Responses of benthic foraminifera to changes of temperature and salinity: Results from a laboratory culture experiment

The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18 degrees C) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12 degrees C, 25 psu and the lowest at 6 degrees C, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially, temperature by shifting foraminiferal species composition and altering the community parameters.