Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Area of Science:

• Marine biology
• Microbial ecology
• Symbiosis

Background:

• Giant clams and corals are keystone reef species relying on microbial symbiosis.
• Coral microbiome research is extensive, but clam microbiomes are understudied.
• Environmental change impacts coral microbiomes, but clam sensitivity is largely unknown.

Purpose of the Study:

• To investigate the influence of increased temperature on giant clam microbial communities.
• To assess how associated benthic species affect clam microbiome composition.
• To explore the sensitivity of clam-associated bacteria and Symbiodiniaceae to environmental factors.

Main Methods:

• Metagenomic analysis of giant clam (Tridacna maxima) microbial communities.
• Creation of artificial benthic assemblages with giant clams and two coral species.
• Monitoring clam health and microbiome composition under varying conditions.

Main Results:

• Giant clam health was contingent on the composition of associated benthic species.
• Distinct clam microbiotypes were identified, including one linked to mortality (Vibrionaceae-dominated).
• Neither elevated temperature nor benthic assemblage composition significantly altered Symbiodiniaceae and bacterial communities.

Conclusions:

• Giant clam populations harbor at least three distinct microbiotypes, offering functional redundancy.
• Microbiotype diversity suggests potential tolerance to environmental variations like increased temperature.
• Benthic assemblage composition can increase clam susceptibility to Vibrionaceae infections, particularly with rising temperatures.