PARENT SESSION

2C (1) - Biomarkers
Hall 7
1:45 PM - 3:30 PM, Tuesday, 29 April 2003
Chair: Hansen, P.D.¹, ¹
Co-chair: Vindimian, E.², ²

(TU7/11) Comparison of biological and reproduction responses of fathead minnows and largemouth bass exposed to pulp mill effluent before and after process changes.

Borton, Dennis¹, Holm, Stewart², Streblow, William¹, Sepulveda, Marisol^{3, 4}, Noggle, Jessica³, Diana, Cook⁵, Timothy, Gross^{3, 4}, ¹ National Council for Air and Stream Improvement, New Bern, NC, USA² Georgia-Pacific Corporation, Atlanta, GA, USA³ University of Florida, Gainesville, FL, USA⁴ USGS-BRD Florida Caribbean Science Center, Gainesville, FL, USA⁵ National Council for Air and Stream Improvement, Corvallis, OR, USA

ABSTRACT- Pulp mills in the US have implemented or are in the process of implementing changes to meet new "cluster rules" for effluent quality. These studies were designed to evaluate the effects of the process changes on reproductive endpoints and status of two fish species, the fathead minnow Pimephales promelas, a fish species often used for regulatory testing in the US, and the largemouth bass Micropterous salmoides, and important gamefish throughout the US. Process changes between biological testing included ECF bleaching, reduced liquor losses, added condensate stripping, and reduced water use from 83m³/ton of pulp to 60³/ton. Fathead minnow life-cycle tests were completed using seven concentrations from 0 to 100% of the secondary-treated effluent before and after process changes. During an overlapping time period, adult largemouth bass were exposed in five concentrations from 0 to 80% effluent beginning approximately three months before spawning. The IC25 (25% reduction compared to controls)for egg production, among the most sensitive and relevant end-points measured during the fathead minnow life-cycle test, was 23% effluent before the process changes but increased to 32% effluent after process changes, even though water use was reduced. Effects on the more sensitive biological indicators of bass reproductive fitness were significantly reduced at 20% effluent before process changes. After process changes, effects on these parameters were found at 40% effluent. Results indicate effects on reproductive fitness were found at similar concentrations in both species. This investigation will continue after additional process changes.

Key words: fathead minnow, pulp mill effluent, largemouth bass, reproduction