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Most seagrasses grow as shoots, i.e., bundles of leaves, that emerge from an underground rhizome. The habitat structure and productivity of a seagrass meadow are a function of the density, lengths, and growth rates of the shoots. This protocol measures these dimensions, along with length of the seagrass leaf sheath, which can be used as a proxy for leaf growth rate (Gaeckle et al, 2006, Ruesink et al. 2018). The protocol also measures quantity of algae and other organic/inorganic material accumulating on (fouling) the shoots. Fouling mass is an important property of seagrass ecosystems because the algae and detritus fouling seagrass leaves can influence seagrass growth by reducing light availability to the plant, and also provide food for small animals. Finally, sampling shoots allows for a closer examination of other factors that might influence seagrass growth and reproduction, such as the presence of disease lesions (e.g., wasting disease Labyrinthula zosterae) or grazing scars from smaller herbivores (e.g., pinfish Lagodon rhomboides).

seagrass shoots

Measured Parameters

  • Blade length (mm)
  • Blade width (mm)
  • Sheath length (mm)
  • Disease lesions (number and length in mm)
  • Grazing scars (number)
  • Fouling biomass (mg)

Selected Literature

Gaeckle, J. L., Short, F. T., Ibarra-Obando, S. E., & Meling-Lopez, A. E. (2006). Sheath length as a monitoring tool for calculating leaf growth in eelgrass (Zostera marina L.). Aquatic botany, 84(3), 226-232.

Ruesink, J. L., Stachowicz, J. J., Reynolds, P. L., Bostrom, C., Cusson, M., Douglass, J., … & Iken, K. (2018). Form-function relationships in a marine foundation species depend on scale: a shoot to global perspective from a distributed ecological experiment. Oikos, 127(3), 364-374.

Short, F.T., McKenzie, L.J., Coles, R.G., Vidler, K.P., Gaeckle, J.L. (2006) SeagrassNet Manual for Scientific Monitoring of Seagrass Habitat, Worldwide edition. University of New Hampshire Publication.

McKenzie, L.J., Campbell, S.J. & Roder, C.A. (2003) Seagrass-Watch: Manual for Mapping & Monitoring Seagrass Resources by Community (citizen) volunteers. 2nd Edition. –>