Growth and Nitrogen Uptake Characteristics Reveal Outbreak Mechanism of the Opportunistic Macroalga Gracilaria tenuistipitata

摘要: Macroalgae has bloomed in the brackish lake of Shenzhen Bay, China continuously from 2010 to 2014. Gracilaria tenuistipitata was identified as causative macroalgal species. The aim this study explore outbreak mechanism G. tenuistipitata, by studying effects salinity and nitrogen sources on growth, different uptake characteristic. Our experimental design based environmental conditions observed bloom areas, these main factors were simulated laboratory. Results showed that 12 20 % suitable for growth. When sources' (NH4+, NO3+) concentrations reached 40 mu M or above, growth rate significantly higher. Algal biomass higher (approximately 1.4 times) when cultured with NH4+ than NO3+ addition. Coincidentally, formed during times moderate (similar %) high conditions. characteristic studied understand potential bloom. best described a linear, rate-unsaturated response, slope decreasing time intervals. In contrast, followed rate-saturating Michaelis-Menten model, kinetic parameters V-max = 37.2 g(-1) DM h(-1) K-s 61.5 M. Further, isotope N-15 tracer method, we found accumulated faster an atom% twice NO3+, suggesting both available, assimilated more rapidly. results present indicate estuarine environment, combination ammonium may stimulate formation.