Continental shelves around the Azorean islands are quite narrow and represent an area of just 1500 km2, half of which is composed of rocks and one third of mixed sediment. Hard substrate is found in each deep-sea biological zone (see Howell, 2010 for classification), but most extensively in the abyssal (> 2700 m). Mixed sediments are also present at each depth level, but the largest area is in the mid-bathyal (1100–1800 m). The most extensive substrate types in the Azores ecoregion are muddy sediment (Figure 7).
