Influence of small-scale gold mining on French Guiana streams: Are diatom assemblages valid disturbance sensors?

The ongoing gold-rush in French Guiana could cause severe disturbance to ecosystems. Although illegal, small gold mining sites are rapidly expanding. Few studies have attempted to measure the consequences of the increased gold mining on the biota of small forest streams, and to date no study has dealt with primary producers. Here we measured the response of diatom assemblages to gold mining in ten sites differently affected by the mining activity (i.e., reference, formerly gold-mined and currently exploited). Our results showed that both taxonomic and functional structure of the diatom assemblages were influenced by the intensity of gold mining activity. A significant relationship between soil erosion and diatom motility ability has been demonstrated. These findings show that diatom assemblages are sensitive to gold mining disturbance and suggest that diatom communities may be used as sensors of the environmental stress caused by small-scale gold mining activities.