engleski

Age and growth of the Mediterranean intertidal limpet Patella rustica Linnaeus, 1758

Mediterranean limpet Patella rustica, collected in eastern Adriatic Sea, was investigated in order to determine its age and growth. Shells were embedded in resin, sectioned from the apex to the margin and acetate peel replicas of shell sections were prepared. An annual periodicity of line formation was validated using marginal increment analysis on 60 smaller individuals (14.4 ± 1.6 mm, mean length ±S.D) collected from July 2011 to June 2012, out of which 6 (10%) were omitted from analysis due to poor visibility of growth lines. Following validation, analysis of inner growth lines were performed on acetate peel replicas of 120 individuals (ranging from 8.1 to 33.6 mm) randomly collected in September 2011. Noteworthy was the loss of pattern definition of the older parts of the shell which had been heavily infested with endoliths, resulting in difficulties in determining the position of first growth line. Based on histological study conducted simultaneously in the same period, the birth date of P. rustica was set as December 1st and this was taken into account in age estimation. Overall, 90.8 % of limpets were < 4 years old, with a mean age of 2.9 ± 1.4 years, belonging to the third age class. Only two (1.6%) individuals were more than 6 years old (6.75 and 7.75 years). Von Bertalanffy growth function was calculated and estimated VBG coefficients were L∞= 40.86 mm for length, W∞= 33.02 mm for width and H∞= 14.07 mm for height, while values of growth constant (k) were 0.23, 0.24 and 0.21 year-1, respectively. In conclusion, age and growth data suggest that P. rustica invest its energy into growth after reproduction season, in winter months, when foraging is facilitated with waves, making the food more accessible and resulting in faster growth rate.

gastropod ; shell sections ; periodicity ; validation

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