Apical dominance and the importance of clonal integration to apical growth in the seagrass Syringodium filiforme

The existence of apical dominance and the importance of clonal integration to apical growth in the seagrass Syringodium filiforme were examined using field and mesocosm experiments. In the field, apical dominance was observed with proliferative branching resulting from the removal of rhizome apical meristems (RAMs). Rhizome internode length and branching increased when plants grew from a dense meadow into a bare patch, providing further evidence for the existence of apical dominance in S. filiforme. The results of the experiments indicated that growth of the RAM is dependent on the translocation of resources from older ramets. Removing 3 shoots from a rhizome runner lead to a significant reduction in the growth of the RAM, and removing 6 shoots had a greater effect. Apical growth was more significantly affected by cutting the rhizome, with the lowest growth observed in clonal fragments comprised of a RAM and the 4 youngest ramets. We conclude that clonal integration is an important factor regulating the growth form and productivity of S. filiforme. These results have implications for damage assessment and restoration projects, and indicate that future studies of meadow structure and plant production should consider RAM health and branch formation along with individual ramet growth.

[1]  Rui Santos,et al.  Population-level effects of clam harvesting on the seagrass Zostera noltii , 2005 .

[2]  N. Marbà,et al.  Scaling of ramet size and spacing in seagrasses: implications for stand development , 2003 .

[3]  N. Marbà,et al.  Carbon and nitrogen translocation between seagrass ramets , 2002 .

[4]  B. I. Tussenbroek,et al.  Dormancy and foliar density regulation in Thalassia testudinum , 2000 .

[5]  N. Marbà,et al.  Rhizome elongation and seagrass clonal growth , 1998 .

[6]  C. Duarte,et al.  Is the apical growth of Cymodocea nodosa dependent on clonal integration , 1997 .

[7]  C. Duarte,et al.  Experimental evidence for apical dominance in the seagrass Cymodocea nodosa , 1997 .

[8]  C. Duarte,et al.  Nutrient constraints on establishment from seed and on vegetative expansion of the Mediterranean seagrass Cymodocea nodosa , 1996 .

[9]  H. Kroon,et al.  Resource allocation patterns as a function of clonal morphology : a general model applied to a foraging clonal plant , 1991 .

[10]  L. L. Doust.  Population dynamics and local specialization in a clonal perennial (Ranunculus repens). II. Responses to light and nutrient supply , 1987 .

[11]  J. Fisher,et al.  Influence of the seagrass, Zostera marina L., on current flow☆ , 1982 .

[12]  L. L. Doust,et al.  Population dynamics and local specialization in a clonal perennial (Ranunculus repens). I. The dynamics of ramets in contrasting habitats , 1981 .

[13]  W. Kenworthy,et al.  Analysis of Seagrass Recovery in Experimental Excavations and Propeller Scar Disturbances in the Florida Keys National Marine Sanctuary , 2002 .

[14]  J. Reid,et al.  Characterizing Manatee habitat use and seagrass grazing in Florida and Puerto Rico: Implications for conservation and management , 1999 .

[15]  M. Fonseca,et al.  Guidelines for the conservation and restoration of seagrasses in the United States and adjacent waters , 1998 .

[16]  F. C. Stephens,et al.  Effects of Shading and Rhizome Isolation on Soluble Carbohydrate Levels in Blades and Rhizomes of the Seagrass Syringodium filiforme , 1996 .

[17]  Curtis R. Kruer,et al.  Scarring of Florida's Seagrasses: Assessment and Management Options , 1995 .

[18]  J. P. Grime.  1 – The Role of Plasticity in Exploiting Environmental Heterogeneity , 1994 .

[19]  D. Tomasko,et al.  Effects of the number of short shoots and presence of the rhizome apical meristem on the survival and growth of transplanted seagrass Thalassia testudinum. , 1991 .

[20]  D. Tomasko,et al.  Evidence for Physiological Integration Between Shaded and Unshaded Short Shoots of Thalassia testudinum , 1989 .

[21]  C. Boudouresque,et al.  Uptake and long-distance transport of carbon in the marine phanerogam Posidonia oceanica , 1987 .

[22]  S. Williams.  Competition between the seagrasses Thalassia testudinum and Syringodium filiforme in a Caribbean lagoon , 1987 .

[23]  J. Fisher,et al.  A comparison of canopy friction and sediment movement between four species of seagrass with reference to their ecology and restoration , 1986 .

[24]  L. E. Anderson,et al.  A Dictionary of Botany , 1980 .

[25]  P. Tomlinson.  Vegetative morphology and meristem dependence — The foundation of productivity in seagrasses , 1974 .