Endocrine-Disrupting Chemicals and Climate Change: A Worst-Case Combination for Arctic Marine Mammals and Seabirds?

Abstract

The effects of global change on biodiversity and ecosystem functioning encompass multiple complex dynamic processes. Climate change and exposure to endocrine-disrupting chemicals (EDCs) are currently regarded as two of the most serious anthropogenic threats to biodiversity and ecosystems. We should, therefore, be especially concerned about the possible effects of EDCs on the ability of Arctic marine mammals and seabirds to adapt to environmental alterations caused by climate change. Relationships between various organochlorine compounds, necessary such as polychlorinated biphenyls, dichlorophenyldichloroethylene, hexachlorobenzene, and oxychlordane, and hormones in Arctic mammals and seabirds imply that these chemicals pose a threat to endocrine systems of these animals. The most pronounced relationships have been reported with the thyroid hormone system, but effects are also seen in sex steroid hormones and cortisol. Even though behavioral and morphological effects of persistent organic pollutants are consistent with endocrine disruption, no direct evidence exists for such relationships. Because different endocrine systems are important for enabling animals to respond adequately to environmental stress, EDCs may interfere with adaptations to increased stress situations. Such interacting effects are likely related to adaptive responses regulated by the thyroid, sex steroid, and glucocorticosteroid systems.

A safe operating space for humanity

“…Our assessment on why chemical pollution qualifies as a planetary boundary rests on two ways in which it can influence Earth System functioning: (i) through a global, ubiquitous impact on the physiological development and demography of humans and other organisms with ultimate impacts on ecosystem functioning and structure, and (ii) by acting as a slow variable that affects other planetary boundaries. For example, chemical pollution may influence the biodiversity boundary by reducing the abundance of species and potentially increasing organisms' vulnerability to other stresses such as climate change (Jenssen 2006, Noyes et al 2009). Chemical pollution also interacts with the climate change boundary through the release and global spread of mercury from coal burning, and from the fact that the majority of industrial chemicals are currently produced from petroleum, releasing carbon dioxide when they are degraded or incinerated as waste.…”

The toxicology of climate change: Environmental contaminants in a warming world

“…▪ Pollutant-exposed ectotherms and species at the edge of their physiological tolerance range may be especially sensitive to temperature increases. Altered environmental salinity ▪ ↓ solubility and ↑ bioavailability of pesticides/POPs ("salting out effect") ( Fortin et al, 2008;Heugens et al, 2001;Moore et al, 2003;Schiedek et al, 2007;Schlenk and El-Alfy, 1998;Schwarzenbach et al, 2003;Song and Brown, 1998;Tachikawa and Sawamura, 1994;Wang et al, 2001;Waring and Moore, 2004) ▪ ↑ salinity + ↑ POP/pesticide exposure may alter osmoregulation due to altered enzymatic pathways Altered ecosystems ▪ Altered POP sequestration and/or remobilization through shifts in food sources and starvation events (AMAP, 2004;Braune et al, 2005;Furnell and Schweinsburg, 1984;Jenssen, 2006;Macdonald et al, 2005Macdonald et al, , 2003Olafsdottir et al, 1998;Ramsay and Stirling, 1982;Schiedek et al, 2007, Stirling et al, 1999) ▪ Shifts in disease vector range and severity coupled with toxicant exposure inhibiting immune response may leave wildlife more susceptible to disease ▪ Low level exposures may impair organism acclimation to ecosystem alterations induced by climate change ▪ Climate change induced changes in trophic food webs may alter POP bioaccumulation and biomagnification mykiss) exposed to the insecticide endosulfan as temperature was increased from 13°C to 16°C. In contrast to these findings, pyrethroids and DDT are generally thought to be more toxic under low temperature conditions, which may be due to a sodium channel modulated increase in nervous system vulnerability at lower temperatures (Narahashi, 2000).…”

“…In addition to a potentially diminished immune response, other toxic effects linked to chronic, low level POP exposures may impair organism acclimation to ecosystem alterations (Jenssen, 2006). High blood levels of POPs, including HCB, oxychlordane, DDT metabolites, and PCBs, have been associated with a decrease in viable offspring, a decrease in adult yearly survival rate, and an increase in wing feather asymmetry (Bustnes et al, 2002(Bustnes et al, , 2003Kuenzel, 2003;Leeson and Walsh, 2004).…”

“…High blood levels of POPs, including HCB, oxychlordane, DDT metabolites, and PCBs, have been associated with a decrease in viable offspring, a decrease in adult yearly survival rate, and an increase in wing feather asymmetry (Bustnes et al, 2002(Bustnes et al, , 2003Kuenzel, 2003;Leeson and Walsh, 2004). Thyroid hormone deficits during early life stages affect neurodevelopment and subsequent behavior and cognitive ability in vertebrates (Donahue et al, 2004;Jenssen, 2006). Studies of polar bears have shown disrupted thyroid hormone homeostasis induced by POP exposures (Norstrom, 2000;Skaare et al, 2001;Wiig, 1995).…”

“…Studies of polar bears have shown disrupted thyroid hormone homeostasis induced by POP exposures (Norstrom, 2000;Skaare et al, 2001;Wiig, 1995). Jenssen (2006) hypothesize that since hunting and survival skills are dependent upon behavioral and cognitive abilities, altered thyroid hormone homeostasis associated with POP exposures may be a factor hindering polar bear acclimatization to retreating sea ice. In another example, PCB levels in the glaucous gull (Larus hyberboreus), a top predator in the Arctic food web, were significantly related to the proportion of time that adult gulls were absent from the nest (Bustnes et al, 2001).…”