Authors

A Dairain²; A Legeay²; A Ciutat¹; P Gonzalez¹; M Baudrimont²; O Maire²; P Y Gourves²; G Daffe¹; X de Montaudouin²;  ¹ CNRS, France;  ² University of Bordeaux, France

Discussion

Bioturbating species are benthic organisms living in the sediment. Through their fossorial life style, bioturbators deeply alter the physical and biochemical properties of sediments and thus are defined as important ecosystem engineer species. Within bioturbators, thalassinidean mud shrimp are considered as among the most influential organisms in marine soft-bottom environments because of the significant roles they play on benthic habitats shaping, nutrient cycling and structuring of benthic communities.
The influence that mud shrimp have on their environment is related to the magnitude of their bioturbation activities and thus to their physiological state. Among factors impairing the fitness of organisms, parasitism is now well established. Mud shrimp are no exception: they host a bopyrid parasite, which are recognized to alter the physiological state of their host and to reduce the magnitude of mud shrimp’s bioturbation activities.
In addition to parasitism, mud shrimp could naturally undergo a variety of others stressors which may interact. For example, anthropogenic trace metals are of major concern in marine environments. Pollutants are recognized to have widespread impacts on organisms with some of them highly toxic from the cell levels (alteration of gene expression) to modification of organism’s behavior. However, studies evaluating both influence of parasitism and trace metals on organisms are still scarce, and none has been conducted on bioturbating species.
The present study aimed in evaluating the interactive effect of trace metal contamination (cadmium used as a model contaminant) and parasitism (bopyrid isopod Gyge branchialis), alone, and in combination on the mud shrimp Upogebia cf. pusilla over a 14-days ex-situ experiment. Kinetics of trace metal bioaccumulation was determined in the abdominal muscle and hepatopancreas of mud shrimp. In addition, the impact of trace metal contamination and parasitism were investigated at the cellular levels (study of gene expression) in both organs and on the behavior of mud shrimp (quantification of bioturbation activities).
Over 14 days of experiment, mud shrimp showed significant Cd bioaccumulation in both organs with parasite presence impairing contaminant bioaccumulation in the mud shrimp’s hepatopancreas. In addition, parasitism and trace metal contamination interfered with genetic expression. However, there was no clear impact of both stressors on mud shrimp’s bioturbation activities.