| 摘要 |
1431535 Rearing crustacea RHONE-PROGIL 25 March 1974 [26 March 1973] 13085/74 Heading A1A A method of attracting aquatic flora and fauna to an area of the sea bed or a river bed whereby the fauna may feed or be fed comprises depositing helicoidal structures having a density of 1.2-2 gm/cc and comprising thermoplastic material upon the sea or river bed such that the fauna use the helices as a habitat. The plastics may be polyvinyl chloride with or without polyethylene. A rough surface may be provided by adding ash. The helices may be arranged in parallel rows or randomly. Helix dimensions are disclosed. |
