Influence of diet in the accumulation of organochlorine compounds in herons breeding in remote riverine environments

Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird species from Lake Ziway, Ethiopia

Abstract

This study presents the assessment of bioaccumulation and reproductive health risk associated with organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) exposure in carnivorous waterbird species. We investigated OCPs and PCBs exposure in muscle tissues of 4 species of carnivorous waterbird species from Lake Ziway, Ethiopia. The influences of trophic position and size on accumulation of organochlorine pollutants are investigated. The result shows that Dichloro-diphenyl-trichloroethanes (DDTs), Endosulfan and PCBs are detected. DDTs constitute the dominant contaminant among OCPs investigated. Trophic position and wing chord length are positively associated with levels of ∑DDTs. Mean levels of ∑DDTs and ∑PCBs vary from 143.9 to 1051.1 ng g−1 wet weight (ww) and not detected (ND)—3.5 ng g−1 ww, respectively. Mean levels of 4,4′-dichloro-diphenyl-dichloro-ethylene (p,p′-DDE), and 4,4′-dichloro-diphenyl-dichloro-ethane (p,p′-DDD) are significantly varied among the bird species. p,p′-DDE contribute 92.3–98.6% of total DDTs. About 26.7% of birds show p,p′-DDE levels above the minimum threshold to cause reproductive failures in birds. Generally, the findings of this study shows that DDT exposure in high trophic levels bird species from Lake Ziway could result in reproductive health risk. The present study may serve as a baseline for future comprehensive exposure and risk assessment studies.

Article Highlights

Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird and fish species from Lake Hawassa, Ethiopia

Abstract

Agricultural, vector-control and industrial activities around Lake Hawassa pose a risk of organochlorine contamination of the lake biota. To assess organochlorine contamination, we measured levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 3 species of carnivorous waterbird and 3 species of fish. A total of 50 samples of fish and bird species sampled from Lake Hawassa in 2019. We investigated factors influencing accumulation of OCPs and PCBs. Reproductive risk associated with tissue levels of 4,4’-dichloro-diphenyl-dichloro-ethylene (p,p’-DDE) is also estimated. Results show that dichloro-diphenyl-trichloroethane (DDT) is the dominant contaminant found in both bird and fish species. p,p’-DDE is the dominant DDT metabolite in both bird and fish species. Geometric mean of p,p’-DDE varied from 49.8–375.3 and 2.2–7.7 ng g−1 ww in birds and fish, respectively. Average p,p’-DDE level in birds is 33.3 times higher than in fish. p,p’-DDE constitutes 93.4–95.2% of total DDTs in bird species. Degree of exposure, chemical stability, and resistance to environmental and biological degradation could explain higher levels of p,p’-DDE both in bird and fish species. There is significant variation in p,p’-DDE levels among bird and fish species owing to differences in feeding habits, foraging habitat, and lipid content. An increase in DDT levels with increasing size is observed in both bird and fish species. A significant positive association between log-transformed p,p’-DDE, and stable nitrogen isotope ratio (δ15N) values is found. There is no reproductive health risk in bird species as a result of the current levels of p,p’-DDE.

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Seabird-mediated transport of organohalogen compounds to remote sites (North West Greenland polynya)

The role of sea birds as carriers of pollutants over long distances was evaluated by analyzing organochlorine and organobromine compounds in lake sediment cores from three remote sites around the North Water polynya (North West Greenland). One lake, NOW5, was in the vicinity of a little auk (Alle alle L.) bird colony, whereas the other two lakes, NOW14 and Q5, were undisturbed by seabirds. The former was strongly acidic (pH = 3.4) but the latter had a pH close to 8. Due to the guano loading, NOW5 exhibited higher chlorophyll concentrations (74 μg/L) than the other two lakes (1.6-3.4 μg/L), higher content of total phosphorous (0.34 mg/L vs. 0.007-0.01 mg/L) and total nitrogen (3.75 mg/L vs. 0.21-0.75 mg/L). The concentrations of all organohalogen compounds were substantially greater in NOW5 than in the other lakes, indicating the strong influence of these seabirds in the transport and deposition of these compounds to remote sites. However, not all compounds showed the same increases. Hexachlorocyclohexanes and endosulfans were more than 18 times higher in NOW5, the drin pesticides and hexachlorobenzene (HCB), between 9.5 and 18 times and DDTs, polybromodiphenyl ethers (PBDEs), polychlorobiphenyls (PCBs) and chlordanes about 2.7-6 times. These differences demonstrated that the bird-mediated deposition has preservation effects of the less stable and more volatile compounds, e.g. those with log Kaw < -2.4, log Koa < 9 and/or log Kow < 6.8. The sedimentary fluxes of PCBs, HCHs, drins, chlordanes, PBDEs, HCB and endosulfans were highest in the upper sediment layer of the polynya lake (year 2014). In contrast, the highest DDT fluxes were found in 1980. These trends indicate that despite restrictions and regulations, bird transport continues to introduce considerable amounts of organohalogen pollutants to the Arctic regions with the exception of DDTs, which show successful decline, even when mediated by bird metabolism.

Ten Bird Species, Six Guilds, Three Habitats, and 59 Chlorinated and Brominated POPs: What do 64 Eggs from the Largest Economic Hub of Southern Africa tell us?

There is little information on how POPs in eggs of different terrestrial, wetland, and aquatic birds share a large urban and rural landscape relate. We collected and analysed 64 eggs belonging to ten species of six feeding guilds, and compared organic chlorinated pesticide (OCP), polychlorinated biphenyl (PCB), and brominated flame retardants (BFR) residue concentrations and compositions. The eggs were collected in the Gauteng and the northern part of the Free Sate provinces of South Africa, one of the largest economic hubs in Africa. White-breasted Cormorant and African Darter eggs (at the highest trophic level as large aquatic predators) had the highest ΣOCP and ΣPCB concentrations, and Cape Sparrow and Southern Masked Weaver (granivores) eggs had the lowest concentrations, corresponding to the lowest trophic level in our collection. The highest percentage p,p'-DDT were in eggs of the terrestrial insectivore Crowned Lapwing (24%) and the scavenging African Sacred Ibis (17%), and the lowest in African Darter (1.0%) and White-breasted Cormorant (0.9%) eggs, suggesting that recency of DDT releases in a region cannot be gauged by this metric. African Sacred Ibis and Southern Masked Weaver eggs had the highest ΣBFR concentrations, with Crowned Lapwing, Cattle Egret, and White-breasted Cormorant eggs the least. Based on feeding guilds, the mean ΣPOP concentrations increased from granivore, aquatic omnivore, scavenger, terrestrial insectivore, small aquatic predator, to large aquatic predator. Mean ΣPOP concentrations in eggs increased from terrestrial, to wetland, to aquatic habitat birds. Interesting patterns were observed with multivariate analyses. There were no significant regressions between egg size and any summed POP classes. ΣBFR concentrations were not correlated with ΣOCPs or ΣPCBs. Eggshell thinning of African Darter eggs was associated with p,p'-DDE and ΣPCB suggesting risk. Other metrics also suggest risk. Therefore, different species of terrestrial and aquatic birds from the same area acquire and deposit POPs in different proportions and quantities in their eggs. Trophic levels and habitat explain the overall patterns, but detailed differences were found, some of which we are unable to explain. Based on POPs residues in terrestrial, wetland, and aquatic bird eggs, different POPs classes behave differently in a shared large inland industrial area, complicating deductions about POPs and associated risks based on one or few species.

Organochlorine Pesticide Residues Among Colonial Nesting Birds in Tamil Nadu, India: A Maiden Assessment from Their Breeding Grounds

Use of pesticides continues to be indiscriminate, and birds are one of the worst affected non-targeted organisms. Information on the ill effects of pesticides on birds far from desired in India. Despite the presence of a wide variety and number of birds, there is exceedingly little data on organochlorine pesticide (OCP) residues in colonial nesting birds in sanctuaries of India. A total of 76 individuals belonging to 14 species of birds found dead between March 2008 and March 2010 were analyzed for pesticide residues in various tissues. Of all the OCPs analyzed, concentration of HCH was found to be the highest. Magnitude of contamination varied widely among species. Accumulation pattern of OCPs in colonial nesting birds was in the order ∑HCH > ∑endosulfan > ∑DDT > heptachlor epoxide > dieldrin. Pesticides, namely p,p-DDE and β-HCH contributed most towards the total OCPs. Concentrations of DDT and its metabolites, HCH and isomers, dieldrin, and heptachlor epoxide were lower than the concentrations reported for various species of birds elsewhere in India. Although the sanctuaries presently studied have official boundaries, physical demarcations are missing and there are no proper earthen dykes particularly in Vedanthangal and Koonthankulam Bird Sanctuaries. During monsoon, runoff not only floods the Sanctuaries but also the cultivated areas nearby. Run off brings in residues of pesticides and fertilizers from the agricultural lands into the sanctuaries. Although OCP results in this study were below threshold limits, it may be noted that the long duration exposure even to low levels of pesticides could create a significant impact at population level. Hence, earthen dykes need to be built to avoid agricultural runoff entering the Sanctuary and also help to hold sufficient amount of water for breeding birds.

Levels of organochlorine pesticide residues in fresh water fishes of three bird sanctuaries in Tamil Nadu, India

Organochlorine pesticide (OCP) residues were determined in nine species of fresh water fishes caught from three bird sanctuaries in Tamil Nadu, India. A total of 302 fishes were analyzed for various types of OCPS. OCPs, namely hexachlorocyclohexane (HCH), dichloro diphenyl trichloroethane (DDT), heptachlor epoxide, endosulfan, and dieldrin were detected among various species of fishes. Among the various OCPs analyzed, HCH was the most frequently detected pesticides. Among the HCH isomers, β HCH contributed more than 50% to the Σ HCH. p,p' DDT, the metabolites of DDT, had high percentage of occurrence. Among the cyclodiene insecticide residues, endosulfan was detected in more than 60% of the fishes. Varying levels of ΣOCPs (a sum of Σ HCH, Σ DDT, Σ endosulfan, heptachlor epoxide, and dieldrin) were detected in various fish species, although it was not significant (p > 0.05). However, significant variations in OCPs were observed among location and between seasons (p < 0.05). However, continuous monitoring is recommended to facilitate the early identification of risks not only to the fishes, but also to fish-eating birds breeding in these sanctuaries.

Can environmental pollution by metals change genetic diversity? Ucides cordatus (Linnaeus, 1763) as a study case in Southeastern Brazilian mangroves

Industrial areas on estuarine systems are commonly affected by heavy metals, affecting all local biota. Random Amplified Polymorphic DNA (RAPD) was used to evaluate genetic diversity of Ucides cordatus at mangroves in southeastern Brazil (Juréia, J; São Vicente, SV; and Cubatão, C), with distinct pollution levels by metals. The genetic diversity of this species was compared with concentrations of metals (Cd, Pb, Cu, Cr and Hg) in the environment. A pollution gradient was confirmed (SV>C>J), with low levels detected in water, except for mercury in SV. All metals in the sediment samples were below Threshold Effect Level (TEL), without an apparent biological risk to the biota. Genetic distance was very similar between J and C, with SV occurring as an out-group. RAPD was a powerful tool to investigate the effect of metal pollution on genetic diversity of this mangrove crab, and to evaluate the conservation status of the mangrove ecosystem.