Abstract
The aim of this study was to evaluate the influence of salinity (S) fluctuations on the growth and carrying capacity of the dinoflagellates Akashiwo sanguinea and Prorocentrum micans, isolated from coastal water in southern Brazil, and the relationship between salinity and their distribution in the environment. The effect of salinity on these species was tested under acclimated conditions and abrupt salinity changes. Cultures were acclimated for one month (S 10, 15, 20, 25, 30 and 35), and the optimum growth was established. The acclimated cultures that presented optimal growth were transferred, without acclimation, to higher and lower salinities. A. sanguinea showed maximum growth at salinity 25 with a broad tolerance (S 10–35), and carrying capacity was highest and lowest at salinities of 30 and 10, respectively. P. micans grew better and had a higher carrying capacity at a higher salinity (25–35). The response of cells to salinity variation was also species-specific: no change (P. micans) or an increased growth rate (A. sanguinea). In the surf zone of Cassino Beach, both species had higher frequency and cell density in summer and autumn. The relationship between salinity and cell density coincided with the results obtained in the laboratory. The ability to grow under salinity changes is an important mechanism that leads to dinoflagellate blooms. With the increasing rainfall in southern Brazil as a result of climate change, A. sanguinea will likely be more successful than P. micans and form blooms in this region, due to its broad range of salinity tolerance.
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Disclosure statement
No potential conflict of interest was reported by the authors.
Editorial responsibility: David Montagnes