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Running head: Contaminant-mediated thermal susceptibility in a warming world
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Corresponding author: Marjorie L. Brooks, 1125 Lincoln Dr, Carbondale, IL 62901- 6501
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USA, Tel: 307-399-0576, FAX: 618-453-2806, mlbrooks@siu.edu
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Title: Metals-mediated climate susceptibility in a warming world: larval and latent effects on a
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model amphibian
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Author names and affiliations: Tyler A. Hallman†‡, Marjorie L. Brooks†§
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†
Department of Zoology, Southern Illinois University, 1125 Lincoln Dr, Carbondale, IL 62901-
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6501 USA
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‡
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97331-3803, Tel: 541-737-4531, FAX: 541-737-3590, tyler.hallman@oregonstate.edu
Current address: Department of Fisheries and Wildlife, Oregon State University, Corvallis OR
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§
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USA, Tel: 307-399-0576, FAX: 618-453-2806, mlbrooks@siu.edu
Corresponding author: Marjorie L. Brooks, 1125 Lincoln Dr, Carbondale, IL 62901- 6501
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Original Research Paper prepared for Environmental Toxicology and Chemistry
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SUPPLEMENTARY MATERIAL
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MATERIALS AND METHODS
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Geochemical analyses followed standard methods for quality assurance consisting of
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internal blanks and standards every 10 samples with external quality checks at the beginning and
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end of each analysis, which also included Certified Reference Materials (CRM): Reference
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Solution IV for ICP, Fluka Analytical [1]; ASTM CRM Bovine Liver [2].
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Opposite ends of each water bath differed by 0.05+0.01 oC (Avg+SD) (hourly readings,
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Onset®, HOBO® U20). Aquaria mesocosms within each temperature regime had standard
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deviations <0.01 oC. We did not use degree days as our predictor metric (the cumulative average
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daily temperatures throughout the test) because this metric does not represent pulsed warming
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events, which are extremely important biologically. Moreover, modelers make climate change
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predictions relative to increased temperature, not in degree days.
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For the sake of simplicity, we discuss free ion “concentrations”, recognizing that we
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actually report chemical activities of each metal. We calculated the ionic concentrations of Cd2+,
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Cu2+, and Pb2+ by entering alkalinity, pH, DOC, and all inorganic solutes (Table S1) into the
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geochemical speciation program MINTEQA2 for Windows (Allison Geoscience). For Cu, the
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hardness-based criterion has been replaced by the Biotic Ligand Model (BLM) [3]. However, the
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BLM produces virtually identical estimates of the free cupric ion Cu2+ at this hardness (29 mg/L
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as CaCO3) and DOC (8.21 mg/L), but cannot simultaneously estimate ion concentrations for
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other elements. Thus, we report BCCUs based on MINTEQA2 outputs.
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The chronic criteria that are protective of freshwater life as “total” concentrations of
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dissolved metals at the hardness of the lake water used herein were 1.64 (Cd), 3.92 (Cu), and
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0.19 (Pb) µg/L. We used multiples of the criterion for Cu and Cd: 0, 5, 1.0, 2.5, 5, and 10 (plus
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the background metals in Touch of Nature Reservoir water). For Pb, our nominal targets were 0,
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0.25, 0.5, 1, 2.5, and 5 because Pb toxicity was proportionally greater in preliminary acute
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toxicity tests (data not shown). Although we added Pb to the lowest 4 treatment concentrations,
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the small increases were not detectably greater from the background concentration of 0.23 µg/L
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in the lake water, (which also exceeded the chronic criterion for that metal).In treatments >9.7
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BCCU direct measures of Pb increased and the subsequent MINTEQA2 calculation of the
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bioavailable fraction, resulted in about 1.2-, 2-, and 4-fold multiples of the bioavailable criterion
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for the highest three treatments.
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Complexation of metals with natural carbonates and DOC can reduce the biologically
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available fraction by over 90% [4]. It is worth noting that we used low metals concentrations.
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The shift in bioavailable ions varied from 90% to 73%. Just as a sponge saturated with water
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cannot absorb additional fluid, solutions with higher metals concentrations had more bioavailable
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ions because metal-binding carbonates and DOC were saturated. Geochemical speciation, clearly
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demonstrated nearly 20 years ago, allows us to calculate how the bioavailable, ionic fractions of
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metals can be dramatically changed by natural geochemistry [5].
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Table S1. Composition of filtered water collected from the Touch of Nature Reservoir (mixture
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of 8 water collections) and Test Waters (averages of weekly water analyses throughout the
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chronic exposures). Phosphate and mercury were below detection.
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Touch of Nature Res.
Test Waters
Dissolved
SD
Dissolved
SD
DOC (mg/L)
8.21
2.71
9.04
1.98
pH
7.50
0.26
7.54
0.25
Alkalinity (as mg/L CaCO3)
35.00
1.00
35.00
1.00
Hardness (as mg/L CaCO3)
29.00
2.24
31.03
3.42
Al (µg/L)
4.05
0.10
4.86
0.20
Fe (µg/L)
18.30
11.05
24.89
9.32
Zn (µg/L)
8.55
1.71
9.96
1.93
F (mg/L)
0.11
0.02
0.11
0.02
Cl (mg/L)
1.20
0.17
1.21
0.12
NO3 (mg/L)
1.82
0.19
1.83
0.13
SO4 (mg/L)
40.97
1.94
40.82
1.37
Na (mg/L)
2.06
0.31
2.04
0.22
Mg (mg/L)
1.80
0.18
1.79
0.13
K (mg/L)
1.81
0.88
1.74
0.62
Ca (mg/L)
0.72
0.04
0.72
0.03
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y = -0.015 + 0.0247 * x
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r = 0.750, p = 0.001
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Figure S1.
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Regression of ash free dry mass (AFDM) of Hyla chrysoscelis metamorphs (defined as complete
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tail resorption) by SVL2 for all individuals (n= 163).
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References for Supplementary Material
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[1]
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Wastewater, 21st ed. American Public Health Association, American Water Works Association,
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and Water Environment Federation, Baltimore, MD.
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[2]
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for Testing and Materials, Philadelphia, PA.
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[3]
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Revision, Office of Water Office of Science and Technology. Environmental Protection Agency,
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Washington, DC.
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[4]
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promelas in the presence of photodegraded natural dissolved organic matter. Can J Fish Aquat
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Sci 64:391-401.
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[5]
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Sons, New York.
APHA, AWWA, WEF. 2005. Standard Methods for the Examination of Water and
ASTM. 2011. Annual Book of ASTM Standards Section 11.01 -11.07. American Society
USEPA. 2007. Aquatic Life Ambient Freshwater Quality Criteria - Copper, 2007
Brooks ML, Meyer JS, Boese CJ. 2007. Toxicity of copper to larval Pimephales
Tessier A, Turner DR eds. 1996. Metal Speciation and Bioavailability. John Wiley and
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