Data of pier in the Qingdao coastal waters

The sampling site (120.04°E, 35.78°N) was located at the end of a 500-m pier in the Qingdao coastal waters of Yellow Sea. Water depth ranged from 7.6 m at high tide to 2 m at low tide. High-frequency monitoring of the tintinnid community was conducted three times per week from February 23, 2024 to February 21, 2025, yielding a total of 149 samples. All samplings were performed during high tide. For tintinnids, 40 L of seawater were gently filtered through a 10-μm mesh plankton net and concentrated to ~250 mL. The concentrates were fixed with Lugol’s solution to a final concentration of 1%. After being fixed and allowed to settle for 24 h, the samples were further concentrated to 15 mL by carefully siphoning off the supernatant. The samples were examined under an Olympus IX 71 (Olympus, Japan) inverted microscope (100× or 400×). The whole sample was counted to determine the total number of all species.