Abstract Vocal plasticity reflects the ability of animals to vary vocalizations according to context (vocal repertoire) as well as to develop vocal convergence (vocal group signature) in the interaction of members in social groups. This feature has been largely reported for oscine, psittacine and trochilid birds, but little has been investigated in birds that present innate vocalization. The smooth-billed ani (Crotophaga ani) is a social bird that lives in groups between two and twenty individuals, and which presents innate vocalization. Here we analyzed the vocal repertoire of this species during group activities, and further investigated the existence of a vocal group signature. The study was conducted in the Southeast of Brazil between May 2017 and April 2018. Two groups of smooth-billed anis were followed, Guararema and Charqueada groups, and their vocalizations were recorded and contextualized as to the performed behavior. The vocal repertoire was analyzed for its composition, context and acoustic variables. The acoustic parameters maximum peak frequency, maximum fundamental frequency, minimum frequency, maximum frequency and duration were analyzed. To verify the vocal signature of the group, we tested whether there was variation in the acoustic parameters between the monitored groups. We recorded ten vocalizations that constituted the vocal repertoire of the Smooth-billed Ani, five of which (“Ahnee”, “Whine”, “Pre-flight”, “Flight” and “Vigil”) were issued by the two groups and five exclusive to the Charqueada group. There were significant differences in the acoustic parameters for “Flight” and “Vigil” vocalizations between the groups, suggesting vocal group signature for these sounds. We established that the Smooth-billed Ani has a diverse vocal repertoire, with variations also occurring between groups of the same population. Moreover, we found evidence of vocal group signature in vocalizations used in the context of cohesion, defense and territory maintenance.

Resumo: O Efeito do Domínio Central (MDE) e o Efeito Rapoport (ER) são duas teorias biogeografias que fazem previsões sobre a distribuição da diversidade ao longo de gradientes. O MDE prevê maior riqueza nas porções centrais de um gradiente, se este estiver dentro de um domínio fechado. O ER prevê uma relação positiva entre altitude e tamanho da distribuição ao longo do gradiente altitudinal. Nosso objetivo foi o de registrar a distribuição de uma comunidade de aranhas ao longo de um gradiente altitudinal na Amazônia Brasileira, e testar se há uma influência do EDC e do ER sobre os padrões de diversidade da comunidade. Nosso estudo foi feito no Parque Nacional do Pico da Neblina (AM, Brasil), e nós amostramos aranhas em seis altitudes diferentes. Nós coletamos 3.140 exemplares adultos de 39 famílias, que foram divididos em 529 espécies/morfoespécies. A riqueza declinou com o aumento de altitude, mas o padrão não mostrou ajuste com as previsões feitas pelo EDC. O tamanho da distribuição altitudinal também não esteve relacionado ao previsto pelo ER. Por fim, a distribuição de abundância ao longo da distribuição altitudinal das espécies variou de maneira específica, o que impediu a ocorrência de um ER nos padrões da comunidade. A influência do EDC sobre os padrões observados foi baixíssima, uma consequência de características de nossa comunidade, já que esta é formada por espécies com pequena distribuição altitudinal. Espécies de distribuição altitudinal médias e grandes ocorreram em todas as partes do gradiente o que impediu a ocorrência de um ER. Por fim, o ER também não foi observado na distribuição de abundância das espécies ao longo do gradiente, já que essa variou de maneira específica.

Abstract: The Mid-Domain Effect (MDE) and the Rapoport (RE) effect are two biogeographical theories that make predictions about biogeogaphic patterns. MDE predicts higher richness in the central portions of a gradient if it is within a bounded domain. RE predicts a positive relation between altitude and species range size along an altitudinal gradient. Our aim was to document the distribution of spider species richness along an altitudinal gradient in the Brazilian Amazon, and to test the influence of MDE and RE on the diversity patterns. Our study was conducted at the Pico da Neblina (Amazonas state, Brazil), and we sampled spiders at six different altitudes using two methods: nocturnal hand sampling and a beating tray. We obtained 3,140 adult spiders from 39 families, sorted to 529 species/morphospecies. Richness declined continuously with an altitude increase, but the fit with the MDE richness estimates was very weak and was not significant. Range size was not related to altitude, i. e., no RE. Finally, the abundance distribution within each species range varied more specifically, which prevented the occurrence of a RE at the community level. The influence of MDE was extremely low, a consequence of our community characteristics, formed mostly by small range size species. Short and medium range species were located at all altitudes, preventing a significant relation between range size and altitude. The distribution of abundance within a species range varied specifically and do not support a RE hypothesis.

RESUMO Testaram-se as hipóteses de que, assim como em reservatórios de grande áreas de superfície, volumes e vazão, em reservatórios pequenos também ocorrem a diluição gradual e contínua da riqueza, da diversidade e abundância de microcrustáceos (Cladocera e Copepoda) a jusante dos mesmos, sem a recomposição da riqueza a jusante pela falta de rios tributários, lagoas marginais e até pelo pequeno porte do riacho, sem condições para o desenvolvimento do potamoplâncton próprio do sistema. Foram estudados dois pequenos reservatórios e seus trechos a jusante, com coletas diárias a cada seis horas em oito pontos de amostragem, sendo dois lênticos e seis lóticos a jusante de cada. Foram encontradas 19 espécies (11 de Cladocera e oito de Copepoda), com destaque para o maior número de espécies litorâneas do que pelágicas, e a maior abundância de cladóceros litorâneos nos pontos a jusante dos reservatórios. Não houve diferença entre os horários, indicando que a escala espacial foi mais importante que a temporal. Houve maiores valores dos atributos ecológicos nos ambientes lênticos, porém houve aumentos significativos de riqueza e diversidade nos últimos pontos dos trechos de riacho, enquanto que a abundância diminuiu gradativamente a jusante. Não foram encontradas correlações significativas da abundância dos táxons com nenhuma variável limnológica (temperatura, pH, oxigênio dissolvido, turbidez, sólidos totais dissolvidos e transparência), indicando pouco ou nenhum efeito destas variáveis. A análise de cluster com distância euclidiana separou dois grandes grupos, o primeiro formado pelo trecho a jusante do primeiro reservatório e o segundo com os demais pontos. Além da presença dos táxons litorâneos vindos dos reservatórios, houve incremento de táxons litorâneos residentes nos riachos. Pode-se concluir que houve uma diluição da abundância das espécies a jusante dos riachos, mas a riqueza e a diversidade permaneceram estáveis devido à contribuição de táxons litorâneos.

ABSTRACT The hypotheses tested were that, as well as in reservoirs of large surface areas, volumes and flow, in small reservoirs there is also a gradual and continuous dilution of the richness, diversity and abundance of microcrustaceans (Cladocera and Copepoda) downstream reservoirs, without the recomposition of richness downstream due to the lack of tributary rivers, marginal lagoons and even the small size of the stream, with no conditions for the development of its own potamoplankton. Two small reservoirs were studied and in their downstream stretches, with daily collections every six hours at eight sampling points, two lentic and six lotic downstream from each. Nineteen species were found (11 from Cladocera and eight from Copepoda), with emphasis on the greater number of coastal species than pelagic ones, and the greater abundance of coastal cladocerans at the points downstream of the reservoirs. There was no difference between the times, indicating that the spatial scale was more important than the temporal scale. There were higher values of ecological attributes in lentic environments, but there were significant increases in richness and diversity in the last points of the stretches of the stream, while the abundance decreased gradually downstream. No significant correlations were found for the abundance of taxa with any physical and chemical variable (temperature, pH, dissolved oxygen, turbidity, total dissolved solids and transparency), indicating little or no effect of these variables. The cluster analysis with Euclidean distance separated two large groups, the first formed by the stretch downstream of the first reservoir and the second with the other points. In addition to the presence of litoranean taxa coming from reservoirs, there was an increase in litoranean taxa resident in streams. It can be concluded that there was a dilution of the abundance of species downstream of the streams, but the richness and diversity remained stable due to the contribution of litoranean taxa.

Resumo: Apresentamos aqui o primeiro estudo que analisou a composição e riqueza de rotíferos de toda a bacia do Rio da Prata, a segunda maior da América do Sul, com amostragens simultâneas e padronizadas. Quinze grandes reservatórios e oito trechos lóticos foram selecionados nas porções alta, média e baixa dos rios Paraná, Paraguai e Uruguai, que atuam como os principais formadores da bacia do Prata. Coletamos um total de 86 amostras (habitats de águas abertas) em 2010. Foi encontrada uma média de 27 ± 11 espécies por sub-bacia, com maior riqueza no Baixo Paraná (41 espécies), seguido por Paranapanema (40 espécies) e Baixo Uruguai (38 espécies). Uma baixa riqueza foi observada no Médio Uruguai e no Médio Paraná. Encontramos 106 espécies pertencentes a 21 famílias e duas ordens. A família com maior número de espécies foi Lecanidae (21), seguida por Brachionidae (20), Trichocercidae (9) e Synchaetidae (8). As espécies com maior ocorrência foram Conochilus dossuarius, Kellicottia bostoniensis, Keratella americana, Keratella cochlearis e Hexarthra mira. Novas ocorrências de rotíferos foram registradas para o Brasil (Colurella adriatica), Estado de São Paulo (Enteroplea lacustris) e Argentina (Gastropus hyptopus, Harringia rousseleti e Lecane thienemanni). A correlação de Spearman entre o número de espécies e as variáveis físicas e químicas demonstrou correlação positiva com clorofila e temperatura, e correlação negativa com oxigênio dissolvido. Estendemos a lista de distribuição para algumas espécies nativas (Lecane ludwigii) e não-nativas de rotíferos (K. bostoniensis). Disponibilizamos também uma lista de espécies de rotíferos Monogononta encontrados nas estações amostradas.

Abstract: We present here the first study that analyzed the composition and richness of rotifers of the entire La Plata River basin, the second largest in South America, based on simultaneous and standardized sampling. Fifteen large reservoirs and eight river stretches were selected in the upper, middle, and lower portions of the Paraná, Paraguay, and Uruguay Rivers, which are the major rivers of the La Plata basin. We took a total of 86 samples (open water habitats) in 2010. A mean of 27±11 species per sub-basin was found, with the highest richness in the Lower Paraná (41 species), followed by the Paranapanema (40 species) and Lower Uruguay (38 species). Low richness was observed in the Middle Uruguay and Middle Paraná. We found 106 species belonging to 21 families and two orders. The family with the highest number of species was Lecanidae (21), followed by Brachionidae (20), Trichocercidae (9), and Synchaetidae (8). The species with higher occurrences were Conochilus dossuarius, Kellicottia bostoniensis, Keratella americana, Keratella cochlearis and Hexarthra mira. New occurrences of rotifers were registered for Brazil (Colurella adriatica), São Paulo State (Enteroplea lacustris), and Argentina (Gastropus hyptopus, Harringia rousseleti and Lecane thienemanni). Spearman correlation between the number of species and physical and chemical variables demonstrated positive correlation with chlorophyll and temperature, and negative correlation with dissolved oxygen. We extend the distribution list for some native (Lecane ludwigii) and non-native species of rotifers (K. bostoniensis). We also list the monogonont rotifer species found at the sampling stations.

RESUMO Esse trabalho caracterizou o zooplâncton e as variáveis ambientais do reservatório Canoas (Assaré, Ceará, Brasil) através de oito coletas consecutivas mensais, durante um período de estiagem intensa. Amostras de zooplâncton foram coletadas com arrastos verticais de rede de plâncton de 50 µm em três pontos distribuídos longitudinalmente. Foram encontradas cinco espécies: Brachionus calicyflorus Pallas, 1938 (Brachionidae: Rotifera), Diaphanosoma spinulosum Herbst, 1967 (Sididae: Cladocera), Thermocyclops decipiens Kiefer, 1929 e T. inversus Kiefer, 1936 (Cyclopoida: Copepoda), e Notodiaptomus cearensis Wright, 1936 (Calanoida: Copepoda). Thermocyclops decipiens apresentou a maior abundância relativa, seguido de N. cearensis e B. calicyflorus. A variação espacial e temporal da comunidade zooplanctônica pode ser explicada pela maioria das variáveis ambientais associadas a N. cearensis e B. calicyflorus, enquanto T. decipiens não se associou a nenhuma delas. A baixa riqueza de espécies e a dominância de T. decipiens e B. calicyflorus podem ser reflexos da elevada condição trófica do reservatório, em período de estiagem intensa, e N. cearensis está associado também com essas condições mais adversas.

ABSTRACT This work characterized the zooplankton and the environmental variables of the Canoas reservoir (Assaré, Ceará, Brazil) through eight consecutive monthly collections during a period of intense drought. Zooplankton samples were collected by vertical plots of 50 µm plankton net at three longitudinally distributed points. Five species were found: Brachionus calicyflorus Pallas, 1938 (Brachionidae: Rotifera), Diaphanosoma spinulosum Herbst, 1967 (Sididae: Cladocera), Thermocyclops decipiens Kiefer, 1929 and T. inversus Kiefer, 1936 (Cyclopoida: Copepoda), and Notodiaptomus cearensis Wright, 1936 (Calanoida: Copepoda). Thermocyclops decipiens had the highest relative abundance, followed by N. cearensis and B. calicyflorus. The spatial and temporal variation of the zooplankton community can be explained by most of the environmental variables associated with N. cearensis and B. calicyflorus, while T. decipiens was not associated with any of them. The low species richness and dominance of T. decipiens and B. calicyflorus may be a reflection of the high trophic condition of the reservoir during severe drought, and N. cearensis is also associated with these more adverse conditions.

ABSTRACT Copepods have been successfully used in many countries for the biological control of larvae of mosquitoes that vector diseases. In Brazil, this line of research has been focused on the use of the copepod Mesocyclops longisetus (Thiébaud, 1914) for the biological control of the mosquito Aedes aegypti (Linnaeus, 1792). The transportation of the copepods from the place where they are reared to where they will be used often involves long distances for extended periods of time. This study assesses the survivorship of M. longisetus during simulation of transport under different conditions. Different loading densities (20, 30, 40, 80, and 120 ind.L) and stirring times (30 minutes, one hour, two hours, and four hours) were tested. Survivorship was high, with 75% of the results equal or higher than 90% survival. Reduced mortality was observed when transportation time was up to 120 minutes and densities were up to 40 ind.L. In higher densities or longer transportation times, the mortality rate was significantly affected.

ABSTRACT Zooplankton exhibit several trends of variation in space and time, and these trends can be more evident in natural environments without anthropic perturbations. Examples of anthropic factors are climate change, eutrophication and construction of reservoirs. This study evaluated the influence of three factors - seasonality, type of environment and the presence of aquatic macrophytes - on various ecological attributes of rotifers in a river-lake system located in the Paraná River floodplain. Monthly samplings were conducted during 1993 and 1994. The mean species richness per sample was 60 species. The seasonality and the type of environment influenced the ecological attributes of rotifer assemblages, while the presence or absence of aquatic macrophytes did not. Species richness was highest in the lake system and during the months when water levels were low. Multivariate analysis indicates a small group of species associated with the low water-level phase. In contrast, many species were associated with high water levels or increasing water levels. The seasonal variation of hydrological cycle and the type of environment are the most important factors for rotifer structure in natural conditions.

ABSTRACT We studied the leading causes of the spatial distribution pattern of fish species assemblage in the transition region between Cerrado-Caatinga biomes, in the São Francisco River (Brazil). Biotic and abiotic variables were collected at 17 sampling sites located in three sub-basins, in two periods during 2015. Some 1689 individual fish were sampled, distributed in 69 species, 51 genera, 22 families and seven orders. There was a low overlap of species, with only seven species in common among the three sub-basins. The most substantial degree of sharing occurred between sub-basins from the Cerrado biome, with 22 restricted species. Crenicichla lepidota, Psellogrammus kennedyi, and Hoplosternum littorale were associated with the sub-basin from Caatinga, and Astyanax aff. eigenmanniorum and Bryconops aff. affinis with Cerrado sub-basins. The fish assemblage showed significant spatial variation between biomes, and the distribution was determined by an interaction of regional altitude variable with local variables such as river width, substrate and water velocity (environmental factors), but geographical factors were also important. Fish assemblage difference along a large river course has significant implications for conservation strategies, management or evaluation of biodiversity, needing several strategies for their preservation considering small geographic areas.

Resumo Objetivo Nós analisamos as relações entre a riqueza de espécies zooplanctônicas e a área de 34 lagos naturais e 55 artificiais no Brasil (total de 89), lagos com tamanhos variando entre 0,01 e 2430 km2. Métodos Foram consultados 33 artigos disponíveis na bibliografia especializada, contendo dados de zooplâncton amostrados nas zonas limnéticas, analisados nesse estudo por meio de estatísticas descritivas, correlação de Spearman e regressão não-linear. Resultados A relação entre a riqueza de espécie zooplanctônicas e a área de lagos brasileiros depende do tamanho e do tipo de ambiente. Contradizendo aspectos biogeográficos teóricos, em ambientes pequenos (até 6 km2) não há influência significativa da área sobre a riqueza, em lagos naturais e artificiais (reservatórios e açudes). Lagos naturais apresentam maiores riquezas e variação de habitat independente do tamanho, possivelmente devido a composição mais diversa de nichos. Grandes lagos naturais são escassos no Brasil, mas em reservatórios, a area e a riqueza do zooplâncton são positivamente correlacionadas em uma escala intermediária, até 39 km2, um ponto crítico de tamanho de área para que a riqueza estabilize. Conclusões Para lagoas artificias de tamanho grande ou intermediário no Brasil há um ponto no qual a riqueza estabiliza, como esperando nas teorias biogeográficas. Porém em ambientes pequenos não há evidências dessa relação. Também foi observados que lagos naturais exibem valores de riqueza maiores e mais variados do que os artificiais.

Abstract Aim We analyzed the relationship between zooplankton species richness and the area of 34 natural and 55 artificial lakes in Brazil (total of 89), with area varying between 0.01 to 2,430 km2. Methods A total of 33 studies were found in the specialized bibliography, containing data from zooplankton sampled in the limnetic areas, here analyzed through descriptive statistics, nonparametric group comparisons, Spearman correlation, and non-linear regression. Results The relationship between zooplankton richness and area in Brazilian lakes depend both on the size and type of the environments. Contradicting aspects of the biogeographic theory, in small environments (up to 6 km2) there is no significant influence of the area on the richness, whether it is natural (ponds) or artificial (dams, reservoirs). The natural lakes present greater richness and habitat variation independent of the size, possibly due to a more diverse composition of niches. Large natural lakes are scarce in Brazil but, with dams, area and zooplankton richness are positively correlated on an intermediate scale, up to 39 km2, critical point of size from which species’ richness stabilizes. Conclusions For the artificial lakes of large or intermediate size in Brazil, area and richness of microcrustaceans have a point from which richness starts to stabilize, as would be expected by the biogeographic theory. But in small size environments there is no evidence confirming this association. Also, it is observed that the natural lakes present higher and more variable values for richness than the artificial ones.

Resumo Objetivos: Foram analisados alguns atributos ecológicos básicos (riqueza e densidade) da comunidade bentônica em um trecho de um rio rochoso sob influência de uma pequena barragem de um metro de altura, formando um pequeno reservatório do tipo fio-de-água. Métodos Amostras de sedimento foram coletadas com draga de Petersen em três períodos e em três pontos: à montante do reservatório (ponto 1), próximo à barragem (ponto 2) e à jusante da barragem (ponto 3). Os organismos foram separados em grandes grupos e gêneros de Chironomidae. Resultados A análise do sedimento indicou que os pontos 1 e 2 são dominados por sedimentos finos, em contraste do ponto 3, composto por sedimentos médio e grosso. Um total de 23 táxons de macroinvertebrados bentônicos e 31 gêneros de Chironomidae foi encontrado. A riqueza e a densidade foram diferentes entre os pontos de amostragem, e para os grandes grupos e Chironomidae esses atritutos aumentaram a jusante, provavelmente devido à composição do sedimento e às condições lóticas originais no ponto 3, confirmados pelas análises estatísticas empregadas. Na região da barragem (ponto 2) houve um decréscimo de riqueza. Análise de escalonamento não-métrico mostrou uma clara separação especial entre os pontos de amostragem, indicando que há táxons típicos de cada compartimento espacial. Análise de correspondência canônica correlacionou apenas cascalho com a abundância dos grandes grupos, e para os gêneros de Chironomidae somente os grânulos foram correlacionados, formando dois grupos na análise: um com os pontos um e dois, e outro com o três. Conclusões Mesmo pequenas barragens em rios rochosos como no presente estudo alteram variáveis ambientais e atributos ecológicos de macroinvertebrados bentônicos.

Abstract Aim: Here we analyzed some basic ecological attributes (richness and density) of the benthic community in a stretch of a rocky river under the influence of a small dam of a meter in height, forming a small reservoir of run-of-river type. Methods Sediment samples were taken with a Petersen collector at three different periods and in three sites: upstream from the dam (site 1), close to the dam (site 2) and downstream from the dam (site 3). Organisms were separated in large groups and Chironomidae genera. Results The particle size analysis indicated that the sites 1 and 2 are dominated by fine sediments, in contrast to site 3, composed of medium and coarse sediments. A total of 23 taxa of benthic macroinvertebrate groups and 31 genera of Chironomidae were found. Richness and density were different among sampling sites, and for large groups and Chironomidae its attributes increased towards downstream, probably explained by the sediment composition and the originally lotic conditions in site 3, confirmed by all statistical analysis used. In the dam site (2) there was a richness decrease. Non metric multidimensional analysis showed a clear spatial separation of large groups of macroinvertebrates and chironomid genera between sampling sites, indicating that there are typical taxa of each spatial compartment. Canonical correspondence analysis correlated only rubble sediment with the abundance of large groups, and for Chironomidae genera only the granules type was correlationed, with two groups of taxa in the anlysis: one with sites 1 and 2, and other with site 3. Conclusions Even very small dams in rocky rivers as in the present study alter the environmental variables and ecological attributes of benthic macroinvertebrates.

Resumo Objetivo: Identificar padrões espaciais em larga escala na limnologia dos corpos d’água laterais da bacia do Rio da Prata, considerando a presença dos barramentos e conglomerados urbanos. Métodos Amostragens foram feitas em uma ampla escala espacial (ao longo de 16 graus de latitude) durante dois períodos sazonais (23 locais no verão e 20 no inverno) para medições de variáveis físicas e químicas, clorofila a e biomassa do perifiton. Resultados A distância geográfica entre os locais foi significativamente correlacionada com a dissimilaridade ambiental (distância Euclidiana). Locais associados a reservatórios e planícies de inundação apresentaram menores concentrações de fósforo. Condições mais eutróficas estiveram associadas a áreas urbanas e regiões com atividades agropecuárias intensivas, como maior condutividade, concentrações de nitrogênio e clorofila a. Maior biomassa de perifiton ocorreu em locais sob influência de reservatórios. Material particulado inorgânico foi maior no verão e orgânico no inverno, devido à contrastante sazonalidade das chuvas na porção superior da bacia do rio Paraná. Não houve correlação significativa entre a dissimilaridade da vegetação e a dissimilaridade ambiental ou distância geográfica entre os locais amostrados. Conclusões As condições limnológicas nos ambientes fluviais laterais da bacia do Rio da Prata são altamente influenciadas pela construção de reservatórios, intensa ocupação urbana e sazonalidade na precipitação.

Abstract Aim: Identify large-scale limnological patterns in lateral water bodies of Río de La Plata Basin, considering the influence of river damming and urban conglomerates. Methods Samplings were performed in a broad spatial scale (along 16 latitude degrees) during two seasonal periods (23 sites in summer and 20 sites in winter) for measurements of physical and chemical variables, chlorophyll a and periphyton biomass. Results Geographical distance between sites was significantly correlated with the environmental dissimilarity (Euclidean distance). Reservoir and floodplain associated sites exhibited lower phosphorus concentration. Eutrophic conditions were higher in sites close to urban areas and regions with intensive agriculture and livestock activities, which exhibited higher conductivity, concentration of nitrogen and chlorophyll a. Sites associated to reservoirs had higher periphyton biomass. Inorganic suspended matter was higher in summer whereas organic suspended matter was higher in the winter, due to contrasting rain seasonality in the upper Paraná River sub-basin. No significant correlation between the dissimilarity of the vegetation and the environmental dissimilarity or geographical distance between sites was observed. Conclusions The limnological conditions in the fluvial lateral habitats in the Río de La Plata basin are highly influenced by reservoirs construction, intensive urban occupation and rain seasonality.

No presente artigo são apresentados novos registros de Boeckella bergi em vários corpos de água na Argentina e no Brasil. Dentro desses registros estão incluídos os limites setentrionais e meridionais de ocorrência de B. bergi na América do Sul. A ampla gama de distribuição é consistente com estudos anteriores, mas se mostra muito mais extensa do que conhecida anteriormente. Observações sobre a taxonomia e os habitats também são feitas. Esta espécie é tolerante a condições de clima temperado na região da América do Sul, com uma grande amplitude de temperatura entre o verão e inverno, e padrões irregulares de precipitação.

We present new records of Boeckella bergi at several water bodies in Argentina and Brazil. Within these records the northernmost and southernmost limits of occurrence of B. bergi in South America are included. The ample range of distribution is consistent with former studies, but it is more extensive than previously known. Observations on habitat preferences are also made. This species is tolerant to temperate climate conditions in this region of South America, with wide amplitude of temperature between summer and winter seasons, and irregular patterns of precipitation.

Species richness and geographical distribution of Cyclopoida freshwater copepods were analyzed along the "La Plata" River basin. Ninety-six samples were taken from 24 sampling sites, twelve sites for zooplankton in open waters and twelve sites for zooplankton within macrophyte stands, including reservoirs and lotic stretches. There were, on average, three species per sample in the plankton compared to five per sample in macrophytes. Six species were exclusive to the plankton, 10 to macrophyte stands, and 17 were common to both. Only one species was found in similar proportions in plankton and macrophytes, while five species were widely found in plankton, and thirteen in macrophytes. The distinction between species from open water zooplankton and macrophytes was supported by nonmetric multidimensional analysis. There was no distinct pattern of endemicity within the basin, and double sampling contributes to this result. This lack of sub-regional faunal differentiation is in accordance with other studies that have shown that cyclopoids generally have wide geographical distribution in the Neotropics and that some species there are cosmopolitan. This contrasts with other freshwater copepods such as Calanoida and some Harpacticoida. We conclude that sampling plankton and macrophytes together provided a more accurate estimate of the richness and geographical distribution of these organisms than sampling in either one of those zones alone.

Planktonic rotifers and cyclopoid copepods were studied in two reservoirs of different trophic states (eutrophic and oligo/mesoeutrophic) in the south of Brazil. During a year, monthly samplings were carried out in three stations in each reservoir. Species richness, frequency and abundance were used to find out useful and indicatives trends of water quality based on these organisms, reinforced by literature data. Species that showed higher differences between reservoirs were chosen. For Rotifera, richness, frequency and abundance of Brachionus were higher in the eutrophic reservoir, but Plationus patulus occurred only in the oligo/mesotrophic reservoir. For copepods, Tropocyclops prasinus dominated in the eutrophic reservoir, but Thermocyclops decipiens, T. minutus, T. inversus and Microcyclops anceps were dominants in the oligo/mesotrophic reservoir. In the canonical correspondence analysis, these species were indicators of the trophic state and were related with chlorophyll-a, total phytoplankton and total phosphorus. The use of these species can be efficient in the studied regions (subtropical/temperate), but comparing with other Brazilian reservoirs of tropical climate, the results could be different. Despite the dominance of T. decipiens over T. minutus, T. inversus has been widely used in Brazil as an indicator of eutrophic waters; in those cases of excessive eutrophication, other species, more rustic, commonly dominate. In the present study, Thermocyclops was dominant in the oligo/mesotrophic reservoir. The dominance of Brachionus for rotifers and Tropocyclops prasinus and Acanthocyclops robustus for copepods were indicative of eutrophic conditions.

Se analizaron los rotíferos y copépodos planctónicos ciclopoides colectados en dos embalses de diferentes estados tróficos (eutróficos y oligo/mesoeutróficos) en el sur de Brasil. Durante un año, se efectuaron muestreos mensuales, en tres estaciones en cada embalse. La riqueza de especies, frecuencia y abundancia, se utilizó para determinar tendencias útiles e indicativas de la calidad del agua sobre la base de estos organismos, complementando con datos de la literatura. Se escogieron aquellas especies que presentaron las mayores diferencias. Para rotíferos, la riqueza, frecuencia y abundancia de Brachionus fueron más altas en el embalse eutrófico, Plationus patulus se detectó sólo en el embalse oligo/mesotrófico. Para los copépodos, Tropocyclops prasinus dominó en el embalse eutrófico, mientras que Thermocyclops decipiens, T. minutus, T. inversus y Microcyclops anceps dominaron en el embalse oligo/mesotrófico. En el análisis de correspondencia canónica, estas especies fueron indicadoras del estado trófico y se relacionaron con la clorofila-a, fitoplancton total y fósforo total. El uso de estas especies puede ser eficaz en las regiones estudiadas (subtropical/templada), pero comparado con otros embalses de clima tropical del Brasil, los resultados podrían ser diferentes. A pesar de la dominancia de T. decipiens por sobre T. minutus, T. inversus ha sido ampliamente utilizado como indicador de agua eutróficas, en aquellos casos de eutroficación excesiva, otras especies, más rústicas, dominan comúnmente. En el presente estudio, Thermocyclops fue dominante en el embalse oligo/mesotrófico. La dominancia de Brachionus para los rotíferos, y Tropocyclopsprasinus y Acanthocyclops robustus para los copépodos fueron indicativos de condiciones eutróficas.