Meeting Abstract
Recent evidence indicates that some of California’s coastal estuaries are contaminated with the chemical 4-nonylphenol (4-NP). The compound 4-NP is a well-established endocrine-disrupting chemical with estrogenic properties, and exposure to 4-NP has been found to alter estrogen hormone signaling in many marine organisms. In fish, estrogen itself can modulate osmoregulatory function and we hypothesize that estuarine fishes exposed to 4-NP in California’s estuaries might suffer deleterious impacts due to impaired osmoregulatory abilities in the rapidly changing salinity conditions of coastal estuaries. The aim of our study is thus to determine if 4-NP interrupts the ability of the estuarine arrow goby (Clevelandia ios) – a benthic fish abundant on the mud flats of California’s estuaries – to osmoregulate under changing salinity conditions. Adult mixed-sex arrow gobies were exposed in seawater (33 ppt) to either high dose 4-NP (100 ug/L), low dose 4-NP (10 ug/L), 17β-estradiol (50 ng/L; positive control), or ethanol vehicle only (negative control) for 12 days. Fish were collected from each treatment tank at times representing either a baseline (0 hrs; all fish at 33 ppt salinity) sample, or at 6 hrs or 24 hrs time points following transferred to tanks containing water of 33 ppt (control), 20 ppt, or 5 ppt salinity. Gills tissue was dissected from each fish for evaluation of Na+/K+ ATPase enzyme activity, and for quantification of relative gene expression levels for several ion and water transport proteins (e.g., sodium-hydrogen exchanger-3, nhe3; aquaporin-3, aqp3) critical for maintaining osmotic balance during seawater to fresh water salinity transitions.
