Details

Autor(en) / Beteiligte

• Hansen, P. J.
• Lundholm, N.
• Rost, B.

Titel

Growth limitation in marine red-tide dinoflagellates: effects of pH versus inorganic carbon availability

Ist Teil von

• Marine ecology. Progress series (Halstenbek), 2007-03, Vol.334, p.63-71

Ort / Verlag

Inter-Research

Erscheinungsjahr

2007

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The effects of dissolved inorganic carbon (DIC) on the growth of 3 red-tide dinoflagellates (Ceratium lineatum,Heterocapsa triquetraandProrocentrum minimum) were studied at pH 8.0 and at higher pH levels, depending upon the pH tolerance of the individual species. The higher pH levels chosen for experiments were 8.55 forC. lineatumand 9.2 for the other 2 species. At pH 8.0, which approximates the pH found in the open sea, the maximum growth in all species was maintained until the total DIC concentration was reduced below ~0.4 and 0.2 mM forC. lineatumand the other 2 species, respectively. Growth compensation points (concentration of inorganic carbon needed for maintenance of cells) were reached at ~0.18 and 0.05 mM DIC forC. lineatumand the other 2 species, respectively. At higher pH levels, maximum growth rates were lower compared to growth at pH 8, even at very high DIC concentrations, indicating a direct pH effect on growth. Moreover, the concentration of bio-available inorganic carbon (CO₂ + HCO₃⁻) required for maintenance as well as the half-saturation constants were increased considerably at high pH compared to pH 8.0. Experiments with pH-drift were carried out at initial concentrations of 2.4 and 1.2 mM DIC to test whether pH or DIC was the main limiting factor at a natural range of DIC. Independent of the initial DIC concentrations, growth rates were similar in both incubations until pH had increased considerably. The results of this study demonstrated that growth of the 3 species was mainly limited by pH, while inorganic carbon limitation played a minor role only at very high pH levels and low initial DIC concentrations.