*2.2. Water Column Measurements*

Water samples were taken at several depths using a 12-bottle Niskin rosette (Ro) system. For water column hydrography profiling, an instrument measuring in situ conductivity, temperature, and pressure (CTD) attached to the water sampling system was used. A total of 12 CTD and 52 CTD/Ro (CTD/rosette water sampling) casts were carried out across the CWC sites (HH, NK, HN, SN, BK). Measurements were taken during six cruises between February 2016 and August 2017, onboard RV *Håkon Mosby*, RV *Kristine Bonnevie*, RV *H. Brattström,* and MS *Periphylla* (Table 1). In October 2016 and January 2017, water sampling was performed over a tidal cycle at HH (26-h) and NK (16-h), respectively. On other sites and times, water sampling was performed a maximum of once per site (Table 1). Data collected in October 2016 and August 2017 have been reported earlier in Skjelvan et al. (2016) [62] and Jones et al. (2018) [48], respectively.

**Figure 1.** The map of (**A**) Langenuen on coastal Norway (white polygon) and Utsira coastal station (red dot), (**B**) CWC sites in Langenuen Fjord: bank reef Bekkjarvik (BV), live corals at depths 200–210, wall reef Straumsneset (SN), live corals at depths 80–220 m, wall reef Hornaneset (HN), live corals at depths 220–240 m, bank reef Nakken (NK), live corals at depths 190–220 m (white polygon) and wall reef Huglhammaren (HH), live corals at depths 80–220 m and (**C**) the Nakken reef area with lander deployment locations ~125 m apart from each other shown with stars. MLM = lander deployed on the CWC bank, SLM = lander deployed south of the CWC bank.

**Table 1.** Summary of cruises, visited locations, and measurements between February 2016 and August 2017. Abbreviations; HM = Håkon Mosby, KB = Kristine Bonnevie, NK = Nakken, HH = Huglhammaren, HN = Hornaneset, SN = Straumsneset, BK = Bekkjarvik. C = carbonate chemistry (AT and CT) samples, N = nutrient samples, I = isotope samples.



**Table 1.** *Cont.*

Processing of the raw CTD data was performed using the software package SBE Data Processing[63]. The wall reefs (HH, HN, and SN) were investigated above, below, and at the respective depths of living *L. pertusa* corals. At the bank reefs (NK and BV), samples were taken at the surface, at intermediate depths (at 80 or 100 m and at 150 m), and at ~5 m above the reef.
