SEA GRASSES AT KHOR UMAIRA, PEOPLE'S 



DEMOCRATIC REPUBLIC OF YEMEN WITH 



REFERENCE TO THEIR ROLE IN THE DIET OF THE 



GREEN TURTLE, CHELONIA MYDAS 



Harold F. Hirth, Lionel G. Klikoff, and K. T. Harper' '- 



ABSTRACT 



Studies were made on the sea grass pastures at Khor Umaira in the People's Democratic 

 Republic of Yemen in July 1972. The standing crop in an equally mixed pasture of Cymodo- 

 cea senuluta and Syrin^odntin isoctifoliuni was greater than that in a pure stand of C. serrii- 

 lata. The average caloric content of the leaves of five genera of sea grasses at Khor Umaira 

 ranged between 4.54 and 4.66 kcal/g dry wt, ash free. These values are similar to those 

 reported for sea grasses in the South Pacific and in the Caribbean. Our results show that the 

 number of calories in the standing crop can be calculated from estimation of percent cover. 

 The role of sea grasses in the management schemes of the green turtle, Chelonia mydas, is 

 described. 



Sea grass meadows are productive and impor- 

 tant marine communities. Besides stabilizing the 

 substrate sea grasses provide cover and are a 

 source of food for a number of marine inverte- 

 brates and vertebrates. The leaves also support 

 a variety of epiphytes and the grass debris serves 

 as the energy base for detritus food chains. It is 

 probable that in earlier days large numbers of 

 manatees, dugongs, and green turtles grazed on 

 these submarine pastures, but the sirenians and 

 marine turtles have been so over-exploited that 

 today many marine meadows are virtually un- 

 grazed by any big vertebrate of economic impor- 

 tance to man. The green turtle, Chelo)na mydas, 

 has been proposed as a candidate for marine 

 ranching by fencing them in underwater sperma- 

 tophyte pastures (for review of management 

 schemes see Hirth, 1971). The purposes of this 

 paper are to describe some basic jiarameters of 

 the sea grass pastures at Khor Umaira in the 

 People's Democratic Republic of Yemen and to 

 provide basic data aimed at answering the ques- 

 tion, "What are the characteristics of good green 

 turtle feeding pastures?" Khor Umaira has been 

 mentioned as a possible site for a green turtle 



' Department of Biology, University of Utah, Salt Lake 

 City, UT 841 12. 



- Most of the field work was done by the senior author 

 during his tenure as Marine Turtle Consultant with the 

 Food and Agriculture Organization of the United Nations. 



ranch (Food and Agriculture Organization, 

 1968). 



THE SITE 



Khor Umaira is the name of a bay (an arm of 

 the Gulf of Aden) and village approximately 80 

 km west of Aden. The bay is almost completely 

 landlocked by a long, narrow sandy spit that 

 extends west-northwest along the coast. The bay 

 itself is about 6.5 km long. Its width varies from 

 about 550 m at the entrance to approximately 

 3.2 km in the middle. The depth of the water 

 near the entrance is between 1 and 6 m, while 

 the depth inside varies from 1 to 11 m. 



Quantitative data were taken inside the bay 

 where a few green turtles are always seen feed- 

 ing. The grass pasture in the bay was adjudged 

 similar to that off the nearby coast at comparable 

 depths where large numbers of grazing turtles 

 are caught in seines. 



METHODS 



Five adult female green turtles, all weighing 

 over 91 kg, were caught on the Ras al Ara 

 pastures (19 km west of Khor Umaira) on 22 

 July 1972. Their stomachs were full of leaves of 

 sea grasses (chiefly S«/n»5rof/H<>» and Cymodocea) 

 along with some stems and a few segments of 



Manuscript accepted May 1973. 



FISHERY BULLETIN: VOL. 71, NO. 4. 1973. 



1093 



