Reef Chemistry Question of the Day #202 Silica accumulating organisms

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #202

Which of the following do not accumulate large amounts of silica/silicate as they grow in the ocean?

A. The cyanobacteria Synechococcus
B. The sponge Guancha lacunosa
C. The diatom Bacillaria paradoxa
D. The sponge Neoschrammeniella norfolki

This one is not as easy as it may seem.


Good luck!






























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[anthonys51]

I would say a

 

[Reefer1978]

By the old school rules of multiple choice, if there are 2 of the same species, (sponges this time), that has to be one of the right answers. Looking at the pictures on google, "B. The sponge Guancha lacunosa" is white in color, "D. The sponge Neoschrammeniella norfolki" is more orange shaded, closer to diatoms.

So going to guess "B. The sponge Guancha lacunosa". This is only a guess.

 

[Alfrareef]

B for sure! [emoji41]

 

[tangerine3486]

Today I got water tests for silica at .8 mg/L. In the search for what this means an article you wrote mentioned sponges. I'll go for B as well!

 

[Randy Holmes-Farley]

And the answer is...
B. The sponge Guancha lacunosa

That sponge has calcium carbonate spicules rather than a silica spicules. Turns out that about 75% of sponges take up dissolved silica (including the other sponge listed in the choices), but not this one.

Curiously, the cyanobacteria Synechococcus takes up silica, something that I had not known before researching this question.

http://www.nature.com/ngeo/journal/v5/n12/abs/ngeo1641.html?foxtrotcallback=true


from it:

"We show that cells of Synechococcus, a small unicellular marine cyanobacterium that dominates in nutrient-depleted waters2, can exhibit cellular ratios of silicon to sulphur, and silicon to phosphorus, approaching those detected in diatoms in the same location. Silicon accumulation was also observed in cultured Synechococcusstrains. We estimate that the water column inventory of silicon in Synechococcus can exceed that of diatoms in some cases. We suggest that picocyanobacteria may exert a previously unrecognized influence on the oceanic silicon cycle, especially in nutrient-poor waters."