Effects of pollutants on fish development and physiology
Team: Patricia Pierson, Guillaume Spennato, Pierre Vandenbussche
Superposition (red/green) of paired otoliths(sagittae) of Dicentrarchus labrax post-larvae
Our Laboratory works in particular on the effects of threats (including pollutants fluxes) on marine species and their habitat. This consists on developing new measurement techniques and new indicators to evaluate threat impact. The global aim of this work is to allow better supervision of the biological quality of marine ecosystem, better management of Mediterranean coastal zone. Concerning the Laboratory research on ecotoxicology, an important point of the study is the characterization of effects of substances potentially inducing a chemical stress, at the whole animal level, and the validation of new biological indicators of environmental perturbation. Our work focalizes on two points.
Part 1 : Stress induction of fluctuating asymmetry in fish
Studies made on drosophila have shown that an environmental stress may lead to an increase of frequency of fluctuating asymmetry acquisition for morphological characteristics during the development of the observed animals. Fluctuating asymmetry is defined as the presence of hazardous differences between left and right sides of an animal for a bilateral characteristic, differences of size, shape or number. The increase of fluctuating asymmetry frequency under stress has also been observed for other animals and these studies have led to propose fluctuating asymmetry as a biological indicator for stress (ex: Parsons 1992). In fish, fluctuating asymmetry has been evaluated by measuring parameters such as characteristics of scales, gills and fins (ex: Wiener and Rago 1987, Estes et al. 2006). Evaluating fluctuating asymmetry has been proposed as an indicator of stress induced by either non appropriated medium conditions (without chemical stress, Vollestad and Hindar 1997) or substances modifying calcium metabolism (Wiener and Rago 1987), presence of effluents from paper factories (Estes et al. 2006), presence of several toxic substances during embryogenesis of the observed animals (Green and Lochmann 2006). Now our aim is to demonstrate that fluctuating asymmetry can be definitively validated as a biological indicator of stress in fishes.
In our present project, we propose to measure the impact on induction of fluctuating asymmetry of substances which may cause a chemical stress, substances such as pollutants in the environmental medium of the fishes. For this study, we work on Mediterranean fishes, particularly Dicentrachus labrax and Oblada melanura. Tested substances for induction of a chemical stress are classical ones and the ones used by other researchers of our Laboratory i.e. either metals, non metals, or endocrine disruptors (xenoestrogens or xenoandrogens). One part of our experiments consist to test potential effects of substances on fishes in aquarium, the other part implying measurements on fishes sampled in situ in more or less polluted area. Fluctuating asymmetry measurements may be done on larvae, post-larvae, juveniles or adults exposed (or not) to pollutants. Concerning fishes during development, we study several otolith parameters to evaluate differences in size and shape. In adults, we will consider parameters among the characteristics measured in previous studies on scales, gills, fins… (ex: Wiener and Rago 1987, Estes et al. 2006). We make these measurements, for precision purpose, on photographs of left and right sides of dissected parts of the fish, which are superimposed, compared for analysis (see Palmer 1994), with specific software for image analysis. This will allow us to conclude if fluctuating asymmetry can be considered as a new stress indicator for fishes.
The SPICE project is included in this part of our research.
Part 2 : Endocrine disruptors impact on physiological parameters of fish
Endocrine disruptors are defined as an exogenous substance which interferes with an hormone production, secretion, effects. As mentioned before, effects of endocrine disruptors will be tested on fluctuating asymmetry in fishes, but we also want to measure their impact on several physiological parameters of these fishes.
Presence of an endocrine disruptor in the environmental medium of fish is susceptible to have very important impact on this kind of animal, as fish is continuously obliged to be in contact with any substance in water. Therefore it is essential to be able to characterize the impacts of presence of one or more endocrine disruptors, in environmental medium of fish, on hormonal secretions and their physiological effects. For each endocrine disruptor tested, we will measure impact on parameters such as survival, reproduction of fishes (known to be disturbed by such substances, see for example Jobling and Tyler 2003, Liao et al. 2009), secretions of selected hormones of interest (quantified by ELISA, see for example Pierson et al. 2004). This study will be completed by characterization of endocrine disruptor mechanisms of action.
- Estes E. C., Katholi C. R. and Angus R. A. Elevated fluctuating asymmetry in eastern mosquitofish (Gambusia holbrooki) from a river receiving paper mill effluent. Environ. Toxicol. Chem. 25 (2006) 1026-1033.
- Green C. C. and Lochmann S. E. Fluctuating asymmetry and condition in golden shiner (Notemigonus crysoleucas) and channel catfish (Ictalurus punctatus) reared in sublethal concentrations of isopropyl methylphosphonic acid. Environ. Toxicol. Chem. 25 (2006) 58-64.
- Jobling S. and Tyler C. R. Endocrine disruption in wild freshwater fish. Pure Appl. Chem. 75 (2003) 2219-2234.
- Liao T., Guo Q. L., Jin S. W., Cheng W. and Xu Y. Comparative responses in rare minnow exposed to 17b-estradiol during different life stages. Fish Physiol. Biochem. 35 (2009) 341-349.
- Palmer, A. R. Fluctuating asymmetry analyses: A primer. T. A. Markow (ed.), Developmental Instability: Its Origins and Evolutionary Implications, Kluwer, Dordrecht, Netherlands (1994) 335-364.
- Parsons P. A. Fluctuating asymmetry: a biological monitor of environmental and genomic stress. Heredity 68 (1992) 361-364.
- Pierson P. M., Lamers A., Flik G. and Mayer-Gostan N. The stress axis, stanniocalcin, and ion balance in rainbow trout. Gen. Comp. Endocrinol. 137 (2004) 263-271.
- Vollestad L. A. and Hindar K. Developmental stability and environmental stress in Salmo salar (Atlantic salmon). Heredity 78 (1997) 215-222.
- Wiener J. G. and Rago P. J. A test of fluctuating asymmetry in Bluegills (Lepomis macrochirus Rafinesque) as a measure of pH-related stress. Environ. Pollut. 44 (1987) 27-36.
Key words: fluctuating asymmetry, fish, otolith, stress indicator, pollution, endocrine disruptors.