Since a series of dinoflagellates emit light, this metabolic feature might be used to monitor algaecidal effects, in analogy to the Lumistox or Microtox test applying luminescent bacteria. Check e.g., Lapota et al. (2007) Marine Pollution Bulletin 54(12):1857. You might find additional info under the keyword "Qwiklite", e.g., www.ncbi.nlm.nih.gov/pubmed/18026774

Interesting idea proposed by Helmut, but only useful for those that bioluminesce and may not be directly linked to cell growth. However, it could be a very useful as a marker of sub-lethal or other physiological effects that many bacteria appear to have on dino cell metabolism.

For photosynthetic species, dinoflagellate growth in batch cultures can be relatively easily by measuring rate of change in chl-a using in-vivo fluorometry. Rapid and simple, but not particularly reliable outside exponential growth phase due to changes in fluorescence/cell in response to nutrient limitation. However, if growth rate is your only interest, then this is simplest and easiest.........assuming you have access to a fluorometer or a modern fluorometric plate-reader.

If you you need to be able to track growth dynamics over the full culture cycle then its either flow cytometry, a particle counter (e.g. coulter-counter) are alternatives but require some preliminary work to validate for each species. Otherwise its back to good old fashioned but time-consuming cell counts!!.

Cheers

chris

I agree with Cris that cell counts are the way to go, with old fashioned counting chambers you'll get to see if there are any morphological changes as well. If a flow cytometer is available then higher resolution counts would be possible along with an assessment of how cell fluorescence and scatter changes with exposure. With flow you could also use metabolic probes to see what else is going on in the dinos and have the chance to pick up cell death at an earlier stage than you would otherwise.

If you have the capacity to do fluorescence microscopy you may also consider using a live dead stain to determine if some of the cells are dead but not lysed. It is possible that the overall live vs dead fluorescence in the control versus the experimental treatment may also be used as a rapid means of assessing algaecidal effects.

I used to count my algae numbers (for herbicide tests) in a simple Neubauer cell chamber under a simple light microscope. This way you can easily see if there are any changes concerning morphology and behaviour and distinguish between alive and dead cells which might not be so easy when using flouresence or a flow cytometer. It also saves time cause you don't have to stain them or anything. Good luck!