48 



8. W. S. Hillman, D. D. Culley, Jr., Am. Sci. 66, 442 (1978). 



9. D. O. Hall, FEES Letters 64, 6 (1976). 



10. K. H. Mann, Mar. Biol. 14, 199 (1972). 



11. K. A. Clendenning, Nova Hed. 32 (Suppl.), 259 (1971). 



12. A. Thorhaug, M. A. Roessler, Aquaculture 12, 253 (1977). 



13. B. C. Wolverton, R. C. McDonald, NASA-ERL Rept. No. 171 (1978). 



14. E. S. Lipinsky, T. A. McClure, R. A. Nathan, T. L. Anderson, W. J. Sheppard, W. T. 

 Lawhon, Battelle Columbus Lab. Task 77 Final Rep. BMI-1957 (Vol. 2) (1976). 



15. J. H. Ryther, Oceanus 22, 21, (1979). 



16. Testimony of Dr. Ab Flowers, Director, Gas Supply Research, Gas. Res. Inst, before 

 Subcommittee on Oceanogr., Comm. on Merchant Mar. and Fish., U.S. House Rep., Sept. 26, 

 1979. 



17. Contribution No. of the Woods Hole Oceanographic Institution. The research was support- 

 ed by SERI Contract No. XR-9-8133-1. 



I 



! 



V 



_J I l_ 



10 15 20 25 30 



.C 



O 50 100 150 200 250 300 



^ 

 "S 



§ 



50 100 150 200 250 300 



PLANT DENSITY: g- ash- free drywt./m^ 



Figure 1. Growth rate (broken line) yield (solid line) of marine diatoms (A), the red seaweed 

 Gracilaria tikvahiae (B), and the freshwater macrophytes, duckweed (Lemna minor) (C), and 

 water hyacinth (Eichhornia crassipes) (D) as a function of plant density. Note that both 

 horizontal and vertical scales differ for the resptective sjjecies. 



Dr. Ryther. For most of my career I have been working at 

 Woods Hole on problems of comparative productivity in yields of 

 different kinds of marine and general aquatic ecosystems, and 

 problems in aquaculture, marine aquaculture in particular, and 

 problems of waste recycling. 



I am trying to combine some of these things together, trying to 

 use marine organisms as a method of removing the nutrients from 

 waste water and growing useful crops and, at the same time, 

 purifying the waste water and removing the nutrients from it. 



