87. ORPURT, P. A., and BORRAL, L.L., "The Flowers, Fruits and Seeds of Tha- 

 taesia testudinum Koenig," Bulletin of Marine Science^ Vol. 14, No. 2, 

 June 1964, pp. 296-302. 



The flowers of turtlegrass {Thalassia testudinum) are redescribed from 

 specimens collected in Blscayne Bay, Florida. An account is given of fruit 

 development and structure. Anatomy of the seed and the germination of turtle- 

 grass are described for the first time. 



88. ORTH, R.J. , "Benthic Infauna of Eelgrass, Zosteva marina, Beds," 

 Chesapeake Science, Vol. 14, No. 4, Dec. 1973, pp. 258-269. 



The infauna of Zostera beds in the Chesapeake Bay-York River estuary and 

 Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments 

 were fine sand or very fine sand. Sediments varied from poor to moderately 

 well sorted and were positively correlated with the density of Zostera. 



A total of 117 macroinvertebrate taxa were collected. Species number 

 decreased both up the estuary and seasonally from March to July. Movement of 

 epifaunal species from the sediments to the leaves in summer partly accounted 

 for this seasonal difference. This seasonal decrease was not noted at the 

 station farthest up the estuary where Zostera was scarce. Faunal similarity 

 as measured by three indices, indicates that the infauna of most Zostera beds 

 in the Chesapeake Bay area is similar, except at the upper estuary limits of 

 Zostera. 



89. ORTH, R.J., "Destruction of Eelgrass, Zostera marina, by the Cownose Ray, 

 Rhinoptera bonasus, in the Chesapeake Bay," Chesapeake Saienae, Vol. 16, 

 No. 3, Sept. 1975, pp. 205-208. 



Destruction of Zostera beds in the York River, Virginia, is attributed to 

 the digging activities of the cownose ray {Rhinoptera bonasus) - The physi- 

 cally stable Zostera habitat with high faunal diversity and density was 

 replaced by an unstable habitat with low faunal diversity and density. 



90. ORTH, R.J., "The Role of Disturbance in an Eelgrass, Zostera mxrina. Com- 

 munity," Ph.D. Dissertation, University of Maryland, College Park, Md., 

 1975. 



Eelgrass {Zostera marina) beds in the Chesapeake Bay, Virginia, were 

 studied. Samples were taken in an intact eelgrass bed and within different- 

 sized patches of eelgrass. Eelgrass areas were subjected to different levels 

 of physical disturbance. Exposed rhizome layers as a result of physical 

 disturbances increased habitat space and allowed a significant increase in 

 abundance of polychaete annelid {Polydora tigni) . A predator exclusion cage, 

 simulating decreased disturbance, produced increased species diversity and 

 density. 



Natural disturbance occurred with the invasion of cownose rays {Rhinoptera 

 bonasus) and toadfish {Opsanus tau) . The rays removed large areas of eel- 

 grass, resulting in much of the patchiness observed in eelgrass beds. The 

 infaunal density and diversity were significantly reduced in an eelgrass bed 

 destroyed by ray activity. 



28 



