Accumulation and biomarker responses in the Atlantic rock crab (Cancer irroratus) exposed to Benzo(a)Pyrene through ingestion of contaminated mussels (Mytilus edulis)

Abstract

The aims of this study were to estimate suitability of the Atlantic rock crab (Cancer irroratus) for environmental monitoring through investigation of 7-ethoxyresorufin O-deethylase (EROD), glutathione peroxidase (GPx) and glutathione (GSH) biomarker responses to Benzo(a)Pyrene (BaP) exposure through ingestion, i.e. as potential monitoring tool for Polycyclic Aromatic Hydrocarbons (PAHs) through a laboratory exposure to contaminated prey items. Biomarker responses were measured in hepatopancreas tissue shortly after starvation period as well as after long-term exposure. Blue mussels (Mytilus edulis) were exposed to 2, 20 and 50 μg BaP/L for 14 days after which they had accumulated 11.5, 192 and 417 μg BaP/g tissue dw., respectively. Subsequently, mussels were fed to crabs for 21 days in daily portions of about 4.7 g soft tissue ww. per crab. Assimilation rate of BaP through ingestion in crabs was estimated at < 1%.Biomarker responses were measured at days 3 and 21 of the experiment. Biomarker values were generally lower than their relative control levels on day 3, likely reflecting degradation of xenobiotic defence systems induced by prolonged starvation. After 21 day of exposure the crabs exhibited significant biomarker response in the highest exposure group, where significantly higher EROD activity and GSH content as well as significantly lower protein content were observed. Biomarker responses proved insufficiently sensitive for implementation in environmental monitoring. This study provides first insight into physiological responses of Cancer irroratus to PAH induced stress post starvation and during long-term exposure.

Markmið verkefnisins var að meta notagildi grjótkrabbans (Cancer irroratus) við mengunarrannsóknir og umhverfisvöktun á fjölhringa vetniskolefni (PAH) þar sem viðbrögð dýranna gagnvart fæðuborinni Benzo(a)Pyrene (BaP) mengun voru mæld með bíómarkerunum 7-ethoxyresorufin O-deethylase (EROD), glutathione peroxidase (GPx) og glutathione (GSH) í meltingarkirtli krabbans. Kræklingur (Mytilus edulis) var mengaður með mismunandi styrk BaP í sjó í 14 daga (2, 20 og 50 μg/L) sem skilaði sér í 11,5, 192 og 417 μg BaP/g þurrvigt í vef kræklings. Krabbarnir voru fóðraðir daglega í 21 dag með menguðum kræklingi og fékk hver krabbi ca. 4,7 g (votvigt) af kræklingavef á dag. Uppsöfnun og niðurbrot (e. assimilation) BaP í kröbbunum var áætlað < 1%.Bíómarkerarnir voru mældir í kröbbunum eftir 3 og 21 dag. Eftir 3 daga voru flest gildin lægri í menguðum kröbbum í samanburði við viðmiðunarhópana. Það er líklega vegna sveltis krabbanna í upphafi, sem þá endurspeglast í minni virkni ensímakerfa/afeitrunarferla og lakari varnarkerfum. Eftir 21 dag kom fram marktæk hækkun í EROD virkni og GSH magni hjá kröbbum sem fengu menguðustu fæðuna og jafnframt höfðu þeir marktækt minna prótínmagn. Næmni bíómarkeranna reyndist ekki nægjanleg gagnvart BaP mengun í grjótkröbbum til að hægt sé að mæla með þessum aðferðum fyrir þessa tegund til vöktunar á slíkri mengun. Hins vegar koma hér fram í fyrsta skipti niðurstöður mælinga á lífeðlisfræðilegum viðbrögðum grjótkrabba gagnvart PAH efninu B(a)P, annars vegar eftir svelti og hins vegar eftir viðvarandi mengunarálag (21 dagur) í gegnum fæðu.