The effect of gradual increase in salinity on the biomass productivity
and biochemical composition of several marine, halotolerant,
and halophilic microalgae
Parisa A. Bahri
Damian W. Laird
Navid R. Moheimani
Received: 24 September 2017 /Revised and accepted: 21 December 2017 /Published online: 11 January 2018
Springer Science+Business Media B.V., part of Springer Nature 2018
Open ponds are the preferred cultivation system for large-scale microalgal biomass production. To be more sustainable, commercial
scale biomass production should rely on seawater, as freshwater is a limiting resource, especially in places with high irradiance. If
seawater is used for both pond fill and evaporative volume makeup, salinity of the growth media will rise over time. It is not possible
for any species to achieve optimum growth over the whole saline spectrum (from seawater salinity level up to salt saturation state).
In this study, we investigated the effects of gradual salinity increase (between 35 and 233 ppt) on biomass productivity and
biochemical composition (lipid and carbohydrate) of six marine, two halotolerant, and a halophilic microalgae. A gradual and slow
stepped salinity increase was found to expand the salinity tolerance range of tested species. A gradual reduction in biomass
productivity and maximum photochemical efficiency was observed as a consequence of increased salinity in all tested species.
Among the marine microalgae, Tetraselmis showed highest biomass productivity (32 mg L
) with widest salinity tolerance
range (35 to 109 ppt). Halotolerant Amphora and Navicula were able to grow from 35 ppt to 129 ppt salinity. Halophilic Dunaliella
was the only species capable of growing between 35 and 233 ppt and showed highest lipid content (56.2%) among all tested species.
This study showed that it should be possible to maintain high biomass in open outdoor cultivation utilizing seawater by growing
Tetraselmis, Amphora,andDunaliella one after another as salinity increases in the cultivation system.
Microalgae have been commercially cultured since the early
1960s, particularly for nutraceutical applications (Borowitzka
1999;Mataetal.2010). Microalgal cultures are also used as
aquaculture feed (Benemann 1992; Borowitzka 1997)oras
sources of high value chemicals like carotenoids, phycobilins,
and omega-3-fatty acids (Pulz and Gross 2004; Borowitzka
2013). Recently, microalgal biomass has been considered as a
potential source of bio-energy such as biodiesel, biogas and
bioethanol (Griffiths and Harrison 2009;Doanetal.2012).
However, the commercial production of biofuel from
microalgae is currently regarded as economically unviable
due to the requirements for large amounts of limiting resources
like freshwater and nutrients (Borowitzka and Moheimani
2013;Ishikaetal.2017). One potential strategy to lower pro-
duction costs is to reduce the consumption of a cost-intensive
and limited resource input such as freshwater. A cost analysis
report on biodiesel production from microalgae indicated that
3.7 kL of freshwater is needed to produce 1.2 L of biodiesel
(Yang et al. 2011). Being able to culture in seawater would
seem to be a convenient option for mass microalgal cultivation
to produce a more environmentally and economically sustain-
able biomass (Borowitzka and Moheimani 2013).
Marine, halotolerant and halophilic microalgal species, be-
ing already tolerant to relatively high salinity levels, would be
the practical choice during cultivation using only seawater.
However, only a handful of these microalgae (e.g., Dunaliella
salina, Dunaliella tertiolecta, Tetraselmis suecica, Tetraselmis
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s10811-017-1377-y) contains supplementary
material, which is available to authorized users.
* Navid R. Moheimani
Algae R & D Centre, School of Veterinary and Life Sciences,
Murdoch University, Murdoch, WA 6150, Australia
School of Engineering and Information Technology, Murdoch
University, Murdoch, WA 6150, Australia
Journal of Applied Phycology (2018) 30:1453–1464