Periphyton and Phytoplankton Assessment in a Shrimp Nursery: Signature Pigments Analysis

Understanding microalgae composition is key for an improved aquaculture system management. The primary objective of this research was to estimate microalgae community structure in a Marsupenaeus japonicus nursery. The secondary objective was to analyze the environmental parameters (salinity, pH, dissolved oxygen, total dissolved ammonia, nitrites, nitrates and phosphates) and shrimp density effect on abundance, composition and development of microalgae in a shrimp nursery. Periphyton and phytoplankton composition and abundance were determined using HPLC signature pigment analysis coupled with CHEMTAX software. Environmental parameters were measured in the tanks with probes or in the laboratory following standard procedures of water quality analysis. A nonparametric repeated-measures ANOVA statistical analysis was done to test differences between treatments. Spearman rank correlation analyses were performed on environmental and biological variables with phytoplankton or periphyton groups in order to examine significant relationship. The results showed diatoms were significantly higher than any other groups in both phytoplankton and periphyton communities. Shrimp density effect on periphyton, phytoplankton composition and environmental parameters was minor. Nutrients played a key role on phytoplankton development, but had a minor effect on periphyton, which was more affected by colonization processes and other environmental variables. The analysis of signature pigments allowed to report the presence of previously undetected groups on periphyton, prasinophytes and prymnesiophytes, which are characterized by high nutritional value. This is especially important in nurseries because shrimp grazing on periphyton can increase post-larvae survival.