Effects of oil exposure and dispersant use upon environmental adaptation performance and fitness in the European sea bass, Dicentrarchus labrax

Abstract

The worldwide increasing recourse to chemical dispersants to deal with oil spills in marine coastal ecosystems is a controversial issue. Yet, there exists no adequate methodology that can provide reliable predictions of how oil and dispersant-treated oil can affect relevant organism or population-level performance. The primary objective of the present study was to examine and compare the effects of exposure to untreated oil (weathered Arabian light crude oil), chemically dispersed oil (Finasol, TOTAL-Fluides) or dispersant alone, upon the ability of fish for environmental adaptation. To reach that goal, we implemented high-throughput, non-lethal challenge tests to estimate individual hypoxia and heat tolerance as surrogate measures of their capacity to face natural contingencies. Experimental populations were then transferred into semi-natural tidal ponds and correlates of individuals' fitness (growth and survival) were monitored over a period of 6 months. In accordance with our stated objectives, the contamination conditions tested corresponded to those observed under an oil slick drifting in shallow waters. Our results revealed that the response of control fish to both challenges was variable among individuals and temporally stable (repeatable) over a 2-month period. Exposure to chemical dispersant did not affect the repeatability of fish performance. However, exposure to oil or to a mixture of oil plus dispersant affected the repeatability of individuals' responses to the experimental challenge tests. At population level, no difference between contamination treatments was observed in the distribution of individual responses to the hypoxia and temperature challenge tests. Moreover, no correlation between hypoxia tolerance and heat tolerance was noticed. During the field experiment, hypoxia tolerance and heat tolerance were found to be determinants of survivorship. Moreover, experimental groups exposed to oil or to dispersant-treated oil displayed significantly lower survival than control or dispersant-exposed groups. Finally, from the four experimental populations tested, the one exposed to chemically dispersed oil presented the lowest growth rate.

Innate immunity and antioxidant systems in different tissues of sea bass (Dicentrarchus labrax) exposed to crude oil dispersed mechanically or chemically with Corexit 9500

“…CAL is a reference product used in other studies (Danion et al, 2011;Claireaux et al, 2013;Dussauze et al, 2015). This oil was artificially weathered with air bubbling during 24 h in order to evaporate lighter compounds and recreate as closely as possible the characteristic of oil weathered at sea during 24 h. At the end of this process, the oil presented a weight loss of approximately 7% and contained 54% saturated hydrocarbons, 12% polar compounds and 34% aromatic hydrocarbons.…”

“…In fish species, an exposure to petroleum compounds can induce an alteration of integrative parameters such as survival (Claireaux et al, 2013) or hydromineral homeostasis (Kennedy and Farrell, 2005;Goanvec et al, 2010). Alterations of immunity were also observed on fish after exposure with oil (Bado-Nilles et al, 2011;Danion et al, 2011;Song et al, 2011) or with aromatic compound such as benzo(a)pyrene (Carlson et al, 2002), Some studies have demonstrated the occurrence of disruption in oxidative homeostasis of fish species exposed to petroleum compounds such as golden gray mullet Liza aurata Milinkovitch et al, 2013), Atlantic cod Gadus morhua (Olsvik et al, 2010), polar cod Boreogadus saida (Nahrgang et al, 2009; or sea bass Dicentrarchus labrax (Ahmad et al, 2008).…”

Acute and long-term biological effects of mechanically and chemically dispersed oil on lumpsucker (Cyclopterus lumpus)

“…However, the deduction of potential damage derived from short term biomarker responses are difficult to predict (Depledge, 2009;Forbes et al, 2006) and in general, little is known about the long term fish population consequences of short acute exposures to dispersed oil (Kerambrun et al, 2012;Claireaux et al, 2013). In order to link any observed short term effects to long term effects, fish growth and well-being were monitored for 1.5 months (M5; 2 months) post-exposure.…”

Effect of dispersed crude oil on cardiac function in seabass Dicentrarchus labrax

“…This process caused the lighter compounds to evaporate mimicking the weathering of an oil slick at sea (Milinkovitch et al, 2011). This weathered CAL was used in other ecotoxicological studies (Milinkovitch et al, 2012;Claireaux et al, 2013;Theron et al, 2014).…”