Tessin, Elinor

Resolving the molecular structure of dinoflagellate cyst walls

A lar­ge por­ti­on of glo­bal pri­ma­ry pro­duc­tion ta­kes place in the sur­face lay­ers of the oce­an. Here, CO2 is fi­xed into or­ga­nic mat­ter, which is then trans­for­med or trans­por­ted la­te­r­al­ly or down­ward through the wa­ter co­lumn. Only a small por­ti­on of this ma­te­ri­al re­aches and is then stored at the oce­an floor.

Wi­t­hin the Clus­ter of Ex­cel­lence “The Ocean Floor – Earth’s Uncharted Interface”, the RE­CEI­VER Re­se­arch unit stu­dies this trans­fer of mat­ter to the oce­an floor. The­me 3 of this unit, “The transfer of matter and signals into the ocean floor” is fo­cu­sed on im­pro­ving our un­der­stan­ding of how such or­ga­nic mat­ter is al­te­red on its way into and wi­t­hin ocea­nic se­di­ments.

One such group of or­ga­nic mat­ter are the or­ga­nic-wal­led cysts of di­n­of­la­gel­la­tes (di­no­cysts). As po­ly­sac­cha­ri­de-ba­sed par­ti­cles that can ea­si­ly be tra­ced back to their bio­lo­gi­cal sour­ce, di­no­cysts from oce­an se­di­ments can be used as pro­xies to stu­dy past cli­ma­tic con­di­ti­ons. This re­qui­res that the pro­duc­tion and sub­se­quent al­te­ra­ti­on of both the pro­xy si­gnal and pro­xy si­gnal car­ri­er are well un­ders­tood. His­to­ri­cal­ly, di­no­cysts were be­lie­ved to be ex­tre­me­ly re­sis­tant to ae­ro­bic de­gra­da­ti­on, but it has been re­pea­ted­ly shown that some cyst spe­cies are far more re­sis­tant than others.

Selec­tive pre­ser­va­ti­on of di­no­cysts is a po­ten­ti­al bias in pa­leo­cli­ma­te stu­dies and mo­dels of CO2 sto­r­a­ge, but also opens up new per­spec­tives of using spe­cies of va­ry­ing re­cal­citran­ce as fi­nely tu­n­ed mar­kers of deep oce­an ven­ti­la­ti­on and ae­ro­bic de­gra­da­ti­on of or­ga­nic mat­ter in ma­ri­ne se­di­ments. It will first be ne­cessa­ry to achie­ve a more com­ple­te un­der­stan­ding of the mole­cu­lar cha­rac­te­ris­tics that make spe­cies la­bi­le or re­cal­cit­rant.

The aim of this pro­ject is to ana­ly­ze the cell wall struc­tu­re of known la­bi­le and re­cal­cit­rant cysts. I aim to re­sol­ve the fol­lo­wing ques­ti­ons:

1. How does molecular structure differ between different species? If such differences exist, Micro-FTIR spectra could be a viable alternative to dinocyst species identification relying on genetic sequencing or morphological characteristics.
2. To what extent is the molecular structure of resistant dinocysts altered by diagenetic processes?
3. How does the molecular structure of cysts of each species differ between regions?