Chronic perchlorate exposure causes morphological abnormalities in developing stickleback

Abstract

Few studies have examined the effects of chronic perchlorate exposure during growth and development, and fewer still have analyzed the effects of perchlorate over multiple generations. We describe morphological and developmental characteristics for threespine stickleback (Gasterosteus aculeatus) that were spawned and raised to sexual maturity in perchlorate-treated water (G1,2003) and for their offspring (G2,2004) that were not directly treated with perchlorate. The G1,2003 displayed a variety of abnormalities, including impaired formation of calcified traits, slower growth rates, aberrant sexual development, poor survivorship, and reduced pigmentation that allowed internal organs to be visible. Yet these conditions were absent when the offspring of contaminated fish (G2,2004) were raised in untreated water, suggesting a lack of transgenerational effects and that surviving populations may be able to recover following remediation of perchlorate-contaminated sites

Perchlorate disrupts embryonic androgen synthesis and reproductive development in threespine stickleback without changing whole-body levels of thyroid hormone

“…In concordance with the T 3 and T 4 hormone results, we found no significant changes in external morphological characters, including those characters that we had previously found to be affected by perchlorate in stickleback from the same study population. It is not clear why our current study did not replicate findings from our earlier study showing induced changes to gross anatomy by chronic perchlorate exposure in stickleback, but our earlier work occurred under different experimental conditions which included use of plastic tanks and natural outdoor lighting and ambient temperatures of the Alaskan summer (Bernhardt et al, 2011). These disparate results underscore the problem that responses to endocrine disruptors may have a strong environmental component, such as interaction with other chemicals.…”

“…Endocrine disruption by exogenous pollutants often perturbs gonad size (Mukhi and Patiño, 2007; Bernhardt et al, 2011; Sharma and Patiño, 2013), shape (Wester, 2003), and reproductive development and behavior (Woodling et al, 2006; Bernhardt and von Hippel, 2008). We previously found that perchlorate masculinizes both male and female stickleback (Bernhardt et al, 2006), leading to the hypothesis that perchlorate can have androgenic effects in some organisms mediated through the thyroid itself.…”

“…Contaminants that interfere with the vertebrate hypothalamic–pituitary–thyroid (HPT) axis have clear deleterious effects, particularly in aquatic organisms (Power et al, 2001; Milnes et al, 2006; Carr and Patiño, 2011). A large number of abnormal phenotypes have been ascribed to thyroid-disrupting chemicals, including altered body size and shape (Lawrence et al, 2005; Bernhardt et al, 2011), disrupted immune function (Capps et al, 2004), modified bone development (Stevens et al, 2000; Bernhardt et al, 2011), and changes in behavior and gonad masculinization or feminization in threespine stickleback ( Gasterosteus aculeatus ) and zebrafish ( Danio rerio ), respectively (Bernhardt et al, 2006; Mukhi and Patiño, 2007; Bernhardt and von Hippel, 2008; Sharma and Patiño, 2013). The biological mechanisms of contaminant-induced phenotypic abnormalities are largely unknown, however.…”

“…Perchlorate exposure in teleost fishes leads to a wide array of altered phenotypes, some of which suggest disruption to development outside of the HPT axis (Crane et al, 2005; Bernhardt et al, 2006; Bernhardt and von Hippel, 2008; Sharma and Patiño, 2013). Effects of chronic perchlorate exposure on stickleback include abnormal lateral plate development, decreased swimming performance, slower growth rates, and reduced pigmentation (Bernhardt et al, 2006, 2011; Bernhardt and von Hippel, 2008). Perchlorate also appears to act via an unknown mechanism to alter gonad development and sex determination in teleosts, a finding not predicted to occur solely via thyroid disruption (Bernhardt et al, 2006; Mukhi and Patiño, 2007; Sharma and Patiño, 2013); the HPT axis, however, has been implicated in effects on reproductive development and function in teleosts (Carr and Patiño, 2011; Flood et al, 2013).…”

Differential Responses of Two Rice Varieties to Perchlorate Stress

“…The toxicity responses due to ClO 4 exposure have been reported in different plants and animals [18,19]. With the potential for food crop to be a significant source of perchlorate exposure in humans, and because phytoremediation has been suggested as a remediation option, a mechanistic understanding of perchlorate's phytotoxicity is warranted.…”