A nanoscale secondary ion mass spectrometry study of dinoflagellate functional diversity in reef‐building corals

Abstract

Summary Nutritional interactions between corals and symbiotic dinoflagellate algae lie at the heart of the structural foundation of coral reefs. Whilst the genetic diversity of S ymbiodinium has attracted particular interest because of its contribution to the sensitivity of corals to environmental changes and bleaching (i.e. disruption of coral–dinoflagellate symbiosis), very little is known about the in hospite metabolic capabilities of different S ymbiodinium types. Using a combination of stable isotopic labelling and nanoscale secondary ion mass spectrometry ( NanoSIMS ), we investigated the ability of the intact symbiosis between the reef‐building coral I sopora palifera , and S ymbiodinium C or D types, to assimilate dissolved inorganic carbon (via photosynthesis) and nitrogen (as ammonium). Our results indicate that S ymbiodinium types from two clades naturally associated with I . palifera possess different metabolic capabilities. The S ymbiodinium C type fixed and passed significantly more carbon and nitrogen to its coral host than the D type. This study provides further insights into the metabolic plasticity among different S ymbiodinium types in hospite and strengthens the evidence that the more temperature‐tolerant S ymbiodinium D type may be less metabolically beneficial for its coral host under non‐stressful conditions.

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