Figure 5. Patches of a pale yellow lobose sponge on the eastern flank of Rockall Bank in association with the cold-water coral Lophelia pertusa (photo credit JNCC).
Rich sponge assemblages are found along the southwestern flank of Rockall Bank in Irish waters (van Soest et al 2007) in association with dead coral framework. These may also represent a variant of deep-sea sponge aggregation types, provided that date could be gathered to establish that the cover or density of live coral does not exceed that of the sponges.
Rosemary Bank
Nearly half of the records from Rosemary Bank were verified as deep-sea sponge aggregations with high confidence (Table 2). These did not conform to the more familiar aggregations of either boreal ostur or Pheronema grounds, but instead are comprised mostly of low-lying massive and encrusting fields of yellow, blue, grey and white sponges (Figure 6). These ranged in depth from 842–867m water depth on mostly pebble, cobble and boulder substrata in waters averaging 8°C (Howell et al 2007, 2010). Psolus were often found in these assemblages, along with the bright orange anemone Phelliactis, and occasionally with scleractinian corals including Lophelia, Madrepora and solitary corals as well as the coiled red-orange antipatharian Stichopathes. Although this overlap with indicator species of cold-water coral reefs or coral gardens might seem to preclude these assemblages as deep-sea sponge aggregations, SIMPER identified sponges as being the most characteristic fauna rather than corals in two of these records (Howell et al 2010).
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