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Master thesis

Title Evaluation of the applicability of an electronic device in counting and chromatic differentiation in ecotoxicology assays
Author Filipa Alexandra Lourenço Baptista
School Universidade de Aveiro, Biologia
Month December
Year 2017
Advisor Sizenando Nogueira de Abreu, Miguel Oliveira e Silva
Group Biomedical Informatics and Technologies
Group (before 2015)

The present study was developed in the ambit of Applied Biology aiming the evaluation of an innovative device applicability in Ecotoxicology bioassays. The study was developed in three distinct phases: a first phase with adaptation to the commands and functionalities of the new equipment (D counter); a second phase using both classical methodology and the innovative approach (provided by the new device) in bioassays; and a third phase performing a standard bioassay in Ecotoxicology, only assisted by the functionalities available from the D counter, mainly in organism counting and chromatic characterization. Preliminary results evaluating the applicability of D counter in counting and chromatic differentiation in Ecotoxicology bioassays were presented at SETAC2017 (Brussels). The study presented to the conference is included in chapter II as an extended abstract, enhancing D counter main features simplifying and automating ecotoxicological tests, minimizing many problems inherent to the classical method of counting and characterizing organisms. Many Daphnia magna testing requires the counting and measurement of large amounts of organisms, which can lead to human error and even impair the visual acuity of the technician. The working procedure with D counter adds objectiveness and accuracy, saves time, and also reduces the exposure period to the chemical tested. A second phase of the present study was to evaluate D counter in classical bioassays tests, comparing D counter performance and the traditional approach, through an essay with D. magna, considering a chronic test of 21 days, and evaluating parameters such as reproduction and growth of the organisms using both procedures in the absence of contamination. In a third phase, the new methodology was applied to chronic test, where the combined effects of the variation of water hardness and ammonia in D. magna were studied. The studied parameters were reproduction and growth of the organisms exposed to combined effects, considering data only acquired and provided by the new device D counter. Overall, this study demonstrated that the new equipment does not exhibit significant differences, when compared to the classical method (p = 0,822), thus being able to assist or even replace the current counting methodology. D counter data showed that water hardness and ammonia have shown to be parameters that affect the size and reproduction of organisms. Medium with lower hardness results in organisms with smaller size, while the opposite was observed in the medium with higher water hardness. Unexpectedly, higher concentrations of ammonium chloride (12 and 20 mg/l) presented higher reproduction rates, compared to the control and lower concentration of ammonium chloride (2mg/l). This study presents and validates the application of new methodologies in ecotoxicology, being able to open new potentialities and evolutions of the equipment in the future.