Biodiversity and species abundance in coral reef ecosystems are controlled by structural complexity (Graham and Nash 2013), which is being impacted by reduced net reef framework accretion resulting from anthropogenic stressors (Kennedy et al. 2013). However, evidence verifying changes in benthic reef communities via long-term visual monitoring is rare. In 2013, during an expedition to the northern Red Sea, we revisited a permanent reef quadrat (Fig. 1a, b) located on a fringing reef near Aqaba (Jordan), which was established in 1976 as one of the earliest long-term reef monitoring sites (Mergner and Schuhmacher 1981). High-resolution, sectional photographs were combined to generate a current overview of the benthic community in the entire quadrat (Fig. 1a; Electronic Supplementary Materials, ESM, 1) for a comparison to the initial record (Fig. 1b; ESM 2). The majority of large branching (i.e., Pocilloporidae and Acroporidae) and massive (i.e., Poritidae and Faviidae) hermatypic coral colonies disappeared (Fig. 1b) and were only partially replaced by new ones (ESM 1). Although some massive corals grew noticeably, colony growth in the few persisting branching corals was insubstantial. Overall, hermatypic coral cover declined by ~10 %, and ahermatypic cover (mostly Xeniidae) increased by ~15 %. These changes were accompanied by a conspicuous increase in sand area (~10 %) and substantial decrease in bare reef framework (~20 %), suggesting major structural habitat loss with implications for net reef accretion and associated biodiversity.

Fig. 1
figure 1

Benthic community in the quadrat U-7 (size: 5 × 5 m) at 10 m depth as recorded in a January 2013 and b February 1976. Colors in b indicate large (>15 cm diameter) colonies of Xeniidae (yellow), and branching and massive corals (red and violet, respectively, for colonies that disappeared and green and blue, respectively, for colonies that persisted)