Technical Bulletin No. 0762: Reproduction Responses of Adult Fathead Minnows Exposed to Pulp or Paper Mill Effluents During Spawning

<p align="justify">Recent laboratory investigations have indicated that pulp mill effluents at high concentrations may alter reproductive responses of fish. Short-term tests that accurately predict reproduction responses of fish or other aquatic organisms during life-cycle exposures would be valuable tools, allowing more effluents, individual compounds, or treatment options to be evaluated. The results of an investigation of an abbreviated exposure of fish to effluents during the spawning period of their life cycles are described in this bulletin. A fathead minnow (Pimephales promelas) abbreviated life-cycle bioassay, a Ceriodaphnia dubia 7-d bioassay, a marine bivalve embryo/larval test, an echinoderm sperm/egg bioassay, and chemical characterization were completed with four pulp or paper mill effluents. Three of the effluents were from kraft pulp mills with (1) OD+ECF bleaching, (2) ECF bleaching, and (3) no bleaching; the fourth effluent was from a deinking recycle fiber mill. The results of the C. dubia 7- d tests, bivalve test, echinoderm test, and chemical characteristics were compared to earlier investigations with effluents from the same mill to evaluate changes in effluent quality between the two testing periods. Based on these measurements, similar biological and chemical characteristics were found for Mill B, Mill C, and Mill D for the two testing periods. However, based on both the biological and chemical characteristics, effluent from Mill A exhibited some degradation compared to earlier testing when life-cycle studies were completed. This mill was undergoing process changes which probably altered the effluent quality compared to earlier testing.<br /><br />During the abbreviated fathead minnow reproduction tests, all fish were maintained as controls throughout their maturation and first three weeks of spawning to provide a reproductive history.</p>