PEDAL MUCUS PRODUCTION BY THE ANTARCTIC LIMPET NACELLA-CONCINNA (STREBEL, 1908)

Pedal mucus production rates were measured in the Antarctic limpet Nac ella concinna (Strebel, 1908). Measurements were taken over 30-min and 24-h periods to allow the relative amounts of mucus produced on attac hment to substrata and during normal locomotory phases to be calculate d. Mucus produced while N. concinna was attaching accounted for 80% of the mucus produced in a 24-h period. Rates of production were also as sessed in relation to shell length, foot area and tissue ash free dry mass (AFDM). Twenty-four hour production rates for specimens ranging f rom 11.7 to 45.9 mm in length (21.0 to 85.2 mg tissue AFDM), ranged fr om 0.49 to 1.87 mg dry mass.day(-1). On a foot area basis mucus produc tion in a 24-h period ranged from 0.61 to 2.34 mg dry mass.cm(-2) and was inversely related 40 animal size. Residuals analysis and multiple regression of mucus produced in a 30-min period against shell length, foot area and AFDM failed to show that any of these parameters account ed for a significantly larger proportion of the observed variation tha n either of the others. However, shell length, foot area and AFDM were all highly correlated with each other. Rates of production were also compared between specimens held in normal laboratory conditions and an imals which had been starved for a 5-week period. Starvation reduced p edal mucus production to 61% of normal levels. C,H,N analysis of the m ucus indicated that it was 24.5% carbon, 4.2% hydrogen and 5.4% nitrog en, on a dry mass basis with the remaining 66% being mainly accounted for by oxygen and ash. These values were used to calculate a proximate composition of 31.1% protein, 12.0% carbohydrate and 2.5% lipid, and energy contents on this basis were 10.93 kJ.g(-1) dry mass and 23.3 kJ .g(-1) AFDM. Comparing these data with previously published estimates of food consumption showed that mucus production accounted for around 12% of the energy intake, but that this fell to 2.5% if the mucus prod uced on attachment was removed from the calculation.