Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
Coral reefs experience phase shifts from coral- to algae-dominated benthic communities, which could affect the interplay between processes introducing and removing bioavailable nitrogen. However, the magnitude of such processes, i. Rates were extrapolated to the relative benthic cover of the studied organisms in co-occurring coral- and algae-dominated areas of the same reef.
In general, benthic categories with high N 2 fixation exhibited low denitrification activity. Total N 2 fixation was twice as high in algae- compared to coral-dominated areas, whereas denitrification levels were similar. We conclude that algae-dominated reefs promote new nitrogen input through enhanced N 2 fixation and comparatively low denitrification. The subsequent increased nitrogen availability could support net productivity, resulting in a positive feedback loop that increases the competitive advantage of algae over corals in reefs that experienced a phase shift.
Nitrogen N is vital for all living organisms and is required for primary production and the production of biomass. Among the key elements required for life i.
Ironically, however, N 2 gas is the least accessible for flora and fauna 1. Yet, coral reefs belong to the most productive ecosystems on earth and are regarded as oases in an oceanic desert 6 , 7 , 8. In this context, microbial N cycling plays a key role by introducing, recycling and removing N from coral reefs 9. Particularly, biological N 2 fixation, i. In addition, the recycling of de novo bioavailable N via nitrification 4 , 11 may serve as a mechanism to prevent the loss of N In contrast, denitrification i.
