PCBs and the energy cost of migration in the European eel (Anguilla anguilla L.)

Abstract

The effect of polychlorinated biphenyls (PCBs) on the energy consum ption of fasting silver European eel (Anguilla anguilla L.) was studied over a 27-day period during w hich the anim als w ere at rest or were sw im m ing 800 km in Blazka sw im tunnels. Three-year-old female hatchery eels (silver stage) betw een 73 and 80 cm long weighing around 1 kg w ere dosed intraperitoneally w ith PCBs at a nom inal dosage of 10x the consum ption standard as a m ixture representative for planar (7 ^gPCB126/kgeel), non-planar (5 m g PCB153/kg eel) and m etabolizable PCBs (50 ^g PCB77/kg eel) found in wild eel, or only w ith the vehicle (corn oil, 10 m l/kg eel). Four m ajor observations were m ade: (1) PCB-exposed anim als lose less w eight com pared to their unexposed controls; (2) PCB-concentrations on a lipid basis are 2.8-14 tim es higher in sw im m ing com pared to resting anim als; (3) the standard m etabolic rate is significantly lower in the PCB-exposed anim als than in unexposed controls. In addition, PCB-exposure significantly reduces oxygen consum ption during swim m ing, and starting at 4 0 0 k m (18 days) this effect increases w ith tim e; (4) the relative spleen and liver w eight significantly increased in the PCB-swim anim als but not in the PCB-rest animals. The sw im m ing anim als lost about 75% m ore w eight com pared to resting anim als and had about 50% lower plasm a fat content. Hematocrit, haem oglobin, plasm a pH, ion levels (sodium and potassium ), and plasm a lactate w ere not affected by PCB-exposure or swim m ing. Apparently, the current levels of PCBs and other dioxin-like com pounds m ay seriously im pair the reproduction of the European eel.

Reproduction of European eel jeopardised by high levels of dioxins and dioxin-like PCBs?

“…While the lipid reserves are depleted during migration, contaminants are released into the blood and may damage reproductive organs and affect embryogenesis . This suggests that such contaminants may have contributed directly to the observed decline in populations (Van Ginneken et al, 2009 (Walker et al, 1994). In a Japanese study it was determined that about 20% of the dioxins in adult female crucian carp were transferred to the eggs (Kajiwara et al, 2007).…”

“…Recent studies pointed out that PCBs and other dioxin-like chemicals play an important role in the actual decline of the European eel (Belpaire et al, 2009(Belpaire et al, , 2011Geeraerts and Belpaire, 2010;Palstra et al, 2006;Van Ginneken et al, 2009), although causative relationships between PCB exposure and effects on population level are difficult to demonstrate, considering the complex life cycle of this panmictic catadromous species. Palstra et al (2006) artificially stimulated female and male silver eel to maturation and reproduction and studied the effects of dioxin-like compounds in muscle and gonad tissues on embryonic development.…”

Contaminant levels in the European eel (Anguilla anguilla) in North Rhine-Westphalian rivers

“…The lipid reserves of the body are released, and the contaminants stored in the lipid tissue are put into circulation again [8]. Thus, during the migration, PCBs and PCDD/PCDFs may reach harmful concentrations in the blood [9]. Polybrominated diphenyl ethers (PBDEs) are another group of pollutants which are also potential endocrine disruptors.…”

Sex Steroids Modulate Fish Immune Response

“…Several anatomical and morphological changes were observed in lymphoid tissues following exposure to xenoestrogens and xenoandrogens. Spleno-somatic and hepato-somatic indices and thymus volume are affected by exposure to sex-steroids (androgens and estrogens) or to their related endocrine disruptor compounds (Grinwis et al, 2009;Kurtz et al, 2007;Tellez-Banuelos et al, 2009;van Ginneken et al, 2009). In the gilthead seabream the dietary intake of 17 -ethynilestradiol promotes the up-regulation of several genes related with leukocyte recruitment (e.g.…”