Influence of temperature and food concentrations on growth and moulting of the barnacle, Microeuraphia permitini (Zevina & Litvinova, 1970) (Chthamalidae, Euraphinae): a laboratory experiment

Chthamalid barnacles may be highly affected by environmental factors as they live in the upper intertidal zone, where other balanids cannot live due to the harsh conditions of the habitat. This study presents some information on the effects of temperature and food availability on the growth and moulting rates of a chthamalid barnacle, Microeuraphia permitini (Zevina & Litvinova, 1970) of the subfamily Euraphinae. Growth and moulting rates were estimated at different temperatures (20, 25 and 30°C) and food concentrations (6, 12 and 25 Artemia ind−1 day−1). The results indicated that growth rate generally increased at 12 and 25 Artemia ind−1 day−1 compared to 6 Artemia ind−1 day−1. Further, the highest growth rates of 0.32 ± 0.02 (% RCD/day) and 0.35 ± 0.01 were observed at 30°C when barnacles were fed with 12 and 25 Artemia ind−1 day−1, respectively. Results of a two-way analysis of variance indicated temperature and food concentrations have a combined positive effect on growth (, ) and moulting (, ) rates of the species. The food concentration in particular has a major effect on growth and moulting activities; whereas the effect of temperature was minor and limited to increased feeding rate, which may be a result of increasing vital activities including rate of cirral beating. Continued observations noted a reduced growth rate before maturity of the specimens, which can be attributed to a loss of tissue as egg masses.