A system for assessing the characteristics and toxicity of a water sample comprising: a test chamber; an optical signal generator configured to emit an optical signal into the test chamber; a first digital filter disposed between the optical signal generator and the test chamber; a first optical transducer disposed to generate a first data signal in response to detecting radiant energy in the test chamber; a second digital filter disposed between the first optical transducer and the test chamber; an aqueous suspension of dinoflagellates contained within the test chamber and mixed with the water sample; a stimulator disposed to stimulate the dinoflagellates to emit a bioluminescence signal; and a microprocessor operatively coupled to the optical signal generator, the first digital optical filter, the stimulator, the first optical transducer, and the second digital filter, wherein the microprocessor is configured to assess the spectral characteristics and toxicity of the water sample.