seeds; few seeds were produced at the highest salinities. Six-week-old plants 

 could tolerate a salinity of 27,000 parts per million; older plants could not 

 tolerate salinities above 21,000 parts per million. 



67. McMAHAN, C.A., "Biomass and Salinity Tolerance of Shoalgrass and Manatee- 

 grass in Lower Laguna Madre, Texas," Jourmat of Wildlife Management, Vol. 

 32, No. 3, July 1968, pp. 501-506. 



Three different shoalgrass (Diplantheva wvightii) stands and a manatee- 

 grass {Syvingodium filiforme) community in lower Laguna Madre, Texas, were 

 sampled for biomass. The standing crop of wet shoalgrass herbage and roots is 

 estimated to be 4,656 pounds per acre. The standing crop of wet manatee- 

 grass is estimated to be 5,795 pounds per acre. Shoalgrass exhibits a sea- 

 sonal abundance; manateegrass is not seasonal. Shoalgrass sprigs planted in 

 culture vessels lived in salinities ranging from 9.0 to 52.5 parts per thou- 

 sand, but died in salinities of 3.5 and 70.0 parts per thousand. Manatee- 

 grass rhizomes planted in culture vessels survived best in a salinity of 35.0 

 parts per thousand; those planted in a vessel containing 52.5 parts per thou- 

 sand died. Shoalgrass is important to waterfowl and provides spawning and 

 nursery grounds for fish and shrimp. Manateegrass appears to be of minimal 

 value. 



68. McMillan, C. , "Experimental Studies on Flowering and Reproduction in 

 Seagrasses," Aquatic Botany, Vol. 2, No. 2, June 1976, pp. 87-92. 



Flowering and reproduction of seagrasses in laboratory cultures were com- 

 pared with responses of the same clones in Redfish Bay, Texas. Under con- 

 trolled conditions, Halophila engelmanni produced flowers continuously from 

 January- to September. Flower production in the bay was confined to the period 

 from April to mid-June. The effects of salinity, temperature, and photo- 

 period were studied in the laboratory and monitored in the bay. Of these, 

 temperature seemed to be the chief control of the flowering period of 

 H, engelmanni- Under laboratory conditions, no flowering was recorded in 

 Thalassia testudinum, Syvingodium filiforme, Ruppia mavitima, or Halodule 

 wvightii, but the flowering of H. wvightii in the bay from May to August sug- 

 gested a response to higher temperatures than indicated for H. engelmanni- 

 Fruit development of H. wvightii in the laboratory also indicated a higher 

 temperature response. 



69. McROY, C.P., "The Distribution and Biogeography of Zosteva marina. Eel- 

 grass in Alaska," Paoifia Science, Vol. 22, 1968, pp. 507-513. 



Zosteva mavina (eelgrass) is common on the Alaska coast, from the lagoons 

 on the north coast of the Seward Peninsula to the southern limit of Alaska and 

 beyond. New records of Z. mavina in Alaska are from Adak and Atka in the 

 Aleutian Islands, Chagvan and Nanvak Bays and Nunivak Island, and Lopp and 

 Ikpek lagoons on the Seward Peninsula. In Prince William Sound, the distri- 

 bution of Z. marina was altered by an uplift associated with the March 1964 

 earthquake . 



70. McROY, C.P., "Eelgrass Under Arctic Winter Ice," Natuve, Vol. 224, No. 

 5221, Nov. 1969, pp. 818-819. 



Eelgrass was found living under the winter sea ice in Safety Lagoon, an 

 embayment of the Bering Sea near Nome, Alaska. A submarine television system 

 revealed that the plants were in good vegetative condition, and in 20 to 30 



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