The Varadero Reef is located south-west of the Cartagena Bay close to the southern strait that connects the Bay to the Caribbean Sea in Colombia (10°18’23.3"N, 75°35’08.0"W). The Bay is a receiving estuary from the Magdalena River through the Canal del Dique, a man-made channel whose construction and operation dates back almost a century. The depth of the particular transplant site in Varadero is 3.5m.

Irradiance was monitored for one year (November 2016 - November 2017) at Varadero with cosine-corrected light sensors (Odyssey submersible PAR logger, Dataflow systems, New Zealand), previously cross-calibrated against a manufacturer-calibrated quantum sensor (LI-1400, LI-COR, USA). The light sensors were cleaned and downloaded periodically (every two months or less) to avoid biofouling. Data in which cumulative light signal loss was evident were discarded.

In order to estimate the variation of the optical properties of water resulting from the Dique plume dynamics, light data recorded underwater were compared with data simultaneously recorded by another sensor in a site onshore close to Varadero (Fig. 5). With this array, we were able to isolate the variations of irradiance associated with the plume from variations due to cloud coverage. The irradiance synchronously recorded by onshore and underwater loggers was used to estimate the variability of Kd based on the Lambert-Beer’s law: Kd = ln (Ez / E0) / -Z,

where Ez is the irradiance recorded underwater, E0 is the irradiance recorded onshore, and Z is the depth at which the underwater sensor was deployed in Varadero (3.5 m). Only data recorded between 7:00 and 17:00 were employed.

Odyssey data logging software (Dataflow systems Ltd., Christchurch, New Zealand) was used to manage the logger and data operations.

Problem report: There are some gaps associated with technical failure of the devices.