ABSTRACT
An inexpensive, low maintenance light-trap was developed for use in determining the distribution and abundance of marine larvae in regions where conventional methods may not be used. The light trap was a portable system (0.021 m3 total volume) designed to attract positively phototropic animals to a small region of strongest illumination, from which they could be captured. The filter system was a cylindrical, opaque vessel to which a 150 μ m mesh filter, airlift system (2.768 L/minute water flow), and omni-directional 40 W halogen light were attached. Water flow was provided by an airlift system constructed of a standard fine pore diffuser (5 cm X3.75 cm), 12 V battery operated air pump (0.5 A, 3.3 L/minute airflow at 100 PSI), average eduction pipe length was 50 cm (1 cm diameter).
The calculations, along with the laboratory and field trials indicated that a light trap was a useful tool to determine the distribution and abundance of photo-sensitive marine larvae. The research showed a trap efficacy of 46% in collecting larvae in a static system in the laboratory. This capture method could also be applied successfully in the field. The light trap, with slight modifications, could become a commercially viable option for removal of mobile lice stages from the environment in regions where aquaculture and fisheries co-exist.
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