Abstract:
The dataset includes toxicity information for the scleractinian coral species Siderastrea siderea following a 48-hour exposure to 1-methylnaphthalene. Laboratory assays were conducted at Nova Southeastern University Oceanographic Center. The dataset includes coral color/condition scores, photosynthetic efficiency (PAM) measurements, growth rate, and mortality of the coral nubbins at each time point. Also included is the concentration of 1-methylnaphthalene in each exposure chamber at the beginning and end of the exposure. This information is used to calculate the sublethal and lethal toxicity endpoints (EC50 and LC50) and critical body burden following application of the target lipid model.
Suggested Citation:
Renegar, D. Abigail; Turner, Nicholas R.. 2019. Toxicity of 1-methylnaphthalene to Siderastrea siderea. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-d2ww-0y33
Data Parameters and Units:
Coral condition score (scale of 0-3, no units), photosynthetic efficiency (Quantum yield (ΔF/Fm), growth rate (grams per day), percent mortality, 1-methylnaphthalene concentrations (mg/L), EC50 (median effect concentration, mg/L), LC50 (median lethal concentration, mg/L), CTLBB (critical target lipid body burden, micromole of chemical/gram of lipid).
Data averaged by Chamber: Chamber = the chamber number, Conc = Geometric mean of 1-MN concentration from 0h and 48h; used in modelling of effects (µg/L), Num = number of coral fragments in the chamber, CC1h – CC48h = the sublethal effect proportion at each time point based on the semi-quantitative scoring rubric for observational changes; coral condition score (scale of 0-3). Each score listed is the average effect proportion of each chamber (N=3). M24h, M36h, and M48h = the lethal effect proportion at each time point. Each score listed is the average proportion dead in each chamber (N=3). G Base= growth rate during the baseline (g/day), G Exp= the growth rate during the exposure (g/day), G P1P7= growth rate during the first week of recovery (g/day), G P7P28= growth rate during recovery weeks 2-4 (g/day). Y Base= quantum yield measured during baseline, Y Exp= quantum yield measured immediately after the exposure, Y P7= quantum yield measured after 7 days of recovery, Y P28= quantum yield measured after 28 days of recovery. Each value listed for growth or yield is the average value for all corals in each chamber (N=3, or all surviving). Missing values indicate no surviving fragments measured.
1-Methylnaphthalene concentrations were measured using a Horiba Aqualog Spectrophotometer. Target = target nominal concentrations in micrograms per liter; ppb. Values listed under Target are the nominal concentrations targeted using passive dosing: 0(control), 1000, 2000, 4000, 8000, and 16000 µg/L 1-methylnaphthalene. Chamber = the chamber number, Sample time = T0 and T48 hours of exposure (beginning and end) to verify concentration and stability. Values listed under sample times are actual measured concentrations in micrograms per liter. Conc = the geometric mean concentration of 1-MN in each chamber in micrograms per liter; used in modeling effects for each chamber.
Results from generalized linear modeling and target lipid model: Time (h), EC50 (median effect concentration, µg/L), LC50 (median lethal concentration, µg/L), CTLBB (critical target lipid body burden, micromole of chemical/gram of lipid).
Data by Coral: Chamber = the chamber number, Frag = the coral number, identifier; CC1h – CC48h = the sublethal effect proportion at each time point based on the semi-quantitative scoring rubric for observational changes. Each score listed is total score divided by the number of categories scored. M24h, M36h, and M48h = the lethal effect proportion at each time point. Each score listed is the average proportion of each coral dead. G Base= growth rate during the baseline (g/day), G Exp= the growth rate during the exposure (g/day), G P1P7= growth rate during the first week of recovery (g/day), G P7P28= growth rate during recovery weeks 2-4 (g/day), missing values indicate no surviving fragments measured. Y Base= quantum yield measured during baseline, Y Exp= quantum yield measured immediately after the exposure, Y P7= quantum yield measured after 7 days of recovery, Y P28= quantum yield measured after 28 days of recovery. Each value listed for yield is the average of 4 measurements on each coral fragment. Missing values indicate no surviving fragments measured.
Methods:
Size and Volume of tanks: 500 mL exposure chamber connected to 2 L dosing reservoir, operating experimental water volume 2500 mL.
Source of Corals: Siderastrea siderea, Broward County, Florida, SAL-18-1994-SRP.
Source of water: laboratory coral system (artificial seawater).
Coral condition scale: Four-level system; 0=within normal limits, 1 = moderate, 2 = advanced, 3 = severe, assessment metrics of coral color, polyp extension/retraction, tissue swelling, mucus production.
Analytical methods: All samples were in certified volatile organic analyte vials with no headspace and maintained refrigerated until analysis. Certified standards of 1-methylnaphthalene (97 %) was obtained from Ark Pharm (Libertyville, IL, USA). Stock solutions were prepared with dichloromethane analytical grade quality (Burdick and Jackson, Fisher Scientific, Fairlawn, NJ, USA) and stored at -20 °C. Working solutions were further diluted in ultrapure water (18.2 MΩ cm-1) obtained by a Nanopure Infinity Ultrapure Water system or HPLC grade water from Fisher Scientific. The method used for determination of 1-methylnaphthalene (1-MN) in seawater is based on the SOP-2011-O-120.4 created and validated at EARL laboratory (FIU). Samples were preserved at 4°C and allowed to reach room temperature before analysis. A calibration curve was produced in artificial saltwater (35 psu). A six-point calibration curve based on the fluorescence intensity value at a specific λex = 290 nm and λem=334 nm was established to create a linear regression plot. The calibration standards consist of 0, 0.1, 0.2, 0.5, 1, 2.5 and 5 ppm solutions. The criterion for acceptance is that the curve must have an r2>0.990. To control the quality of the results, blanks were run to determine that no emission was observed at the wavelengths (excitation and emission) used for 1-methylnaphthalene. Also, a continuing calibration standard at 0.5 ppm was made from the same material of the calibration solutions is used at the end of each analytical batch to assess deviations from the initial calibration. Calibration verification is also used at the beginning of each analytical sequence and for the following 12 samples in a batch. No extractions were needed and the concentrations of 1-methylnaphthalene were measured in a Horiba Aqualog Spectrofluorometer. For quality controls, fortified blanks and matrices were evaluated showing great recoveries ranging from 84% to 110%. Calibration verifications were all within the method criteria (less than 7% variation). Duplicate samples were very reproducible, showing less than 3% variability.
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