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In this study, we examined the short-term variation in the abundance of copepod Acartia specimens, identified previously as Acartia pacifica, in Laizhou Bay, an estuarine bay in the southern Bohai Sea in northern China. Monthly samples were collected from May 2011 to April 2012, excluding December 2011 and January to February 2012 due to ice. Based on its morphological characteristics, Acartia ohtsukai was distinguishable from A. pacifica for the first time in Laizhou Bay. A. ohtsukai was sporadically present from summer to autumn, with the highest abundance and occurrence in September. It appeared in June when the water temperature was above 20°C, and disappeared in November when the water temperature decreased to less than 10°C. During the surveyed months, A. ohtsukai was more commonly found inshore with salinity less than 28 than offshore in the bay. Correlation analysis revealed that temperature and chlorophyll a concentration significantly influenced the monthly variations in A. ohtsukai abundance. We also compared the occurrence of A. ohtsukai with that of three species from the genus Tortanus (Tortanus derjugini, Tortanus forcipatus, and Tortanus spinicaudatus) in Laizhou Bay. The coexistence of A. ohtsukai and T. derjugini in the bay suggests that their ecological habitats are similar to those of brackish-water species. [ABSTRACT FROM AUTHOR]

The recent accelerated ocean acidification and global warming caused by increased atmospheric carbon dioxide may have an impact on the physiology and ecology of marine animals. This study was conducted to determine the egg production rate (EPR) and hatching success (EHS) of Acartia ohtsukai in response to the combined effects of an increase in temperature and a lower pH. Acartiaohtsukai with fresh surface seawater were collected in the northwestern Yeoja Bay of Korea in September 2017. The temperature and pH conditions applied included two different pH levels (representing the present: 7.9 and the future: 7.6) and three temperature values (26 °C, 28 °C, and 30 °C). In the pH 7.9, EPR significantly increased with increased temperature, but in pH 7.6, it significantly decreased as the temperature increased. EHS was lower in pH 7.6 than in pH 7.9. These results suggest that changes in the marine environment due to global warming and ocean acidification may affect Acartia populations and cause overall fluctuations in copepods of the genus Acartia.

The recent accelerated ocean acidification and global warming caused by increased atmospheric carbon dioxide may have an impact on the physiology and ecology of marine animals. This study was conducted to determine the egg production rate (EPR) and hatching success (EHS) of Acartia ohtsukai in response to the combined effects of an increase in temperature and a lower pH. Acartiaohtsukai with fresh surface seawater were collected in the northwestern Yeoja Bay of Korea in September 2017. The temperature and pH conditions applied included two different pH levels (representing the present: 7.9 and the future: 7.6) and three temperature values (26 °C, 28 °C, and 30 °C). In the pH 7.9, EPR significantly increased with increased temperature, but in pH 7.6, it significantly decreased as the temperature increased. EHS was lower in pH 7.6 than in pH 7.9. These results suggest that changes in the marine environment due to global warming and ocean acidification may affect Acartia populations and cause overall fluctuations in copepods of the genus Acartia. [ABSTRACT FROM AUTHOR]