Energetics of the limpet Lottia kogamogai (Gastropoda: Acmaeidae) in an intertidal rocky shore in southern Hokkaido, Japan

Abstract

We investigated, at both individual and population levels, the energy budget of a small limpet, Lottia kogamogai, which is a numerically dominant species in intertidal areas of Usujiri, southern Hokkaido, Japan. Annual energy consumption was estimated to be 0.20, 1.42, 3.06, 4.75, 5.85 and 6.97 kJ year −1 ind. −1 for 0–5 year old limpets, respectively. Assimilation efficiency was 65.9%. Of the assimilated energy, a major proportion was used for mucus secretion and the proportion increased distinctly with age, from 40% in 0 year animals to 80% in individuals over 3 years old. Metabolic loss of assimilated energy declined from 30% in 0 year old animals to 15% in limpets over 3 years old. Energy loss due to ammonia excretion is negligible, accounting for less than 0.5% of consumption. Growth efficiencies of 0–5 year old individuals were 19.0, 7.7, 4.7, 3.0, 2.8 and 2.3%, respectively. In one year, approximately 434 kJ m −2 energy flowed through the population, of which about 147 kJ m −2 was defecated as faeces. The energy allocated to growth and reproduction was relatively low, only 24.7 kJ m −2, while that expended for mucus secretion and metabolism were 206.7 kJ m −2 and 55.4 kJ m −2, respectively. The population had a P/B ratio of 1.67. The net growth efficiency, gross growth efficiency and ecological efficiency were 8.6%, 5.7% and 4.6%, respectively.