Histologic, immunologic and endocrine biomarkers indicate contaminant effects in fishes of the Ashtabula River Luke R. Iwanowicz • Vicki S. Blazer • Nathaniel P. Hitt • Stephen D. McCormick • David S. DeVault • Christopher A. Ottinger Accepted: 17 August 2011 / Published online: 1 September 2011 Ó Springer Science+Business Media, LLC (outside the USA) 2011 Abstract The use of fish as sentinels of aquatic ecosys- tem health is a biologically relevant approach to environ- mental monitoring and assessment. We examined the health of the Ashtabula River using histologic, immuno- logic, and endocrine biomarkers in brown bullhead (BB; Ameiurus nebulosus) and largemouth bass (Micropterus salmoides) and compared fish collected from a reference site (Conneaut Creek). Seasonal analysis was necessary to distinguish differences in fish between the two rivers. Overall BB from the Ashtabula River had a lower condi- tion factor and significantly more macrophage aggregates than those from the reference site. Reduced bactericidal and cytotoxic-cell activity was observed in anterior kidney leukocytes from both BB and largemouth bass from the Ashtabula River. Lower plasma thyroxine and triiodo- L-thyronine in both species in the Ashtabula River indicated disruption of the thyroid axis. Differences in physiological biomarker responses were supported by body burden chemical concentrations when data were analyzed on a seasonal basis. The use of two fish species added a level of rigor that demonstrated biological effects were not exclu- sive to a single species. The results provide strong evidence that contaminants have affected fish in the Ashtabula River, a Great Lakes Area of Concern, and provide a baseline by which to evaluate remediation activities. Keywords Immunomodulation  Endocrine disruption  Bullhead  Bass  Great Lakes  Area of Concern  Ashtabula River  Northeastern Ohio Introduction The Ashtabula River is located in northeastern Ohio and drains a 350 km 2 watershed that empties into the central basin of Lake Erie (Imamoglu et al. 2002). Like many rivers that flow into Lake Erie, the Ashtabula River is contaminated with a multitude of industrial chemicals, and the lower two miles is listed as a Great Lakes Area of Concern (AOC). This AOC designation was issued by the International Joint Commission during 1988 based on numerous Beneficial Use Impairments (BUI) including, but not limited to (1) restrictions on fish and wildlife con- sumption, (2) degradation of fish and wildlife populations, and (3) fish tumors or other deformities. Contamination of the Ashtabula River is primarily the result of decades of industrial metals-fabrication, chemical production and mismanagement of waste disposal along Fields Brook, a United States Environmental Protection Agency (USEPA) Superfund site. Fields Brook is a tributary of the Ashtabula River with a confluence at approximately river kilometer 2.57, and was the major source of hazardous substances Electronic supplementary material The online version of this article (doi:10.1007/s10646-011-0776-0) contains supplementary material, which is available to authorized users. L. R. Iwanowicz (&)  V. S. Blazer  C. A. Ottinger US Geological Survey, Leetown Science Center, Fish Health Branch, Kearneysville, WV 25430, USA e-mail: liwanowicz@usgs.gov N. P. Hitt US Geological Survey, Leetown Science Center, Aquatic Ecology Branch, Kearneysville, WV 25430, USA S. D. McCormick US Geological Survey, Leetown Science Center, Conte Anadromous Fish Research Center, Turners Falls, MA, USA D. S. DeVault US Fish and Wildlife Service, Ecological Services, 1 Federal Drive, Fort Snelling, MN 55111, USA 123 Ecotoxicology (2012) 21:165–182 DOI 10.1007/s10646-011-0776-0