Use of paired fathead minnow (Pimephales promelas) reproductive test. Part 1: Assessing biological effects of final bleached kraft pulp mill effluent using a mobile bioassay trailer system

Abstract

Reproductive effects have been recorded in wild fish in waters receiving pulp mill effluent (PME) since the mid to late 1980s. Laboratory assays with fathead minnow (FHM; Pimephales promelas) have been developed to better understand fish responses to PME. However, observations from laboratory studies have been variable, making it difficult to establish cause/effect relationships. A lack of environmental relevance in these laboratory studies may have contributed to the variability observed. The objectives of the present study were, first, to determine the effects of bleached kraft PME (BKME) on FHM under environmentally realistic conditions (i.e., ambient water and effluent quality) and, second, to determine the suitability of pair-breeding FHM to better link BKME-induced changes in indicators at the biochemical, individual, and population levels. A mobile bioassay trailer was situated on-site at a bleached kraft mill for 60 d, allowing supply of both ambient water (Lake Superior, Canada) and final BKME. The reproductive output of FHM was initially assessed for 21 d to obtain baseline data pre-exposure. At the end of the pre-exposure period, selected breeding pairs were exposed to final BKME (100% v/v and 1% v/v) for 21 d. Results demonstrated a stimulatory response pattern at 1% BKME (e.g., increased egg production) compared to control. In the 100% treatment, spawning events were reduced and fewer eggs were produced during the first two weeks of exposure. Exposure to 100% (v/v) BKME also resulted in ovipositor development in males and development of male secondary sex characteristics in females. Obtaining pre-exposure data and use of pair-breeding FHM in this assay gave a sensitive indication of effluent effects and allowed accurate comparisons of endpoints to be made.

The use of field-based mesocosm systems to assess the effects of uranium milling effluent on fathead minnow (Pimephales promelas) reproduction

“…They are also tolerant of a wide range of water quality parameters such as pH, temperature, alkalinity and hardness (Ankley and Villeneuve 2006). The partial lifecycle reproductive assay using fathead minnows as outlined by Ankley et al (2001) and modified by Rickwood et al (2006aRickwood et al ( , b, 2008) is a useful tool in assessing the effects on both adult fish and their offspring.…”

Investigating the link between pulp mill effluent and endocrine disruption: Attempts to explain the presence of intersex fish in the Wabigoon River, Ontario, Canada

“…A summary study by Kovacs et al [4] on five Canadian pulp and paper mills (PAPMs) found that none of the effluents affected overall fish reproduction; however, three of the five mills did show vitellogenin induction in males. A similar study by Rickwood et al [5], which did reveal endocrine disruption leading to decreased reproduction, found that increased levels of testosterone in female fathead minnows were linked with decreased egg production. Other studies have found that PME-induced endocrine disruption led to male-biased populations and intersex fish in laboratory [14] and field experiments [15].…”

“…The short-term fathead minnow bioassay [5,6,19] requires a pre-exposure and exposure period, each of approximately 21 d in length. The pre-exposure trial was performed in the absence of effluent to establish baseline reproductive data and successful breeding pairs to be used in the exposure period.…”

Pulp and paper mill effluents induce distinct gene expression changes linked to androgenic and estrogenic responses in the fathead minnow (Pimephales promelas)

“…Male secondary sexual characteristics have been observed in females following much longer life-cycle tests with bleached sulfite mill effluent [26] or kraft mill effluent following secondary treatment [2,4], although not in all cases [7,13].…”

“…Handa et al [30] postulated that testosterone as well as dehydrotestosterone can be metabolized by P450 enzymes to compounds that can bind ERb [2,31,32]. In fish species, Menuet et al [33] showed a downregulation of zebrafish ERb after treatment with estradiol.…”