RESPONSE OF MESOCYCLOPS (CYCLOPOIDA, COPEPODA) TO BIOLOGICAL AND PHYSICOCHEMICAL ATTRIBUTES OF RAINWATER TANKS

The population growth and survival of Mesocyclops aspericornis (Daday) and Mesocyclops darwini (Dussart & Fernando) were compared in rainwater tanks at Amity Point, Stradbroke Island, and natural breeding habitats in other Queensland localities. The biological and physicochemical attributes of these biotopes were measured and it was found that pH, protozoan numbers, and chlorophyll level all significantly affected Mesocyclops persistence and population growth. While these three factors accounted for 82% of the variation, low food levels were considered to be the major factor limiting growth and survival. Protozoan and algal levels in tanks were one-fifth that of natural breeding sites. In a series of laboratory trials, Mesocyclops population growth was maximal in the pH range of 6.0-8.0 and in salinities below 1.66 parts per thousand. Greatest growth also occurred in media with both protozoans and algae at levels greater than 32,000 per ml and 3.9 mug/liter, respectively. The variability of and low food levels in rainwater tanks will limit broad scale use of copepods for biocontrol of Aedes larvae in these sites.