Abstract: The disclosure provides a tracer composition. The composition comprises a fluorescent molecule which fluoresces when exposed to an excitation wavelength, and thereby emit a photon with a wavelength between 400 and 600 nm; and a gelling agent.

Abstract: A ballast water monitoring device and a method for detecting live phytoplankton are disclosed. The device comprises a chamber for receiving a sample, at least one light source to emit light towards the sample, a light detector to receive light from the sample and generate a light signal, and a controller. The controller is configured to control the at least one light source to emit a single pulse of light, calculate the variable fluorescence [Fv] of the sample in response to the pulse of light, at time intervals less than the duration of the pulse of light, compare the calculated variable fluorescence to a predetermined reference limit, and perform an action if the calculated variable fluorescence is greater than the predetermined reference limit.

Abstract: A ballast water monitoring device and a method for detecting live phytoplankton are disclosed. The device comprises a chamber for receiving a sample, at least one light source to emit light towards the sample, a light detector to receive light from the sample and generate a light signal, and a controller. The controller is configured to control the at least one light source to emit a single pulse of light, calculate the variable fluorescence [Fv] of the sample in response to the pulse of light, at time intervals less than the duration of the pulse of light, compare the calculated variable fluorescence to a predetermined reference limit, and perform an action if the calculated variable fluorescence is greater than the predetermined reference limit.

Abstract: A device (100) for reading fluorescent signals comprising: an illuminator (110) for illuminating a material (130) bound with a fluorophore, at an appropriate wavelength to induce fluorescence; a detector (140) for detecting fluorescent signals emitted by the material (130); a signal processor for processing the signals detected; the device defining an optical system (170, 120, 240, 190, 180, 200, 150, 220, 210) having an excitation optical path and a detection optical path; characterised in that the illuminator (110) comprises a light emitting diode (LED), and in that the illumination illuminates all, or a substantial portion of the material (130) simultaneously.