Effects of Acclimation on the Toxicity of Stream Water Contaminated with Zinc and Cadmium to Juvenile Cutthroat Trout

Abstract

We investigated the influence of acclimation on results of in situ bioassays with cutthroat trout in metal-contaminated streams. Cutthroat trout (Oncorhynchus clarki) were held for 21 days (1) in live containers at a reference or "clean" site having dissolved metals near detection limits (0.01 microg/L cadmium [Cd] and 2.8 microg/L zinc [Zn]; hardness 32 mg/L as CaCO(3)) and (2) at a site in a mining-impacted watershed having moderately increased metals (0.07 microg/L Cd and 38 to 40 microg/L Zn; hardness 50 mg/L as CaCO(3)). The 96-hour survival of each treatment group was then tested in situ at five sites from September 5 to 9, 2002, and each group exhibited a range of metal concentrations (0.44 to 39 microg/L arsenic [As], 0.01 to 2.2 microg/L Cd, and 0.49 to 856 microg/L Zn). Survival was 100% at three sites for both treatments. However, a higher percentage of metal-acclimated fish survived at the site with the second highest concentrations of Cd and Zn (0.90 and 238 microg/L, respectively) compared with fish acclimated at the reference site (100% vs. 55%, respectively). Survival was 65% for acclimated fish and 0% for metal-naïve fish at the site with the largest metal concentrations (2.2 microg/L Cd and 856 microg/L Zn). Water collected from the site with the largest concentrations of dissolved metals (on October 30, 2002) was used in a laboratory serial dilution to determine 96-hour LC(50) values. The 96-hour LC(50) estimates of naïve fish during the in situ and laboratory experiments were similar (0.60 mug Cd/L and 226 microg Zn/L for in situ and 0.64 microg Cd/L and 201 microg Zn/L for laboratory serial dilutions). However, mortality of naïve cutthroat trout tested under laboratory conditions was more rapid in dilutions of 100%, 75%, and 38% site water than in situ experiments.

Functional genomic characterization of metallothioneins in brown trout (Salmo trutta L.). using synthetic genetic analysis

“…Although mining in the region has ceased, many rivers remain polluted with metals 7,8 . Despite evidence that these rivers contain metal concentrations known to affect fish physiology 9–11 ; populations of resident brown trout ( Salmo trutta L.) are found within them. Study of these metal-tolerant trout populations has shown that their genetic structure is different compared to fish from neighbouring control rivers, and that these demographic changes have occurred in association with periods of increased mining activity 12 .…”

Incubating Rainbow Trout in Soft Water Increased Their Later Sensitivity to Cadmium and Zinc

“…We think this alternative explanation is unlikely because the Zn concentrations in the SFH of about 3-8 µg/L were <≈0.1× the Zn LC50 concentration and were less than acclimation concentrations that have been shown to cause a significant increase in Zn resistance. Harper et al (2008) acclimated juvenile cutthroat trout (Oncorhynchus clarki) in soft water stream sites (hardnesses of 33 to 50 mg/L as CaCO 3 ) with mean Zn concentrations of 2.9 or 38 µg/L and observed that the fish acclimated in 38 µg/L Zn were considerably more resistant to a dilution series of stream water contaminated with Cd and Zn. We are only aware of one study that tested a wide range of Cd or Zn pre-exposures to determine a threshold for Fig.…”

Thermal acclimation offsets the negative effects of nitrate on aerobic scope and performance

“…Studies on fish have shown that a thermal shock treatment can increase tolerance of subsequent chemical (Brown et al, 1992), osmotic (Todgham et al, 2005) and hypoxic challenges (Burleson and Silva, 2011). Similarly, prior exposure to zinc, for example, increases tolerance to subsequent exposure to other heavy metal mixtures (Brinkman and Woodling, 2014;Harper et al, 2008). Selection for cross-tolerance between two environmental stressors can arise in species co-adapted to both stressors or from long-term acclimation to one stressor if they influence similar behavioural or physiological mechanisms (Todgham et al, 2005).…”