Abstract:Golden mussel (Limnoperna fortunei Dunker, 1857) is an invasive benthic macroinvertebrate species with high dispersal ability and strong environmental adaptability. It is native to southern China, and its distribution has expanded to northern China, southeastern Asia, and many areas in South America. Its invasion and dense attachment on natural environments and water transfer works not only causes damage to the local bio-community, but also leads to high risk to the works owing to difficulties in removing adult mussels due to their tight attachment to the surface. Consequently, prevention of the entry of golden mussel larvae into the water transfer works has been considered as the most efficient means of avoiding invasion of this species. This experiment studied the attachment characteristics of golden mussel larvae, and proposed measures for attracting the larvae in raw water to attach onto suitable materials. This reduced the density of golden mussel larvae entering into the water transfer works and therefore the attachment density of adult mussels on the water transfer pipelines. Hessian material, which the results of our previous study indicated as a suitable material for golden mussel attachment, was selected and set up into attachment plates for the species. Five different sets of attachment plate lengths (1, 3, 5, 6 and 8 m) and five different discharges (3.1, 5.7, 6.7, 9.6, and 12.1 L/s) were tested to study the influences of the length of attachment material and flow discharge on attaching behaviors of golden mussel larvae. A microscope was applied to observe the larvae with assistance of the SmartV Camera image acquisition system to capture images. The images analysis software MIVNT was used to measure the sizes of the larvae in the captured images. Variation of larval density upstream and downstream of the attachment plates was analyzed and used to indicate attachment efficiency. Optimum conditions of the attachment material length and flow discharge were then determined that would attract larvae to the maximum extent. The experimental results indicated that (1) the attachment rate of golden mussel larvae on the hessian material was positively related to the attachment plate length. Attachment rate reached 50% when the attachment plate length was 3-5 m. The average attachment rate reached 62%-76%, with the highest rate being as high as 93% when plate length was 6-8 m; (2) the attachment rate of golden mussel larvae decreased with increase in flow discharge; (3) the attachment rate of pediveligers and plantigrade veligers on the material was much higher than that of umbonated veligers; (4) dense arrangement of the hessian attachment plates at a short distance was more effective in improving the attachment efficiency than was sparse arrangement at a longer distance.