Acute Effects Of Single And Mixed Polycyclic Aromatic Hydrocarbons Associated To Oil Spills On The Copepod Oithona Davisae. Carlos Barata 1, Albert Calbet 2, Enric Sainz 2, Laura Ortíz 3, Josep Maria Bayona 3. 1 Laboratory of Environmental Chemistry, UPC, Terrassa 2 Dept. Biologia Marina i Oceanografia, CMIMA, CSIC, Barcelona 3 Dept of Environmental Chemistry, IIQAB-CSIC, Barcelona

Acknowledgements Financial Support: MEC Spanish project PETROZOO (VEM ). MEC R y C contract to Carlos Barata and Albert Calbet

Objectives Develop a modelling framework to predict the toxicity of mixture combinations of petrogenic PAHs in copepod species

Effects of crude oil spills in marine planktonic food webs??? zooplankton species constitute the major food source for larval fish Overview – in brief

Polycyclic aromatic hydrocarbons (PAHs) Log K ow Toxicity – EC50 Toxicity by non-polar narcosis 1.Toxicity = F (1/log K ow ) 1. Most toxic and persistent components of class 2 fuel oils (Prestige) 2. Occur in complex mixtures Environmental fate 2.Toxicity complex mixtures is additive Effect PAHs

Methods Measured variables: Lethal, Narcosis– after 48 h (%) Test Species: Oithona davisae Chemicals: Naphthalene, 1-methylnaphthalene, 1,2-Dimethylnaphthalene Phenanthrene,1-methylphenanthrene,3,6-dimethylphenanthrene Fluorene, Dibenzothiophene, Pyrene Analysis: SP -HPLC-UV

Experimental design Exposure scenarios Individual exposures 10 PAHs Mixture combination of only 9 PAHs using an equitox ratio C i = EC50 j / n ; n= 9; C j = 1/9 TU j Experimental conditions: No food supply, filtered sea water (38 0/00 ) 20 o C

Data analysis  i i i PAHEC control mobileMobile   50 % Modeling % responses: Allosteric decay function Survival PAHs (  mol/L)

Data analysis Modelling single and mixture toxicities (EC50) of PAH j : bloga 50 1  owj j K EC Log K ow EC50 Single - Quantitative Structure Activity Relationship (QSAR)    n j j j ECx c 1 1, For c j = EC 50 j /n; 1 = 50% Mixture - Concentration Addition model

Results- Single solutions Naphthalenes (% mobile vs Control) PAHs (  mol/L) NN1 N2 Narcosis, survival

Results- Single solutions Phenanthrenes (% mobile vs control) PAHs (  mol/L) Narcosis, survival P P1

Results- Single solutions Rest of PAHs (% mobile vs control) Narcosis, survival PAHs (  mol/L) FDBT FtPy

Results- QSAR Log K ow NarcotizationSurvival N N1 P1 F DBT N2 P Py Ft EC 50(  mol/L) R 2 =0.9 5log  owj j K EC Log

Results- Mixtures Mixture of 9 PAHs at their EC50/ Toxic Units = 1 = Survival Narcotization (% mobile vs control EC 50 = 1.1 ( )   9 j j 9 EC50 1

Conclusions 3. Mixture toxicity of PAHs was additive following the CA model. 1. Allosteric decay function predicted accurately acute responses 2. Acute responses were inversely related to log Kow QSAR 9 PAH = Daphnia magna QSAR >100 non polar narcotics

Risk Assessment Implications NaphthaleneAlkylated Naphthalenes EC 50 (  g/L) Number Mixture components Prestige Highest Background

Future Work 2. How toxicity of real samples (elutriates or water –accommodated fractions of fuel Oil) can be predicted from Chemical analysis using QSAR models 1.Derive QSAR models for sublethal responses 2.9log  owj j K EC Log Clearance rates (feeding) N N2  g/L Kow Prestige 50

Thanks END Environmental Toxicology and Chemistry. Volume 24, No. 11, November 2005.