Trophic transfer and effects of DDT in male hornyhead turbot ( Pleuronichthys verticalis ) from Palos Verdes Superfund site, CA (USA) and comparisons to field monitoring

Abstract

<p class="first" id="P1">High concentrations of DDT and metabolites (ΣDDT) have been detected in sediment and the demersal flatfish hornyhead turbot ( <i>Pleuronichtys verticalis</i>) collected from Palos Verdes (PV), California, USA, a site contaminated with over 100 metric tons of DDT throughout 1960s to 70s. This study was elaborated to assess the transfer of ΣDDT from PV-sediment into polychaete ( <i>Neanthes arenaceodentata</i>) and hornyhead turbot, and to investigate if the genomic responses in turbots from two different laboratory exposures mimic those in turbots caught in PV (PV-turbot). Turbot fed PV-sediment-contaminated polychaete for 7 days had liver concentrations of ΣDDT similar to PV-turbot. After 28 days, ΣDDT also accumulated by livers of turbot gavaged with ΣDDT mixture. <i>In vitro</i> cell bioassays indicated significant increases of 17β-estradiol equivalents (EEQ) in turbots as compared to the control in the 7-day study. These responses corresponded to those measured in PV-fish. Glucocorticoid receptor (GR), anti-androgen receptor (anti-AR), estrogen receptor (ER) or aryl hydrocarbon receptor (AhR) activities were also observed in PV-sediment, and PV-sediment-exposed worm. Anti-AR, AhR and GR activities were significantly higher in PV-sediment than reference sediment (San Diego, SD). Higher transcripts of hepatic VTG, ERα and ERβ were found in PV-turbot than SD-turbot, but unaltered in fish exposed to sediment-contaminated worms for the 7-day study. In contrast, liver extracts from the 28-day treatment of ΣDDT showed lower EEQ but similar hepatic VTG and ERβ transcripts relative to those of PV-turbot. These data indicated that trophic transfer of sediment-associated DDT in 7-day exposures corresponded to field measurements of DDT residues and <i>in vitro</i> ER bioactivities, but failed to mimic <i>in vivo</i> biological effects observed in field fish. In contrast, treatment with ΣDDT alone for 28 days mimicked <i>in vivo</i> biological effects of DDTs in PV fish, but did not correspond to liver concentrations or <i>in vitro</i> bioactivities. </p><p id="P2"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/eda137e6-bad3-4f03-8ba4-929dd0f65d9e/PubMedCentral/image/nihms-776203-f0001.jpg"/> </div> </p>