Effect of aquaculture water eutrophication on color development in Biolog EcoPlates

Biolog EcoPlates are useful tools to study the metabolic function of microbial community in water bodies; however, the influence of aquaculture water, which contains complex chemical compositions, on color development in Biolog EcoPlates, has not been clearly illustrated. Previously, we detected a delayed color development in original water samples, comparing to that in the tenfold diluted samples. The objective of this study was to evaluate the differences of average well color development (AWCD) and community-level physiological profiles (CLPP) between the original and tenfold diluted water samples collected from three intensive Litopenaeus vannamei culture ponds, and to explore potential causes of the delayed color development by measuring microbial community structure and physiochemical indexes. Compared with the tenfold diluted samples, the original water samples from all three ponds exhibited delayed color development and reduced microbial metabolic activity. The original water samples exhibited higher utilization of carbohydrates, while significantly higher utilization of amino acids was observed in the corresponding diluted samples. The CLPP of the original water samples was significantly correlated with the microbial community structure at 48 h of incubation, meanwhile both CLPP and community structure were substantially influenced by NO 3 –N and NO 2 –N. Therefore, NO 2 -N and NO 3 -N accumulation in the intensive Litopenaeus vannamei culture pond might be responsible for the delayed color development in Biolog EcoPlates. In order to minimize the influence of aquaculture water on color development in Biolog EcoPlates, a shorter incubation period is recommended.