Fig. 1

Screening report. The number of articles (n) assigned to each screening criteria is reported. Black boxes are articles removed from consideration. Orange boxes contain articles included for the next level of screening. Note that a single article could be excluded for multiple reasons i.e. not reporting data shallower than 30 m and not containing the right type of data. Short and long string refer to the two search strings defined in our protocol paper. Our five tags were assigned to articles while screening by outcome at abstract level. At data extraction multiple studies (s), data from combinations of taxa and locations, were reported in some articles. A list of studies can be found in Additional file 3