One of the most preocupant environmental problems in our área (that’s Ovar, Aveiro, Northern Center Portugal) is related with the BE/LP (aka only the Barrinha) and as so we decided to base one of our obligatory school projects on this subject. We started by analysing an official report on the contamination of the Barrinha (developed by SIMRia-Águas de Portugal, a public company responsible for public waters and so) and we were able to conclude that the biggest issues were related to high concentrations of PCBs, arsenic and manganese.
At the time we were only a two man group so we focused only on PCBs, mainly because it was unknown to us, not very discussed among Portuguese ecological agenda but, at the same time, highly dangerous and a true menace. So we started to work with vegetable models, exposing rye seeds and onion’s adventitious roots to Aroclor 1254 (our source of PCBs) and analysing the results (we used the Feulgen staining method).
In the meantime, we found out that in Arouca, a city near Ovar, they already had some experience working with heavy metals, including arsenic and manganese, so we thought of expanding our project.
In early discussions we decided we wanted our project to be more than just an analysis/determination of the toxicity of these pollutants, but to also have a practical application side to it. So we studied some bibliopgraphy and concluded that it would be interesting to work in biomonitorization field, specially when we went to confirm the results of the mentioned report and verified that such type of analysis were very expensive and not fast at all; opposing this, bioassays are generally regarded as more economic, relatively quick and just as reliable/precise. Being able to apply our results on ecosystems other than the Barrinha was also a priority.
The next step was to choose our model. Although the Barrinha has fresh water in the water canals system and brackish water in the lagoon, the truth is one of the most preoccupant scenarios is actually when the Barrinha dyke opens and communication is established between the sea and the lagoon – for example, PCBs, as very persistent compounds, can travel long distances and disturb many other environments. Along side with this, Europe’s major PCBs, As and Mn contamination hotspots are related directly or non directly with saline water ecosystems. So we decided our model should be suited to test such waters. We made some research and concluded that P. lividus, a sea urchin species, would be the best model for us, due to its high sensitivity, its presence near the Barrinha (and of easy access for us, as so) and because it’s a well studied and accepted model.
Concluding: This work aims to develop and test a study model for lagoon and estuarine ecosystems, like BE/LP, using toxicity bioassays developed in the sea urchin Paracentrotus lividus Lmk. This research integrated various cytological, embryological and cytogenetic parameters concentrated in the formulation of a methodological study to provide data that confirms the efficacy of the selected tests in P. lividus and that, eventually, allows to discriminate the bioavailability of a determined type of pollutant.
The higher concentrations were used to simulate the effect of the bioavailability of accumulated pollutants and of bioaccumulation. The lower concentrations were chosen for corresponding to the toxic values found in the sediment and the superficial and subterraneous waters of the BE/LP.
In order to assess the quality of P. Lividus as a biomonitorization model for lagoonal and estuarine ecosystems, a grid of cytological and cytogenetic tests focusing on the first 72 hours of post-fertilization development was designed and thoroughly applied. As toxicity indicators, are considered the viability of the gametes, the dynamics of the egg cleavage and the morphology of the larvae in the pluteus stage.
In assessing the genotoxicity induced by pollutants, the following cytogenetic parameters were considered: changes in mitotic activity and presence of cells with evidence of necrosis and apoptosis (Table 4).
Changes to the mitotic activity were evaluated by the cell division synchronism measured by the frequency of embryos in interphase (IE) and the average number of mitosis per embryo (MPE). The identification of embryos undergoing necrosis and apoptosis was made by the observing DNA, which has a characteristic pattern in these stages.
At the time we were only a two man group so we focused only on PCBs, mainly because it was unknown to us, not very discussed among Portuguese ecological agenda but, at the same time, highly dangerous and a true menace. So we started to work with vegetable models, exposing rye seeds and onion’s adventitious roots to Aroclor 1254 (our source of PCBs) and analysing the results (we used the Feulgen staining method).
In the meantime, we found out that in Arouca, a city near Ovar, they already had some experience working with heavy metals, including arsenic and manganese, so we thought of expanding our project.
In early discussions we decided we wanted our project to be more than just an analysis/determination of the toxicity of these pollutants, but to also have a practical application side to it. So we studied some bibliopgraphy and concluded that it would be interesting to work in biomonitorization field, specially when we went to confirm the results of the mentioned report and verified that such type of analysis were very expensive and not fast at all; opposing this, bioassays are generally regarded as more economic, relatively quick and just as reliable/precise. Being able to apply our results on ecosystems other than the Barrinha was also a priority.
The next step was to choose our model. Although the Barrinha has fresh water in the water canals system and brackish water in the lagoon, the truth is one of the most preoccupant scenarios is actually when the Barrinha dyke opens and communication is established between the sea and the lagoon – for example, PCBs, as very persistent compounds, can travel long distances and disturb many other environments. Along side with this, Europe’s major PCBs, As and Mn contamination hotspots are related directly or non directly with saline water ecosystems. So we decided our model should be suited to test such waters. We made some research and concluded that P. lividus, a sea urchin species, would be the best model for us, due to its high sensitivity, its presence near the Barrinha (and of easy access for us, as so) and because it’s a well studied and accepted model.
Concluding: This work aims to develop and test a study model for lagoon and estuarine ecosystems, like BE/LP, using toxicity bioassays developed in the sea urchin Paracentrotus lividus Lmk. This research integrated various cytological, embryological and cytogenetic parameters concentrated in the formulation of a methodological study to provide data that confirms the efficacy of the selected tests in P. lividus and that, eventually, allows to discriminate the bioavailability of a determined type of pollutant.
The higher concentrations were used to simulate the effect of the bioavailability of accumulated pollutants and of bioaccumulation. The lower concentrations were chosen for corresponding to the toxic values found in the sediment and the superficial and subterraneous waters of the BE/LP.
In order to assess the quality of P. Lividus as a biomonitorization model for lagoonal and estuarine ecosystems, a grid of cytological and cytogenetic tests focusing on the first 72 hours of post-fertilization development was designed and thoroughly applied. As toxicity indicators, are considered the viability of the gametes, the dynamics of the egg cleavage and the morphology of the larvae in the pluteus stage.
In assessing the genotoxicity induced by pollutants, the following cytogenetic parameters were considered: changes in mitotic activity and presence of cells with evidence of necrosis and apoptosis (Table 4).
Changes to the mitotic activity were evaluated by the cell division synchronism measured by the frequency of embryos in interphase (IE) and the average number of mitosis per embryo (MPE). The identification of embryos undergoing necrosis and apoptosis was made by the observing DNA, which has a characteristic pattern in these stages.
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