Optimum growth conditions for Amphidinium carterae Hulburt from eutrophic waters in Alexandria (Egypt) and its toxicity to the brine shrimp Artemia salina

Abstract

Cultures of a strain of Amphidinium carterae Hulburt isolated from a eutrophic basin in Alexandria were investigated for the optimum growth conditions, including vitamin requirements, the assimilation index and the potential toxicity of this species. A division rate of 2.7 day^–1, was reached on the second and third day under optimum conditions, with and without addition of B₁₂ and biotin. The rate of C₁₄ assimilation per unit chlorophyll ranged from 0.2 to 5.4 mgC.(mg Chla)-1.h^–1 according to the growth conditions and to cell size. As the cell density increased in the cultures, the cell size decreased and their photosynthetic efficiency increased. Toxicity of A. carterae to brine shrimp resulted from grazing and not from membrane diffusion of extracellular toxins.