Feathers of Bulbulcus ibis (L.) as a non-destructive biomonitoring tool for assessment of lead pollution: A case study from various severely contaminated wetland habitats

Abstract

Present study aims to determine the lead (Pb) concentrations in the feather samples of cattle egret (Bulbulcus ibis) found in different contaminated wetland habitats present in the state Odisha, India. This study also focused on the heavy metal concentrations of top layer soil and on the level of metal accumulation in prey samples (i.e. small fishes) preferred by cattle egrets for explaining the level of amplification of Pb in different polluted wetland habitats. Moreover, reasons behind the variations of Pb concentrations within the sampled wetland habitats are explained. Feathers, Prey samples and sediments from their foraging habitats were collected from eight different heronries. Determination of Pb concentrations in samples has undergone acid digestion followed by elemental analysis (i.e. Pb) in Atomic Absorption Spectrophotometer (AAS). The results indicated that Pb concentration was varied significantly in soil (15.13-56.26µg/g), Prey (0.21-55.76µg/g) and feathers (5.6-49.86µg/g) in different sites. The highest concentration was found at Hirakud in soil and prey. However, feather samples showed the highest concentrations of lead in Talcher may be due to the mining activities in and around the sampling location. Present study found the positive correlation (p<0.05) between soil, prey and feather samples of cattle egret among the eight sampling locations may be due to many of the mining, industrial and anthropogenic sources. The processes like geophagy and biomagnification may contribute to the positive correlation among the sampling habitats. Concluding this work, it might be confirmed that avian feathers can be used as non-destructive biomonitoring tool for assessment of the heavy metal contamination level in various segments of different ecosystems. Hence, based on the results of the study, the environmental management plan could be suggested and implemented for better conservation of the avian fauna.

Evidence of Low-Habitat Contamination Using Feathers of Three Heron Species as a Biomonitor of Inorganic Elemental Pollution

“…Herons can be good indicators of elemental exposure for different reasons including the following: (i) they feed in the aquatic habitat; (ii) they are long-lived organisms; (iii) they are secondary consumers, and thus exposed to a wide range of chemicals; and (iv) their position at the top of the food chain makes them susceptible to bioaccumulation of heavy metals from various sources [19][20][21]. Many tissues of birds, such as feathers, liver, bones, and blood, but also eggs and eggshells, have been used to monitor avian exposure and assess the risk [22][23][24][25]. Among these, feathers have many advantages because they can be obtained quickly and repeatedly from the same individual without affecting its health, and their preservation does not require refrigeration [25].…”

“…Many tissues of birds, such as feathers, liver, bones, and blood, but also eggs and eggshells, have been used to monitor avian exposure and assess the risk [22][23][24][25]. Among these, feathers have many advantages because they can be obtained quickly and repeatedly from the same individual without affecting its health, and their preservation does not require refrigeration [25]. Moreover, in the case of herons, feathers reflect the local contamination better than other tissues, because chicks feed on prey collected close to the colony, and considerable amounts of elements are stored in the feathers during the breeding of chicks [26].…”