Ni and black carbon influence bacterial production, respiration and community composition in the barrier reef Lagoon of Noumea (New Caledonia): an experimental study

The barrier reef lagoon of Noumea (New Caledonia) is potentially influenced by Ni and black carbon (BC) rich aerosols (the two latter originating from a Ni power plant).  Experiments were performed with lagoon water collected close to the reef crest to assess the effect of anthropogenic influences on bacterial abundance (BA), production (BP), respiration (BR), growth efficiency (BGE) and community composition (BCC) in artificial produced aggregates. In both treatments, BA were not affected or enhanced compared to the unamended control (up to 40% for BA and 180% for VA). BP was not or negatively affected (up to 70%). No clear trend was found for BR in the Ni treatment; in the BC treatment BR was enhanced by 63-69%. BGE was reduced in both treatments. The strongest effects on BCC profiles as determined by 16S rDNA denaturing gradient gel electrophoresis were due to incubation time treatment particularly for BC. A phylotype corresponding to a specific BC band was closely related to Acinetobacter oleivorans DR1. Thus, this experimental study confirms potential anthropogenic influences on the bacterial community on aggregates in the Bay of Noumea.