For general public

 

The impacts of pollutants on freshwater and deep-sea marine fish

The deep sea is the largest ecosystem on Earth, containing 99% of its living biomass.
Submarine exploration revealed the presence of fishes down to 6000 meters deep, where pressure reaches 600 kg/cm2. This incredible fauna is largely unknown as we consider that only 1-2 % of the  deep sea has been explored so far.

This fragile ecosystem is being threatened by human activities. 
Among these threats, the presence of high amounts of pollutants, such as PCBs and DDTs, which appear to end up their journey in the deep ocean.  There, long-lived fish species such as rattails accumulate toxicants in their tissues at levels hundred times higher than in shallow species. These pollutants are known to induce several damage to liver and brain in marine fish.  However not much is known about their impact in deep-sea species and the ability of this fauna to cope and resist to these chemicals.

The impossibility to collect and keep deep-sea fish alive at the surface for a period sufficient to allow experimentation largely explains our ignorance on this matter. Therefore our work aims at developing in vitro techniques for investigating the impacts of pollutants on deep sea fishes. We have adapted a technology developed for analyzing the potential liver toxicity of pharmaceutical drugs on rats and humans to deep-sea fish. This consists in liver slices incubated in an appropriate culture medium as to keep them alive and functional. Thanks to specially designed hyperbaric chambers, these slices can be maintained at the high pressure prevailing in the deep sea. Another objective is to study the possible role of pollutants in the decline of the eel Anguilla anguilla, a species migrating back and forth between the deep ocean and European rivers where they accumulate very high amounts of pollutants.

The crosstalk between pollutants and nutritional factors may affect the way fish cells resist to stressors. In this context, we investigate how individual polyunsaturated fatty acids influence the survival of fish (trout, zebrafish) cells exposed to metals such as mercury and Cadmium.