Fipronil and 2,4-D effects on tropical fish: Could avoidance response be explained by changes in swimming behavior and neurotransmission impairments?

The Longitudinal Profile of a Stream Contaminated With 2,4-D and its Effects on Non-Target Species

“…Previous research assessed 2,4-D toxicity using laboratory experiments and microcosms (Silva et al 2020b;Moreira et al 2021;Pinto et al 2021a, c). To the best of our knowledge, this research is the first to evaluate 2,4-D retention and toxicity along a stream reach through a controlled whole-stream addition of the herbicide.…”

“…Furthermore, pesticide mixtures, including 2,4-D and other herbicides, can synergistically affect aquatic communities at concentrations below 16 µg L −1 (Relyea 2009). In the last few years, several studies evaluated the 2,4-D toxicity to non-target aquatic organisms from different trophic levels, aquatic compartments, and life patterns, including the microalgae Raphidocelis subcapitata (Moreira et al 2020), the neotropical cladoceran Ceriodaphnia silvestrii (Silva et al 2020b), the tropical midge Chironomus sancticaroli (Pinto et al 2021c), the tropical amphipod Hyalella meinerti (Pinto et al 2021b), the tadpole Lithobates catesbeianus (Freitas et al 2019), and the fish Danio rerio and Hyphessobrycon eques (Moreira et al 2021). Documented effects of pesticides in non-target species are not surprising since these compounds can disturb physiological mechanisms that are essential for their survival and are common across habitats (Rydh Stenström et al 2021).…”

Could Contamination Avoidance Be an Endpoint That Protects the Environment? An Overview on How Species Respond to Copper, Glyphosate, and Silver Nanoparticles

“…As the use of avoidance in multi-compartmented exposure systems, first proposed by Lopes et al [14], supposes a shift in the paradigm of how organisms are exposed to contaminants and which kind of response is measured (not toxicity, but repellence instead), this approach provides a complementary perspective concerning the risk that contamination may represent to ecosystems. This response can be applied in different approaches, either by integrating the loss of population due to avoidance with mortality and reproduction [34,35] thereby assessing the decline of populations due to these three responses; simulating changes in the avoidance response and spatial distribution of organisms under scenarios of global changes [36] to predict the loss of populations due to the inhospitable environmental conditions or integrating it with other responses to assess how avoidance can be impaired if some toxic effects occur in organisms [37,38]. As a complementary tool to evaluate how contamination affects the spatial distribution of species, this approach allows researchers to apply a more ecological view of ecotoxicology by simulating some real scenarios, in which the chemical heterogeneity can generate attractive and repellent areas.…”

Not Only Toxic but Repellent: What Can Organisms’ Responses Tell Us about Contamination and What Are the Ecological Consequences When They Flee from an Environment?

“…This is of great importance if static systems (without peristaltic pumps) are used, as it is difficult to maintain the gradient for a long time when the fish are swimming continuously. Avoidance studies with fish have also been performed with different contaminants such as: tuna fish processing plant effluent [72], triclosan [73], atrazine [74], river samples [75,76], bisphenol [77], copper [78,79], fipronil and 2,4-D [80], dairy wastewater [76], among others. In the study by Araújo et al [71], the avoidance response was assessed during very short exposure periods, sometimes not exceeding 4 h. In almost all cases, the avoidance initially observed (e.g., after 30 min) was similar to the avoidance at different periods during the remaining hours of the experiment.…”