Coexistence of phototrophs in sulfide-driven estuarine blooms

Estuaries are globally widespread ecosystems that are important for global element cycles, especially the carbon and nitrogen cycle. They are also important in our daily lives, because roughly 40% of the world population lives close to the coast. Understanding these ecosystems is important, because their biodiversity and function is directly impacted by natural and anthropogenic disturbances.

The study site “Trunk River” is a shallow brackish lagoon in Falmouth, MA. (Photo: MBL)

We are investigating blooms of phototrophic microorganisms that frequently occur in shallow lagoons. They are driven by sulfide that is produced from seaweed and other organic material decaying on the bottom of the lagoon.

A lorg-term “observatory” allows to regularly sample the phototrophic bloom without disturbing the established physicochemical and microbial gradients. (Photo: S. Kopf)

The phototrophic blooms are ideal model communities to investigate ecological niches of oxygenic and anoxygenic pohototrophs, their coexistence and their interactions with each other and the environment.

Filamentous cyanobacteria wiggling in circles on an agar plate. The small moving blobs are amoeba, e.g. in the upper right corner. The time lapse movie was taken with an ordinary stereo microscope and shows five minutes in the life of a microbial zoo. (Video: E. Ruff, MBL)

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