PHYSICAL FACTORS AFFECTING THE FATE OF PEDAL MUCUS PRODUCED BY THE COMMON LIMPET PATELLA-VULGATA

Physical factors affecting the fate and functional capabilities of the pedal mucus of Patella vulgata L. deposited in the intertidal have been examined. Mucus dehydration, rehydration and degradation were assessed. Mucus dehydration is dependent on ambient wind speed, temperature and relative humidity. Of these, over naturally encountered ranges, wind speed produces the greatest water loss over a 6-h period and it is surmised that mucus deposited at mid-shore will lose >60% of its water when exposed by the tide on days when the air is not still. The more dehydrated pedal mucus is, the longer it subsequently takes when immersed to reach a fully hydrated state. Dehydrated mucus at mid-shore is unlikely to reach full hydration during tidal immersion. Degradation of mucus measured using gravimetric and organic nitrogen leaching techniques gave similar results (10.7% w:w (6 h)-1 and 7.9% w:w (6 h)-1, respectively). Degradation was independent of the hydration state of the mucus, the aeration of the water and the sterilizing of the system. The rate of release of energy from P. vulgata as pedal mucus into the aquatic environment and the energy exported thus from a specific shore were calculated (96 J g-1 and 21 J m-2 d-1, respectively for the first 6 h of degradation). The results are discussed in terms of the potential of mucus to act as a provendering agent and its roles in nearshore ecosystems.