Biochemical and toxicological effects of organic (herbicide Primextra® Gold TZ) and inorganic (copper) compounds on zooplankton and phytoplankton species

Abstract

a b s t r a c tIn Europe, mainly in the Mediterranean region, an intensive usage of pesticides was recorded during the past 30 years. According to information from agricultural cooperatives of the Mondego valley (Figueira da Foz, Portugal), Primextra ® Gold TZ is the most used herbicide in corn crop fields and one of the 20 best-selling herbicides in Portugal. Copper is mainly used in pesticide formulations. This study aims to determine the ecotoxicological and biochemical (namely fatty acid profiles) effects of the herbicide Primextra ® Gold TZ and the metal copper on marine plankton. The organisms used in this study are three planktonic species: the marine diatom Thalassiosira weissflogii, the estuarine copepod Acartia tonsa and nauplii of the marine brine shrimp Artemia franciscana. Fatty acids (FAs) are one of the most important molecules transferred across the plant-animal interface in aquatic food webs and can be used as good indicators of stress. The conducted lab incubations show that T. weissflogii is the most sensitive species to the herbicide followed by A. tonsa (EC 50 = 0.0078 mg/L and EC 50 = 0.925 mg/L, respectively), whereas the copepod was the most sensitive species to the metal followed by T. weissflogii (EC 50 = 0.234 mg/L and EC 50 = 0.383 mg/L, respectively). A. franciscana was the most tolerant organism both to the herbicide and to the metal (EC 50 = 20.35 mg/L and EC 50 = 18.93 mg/L, respectively). Changes in the FA profiles of primary producer and primary consumers were observed, with the increase of saturated FA and decrease of unsaturated FA contents, especially of highly unsaturated FAs that can be obtained mainly from food and therefore are referred to as 'essential FA'. The study suggests that discharges of Primextra ® Gold TZ or other pesticides mainly composed by copper may be a threat to plankton populations causing changes in the FA contents and thus in their nutritive value, with severe repercussions for higher trophic levels and thus the entire food web.

Fatty Acids’ Profiles of Aquatic Organisms: Revealing the Impacts of Environmental and Anthropogenic Stressors

“…Before the beginning of bioassays, an inoculum of T. weissflogii was harvested from the bulk culture and incubated for 3 days in a chamber with photoperiod (16h L : 8h D ) at 20°C [18]. This procedure was repeated from other two temperatures (15 and 25°C) to the salinity experiments where a set of different temperatures (15, 20 and 25°C) were assessed to a range of salinity concentrations.…”

“…Fatty acids are considered to be an accurate tool in trophic interaction studies [15], mainly due to their importance in the health/stability of the ecosystem, and because they are transferred conservatively to higher trophic levels along the trophic food web [4,16]. Furthermore, FA profiles can reflect structural changes in species' biochemical composition in response to stressors [17][18][19][20]. Lipid components are also very sensitive to environmental changes, which make them an efficient assessment tool to monitor toxicological effects on the marine biota as bio-indicators of ecosystem health [19].…”

Lipid Composition Modifications in the Blue Mussels (Mytilus edulis L.) from the White Sea

“…There was also a substantial decrease in phospholipids, apparently in connection with membrane destruction [84][85][86]. Some papers have reported the modiications in lipid and faty acid composition of hydrobionts, including marine mussels, in response to organic and inorganic pollutants' efect [34,37,[87][88][89][90][91][92][93]. Since the lipid metabolism plays an important role in living organism, it is believed that the lipid and faty acid proile may be used to indicate the organism's health under stress conditions of pollutant efect.…”

Environmental monitoring using bioassays

“…Factors which could affect the toxicity of a compound are physicoÀchemical properties such as pH, temperature, and light (irradiance and exposure time) [25]. Other biomarkers which have been proven to be excellent when studying environmental stressors are biomolecular and biochemical measures [8,9].…”

“…Since microalgae are the first step in the food web, the contamination affects other organisms on a higher level in the food chain. A change in microalgae populations or in their chemical composition due to contamination may have a harmful impact on higher trophic levels in the environment [8]. As microalgae are very sensitive to toxic elements they could be used as an early warning system when monitoring pollution.…”