Cytochrome P450 induction in crustaceans (barnacles and crabs) as a diagnostic tool in the ecotoxicological assessment of offshore gas extraction: a review of two monitoring studies.

The present work constitutes part of two more extended research projects called “Biomare” and “Biodiversity” developed by the Department of Environmental Science at University of Siena and supported by ENI-Exploration and Production. Since 1960’s Italian gas offshore activity is predominantly on the northern sector of the Adriatic sea, in which are operating about 30 installations. During year 2008 the total amount of natural gas production averaged 191,000 barrels oil equivalent per day (boe/day) and represented approximately 70% of hydrocarbon production in Italy. Natural gas fields located in the Adriatic Sea collectively accounted for 54%. Produced water is the largest wastewater stream in the oil and gas exploration and production processes. Toxicological effects of produced water on living organisms may be due to adsorption of water soluble components through their surface epithelia (e.g. body surface and gills) and/or to oral ingestion and digestion of particulate material. Several studies were carried out on toxicological effects of produced waters on marine fauna such as fish and invertebrates. In this aspect, a majority of the published works are concerned with bivalve molluscs, particularly mussels but there is very little information available in other marine invertebrates like lower order crustaceans, a large, diverse and complex group of animals. The aim of this work was to propose a suite of biomarkers (Benzopyrene monoxygenase activity (BPMO), NAD(P)H Reductases activity, Acetylcholinesterase activity (AChE), Porphyrins, Antioxidant enzymes), PAHs levels and heavy metals as potential diagnostic tools in the ecotoxicological monitoring of extractive offshore activities, applied in marine invertebrates, the barnacles Balanus perforatus and Balanus trigonus and the crab Liocarcinus depurator proposed as new bioindicators. Previous studies carried out by this Department demonstrated that barnacles Balanus perforatus and Balanus trigonus and the crab Liocarcinus depurator are the most common species of crustaceans identified in macrobenthic assemblages along the piles of offshore installations. In order to validate the use of crustaceans in ecotoxicological monitoring of offshore activities, two experimental phases were carried out: a laboratory and a field study. During phase 1 B. perforatus and B. trigonus were experimentally exposed to water containing increasing doses of gasoline (a liquid mix of hydrocarbons extracted with gas, and produced water) to check the sensitivity of selected bioindicators and identify the most suitable biomarkers for each experimental design. Laboratory phases were followed by field studies to validate the use of multi trial biomarkers approach in a real environmental situation. Specimens of B. perforatus, B. trigonus and L. depurator were collected along the piles of 4 different platforms in two different areas: north Adriatic and Ionian sea. Laboratory studies showed high sensitivity of response in barnacles for all biomarkers tested, particularly MFO and esterases, and high bioaccumulation capacity. Field results showed differences in biomarker responses and PAH levels between the two sites for barnacles and crabs. Moreover a different sensitivity of response between the two species of barnacles was also found. In conclusion, this study provided innovative results for the use of the selected bioindicators and for the responses generated after chronic and acute exposure to petroleum derivatives. These results suggest that barnacles and crabs could be used in future biomonitoring programs to evaluate both the effects of petroleum derived contamination, and the level of contamination itself.