The role of nutrients in decomposition of a thecate dinoflagellate

The role of nutrients in decomposition of a thecate dinoflagellate

Tamar Zohary, Hans Güde, Utsa Pollingher, Bina Kaplan, Riki Pinkas, Ora Hadas

Limnology and Oceanography, Volume 45, Issue 1, January 2000, Pages 123–130

DOI: 10.4319/lo.2000.45.1.0123

PDF Available.

Because of the low N and P content of thecae (C:N:P atomic ratios >3000:19: 1) relative to protoplasts (276 :51:1), the microbial utilization of thecae was expected to depend much more on the availability of external nutrient sources than the utilization of protoplasts. Indeed, decomposition of thecae did not occur in the absence of external nutrients but was rapid (1–2 d to their disappearance) after nutrients were added.

The results suggest that intensive regenerative nutrient cycling or external nutrient inputs are a necessary precondition for an efficient trophic transfer of the energy stored in blooms of thecate dinoflagellates. The high nutrient demands of microbial degradation imply furthermore a competition for nutrients between heterotrophic degradative and phototrophic productive processes.

Because of the generally assumed stronger competitive ability of heterotrophic bacteria, reduced primary production is expected as an indirect result of dinoflagellate bloom degradation. Indeed, reduced primary production is observed in Lake Kinneret every summer after the decline of the annual Peridinium bloom in June–July.

All from the abstract, so if you need more answers and explanations, please click through and read the PDF!

But my take is that this explains or jives with at least 90% of what we see in reef tank dino blooms, where N and P levels seem to be held down as if by magnets once a dino bloom has taken hold.  Even once nitrate and phosphate dosing have been initiated, it can seem for the reef keeper as if a ton of them have to be dosed before the overall condition improves.

It also speaks to the after effects of holding down competing populations of phototrophs as well as their allies and neutrals.



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