DOI: 10.3897/zoologia.37.e37658

Authors: Aline Nunes-Silva, Isabela de Lima-Keppe, Robson V. de Souza, Gilmar Perbiche-Neves

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.

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DOI: 10.3897/zoologia.36.e24191

Authors: Moacyr Serafim-Júnior, Gilmar Perbiche-Neves, Fabio Lansac-Toha

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.

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DOI: 10.3897/zoologia.35.e12895

Authors: Milton P. Ávila, Rafaela Neves Carvalho, Lilian Casatti, Juliana Simião-Ferreira, Lorrane Faria de Morais, Fabrício B. Teresa

Abstract: The development of effective monitoring tools depends on finding sensitive metrics that are capable of detecting the most important environmental impacts at a given region. We assessed if metrics derived from stream fish assemblages reflect physical habitat degradation and changes in land cover. We sampled the ichthyofauna and environmental characteristics of 16 stream sites of first and second order in the Upper Tocantins River basin. The streams were classified according to their environmental characteristics into reference (n = 5), intermediate (n = 4), and impacted (n = 7). A total of 4,079 individuals in five orders, 12 families, and 30 species were collected. Of the 20 metrics tested, eight were non-collinear and were tested for their performance in discriminating among groups of streams. Three metrics were sensitive to the gradient of degradation: Berger-Parker dominance index, percentage of characiform fish, and percentage of rheophilic individuals. Some commonly used metrics did not reflect the disturbances and many others were redundant with those that did. These results indicate that the metrics derived from fish assemblages may be informative for identifying the conservation status of streams, with the potential to be used in biomonitoring.

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