Coccolithophores Gephyrocapsa oceanica and Emiliania huxleyi (Prymnesiophyceae = Haptophyceae) in New Zealand's coastal waters: Characteristics of blooms and growth in laboratory culture

Abstract

Gephyrocapsa oceanica and Emiliania huxleyi were major components of extensive blooms in New Zealand's coastal waters from September to February, 1992/93. Unusually cold sea surface temperatures at that time were related to the El‐Nino phase of the Southern Oscillation and consequent climatic patterns. G. oceanica co‐dominated with Fibrocapsa japonica (Raphido‐phyceae) along the north‐east coast (spring‐early summer) in a bloom which immediately preceded a toxic dinoflagellate event. E. huxleyi bloomed in the colder waters of Big Glory Bay, Stewart Island, where a significant water column temperature gradient and depleted nitrate and phosphate concentrations were recorded. An isolate of E. huxleyi from Big Glory Bay grew optimally at a salinity of 29 × 10⁻³, pH of 7.5–8.9, and temperature of 15–25°C. An isolate of G. oceanica from Leigh grew optimally at salinity 17–29 × 10⁻³, pH 8.4–8.9, and 20–25°C. G. oceanica grew with ammonium chloride, urea, or potassium nitrate as nitrogen source; E. huxleyi grew optimally with ammonium chloride. Maximum growth rates were 1.9 doublings d⁻¹ for E. huxleyi and 1.4 doublings d⁻¹ for G. oceanica.

Keywords:

• coccolithophores
• Emiliania huxleyi
• Gephyrocapsa oceanica
• Haptophyceae
• blooms
• Prymnesiophyceae
• growth studies