Seasonal variation of transcriptomic and biochemical parameters of Donax trunculus related to its infection by Bacciger bacciger (trematode parasite)

Abstract

The wedge clam (Donax trunculus) is widely distributed along exposed Atlantic coasts, from France to Senegal. This species has high commercial importance, with the mean capture production on the last ten years of approx. 850 tonnes (50% represented by Portugal captures). D. trunculus populations are modulated by several drivers such as tidal range, temperature, sediment grain size, fishing pressure, predation and parasitism. Regarding parasitism, D. trunculus is the first intermediate host of Bacciger bacciger (trematode parasite) where the sporocysts develop. The sporocyst is the most damaging stage, reported as being responsible for bivalve castration and flesh mass depletion. In order to test the hypothesis that B. bacciger infection modified wedge clam health status, including its biochemical performance and gene expression, clams were sampled every other month during one year in the Faro beach (south coast of Portugal). The results obtained revealed that B. bacciger total prevalence ranged between 0 and 33% in May and July, respectively. Overall, transcriptomic and biochemical results showed that B. bacciger induced in D. trunculus defense mechanisms against oxidative stress and increased the host metabolism and energy demand, especially in spawning and spent periods. The present work concluded that the markers used can provide additional and ecologically relevant information not only about the environmental conditions that animals experience but also the invasion effects of pathogens. These findings can contribute to predicting organism chance of reproduction and survival in their natural context, which can be applied in bivalve conservation and disease episodes management.