Mireille Consalvey PhD Thesis - University of St Andrews

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of experiments could resolve whether or not cells could be induced to migrate
during the night-time low/high tide. The effects of this experiment would be
limited by the depth of light penetration and therefore any investigation should
incorporate measurements of the light attenuation co-efficient (k).
The in situ migration work on the Eden Estuary provided a unique and
valuable insight into the temporal behaviours of the Eden microphytobenthos.
However, the work was limited to the exposure period. The data suggested that
on certain days the microphytobenthos may start to migrate to the sediment
surface in anticipation of the exposure period. Light seemed to be the main
stimulus but as migration also occurred at low PPFDs this would require further
investigation.
5.4.4. Summary and Conclusions
1) The minimum fluorescence yield after 15 min of dark adaption
(F, 15)
has proven to be a useful tool to monitor the migrational activity of
microphytobenthic communities under in situ conditions as well as in
situ, and demonstrated migratory patterns to vary between sites/ days
2) Diatom cells from the Tagus Estuary demonstrated both an
endogenous migratory rhythm as well as an apparently light
responsive one
3) The euglenold dominated biofilm of the Hythe demonstrated an
endogenous rhythm that was subject to light/tidal cues
4) The diatom dominated biofilm of Arlesford Creek demonstrated very
different migratory rhythms on two separate days. The rhythms
appeared to be largely independent of light and tidal cues
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