Keys waters. Where the continental influ- 

 ence increases the organic matter in the 

 sediments, manatee grass appears to occur 

 less commonly. Lower organic matter in 

 Caribbean sediments, due to the lack of 

 continental effect, may slow the develop- 

 mental process. 



As successional development proceeds 

 in a blowout, turtle grass will begin to 

 colonize the region. Because of stronger, 

 strap-like leaves and massive rhizome and 

 root system of turtle grass, particles are 

 trapped and retained in the sediments with 

 much greater efficiency and the organic 

 matter of the sediment will increase. The 

 sediment height rises (or conversely the 

 water depth above the sediment decreases) 

 until the rate of deposition and erosion 

 of sediment particles is in balance. This 

 process is a function of the intensity of 

 wave action, the current velocity, and the 

 density of leaves. 



The time required for this recovery 

 will vary depending on, among other fac- 

 tors, the size of the disturbance and the 

 intensity of the waves and currents in 

 the region. In Barbados, blowouts were 



SOLID 

 SUBSTRATE 



O 



EPILITHIC 

 ALGAE 



SANDY 

 SUBSTRATE 



MUDDY 

 SUBSTRATE 



RHIZOPHYTIC 

 ALGAE 



restabilized within 5 to 15 years (Patri- 

 quin 1975). During the study of Patriquin 

 (1975) the average rate of erosion of the 

 blowout was 3.7 mm/day, while the rate of 

 colonization of the middle of the recovery 

 slope by manatee grass was 5 mm/day. Once 

 recolonization of the rubble layer began, 

 average sediment accretion averaged 3.9 

 mm/yr. 



With the colonization of turtle 

 grass, the normal algal epiphyte and 

 fauna! associates begin to increase in 

 abundance and diversity. Patriquin (1975) 

 noted that the most important effect of 

 the instability caused by the blowouts is 

 to "limit the serai development of the 

 community. The change in the region of 

 the blowouts of a well -developed epi fauna 

 and flora, which is characteristic of 

 advanced stages of serai development of 

 the seagrass community, is evidence of 

 this phenomenon." 



In areas that are subject to contin- 

 ued or repeated disturbances, the succes- 

 sional development may be arrested at any 

 point along the developmental gradient 

 (Figure 13). Many stands of manatee grass 



o 



CORALLINE ALGAE 

 HALIMEDA 



THALASSIA 



={> HALODULE 



SYRINGODIUM 



ECOSYSTEM DEVELOPMENT 



Stable Environmental Conditions 



Disturbance 

 Figure 13. Ecosystem development patterns in south Florida marine waters, 

 generalized pattern, and all stages may not be present. Note that in the 

 disturbance that the tendency is to a Thalassia climax. 



37 



This is a 

 absence of 



