Higher Nighttime Rates of CaCO₃ Dissolution in the Nature Reserve Reef, Eilat, Israel in 2015–2016 Compared to 2000–2002

Abstract

Open ocean measurements over the past few decades have shown that surface water pH has been decreasing at an average rate of ca. −0.002 pH units•yr −1 (e.g., Bates et al., 2014). Concomitantly, saturation levels (Ω) of CaCO 3 minerals (aragonite and calcite) are also decreasing at a corresponding rate of ca. −0.008 units yr −1 (e.g., Bates et al., 2014). Reef-building corals have been shown to secrete their CaCO 3 skeletons at a rate that is positively related to seawater pH or Ω arag , and therefore decreasing with OA (e.g., Andersson & Gledhill, 2013 and references therein), where aragonite is the primary CaCO 3 mineral precipitated by hermatypic corals (e.g., Drake et al., 2020 and references therein). These relations have also been shown to occur at coral reef ecosystem scales based on direct observations (e.g., Erez

Characterizing Reef Net Metabolism Via the Diel Co‐Variation of pH and Dissolved Oxygen From High Resolution in Situ Sensors

“…This algal‐coral symbiosis is also referred to as the “biological engine producing the reef” (Roth, 2014). Dissolution typically happens at night (e.g., Moav‐Barzel et al., 2023; Page et al., 2016; Romanó de Orte et al., 2021) as a consequence of decreasing pH and [CO 3 2− ], which results from CO 2 generated by respiration no longer being consumed by photosynthesis. Net reef dissolution can be an indicator of reef ecosystem health decline, and has been associated with vulnerability to environmental stress (Hoegh‐Guildberg et al., 2007).…”