Coral larvae increase nitrogen assimilation to stabilize algal symbiosis and combat bleaching under increased temperature

PLoS Biology, Journal Year: 2024, Volume and Issue: 22(11), P. e3002875 - e3002875

Published: Nov. 12, 2024

Rising sea surface temperatures are increasingly causing breakdown in the nutritional relationship between corals and algal endosymbionts (Symbiodiniaceae), threatening basis of coral reef ecosystems highlighting critical role reproduction maintenance. The effects thermal stress on metabolic exchange (i.e., transfer fixed carbon photosynthates from symbiont to host) during sensitive early life stages, however, remains understudied. We exposed symbiotic Montipora capitata larvae Hawaiʻi high temperature (+2.5°C for 3 days), assessed rates photosynthesis respiration, used stable isotope tracing (4 mM 13 C sodium bicarbonate; 4.5 h) quantify metabolite exchange. While did not show any signs bleaching experience declines survival settlement, depression was significant under temperature, indicated by a 19% reduction respiration rates, but with no change photosynthesis. Larvae showed evidence maintained translocation major photosynthate, glucose, symbiont, there reduced metabolism glucose through central glycolysis). larval host invested nitrogen cycling increasing ammonium assimilation, urea metabolism, sequestration into dipeptides, mechanism that may support maintenance stress. Host assimilation via dipeptide synthesis appears be limitation Symbiodiniaceae, we hypothesize contributes retention favoring photosynthate host. Collectively, our findings indicate although these susceptible diverting energy maintain population density, photosynthesis, allow avoid highlights potential stage specific responses

Language: Английский

Symbiotic nutrient cycling enables the long-term survival of Aiptasia in the absence of heterotrophic food sources

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2022, Volume and Issue: unknown

Published: Dec. 11, 2022

Abstract Phototrophic Cnidaria are mixotrophic organisms that can complement their heterotrophic diet with nutrients assimilated by algal endosymbionts. Metabolic models suggest the translocation of photosynthates and derivatives from algae may be sufficient to cover metabolic energy demands host. However, importance heterotrophy nutritional budget these holobionts remains unclear. Here, we report on long-term survival photosymbiotic anemone Aiptasia in absence food sources. Following one year starvation, anemones remained fully viable but showed an 85 % reduction biomass compared regularly fed counterparts. This shrinking was accompanied a host protein content density, indicative severe nitrogen limitation. Nonetheless, isotopic labeling experiments combined NanoSIMS imaging revealed contribution algal-derived metabolism unaffected due increase photosynthesis more efficient carbon translocation. Taken together, our results that, one- timescale, feeding is not essential fulfilling requirements holobiont. But, while symbiotic nutrient cycling effectively retains holobiont over long time scales, data critical source required for growth under oligotrophic conditions.

Language: Английский