Pesticides and polychlorinated biphenyls (PCBs) contamination and ecotoxicity in estuarine biota

Tese de mestrado, Ciências do Mar, 2022, Universidade de Lisboa, Faculdade de CiênciasThis project reports the analysis of organochloride pesticides and polychlorinated biphenyls (PCBs) compoundsin a marsh environment, to observe its toxicological effects on a marine model organism. To achieve this goal, it was quantified the concentration of organocloride pesticides and PCBs in sediments and plants, with origin in Alcochete, Rosário in Seixal estuaries. In this case, we chose to study Spartina maritima. To extract the pollutants, it was used the ASE and QuEChERS techniquesin sediments and plants samples, respectively, and the GC-ECD technique to analyze its content. With this experiment, it was possible to conclude that pesticide compounds were more predominant in Rosário, while PCBs compounds were more predominant in Seixal, derived from the activities that occurred in the vicinity of those sites. Alcochete was the less polluted site that was analysed in this work. When comparing the results obtained in this work with other concentrations from the same compounds in other Portuguese estuaries, it was possible to observe that the Tagus estuary presented a higher level of these contaminants. This is due to the higher population and activity that occurs in this zone, in comparison to other Portuguese estuaries. When studying the compounds’ concentration on plants, it was possible to observe a higher concentration on the rhizosediments. To test the toxicity of these compounds we exposed PCB 153 at 1 µg/L, 3 µg/L and 6 µg/L to the diatom model Phaeodactylum tricornutum. Afterwards, we analysed the biomarkers growth rate, photochemistry, pigment, fatty acids, lipid peroxidation and antioxidant enzyme activity of the cell. It was possible to observe that, when exposed to the compound, the cells suffered from growth inhibition, oxidative stress, and photosynthesis inhibition, such as the closure of the reaction’s centres and damage in the photosystem. This occured even though they presented counter mechanisms to the toxic effects, such as the incrementation of photosynthetic effects, such as the grouping probability, increase of efficiency of the electron transport from PQH2 to PSI, and biochemical such as the incrementation of photoprotective pigments and pigments which increase the ability to trap photons for the reductions that happen in the photosynthesis and increases the activity of antioxidant enzymes

Carnivores cross irrigation canals more often through overpasses than through culverts

As rainfall becomes scarcer or more erratic, we rely more on irrigation systems for agricultural and human water provision. Impacts of irrigation canals such as the barrier effect on wildlife movements are poorly documented. Although canal culverts and overpasses can be used by wildlife, little is known about their crossing behavior to guide barrier effect mitigation efforts. Over seven years, we recorded medium-sized carnivore crossings by video-surveillance through 30 culverts and 28 overpasses in a large irrigation project in south-central Portugal. We examined the in fl uence of the structures ’ features and landscape con- text on the likelihood of canal crossing. Culvert crossings were positively in fl uenced by the proportion of nearby montado, a high nature value farming system. Overpass crossings were more likely in areas away from paved roads and with more nearby wetlands. Overpasses increased the crossing rates by about 11% relative to culverts and both were crossed more often in land- scapes with evenly distributed land uses. In the project area, 20% of the montado has recently transitioned to irrigated agricul- ture, and wetlands have increased by 43%. It is therefore plausible that the increase in the crossing rate of overpasses relative to culverts will be accentuated. Our study produced the fi rst evidence of a contrast in crossing rates among irrigation canal cross- ing structures. We have shown that the landscape can be a driver of animal crossings but irrigation projects can in turn be trans- formative of the landscape. Broadly, the fact that the deployment of irrigation canals may favor some land uses over others creates a conundrum that needs careful consideration when planning barrier effect mitigation interventions

Toxicological evaluation of pterospartum tridentatum flower water

Pterospartum tridentatum Willk. (prickled broom) is an autochthonous plant, common in Portuguese territory. The yellow flowers are widely used in traditional medicine, as a potential cure for all body illnesses, mainly for throat irritation treatment or for diabetes, hypertension and hypercholesterolemia therapy. Despite its wide traditional use, no toxicological assessment of this plant has been performed, as far as we know. The major goal of this work was the P. tridentatum water extracts safety assessment. Methodology: Chemical characterization of MS analysis of P. tridentatum flower extract was performed by ESI-MS spectroscopy; phenols and quercetins content were also determined. Antioxidant activity was evaluated through -carotene bleaching test and ABTS radical-scavenging activity. Oxygen consumption of isolated mitochondria was determined polarographically with a Clark oxygen electrode and mitochondrial respiratory rates evaluated accordingly to Chance and Williams (1956) and mitochondrial swelling was evaluated the apparent absorbance changes at 520 nm. Results and discussion: A high antioxidant activity of P. tridentatum flower water extract was assessed in good agreement with its ESI-MS spectrum that revealed the presence of several flavonoids, as luteolin-O-(O-acetyl)-glucuronide, luteolin-Oglucuronide or isorhamnetin-O-hexoside. Mitocondrial respiratory rates (state 4, state 3 and FCCP-stimulated respiration) and respiratory indexes (respiratory control and P/O ratios) showed no consistent decrease of respiratory and phosphorylative efficiencies for the concentrations tested (up to 500 μg.mL-1). In conclusion, for the concentration range commonly used P. tridentatum flowers usage can be regarded as harmless and trustworthy and due to its great antioxidant properties it is useful to counteract diabetes mellitus associated diseases

Detection and possible elimination of the first recorded population of the zebra mussel (Dreissena polymorpha) in Portugal from a reservoir

The zebra mussel, Dreissena polymorpha, has strong economic and environmental effects within a wide range of habitats, including reservoirs, and there is a need to monitor in advance of an arrival so that an elimination might be possible. We report the establishment of the zebra mussel in the Alfundão Reservoir, a small reservoir in south Portugal, 190 km away from the closest known population in Spain. The area has been monitored using suspended ropes since 2016, and during October 2019, mussels of 5–43.8 mm shell length were recorded for the first time in the Alfundão reservoir. The shallow lined reservoir was then chlorinated and drained. To date, this treatment appears to have been successful in eliminating this population. It is unknown how this mussel arrived, since the reservoir area has a surrounding exclusion zone

Antioxidant capacity and toxicological evaluation of pterospartum tridentatum flower extracts

Pterospartum tridentatum Willk. (prickled broom) is an autochthonous plant, common in Portuguese territory. The yellow flowers are used in traditional medicine, as a potential cure for all body illnesses, mainly for throat irritation treatment or for diabetes, hypertension and hypercholesterolemia therapy.Despite its traditional use, no toxicological assessment has been performed as we know. A high antioxidant activity of P. tridentatum flower water extract was acessed in good agreement with its ESI-MS spectrum that revealed the presence of several flavonoids, as luteolin-O-(O-acetyl)-glucuronide, luteolin-O- glucuronide or isorhamnetin-O-hexoside. Mitocondrial respiratory rates (state 4, state 3 and FCCP-stimulated respiration) and respiratory indexes (respiratory control and P/O ratios) showed no consistent decrease of respiratory and phosphorylative efficiencies for the concentrations tested (up to 500 μg.mL-1). Cytotoxicity evaluation, using MTT assay, was reliable with the previous results. In conclusion, for the concentration range commonly used P. tridentatum flowers usage can be regarded as harmless and trustworthy