The effects of heavy metals on the incidence of morphological deformities in Chironomidae (Diptera)

Abstract

ABSTRACT. Streams in urban areas are strongly impacted by the input of organic matter and metals, for instance copper (Cu) and zinc (Zn). These metals are essential for the aquatic biota, but when absorbed in excess they are toxic. In Chiro nomidae larvae, the deleterious effects of heavy metals can be ascertained by analyzing the morphological deformities of the larval mentum, a structure of the oral cavity. In this study, we evaluated I) the bioavailability of Cu and Zn in urban stream sediments and II) the relationship between Cu and Zn concentrations and the incidence of deformities in the mentum of Chironomus larvae. Chironomid flies were collected from four locations in two streams at an urban area in southern Brazil.They were identified and the incidence of deformities in the mentum was quantified. Sediment samples were collected at the same locations where larvae were collected, to quantify the bioavailable fractions of Cu and Zn. The concentrations of Cu in the sediment were similar between the collection sites. However, Zn concentrations varied among sites, being greater in the stretch directly influenced by the input of the organic waste. In total, 2,895 Chironomid larvae were collected. The incidence of deformities in the mentum was above 30% and was correlated with the concentrations of Cu (r = 0.68) and Zn (r = 0.87). This correlation indicates that the municipal waste that is thrown into the city's streams has influenced the occurrence of deformities.

Use of Larval Morphological Deformities in Chironomus plumosus (Chironomidae: Diptera) as an Indicator of Freshwater Environmental Contamination (Lake Trasimeno, Italy)

“…In several laboratory and field studies, an association between environmental contamination level (metals, such as As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, and organic compounds, such as polychlorinated biphenyls (PCBs) and pesticides) and the onset of sublethal effects as deformities of mouthparts (i.e., mentum, mandibles, and pectin epipharyngis) in chironomid larvae has been observed. In this regard, studies on chironomid mouthpart deformities have been developed since the 1970s [26][27][28] and a vast amount of literature based on laboratory bioassays [22,23,[29][30][31][32][33][34][35][36][37][38][39][40][41] and field surveys [21,[42][43][44][45][46][47] endorses that the incidence of these deformities is well associated with the degree of sediment toxicity, whereas no relationship has been detected between deformed phenotypes and organic enrichment; hence, the water quality assessment indices are not always consistent with the use of chironomid deformities [48]. However, some studies have expressed concerns about the association between deformity incidence and toxicants [24,49].…”

Impacto de los efluentes mineros en los macroinvertebrados acuáticos en la cabecera del río Tingo, Cajamarca, Perú

“…Impacto de efluentes mineros… [104] considerados para evaluar la calidad ecológica de los ríos (Shahady & Boniface, 2018;Springer, 2010). Cabe destacar la alta abundancia de la familia Chironomidae, al ser un buen indicador de alteraciones en la calidad del agua, normalmente por compuestos orgánicos y metales pesados (Borkent & Dominiak, 2020;Deliberalli et al, 2018;Youbi et al, 2020). Tabla 2.…”

Assessment of Different Contaminants in Freshwater: Origin, Fate and Ecological Impact

“…Morphological deformities of chironomids are known to provide information about contamination by heavy metals, pesticides and, in general, substances that act as endocrine disruptors [25]. Goretti et al [26] examined the incidence of mentum deformities in populations of Chironomus plumosus (Diptera: Chironomidae) in Lake Trasimeno, central Italy.…”