Development of molecular indicators for adverse health responses of effluent exposure in caged longnose dace (Rhinichthys cataractae) in ACWA raceways

The goal of this experiment was to assess transcriptomic responses in caged longnose dace (Rhinichthys cataractae) (LND) females and males exposed to 5% final effluent over time to identify potential transcriptomic markers that can be used as reliable indicators and that can further be explored in field-based ecotoxicogenomic studies in the Bow River. We used the Advancing Canadian Wastewater Assets (ACWA) artificial streams to cage LND for 28 days exposed to either 5% final effluent or control. Overall design: Wild longnose dace (Rhinichthys cataractae; LND) were collected from an upstream reference site in the Bow River, Calgary, Alberta. Captured LND (376) were placed in minnow buckets subsequwntly deployed in six artificial raceways at the ACWA facility. Each cage was stocked with 20 LND males and females. Three out of six raceways contained Bow River water (control treatment) while the remaining three contained 5% Pine Creek final effluent mixed with Bow River water (exposure treatment). There were three cage replicates per each Bow River and Pine Creek raceway. Before the onset of the experiment, a subsample of 15 LND females and 16 males was processed immediately upon collection from the reference site in the Bow River, to establish baseline responses, and this marked day 0. A subset of these samaples were subjected to RNA sequencing (n = 10; 6 males + 4 females; group A). Caging exposure lasted 28 days; LND were sampled on day 7, 14, and 28 by randomly retrieving a cage replicate from each of the 6 raceways. Subsets of fish including both male and female LND from all sampling points were also subjected to RNA sequencing day 7 (n = 24; (6 males + 6 females) x 2 treatments; groups B and C), day 14 (n = 24; (6 males + 6 females) x 2; treatments groups D and E) and day 28 (n = 24; (6 males + 6 females) x 2; treatments groups F and G).