Effects of Culture of Patinopecten yessoensis and Gracilaria lemaneiformis on Phytoplankton Community Structure Based on an Enclosure Experiment

Abstract:

Enclosure experiments were carried out in Sanggou Bay in autumn 2015 to study the effects of high-capacity Patinopecten yessoensis and Gracilaria lemaneiformis culture on physical, chemical, and biological (phytoplankton community) factors of aquatic water within 60 h. The results showed that the concentration of dissolved oxygen (DO) and dissolved inorganic nitrogen (DIN) in water, and the abundance and composition of phytoplankton population can significantly change within 60 h. After 12 h, phytoplankton abundances in the experimental groups of P. yessoensis and G. lemaneiformis were significantly lower than that in the control groups. The filter effects of P. yessoensis on four dominant diatom species (Nseudo-nitzschia delicatissima, Surirella sp., Nitzschia spp., and Synedra spp.) in aquatic water were significantly different, indicating a greater filter effect on P. delicatissima and Surirella sp., than that on Nitzschia spp. and Synedra spp.. The characteristics of photosynthetic pigments in water also revealed the selective feeding effect of P. yessoensis on phytoplankton; that is, P. yessoensis could significantly filter fucoxanthin (characteristic pigment of diatoms) and alloxanthin (characteristic pigment of Cryptphytes) in water. On the contrary, prasinoxanthin (the characteristic pigment of pico-algae) was significantly higher in the scallop groups than in the control groups and the macroalgae groups after 48 h, which indicated that the cultivation of G. lemaneiformis had no significant effect on the biomass of pico-algae.