Abstract:Tintinnid is one of the major species of microzooplankton, and it has been suggested to be the food source of the first-feeding fish larvae in the marine environment. We studied a large number of large tintinnid in Laizhou Bay during 9 cruises from May to November in 2011 and from March to April in 2012. The study on the horizontal distribution of large tintinnids in Laizhou Bay from March to November enriched the basic data for the development and utilization of fish resources in Laizhou Bay. The total abundance of tintinnid was higher in the inner bay than in the outer bay from March to May. Most tintinnids concentrated in the inner or outer bay from June to November. The temperature and salinity related to the largest tintinnid abundance remained stable in different months, which suggested that tintinnid might be adapted to different temperatures and salinities within a certain range. The distribution of tintinnid in June was consistent with the distribution of fish eggs and larvae, which indicated that tintinnid was the seasonally advantageous for the first-feeding fish larvae as a food source. The richness of tintinnid species ranged from 5 to 20. A total of 17 species were identified as dominant species in the 9 different months. The maximum abundance of Codonellopsis mobilis, a dominant species, was 489×103 ind/m3 in May, but the maximum abundance of another dominant species, Tintinnopsis hemispiralis, was only 4×103 ind/m3 in November. The richness of the dominant species ranged from 2 (in April) to 10 (in July and August). In July and August, the abundances of dominant species were small, and the tintinnids were distributed. In other months, a large proportion of dominant species abundance concentrated in the inner or outer bay, and it dramatically affected the total abundance. C. mobilis, Stenosemella nivalis, Tintinnopsis radix, Tintinnopsis tocantinensis, and T. hemispiralis were the major dominant species that had been dominant for at least 3 months consecutively. Tintinnopsis estuariensis was found in August which appeared nearby the Yellow River estuary, although the salinity was higher than the previous records. It was a newly recorded species.
