Long-Term Consequences of High Polychlorinated Biphenyl Exposure: Projected Decline of Delphinid Populations in a Hotspot for Chemical Pollution

Abstract

Rough-toothed dolphins, Steno bredanensis, are closely associated with coastal waters in the Southwestern Atlantic Ocean, increasing the exposure to multiple stressors, such as chemical pollution. Persistent organic pollutants (POPs) are known to affect the health of cetacean species. To comprehend the potential impacts of POPs on populations’ viability, it is necessary to distinguish populations and predict their risk of long-term exposure. Blubbers of rough-toothed dolphins (n = 28) collected along the southeastern (SE) and southern (S) Brazilian coast were screened for polychlorinated biphenyls (PCBs) and pesticides in a gas chromatograph coupled to a mass spectrometer. Based on the contamination profile, a discriminant function analysis separated the rough-toothed dolphins into three ecological populations: two coastal and one offshore. POP concentrations were the highest reported for the species worldwide and highest among the delphinids in Brazilian waters, reaching 647.9 μg g–1 lw for PCBs. The SE population presented 212.9 ± 163.0, S population presented 101.0 ± 96.7, and OCS/S population presented 183.3 ± 85.3 μg g–1 lw (mean ± SD) of PCBs. The potential risk of effects triggered by elevated PCB concentrations was assessed in an individual-based model. A risk of severe decline in population size is projected for the three populations in the next 100 years, especially in SE Brazil, varying between 67 and 99%.

Brominated Flame Retardants and Natural Organobrominated Compounds in a Vulnerable Delphinid Species Along the Brazilian Coast

“…The relative contribution of POPs has been repeatedly used to distinguish cetacean aggregations within a geographic range (Borrell et al, 2006;Bruhn U et al, 1999;Hobbs et al, 2001;Lailson-Brito et al, 2012;de Oliveira-Ferreira et al, 2021;Santos-Neto et al, 2014). The detrended correspondence analysis (DCA) pointed to a differentiation between Guiana dolphins from the nine localities considered in this study (p = 0.0009; Fig.…”

“…Its drainage basin counts 14 million habitants and over 12,000 industries of variate sorts (Kjerfve et al, 1997). A few other studies approached the contamination by organic pollutants in this bay and, repeatedly, the concentrations reported for marine fauna are found to be as high as heavily degraded areas from the Northern Hemisphere (Lailson-Brito et al, 2010;de Oliveira-Ferreira et al, 2021). Hence, marine mammals residing and/or using the bay are under exposure to multiple stressors.…”

“…The S region is undergoing an industrial expansion and already hosts large and important industrial poles (CNI, 2017). The anthropogenic growth in a developing country allows these contaminants reach the marine ecosystem and elevated concentrations of POPs have been recurrently reported in local marine species (Lailson-Brito et al, 2012;de Oliveira-Ferreira et al, 2021;Santos-Neto et al, 2014;Yogui et al, 2010).…”

Large groups of Atlantic spotted dolphin (Stenella frontalis) in a coastal bay from southeastern Brazil

“…While studies have been conducted on many aspects of the biology and ecology of this species (Azevedo et al, 2010; Bisi et al, 2013; Bittencourt, Barbosa, Santos‐Neto, et al, 2020; Caballero et al, 2013; Di Beneditto et al, 2001; Di Tullio et al, 2016; do Amaral et al, 2015; Dorneles et al, 2010; Lavandier et al, 2019; Leonel et al, 2012; Lima et al, 2016; Lopes et al, 2012; Méndez‐Fernandez et al, 2018, 2020; Moreno et al, 2005), information about habitat use, abundance, and behavior are scarce in SWAO. In southeastern Brazil cetaceans face several threats, such as chemical and noise pollution, habitat degradation, and bycatch (Bittencourt, Barbosa, Bisi, et al, 2020; Di Beneditto, 2003; Moreno et al, 2005; Oliveira‐Ferreira et al, 2021; Secchi et al, 2021), and Atlantic spotted dolphins are frequent in this region (Bisi et al, 2013; Moreno et al, 2005).…”

Insight into the Mechanism Underlying Dehalococcoides mccartyi Strain CBDB1-Mediated B12-Dependent Aromatic Reductive Dehalogenation

“…Halogenated aromatics are a class of particularly concerned pollutants due to their substantial emission into the environment, intrinsic properties akin to persistent organic pollutants, and lasting threats to health and the ecosystem. − One well-known example is polychlorinated biphenyls (PCBs) that have been globally banned since 2001. However, recent studies − still identified significantly high burdens of PCBs in marine mammals, collapsing the global population of killer whales by up to 50%. Meanwhile, huge quantities of less regulated emerging aryl halides, such as novel brominated flame retardants and polyhalogenated carbazoles, , have been loaded into the environment, which undermine our health and ecosystem further.…”