MEPS 375:185-194 (2009)  -  DOI: https://doi.org/10.3354/meps07726

ABSTRACT: The contribution of the intertidal barnacle Chthamalus montagui to CO₂ fluxes via respiration and calcification was measured both in the air and underwater. The mean biomass of the species was 44.92 g ash-free dry weight (AFDW) m^–2 on the coast of Brittany, France. Underwater respiration, determined from changes in dissolved inorganic carbon (DIC), fluctuated from 6.14 µmol g^–1 h^–1 in winter to 13.37 µmol g^–1 h^–1 in summer. The contribution of C. montagui respiration to DIC fluxes for an average daily immersion time of 8 h was 3.21 mmol m^–2 d^–1. Mean aerial CO₂ respiration was estimated at 7.60 µmol g^–1 h^–1 using an infrared gas analyser, corresponding to 5.46 mmol m^–2 d^–1 if the mean daily emersion time is 16 h. Net calcification was positive, with a mean value of 1.01 µmol g^–1 h^–1, corresponding to a CO₂ flux of 0.25 mmol m^–2 d^–1. The total mean daily emission of CO₂ by C. montagui populations was 8.92 mmol m^–2 d^–1. The annual carbon production by the species was 39.07 g m^–2 yr^–1 with relative contributions by aerial respiration, underwater respiration and net calcification of 61, 36 and 3%, respectively. The daily ratio of aerial:underwater carbon emission was 1.7, emphasizing the prevalence of aerial respiration and the metabolic adaptation of C. montagui to amphibious life.

KEY WORDS: CO₂ · Barnacle · Respiration · Calcification · Crustacean · Intertidal