Occurrence and endocrine effects of agrichemicals in a small Nebraska, USA, watershed

Abstract

The Bow Creek watershed (Nebraska, USA) is dominated by the production of beef cattle and row crops; therefore, surface waters are likely to receive runoff containing steroid hormones and pesticides. The goal of the present study was to determine the occurrence and endocrine effects of agrichemicals in this watershed. To accomplish this, four sites within the watershed-Pearl, Bow, and East Bow Creeks and a site at the confluence with the Missouri River-were selected. In June of 2008, polar organic chemical integrative samplers (POCIS) were deployed at each site, whereas in June of 2009, water and sediment samples were collected. Caged fathead minnows (Pimephales promelas) were deployed at all of the selected sites in both years. Analysis of these samples revealed that steroid hormones were not present; however, pesticides were present in POCIS extracts and water samples. In general, the amount of pesticides was higher in POCIS retrieved from Pearl and Bow Creeks than in POCIS from East Bow Creek and the confluence. This variation between sites appeared to be related to row crop density, as row crop land cover surrounding the Pearl and Bow Creek sites was higher than that surrounding the East Bow and confluence sites. To determine the endocrine effects of agrichemicals within this watershed, the hepatic mRNA expression of vitellogenin and estrogen receptor α (ERα), as well as the gonadal expression of P450 aromatase A, was determined for the caged minnows. Females deployed at East Bow Creek and the confluence experienced decreases in the expression of ERα, suggesting that these females had been defeminized; however, this defeminization could not be attributed to any of the pesticides detected at these sites.

Compensatory response of fathead minnow larvae following a pulsed in-situ exposure to a seasonal agricultural runoff event

“…Indeed, field studies exposing fish to seasonally occurring agricultural runoff have documented endocrine disruption in the reproductive axis of otherwise intact adult females (Sellin et al 2009;Sellin Jeffries et al 2011a;Sellin Jeffries et al 2011b;Knight et al 2013;Ali and Kolok 2015;Zhang et al 2015). Periods of elevated discharge and pesticide loads were associated with decreased expression of the steroid responsive genes vitellogenin (VTG), estrogen receptor subtype α (ERα) and androgen receptor (AR) (Knight et al 2013;Ali and Kolok 2015;Zhang et al 2015).…”

The spring runoff in nebraska's (USA) Elkhorn River watershed and its impact on two sentinel organisms

“…The Elkhorn River in Nebraska, USA, is one such agriculturally dominated watershed in which spring snowmelt and heavy rainfall can result in the transport of agrichemicals from row crop landscapes to local waterways . These transported agrichemicals can act as a source of endocrine active compounds to watersheds such as the Elkhorn River, and exposure to such compounds has been shown to result in significant impairments in endocrine function . For example, deployment of female fathead minnows ( Pimephales promelas ) in the Elkhorn River for 7 d has been shown to result in significant reductions in the mRNA expression of the estrogen‐responsive genes vitellogenin (VTG) and estrogen receptor alpha (ERα) .…”

“…Historically, fathead minnows have been used as the environmental sentinel organism to determine the impact of agrichemical runoff in the Elkhorn River watershed .However, because agricultural ponds have been shown to provide breeding grounds that actively support amphibian populations , amphibians may also be exposed to agrichemical runoff. This would suggest that amphibians are also important environmental sentinel organisms in the midwestern United States, particularly given their purported sensitivity to atrazine .…”

Predicting characteristics of rainfall driven estrogen runoff and transport from swine AFO spray fields

“…While the potential effects of steroidal estrogens on aquatic populations are well established (Sellin et al, 2011; Leet et al, 2012), few studies have investigated the mobilization and transport of these compounds from AFO spray fields following rainfall-induced runoff events (Shappell et al, 2010; Zhao et al, 2010; Gall et al, 2014). Therefore, there is limited understanding of how the surface runoff and transport of estrogens from AFO point sources may be affected by various combinations of environmental variables, such as lagoon slurry application rates, weather, crop management, and soil characteristics.…”