Marine bacteria are essential for coral reef health

A particular group of marine bacteria is able to provide a large fraction of the nutrients needed for coral reef ecosystems to flourish. This is the striking result of a year-long study carried out at the Red Sea in Jordan by an international research team led by Prof. Dr. Christian Wild (Marine Ecology, University of Bremen). These findings have now been published in the prestigious journal “Ecosystems” by lead author Dr. Ulisse Cardini, who recently (3/2015) obtained his PhD at the University of Bremen.

Photo: Ulisse Cardini

Photo: Ulisse Cardini

An entire reef habitat examined

In their study, the group of scientists collected a large dataset of physiological measurements for all key photosynthetic organisms and their associated bacteria in a Red Sea fringing reef in Aqaba (Jordan) over the course of the entire year 2013. After collecting the field data, researchers extrapolated their results to the entire reef habitat using complex geospatial analyses. By doing so, they demonstrated that a specific group of bacteria is able to provide important nutrients to the entire reef habitat. This is particularly the case when the organisms’ need of nutrients is highest, because of the lack of alternative nutrient sources.

Additionally, the research team found that the activity of these “nutrient-providing” bacteria is highly susceptible to environmental changes, indicating that climate change and other human-driven impacts may affect their important role in coral reefs, with negative repercussions for the health of the whole reef ecosystem.

Why this is important for us all

These findings are remarkable, because they may explain how coral reef ecosystems are able to thrive in very nutrient poor tropical waters. By helping photosynthetic organisms to grow on coral reefs, these bacteria enable these highly diverse and productive ecosystems to flourish. This, eventually, allows coral reefs to provide all the ecosystem goods and services like tourism and food that make them so important to humans.

Our impact on the natural environment is growing stronger every day, and the loss of coral reefs worldwide is increasing dramatically. As such, the authors hope that the data reported in their study will be useful for planning and evaluating the effects of management on coral reef ecosystems, helping to protect these important habitats and the goods and services that they provide.

Publication:
Cardini et al. Budget of primary production and dinitrogen fixation in a highly seasonal Red Sea coral reef. Ecosystems (in press)

Photo credit: Ulisse Cardini

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