We evaluated behavioral responses of zebrafish Danio rerio exposed to sublethal concentrations of sodium hypochlorite using an image analysis biomonitoring system (IABS). First, the limits of normal variation in swimming activity of zebrafish were determined by monitoring traveled distance of 40 control fishes using the IABS. An acute toxicity test was performed to determine the LC(50(24 h)) for D. rerio to NaOCl. To evaluate the toxic effects in swimming activity, 32 fishes were exposed to 40%, 30%, 20%, 10% of the LC(50 )and 32 were used as control using the IABS. We considered toxic concentrations where more than 10% intervals of the treated group were below the limits of normal variation and were significantly different from the control group. Two main responses were observed: an escape response (increased swimming activity) at 10% treated group, a gradual decrease in swimming activity from the 20% of the LC(50) on, and an avoidance response at higher concentrations. The response of the 20% treated group were considered as a NOAEL and responses of the 30% and 40% treated groups indicated significant hypoactivity (adverse effect). This behavioral biomonitoring system has proven to be a useful tool to detect sublethal toxicity that could be incorporated in biomonitoring protocols in Brazil.

This study evaluated the sub-lethal toxicity of cyanobacteria, especially Cylindrospermosis raciborskii, on Daphnia pulex (water-flea) and Danio rerio (fish), through automated image processing, with the aim to develop a Real-Time Biomonitoring System (RTBS) for detection of toxic cyanobacteria in water supplies. A system composed of a video camera coupled to an image analyzer (Videomex-V®) and to a computer was used to evaluate the swimming activities of D. rerio and D. pulex. The parameters ‘mean distance performed’ and ‘mean velocity’ were used as endpoints to evaluate the effect of samples of cyanobacteria cultures or to raw water from the eutrophic Funil Reservoir. Results showed that both cyanobacteria cultures and water samples from the reservoir altered the swimming activities of D. rerio, elevating the values of mean distance performed and mean velocity. For D. pulex, the cyanobacteria cells caused the opposite effect, decreasing the swimming activity parameters, which can be related to the mechanism of action of saxitoxins. It was concluded that this system can be efficiently used in the detection of toxic blooms of saxitoxin producing cyanobacteria in water supplies.

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The swimming behavior of Poecilia vivipara was evaluated using an image analysis system comparing laboratory-reared uninfected fish before and after experimental infection with different intensities of cercariae of the trematode Acanthocollaritrema umbilicatum. Two experiments were performed, each with 30 fish which were individually exposed to 30 and 50 cercariae, respectively, shed from experimentally infected molluscs, Heleobia australis. Before and after (17-27 days) infection, the behavior of each fish was monitored in terms of Distance travelled, Ambulatory time, Stereotypic time, Resting time and Average speed. At the end of the experiments, the fish were dissected to count the number of metacercariae recovered. In the experiment with 30 cercariae, fish with 2-10 metacercariae did not exhibit any significant differences in their swimming activity, but those with 11-22 metacercariae had a significantly enhanced Stereotypic time and a reduced Time Resting. In the experiment with 50 cercariae, fish with 5-22 metacercariae had an enhanced Distance travelled and a reduced Average speed; highly significant differences occurred with regard to all behavioral parameters when considering the subgroup 23-36 metacercariae: Distance travelled, Stereotypic time, Resting time, Ambulatory time and Average speed. The swimming behavior of P. vivipara changed influenced by an intensity-dependence on metacercariae of A. umbilicatum, supporting the prediction that parasites are able to alter the behavior of their hosts.

ResumoAnopheles aquasalis é um mosquito ora encarado como antropofílico, ora como zoofílico ou eclético. Realizou-se estudo em Guapimirim, Estado do Rio de Janeiro, de maio a novembro de 1992, com o intuito de se verificar a fonte alimentar preferida desse anofelino através de teste imunológico de precipitina. De 1.366 fêmeas capturadas em abrigos naturais, 725 estavam ingurgitadas. O conteúdo digestivo de apenas 473 delas reagiu no teste de precipitina, sendo que em 75,3% dos casos foi identificada apenas uma fonte alimentar. Mais da metade dessas fêmeas havia se alimentado em boi (52,2%), enquanto poucas tinham sugado homem (1,1%). Por outro lado, 24,7% dos espécimes haviam se alimentado em mais de uma fonte sangüínea, principalmente boi e cavalo. Conclui-se que An. aquasalis é zoófilo nessa região do País, utilizando grande variedade de hospedeiros, porém preferindo se alimentar em animais de grande porte, especialmente o boi e cavalo. (human, cow, horse, pig, dog and chicken). The majority of the females -356 (75.3%) -had blood from Anopheles. Preferências alimentares. Ecologia de vetores. Abstract Anopheles aquasalis has shown local variations in blood-host preference in