The response of calcareous organism to temperature from continental shelf sediments under culture experiment-A case of benthic foraminifera

Calcareous foraminifera are significant indicators of past temperatures, but their ecological characteristics and relationship with temperature have not been extensively studied under culture experiment, particularly in continental shelf environments. In this research, we focused on Jiaozhou Bay (9-26 m) as a case study and collected surface sediments. For the first time, we cultured living foraminifera under five different temperature gradients (6, 12, 18, 24, and 30 degrees C) to investigate the impact of temperature changes on calcareous foraminifera in continental shelf sediments. Each treatment was replicated three times, and the experiment lasted for 80 days. A total of 4162 live foraminifera were collected. As the culture temperature increased, the foraminiferal parameters (abundance, species diversity, and Shannon-Wiener index) initially increased and then decreased, with the exception of the Margalef index. The study revealed that the ecological inflection point in continental shelf foraminifera occurred at or before 18 degrees C. Furthermore, a linear relationship was established between the Margalef index and temperature, represented by the eq. Y = 0.0038*T + 0.0962. Notably, the study indicated that foraminifera inhabiting the deeper continental shelf exhibited greater sensitivity to temperature variations compared to the intertidal community. This finding suggests that ecosystems located in deeper waters may be more susceptible to potential harm. Based on projections, crossing the temperature inflection point could potentially result in a 20% decrease in the biomass of calcareous foraminifera in shallow waters, as well as an 8.6 million ton decline in carbonate sedimentation in the future. Overall, this research provides novel insights and contributes to a better understanding of the response of calcareous organisms to temperature, as well as aids in paleotemperature reconstruction efforts.