou o ictioplâncton em ambos os estuários. Outros fatores, como profundidade, temperatura da água e largura do canal, também foram preditoras para a distribuição de ovos e larvas. O ictioplâncton foi dominado por espécies marinhas dependentes em ambos os estuários, representando 76% dos indivíduos. A presença de estágios iniciais de espécies tipicamente marinhas sugere que ambientes hipersalinos fornecem áreas de berçário importantes e desempenham um papel essencial para algumas espécies de peixes costeiros.(AU)

Composition and dynamics of mixed flocks of birds in a remnant of Submontane Atlantic Rain Forest in southern Brazil

Mixed flocks are associations of two or more species that are formed and maintained through mutual behavioral responses, with advantages such as maximizing foraging and protecting against predation. This study aimed to evaluate the composition, temporal dynamics, and presence of core species in mixed flocks of birds in a remnant of the Submontane Atlantic Rain Forest in the Parque Nacional Aparados da Serra, southern Santa Catarina state, Brazil. Data collection took place from October 2016 to September 2017 through monthly campaigns, consisting of three consecutive observation days, with sampling sessions of six hours per day, resulting in a total effort of 216 h of observations. For each contact with the flocks, we recorded the species and number of individuals, stratum of occurrence, substrates of search, and agonistic interactions. We recorded 152 mixed flocks, with a total of 76 species belonging to 24 families, and five orders, with Thraupidae, Tyrannidae, Furnariidae, and Rhynchocyclidae being the richest. The flocks had an average of 4.5 ± 2.7 species and 8.7 ± 5.8 individuals, with richness and the number of individuals being positively correlated (R² = 0.8). Mixed flocks occurred throughout the year. There was a great variation in the number of contacts from October to February (from 5 to 20 contacts). Meanwhile from March to September, the coldest period of the year in the region, the number of contacts did not vary (from 9 to 14 contacts). However, there was no difference in the number of contacts between these months (z = 0.37; p = 0.691). Basileuterus culicivorus and Habia rubica were the core species because, in addition to their high participation (46.7 and 32.9%, respectively), they showed frequent and conspicuous movement and vocalization. Thus, a high capacity to enlist a greater number of individuals from different species for the flocks was demonstrated.(AU)

Individual variation in the advertisement call of Aplastodiscus albosignatus (Anura: Hylidae) is correlated with body size and environmental temperature

The importance of amphibian bioacoustics is widely documented in ecological, taxonomical and evolutionary studies, as calls might act as a primary mechanism of reproductive isolation. The influence of air temperature and male size on the variation of the advertisement calls in anurans is widely recognized but still insufficiently analyzed in Brazilian species. Our goals were to (1) describe the advertisement call of Aplastodiscus albosignatus (Lutz & Lutz, 1938), (2) test the influence of temperature and body size on its acoustic signals and (3) evaluate the variation of within and between-male acoustic signals. Advertisement calls of A. albosignatus consist of an unpulsed note with four harmonics. In most cases, the dominant frequency is the third harmonic but, in some calls, it was the minimum frequency (first harmonic). The average duration of calls was 0.191 s, the interval between calls was 2.08 s and the repetition rate was 33 calls per minute. On average, the minimum frequency was 550.15 Hz, the maximum frequency was 3531.70 Hz and the third harmonic was 2498.9 Hz. To evaluate the effect of air temperature, and body size on the variation of call parameters, we performed generalized linear models. The most explanatory model for spectral parameters was temperature plus body size. Concerning temporal variables, the best model that explains the variation in call duration was body size, while for the interval between calls was air temperature. The maximum frequency and the frequency of the third harmonic had little variation in the calls of both the same male and different males. Thus, these parameters were considered important in species recognition.(AU)

Population dynamics and seasonality of Euspilotus (Hesperosaprinus) azureus Sahlberg (Coleoptera: Histeridae: Saprininae) / Dinâmica populacional e sazonalidade de Euspilotus (Hesperosaprinus) azureus Sahlberg (Coleoptera: Histeridae: Saprininae)

The effect of climatic conditions on the structure of populations has been perceived for different orders of insects and families of beetles. Here we described the population dynamics of Euspilotus azureus (Sahlberg, 1823) and determined its relationship with climatic variables. The specimens were collected monthly for one year in an area of Seasonal Semideciduous Forest, in Viçosa, Brazil. The seasonality of the population and of sexes was estimated through the absolute frequency of occurrence (AF) and the percentage frequency of occurrence (FO%) of the population and each sex, which were determined monthly. To test whether the changes in monthly AF of the population and of each sex are correlated with climatic variables, Spearman correlation tests were performed. To identify whether there are temporal fluctuations in the sex ratio, considering months and seasons, and within each season, we performed Chi-square tests. A total of 3,126 individuals (1,009 females and 2,117 males) were collected. The population had the highest abundance in spring and summer, and the lowest in autumn and winter. The highest AF and FO were found in December and January, and the lowest in June and July. The sex ratio of the population did not differ in the months of the year, but in the spring there was a marked predominance of males. For E. azureus, the temporal fluctuation in abundance of the population and in the sex ratio is related to the climatic variables of maximum temperature, humidity, and precipitation. Climatic variables, especially the temperature, provided a greater abundance of the population in the hottest and rainiest periods of the year for inducing reproductive activity and altering the population's sex ratio.

O efeito das condições climáticas na estrutura das populações tem sido percebido para diferentes ordens de insetos e famílias de besouros. Nós descrevemos a dinâmica populacional temporal de Euspilotus azureus (Sahlberg, 1823) e determinamos sua relação com as variáveis climáticas. Os espécimes foram coletados durante um ano em uma área de Floresta Semidecidual Sazonal, em Viçosa, Brasil. A sazonalidade da população e dos sexos foi estimada através da frequência de ocorrência absoluta (FA) e da frequência de ocorrência percentual (FO%) da população, as quais foram determinadas mensalmente. Para testar se as mudanças mensais na FA da população e de cada sexo estão correlacionadas com as variáveis climáticas, testes de correlação de Spearman foram realizados. Para identificar se há oscilações temporais na razão sexual considerando meses e estações, e dentro de cada estação, foram realizados testes de Qui-quadrado. Um total de 3.126 indivíduos (1.009 fêmeas e 2.117 machos) foram coletados. A população teve maior abundância na primavera e verão, e menor no outono e inverno. As maiores FA e FO foram em dezembro e janeiro, e a menores em junho e julho. A razão sexual da população não diferiu nos meses do ano, mas na primavera houve uma predominância marcante de machos. Para E. azureus, a flutuação temporal na abundância da população e na razão sexual é explicada pelas variáveis climáticas de temperatura máxima, umidade e precipitação. As variáveis climáticas, especialmente a temperatura, propiciaram uma maior abundância da população nos períodos os mais quentes e chuvosos do ano por induzirem a atividade reprodutiva e a alterar da razão sexual da população.

Spatiotemporal analysis of distribution of pest and predator in corn crops

Crop pests have negative impacts on yield. This paper proposes a spatiotemporal geostatistical modeling to compare data of adult Syrphidae fly count and corn leaf aphid Rhopalosiphum maidis (Fitch, 1856) colonies in corn crops. The use of a geostatistical model that allows the space-time variation makes the approach more interesting because it is a more complete model. Multiple regression was used to model the trend component for the variable response adult Syrphidae fly count and corn leaf aphid colonies, with the coordinates serving as covariates and the spatiotemporal variations around the deviation are described by a random spacetime residual field. Finally, the prediction map obtained by kriging may be a biological indicator of possible corn leaf aphid colonies in the corn crop. It was possible to verify that the occurrence of the pest provided a significant increase in adult predators and seminatural habitats may favor populations of natural enemies.

Variation in dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) assemblages in a tropical forest remnant from a Mexican National Park

Abstract The Cañón del Sumidero National Park (PNCS) is a priority area for conservation, but there are few studies on its fauna, which evidences the need for further basic studies to produce adequate knowledge on its biodiversity. This study aimed to determine dung beetle assemblages temporal distribution, trophic preference, and daily activity patterns. We conducted samplings using baited pitfall traps in a PNCS tropical sub deciduous forest remnant, during the dry and rainy seasons between 2014 and 2015. We captured a total of 863 individuals of 20 species, 12 genera, and five tribes of Scarabaeinae. Estimators suggest that we obtained high faunistic representation (> 80%), but species richness is low compared to other regional studies. The community was characterized by a high number of rare species and few dominant species. We captured the greatest richness and abundance during rainy months, however, species composition between seasons did not differ significantly. Trophic preference was mainly generalist and we considered only four species as specialists to tapir dung. We observed a clear segregation between activity hours. Nevertheless, we determined only nine species as specialists (six nocturnal and three diurnal) and two others had generalist habits. The low diversity we found could be influenced by the constant pressure of the urban area and non-native species within the park, which alter the dung beetle assemblages. However, performing samplings for longer periods and using a wider range of resources would help us obtain more robust results and better understand species distribution patterns.

Variation in dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) assemblages in a tropical forest remnant from a Mexican National Park

Abstract The Cañón del Sumidero National Park (PNCS) is a priority area for conservation, but there are few studies on its fauna, which evidences the need for further basic studies to produce adequate knowledge on its biodiversity. This study aimed to determine dung beetle assemblages temporal distribution, trophic preference, and daily activity patterns. We conducted samplings using baited pitfall traps in a PNCS tropical sub deciduous forest remnant, during the dry and rainy seasons between 2014 and 2015. We captured a total of 863 individuals of 20 species, 12 genera, and five tribes of Scarabaeinae. Estimators suggest that we obtained high faunistic representation (> 80%), but species richness is low compared to other regional studies. The community was characterized by a high number of rare species and few dominant species. We captured the greatest richness and abundance during rainy months, however, species composition between seasons did not differ significantly. Trophic preference was mainly generalist and we considered only four species as specialists to tapir dung. We observed a clear segregation between activity hours. Nevertheless, we determined only nine species as specialists (six nocturnal and three diurnal) and two others had generalist habits. The low diversity we found could be influenced by the constant pressure of the urban area and non-native species within the park, which alter the dung beetle assemblages. However, performing samplings for longer periods and using a wider range of resources would help us obtain more robust results and better understand species distribution patterns.

Nestedness of stream insects in Subtropical region: importance of inter-annual temporal scale

ABSTRACT Stream insects use in different ways the stream habitats which affect patterns of species occurrence on stream. The nestedness is one of these patterns being an ecological mechanism that generates beta diversity. In this study, we verify the effects of temporal environmental variations on nestedness patterns of Chironomidae assemblages on subtropical streams. We collected chironomid larvae during winter and summer during three years (2010, 2011 and 2012) in Brazilian Subtropical low-order streams (Erechim, state of Rio Grande do Sul, Brazil). We measured environmental variables in each stream. To assess if assemblages will show nested patterns intra- and interannual we used a NODF metric. We observed nestedness only in one year, this pattern was due to variation of limnological factors, which are directly associated with climatic conditions (precipitation and water temperature) and agricultural management (e.g. dissolved oxygen and nutrients). Climatological events affect Chironomidae community through the time. The variations on precipitation values could be one of the mainly factors that influence nestedness for this community. Finally, studies on nesting on time scales should consider inter-annual comparisons, as climatic variations are more evident.

Diet of a bromeligenous species of treefrog in the Brazilian semiarid / Dieta de uma espécie bromelígena de anuro do semiárido brasileiro

Phyllodytes tuberculosus is a bromeligenous anuran species whose geographic distribution is restricted to areas of the Caatinga and to transition zones between Caatinga and Atlantic Forest in the central-south of the state of Bahia. Its existence in close relationship with bromeliads and its occurrence in dry and highly seasonal environments drove us to the supposition that species is opportunistic/generalist regard to diet. We collected the items present in the stomach of 43 P. tuberculosus individuals with stomach-flushing method. Of these, 18 stomach contents were obtained during the dry period (April­October), and 25 during the rainy period (November­March). We recorded nine classes of prey, finding the greatest relative importance for the categories Formicidae and Coleoptera in dry season and Blattodea (Termites), Formicidae and Coleoptera in the rainy season. Phyllodytes tuberculosus presented a varied, possibly opportunistic diet in semiarid environments. Additionally, we report an apparent temporal differentiation related to the typical Caatinga seasonality. This study adds to the data on the natural history of an anuran species adapted to a semiarid environment with a narrow geographic distribution.

Phyllodytes tuberculosus é uma espécie de anuro bromelígena cuja distribuição geográfica está restrita a áreas de Caatinga e zonas de transição entre Caatinga e Mata Atlântica no centro-sul do estado da Bahia. Sua relação próxima com bromélias e sua ocorrência em ambientes secos e fortemente sazonais nos levou a supor que a espécie apresenta uma dieta generalista/oportunista. Por meio de lavagem estomacal, coletamos os itens alimentares presentes no estômago de 43 indivíduos de P. tuberculosus. Destes, 18 estômagos foram obtidos durante a estação seca (Abril-Outubro) e 25 durante a estação chuvosa (Novembro­Março). Nós registramos nove classes de presas, sendo que as maiores importâncias relativas foram observadas para os itens Formicidae e Coleoptera na estação seca e Blattodea (Termites), Formicidae e Coleoptera no conteúdo recuperado na estação chuvosa. Phyllodytes tuberculosus apresentou uma dieta variada, possivelmente oportunista, condizente com a vida em ambientes semiáridos. Ademais, também observamos uma aparente diferenciação temporal relacionada a sazonalidade típica da Caatinga. Este estudo adiciona dados a respeito da história natural de uma espécie de anuro adaptada a ambientes semiáridos e com distribuição geográfica restrita.