Abstract: Aquavoltaics represents an innovative model for integrated development that synergizes the practices of aquaculture with photovoltaic energy generation. This model can meet human energy demand and save land resources. However, its impacts on the environment of mariculture ponds and aquaculture organisms reared therein are not fully understood. We employed two distinct configurations of photovoltaic arrays \[(stationary photovoltaic (SPV group) and tracking photovoltaic (TPV group)\] to explore their influences on ecological environment and digestive physiology of sea cucumber Apostichopus japonicus in summer (July to September). The results showed that both photovoltaic systems significantly reduced surface light intensity and water temperature in the ponds. Light intensity and water temperature were decreased by 85.3% and 1.05 ℃ in the SPV ponds, and by 84.6% and 0.76 ℃ in the TPV ponds, respectively. However, differences in light intensity and water temperature were not statistically significant between the two photovoltaic types. The total abundance of phytoplankton was not affected by the presence of photovoltaic types, though specific increases were observed in Cyanophyta in SPV ponds and Pyrrophyta in TPV ponds. The composition and abundance of zooplankton were not influenced by the PV systems. Chlorophyll a concentration showed negligible changes between the photovoltaic types, with a singular exception noted in July. Organic matter content in surface sediments and the activity of digestive enzymes in A. japonicus were stable. Both photovoltaic types can effectively reduce pond water temperatures via shading, but did not affect the composition and abundance of plankton and digestive enzymes of the cultured A. japonicus in the ponds, which has the potential advantage of preventing the mass mortality of A. japonicus caused by extreme high temperature.

Key words: aquavoltatics, sea cucumber mortality during summer, Apostichopus japonicus, culture pond, ecological effect