From November 1992 to October 1993, Billings Reservoir in Sao Paulo State was analyzed to identify its environmental quality. Several physical, chemical, biological, and microbiological parameters were evaluated, phytoplankton being among them. Phytoplankton samples were taken monthly at eight sites, including one located on the Rio Pequeno arm. From the samples taken at Rio Pequeno, a ( ) total of 69 taxa were recorded. Cylindrospermopsis raciborskii Wolosz. Seenaya and Subba Raju was ( ) the dominant species from November 1992 to May 1993. Then Scenedesmus quadricauda Turp. Breb.( ) and S. opoliensis P. Richt Chlorophyceae became dominant. Another Cyanophyceae that was frequent but less expressive in terms of density and biomass was Oscillatoria sp. Physical and chemical ( ) water parameters, including pH, dissolved oxygen, transparency Secchi disk , conductivity, water and air temperatures, depth, total organic nitrogen, nitrate, total phosphorus, aluminum, and iron also were analyzed. Water temperature, pH, dissolved oxygen, and depth were positively correlated with C. raciborskii density, while aluminum was negatively correlated. S. quadricauda and S. opoliensis densities were inversely correlated to the same factors. There was no indication of correlation between Oscillatoria sp. density and the abiotic factors analyzed. C. raciborskii seems to be favored by physical and chemical characteristics of Rio Pequeno, such as high pH and high levels of iron, and also by biological characteristics such as the capability to migrate on the water column and to fix atmospheric nitrogen. The species toxicity is another possible explanation for the dominance of C. raciborskii, through the growth suppression of other phytoplanktonic groups and protection against grazing by zooplankton. The toxicity of these algal blooms could be responsible for fish kills which occurred at the same place in 1990. C. raciborskii dominance at Rio Pequeno during most of the year advises against the use of this water for domestic supply, due to its potential toxicity, which represents risks to human health, requiring appropriate treatment.
Since the development of the TIE (Toxicity Identification and Evaluation) in 1988 it has been assumed that the capacity of EDTA and sodium thiosulfate to complex some metals, and thus remove their toxicity, can be applied to both freshwater and seawater ecotoxicological tests and the results subsequently interpreted. However, it is now known that there is a wide variability in the extent of this complexation. In this context, the removal of toxicity caused by the presence of Hg(2+), Cd(2+), Cu(2+), Cr(6+), Zn(2+), Ni(2+), Pb(2+), Ag(1+) and Se(2+), through metal complexation by EDTA and sodium thiosulfate, in relation to the performance of embryo-larval tests with the sea urchin Arbacia lixula was investigated. It was observed that EDTA was capable of removing the toxicity of Pb(2+), Zn(2+) and Cu(2+) while sodium thiosulfate only reduced the toxicity of Ag(1+). Compared to the complexation observed in freshwater ecotoxicological tests, the complexing agents used in this study (EDTA and sodium thiosulfate) have a lower capacity to complex metals in the marine ecotoxicological test with A. lixula.
RESUMONo Brasil, a Ecotoxicologia é uma ciência relativamente nova e com poucas espécies de uso rotineiro em testes de toxicidade. Larvas (Naupliu) de craca têm sido utilizadas por diferentes grupos de pesquisa no mundo como organismo-teste e com uma variedade de métodos e aplicações. Esse organismo tem como vantagens sua facilidade de obtenção em campo, disponibilidade ao longo do ano e fácil manipulação em laboratório. O uso desses organismos, no Brasil, ainda é limitado a testes da atividade de substâncias antiincrustantes e praticamente nada foi feito para investigar sua sensibilidade para uso na Ecotoxicologia. Este trabalho apresenta um protocolo de teste agudo utilizando larvas do Cirripedia Megabalanus coccopoma, um dos maiores exemplares da Subordem Balanomorpha e de ampla distribuição na costa brasileira. Foi investigada a sensibilidade de Naupliu II ante o sulfato de zinco e seu efeito sobre a mobilidade e a mortalidade. Naupliu de M. coccopoma foram obtidos de lamelas ovígeras de adultos e utilizados em testes de toxicidade sob efeito de sulfato de zinco, em experimentos estáticos de 48 horas e com a quantificação de organismos de baixa mobilidade e mortos a cada 12 horas. Nos testes de mobilidade a CE 50 Incipiente de 0,24 mg L -1 (Zn) foi obtida em 24 horas, enquanto a CL 50 Incipiente de 0,27 e 0,22 mg L -1 (Zn) ocorreu em 36 e 48 horas, respectivamente. Observou-se que não houve diferença significativa entre os valores de CE 50 e CL 50 , o que permite o desenvolvimento dos testes em 24 horas para mobilidade ou de 48 horas para o de mortalidade. Os valores de CE 50 e CL 50 para a espécie demonstram sensibilidade similar ao misidáceo Mysidopsis juniae e ao Copepoda Acartia lilljeborgi. ABSTRACT Barnacle larvae of Megabalanus coccopoma (Darwin, 1854) as toxicity test organismsIn Brazil, Marine Ecotoxicology is a retelatively new science with few species routinely used in toxicity tests. Barnacle larvae (Naupliu) have been used for different research groups in the world as test organisms with a variety of methods and applications. These organisms have the advantages of easy obtainment in the field, availability throughout the year and easy manipulation in the lab. The use of these organisms in Brazil is still limited to tests of the activity of anticrustant substances and few work has been done to investigate their sensitivity as test-organisms in Ecotoxicology. This work presents a standard operating procedure to perform toxicity tests with naupliu of the barnacle Megabalanus coccopoma one of the biggest examplers of the subordem Balanomorpha and of great distribution around the Brazilian coast. The sensitivity of naupliu II to Zinc (Zn) was evaluted through mobility and mortality endpoints. Nauplius of the M. coccopoma were obtained from egged lamels of adults and used in 48 hours toxicity tests to assess the effect of zinc sulphate in static experimental conditions; poorly mobile and dead organisms were quantified every 12 hours. On the mobility tests, the EC 50 of 0.24 mg L -1 (Zn) was obtained fo...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.