HARVEST AND REGROWTH OF TURTLE GRASS (THALASSIA 

 TESTUDINUM) IN TAMPA BAY, FLORIDA' 



John L. Taylor,^ Carl H. Saloman,' and Kenneth W. Prest, Jr.' 



ABSTRACT 



A comparison of leaf growth and new leaf production in plots of cut and uncut turtle 

 grass, Thalassia testudinum, indicated that plants suffered no damage when harvested 

 twice during a 6-month growing season in Boca Ciega Bay (Tampa Bay), Fla. In 

 deeper or warmer waters where the growing season is protracted, three or more cuttings 

 per year may prove practical. 



One of the environmental catastrophes to occur 

 in the past 30 years is the destruction of vast 

 beds of turtle grass through dredge-fill opera- 

 tions, other types of coastal engineering, and 

 pollution in its many forms (McNulty, 1961; 

 Taylor and Saloman, 1968; McNulty, Lindall, 

 and Sykes, in press). The most recent devel- 

 opment that may affect turtle grass is the pos- 

 sibility of its harvest for use as a food supple- 

 ment for livestock. 



Interest in the nutrient content of turtle grass 

 was first stimulated by Burkholder, Burkholder, 

 and Rivero ( 1959) , who showed that turtle grass 

 leaves contain about 13% protein. Their anal- 

 ysis was substantiated by Bauersfeld et al. 

 (1969), who further found that turtle grass in 

 pellet form significantly increased the weight 

 gain and feed utilization of experimental sheep 

 over that of control animals when added to nor- 

 mal rations as a replacement for alfalfa at a level 

 of about 10%. One of the many questions 

 raised by the success of these feeding trials is 

 whether or not beds of turtle grass can survive 

 and regrow after harvest. This report presents 



^ Contribution No. 76, Gulf Coastal Fisheries Center, 

 St. Petersburg Beach Laboratory, National Marine Fish- 

 eries Service. 



' Gulf Coastal Fisheries Center, National Marine Fish- 

 eries Service, NOAA, St. Petersburg Beach, FL 33706; 

 present address: 1307 Pass-A-Grille Way, St. Peters- 

 burg Beach, FL 33706. 



* Gulf Coastal Fisheries Center, National Marine Fish- 

 eries Service, NOAA, 75 33d Avenue, St. Petersburg 

 Beach, FL 33706. 



Manuscript accepted June 1972. 



FISHERY BULLETIN: VOL. 71, NO. 1, 1973. 



results of a study in which leaves in an exper- 

 imental plot of turtle grass were repeatedly cut, 

 measured, and compared with those taken from 

 a control area between August 1968 and Novem- 

 ber 1969. 



In the Gulf of Mexico and Caribbean Sea, the 

 dominant sea grass is turtle grass, Thalassia 

 testudinum Koenig and Sims. Generally, it 

 flourishes in estuaries and coastal waters from 

 the level of low water to depths of 10 m or more 

 depending on water clarity. Throughout its 

 range in the central, western Atlantic, turtle 

 grass meadows attain maximum development in 

 muddy sands where average salinity is between 

 25 and 39^/f (Phillips, 1960; Hartog, 1970). 

 Morphological features of turtle grass have been 

 reported by Tomlinson and Vargo (1966) and 

 Tomlinson (1969a, b), who showed that new 

 grass beds are established from seeds, which 

 mature during spring and summer months, or 

 vegetatively by rhizome fragments that are 

 broken off and relocated by storm action and 

 currents. Kelly, Fuss, and Hall (1971) demon- 

 strated that the normally slow and uncertain 

 spread of turtle grass can be accelerated by 

 transplanting and securing sprigs treated with 

 naphthelene acetic acid. This procedure may 

 prove useful in establishing and replacing turtle 

 grass in unvegetated areas — especially through 

 the northern part of its range where apparently 

 there is little or no seed production (Phillips, 

 1960). 



145 



