Responding of Diatoms to Environmental Variables Change in the Porphyra Cultivation System Based on Gbt Model and Gam

Abstract

In Haizhou Bay, extensive Porphyra cultivation areas are present, representing a significant component of the local aquaculture industry. To investigate the spatiotemporal variations of phytoplankton, particularly diatoms, and their response to Porphyra cultivation activities, monthly surveys of the phytoplankton community structure and environmental variables were conducted in Haizhou Bay throughout 2023. The results showed that the phytoplankton species richness and abundance in the Porphyra cultivation system in Haizhou Bay had obvious succession and variation throughout the year, and the Porphyra cultivation activities had a certain degree of influence on the aggregation of diatoms. Using Generalized Additive Model (GAM) and Gradient Boosting Trees (GBT) model analysis, both models indicated that the key environmental variables affecting diatom abundance in Haizhou Bay were temperature (T), dissolved oxygen (DO), chemical oxygen demand (COD), and nutrient levels (SiO32-, NH4+, NO2-). We recommend using the GBT model first in future studies with similar data types to obtain more reliable and accurate results. This research also established a crucial foundation for long-term monitoring and prediction of diatom community structure and the prevention of diatom HABs in Haizhou Bay.

Keywords: phytoplankton community structure, Diatoms, GAM, GBT model, Haizhou Bay, Porphyra cultivation