The influence of symbiont identity and nitrogen source on the thermal disruption of carbon and nitrogen cycling in a model cnidarian-dinoflagellate symbiosis

作者：Oscar Crehan, C. Ferrier-Pagès, R. Grover, S. Davy · 发表于：Marine Biology · 年份：2026 · DOI：10.1007/s00227-026-04886-7

This study examined how carbon and nitrogen assimilation and exchange shift under normal and elevated temperatures in three cnidarian-dinoflagellate symbioses involving Exaiptasia diaphana (Aiptasia) with either the native symbiont Breviolum minutum or the non-native symbionts Breviolum psygmophilum or Durusdinium trenchii. Carbon was provided as 13C-bicarbonate and nitrogen as 15N-ammonium, nitrate, dissolved free amino acids and Artemia salina nauplii. At control temperature, symbionts differed in carbon fixation—B. minutum achieved the highest rate of population-level carbon fixation, D. trenchii showed higher per-cell photosynthesis but low population-level production due to its low density, while B. psygmophilum had similar per-cell photosynthesis to B. minutum, but lower population-level production. Artemia salina feeding was associated with a higher rate of photosynthetic carbon fixation relative to incubation with dissolved nitrogen. Across the different host-symbiont pairings, photosynthesis unexpectedly increased at 32 °C, while nitrogen pathways shifted: for the hosts and their symbionts, ammonium assimilation rose substantially and dissolved free amino acid uptake stayed stable or declined, while the hosts relied more on heterotrophic nitrogen. The C:N ratio of B. minutum significantly increased, suggesting signs of increased nitrogen limitation, while the C:N ratio of D. trenchii decreased, likely due to an increased reliance on heterotrophic nitrogen. B. psygmop...