Carrano etal, (2009) present a review on boron and marine life. Many studies have shown boron is an essential trace element for both terrestrial higher plants and freshwater and marine algae.  Lewin (1965, 1966) showed that Boron is essential for marine diatom growth based on results with 16 centric and pennate species and essential for some but not all marine flagellate species. Diatom cell division was much reduced at boron concentrations less than 0.5 mg/L or ~0.05 mM (~10% of the typical 4.5 mg/L natural seawater concentration).  While boron is a component of many culture media it is not present in  some common media such as Guillards f or f/2 which have been used widely to support marine microalgal growth including diatoms.  The presence of boron leaching into media from borosilicate glassware may account for some of this positive diatom growth but scale-up of diatom growth in plastic bags (e.g. 100 – 500 L) in mariculture operations argues that boron may not be essential for all species.  Boron is required by heterocystous cyanobacteria through its role in nitrogenase activity in dinitrogen fixation and heterocyst morphology may alter without boron. Non-heterocystous cyanobacteria display no alteration in growth or nitrogen fixation. (Bonilla et al, 1990).

Bonilla, I., M. Garcia-González, et al. (1990). Boron requirement in cyanobacteria. Its possible role in the early evolution of photosynthetic organisms. Plant Physiol. 94: 1554-1560.

Carrano, C. J., S. Schellenberg, et al. (2009). Boron and Marine Life: A New Look at an Enigmatic Bioelement. Marine Biotechnology 11(4): 431-440.

Lewin, J. C. (1965). Boron Requirement of a Marine Diatom. Naturwissenschaften 52(3): 70

Lewin, J. (1966). Boron as a Growth Requirement for Diatoms. Journal of Phycology 2(4): 160-163