Smothering Intermediate Very high Low Moderate

Cladophora rupestris is a stout shrub-like seaweed, whose fronds may grow up to 20 cm in height. A covering of sediment to a depth of 5 cm is likely to partially cover the seaweed, and at low tide the whole plant may be covered whilst lying limply on the rock. Unless the sediment is removed by the incoming tide, photosynthesis would be inhibited and fronds begin to decay over the duration of one month. Spores, germlings and juveniles are likely to be highly intolerant of smothering by sediment (Vadas et al. 1992). An intolerance assessment of intermediate has been made to reflect the probable impact of smothering on germlings, thereby preventing recruitment for that period, and the inhibitory effects upon more mature specimens. On return to prior conditions, the species is likely to recover, either new growth will arise from the resistant multicellular branching rhizoids (van den Hoek, 1982) that may remain in situ, or the species is likely to recruit to cleared substrata via its 'swarmers' (reproductive propagules). Recoverability has been assessed to be very high. For instance, after the Torrey Canyon tanker oil spill in mid March 1967, recolonization by sporelings of Ulva and Cladophora had occurred by the end of April.