We assess leaf herbivory on several populations of four temperate and five tropical seagrass species and examine, along with a compilation of published reports, the extent of herbivory variability and how it affects its general magnitude to help solve the apparent controversy about the importance of herbivory on seagrasses brought out by recent reports. We further test whether herbivory variability is related to differences in leaf specific growth rate (SGR) as a descriptor of leaf nutritional quality for herbivores. The extent of herbivory varied broadly, both within and among species, ranging from negligible values up to 50% of leaf production removed within some species. This variability, along with that shown by other published reports, claim that the classical statement that herbivory represents minor losses of seagrass production, being considered negligible in most cases, can he misleading and lead to the neglect of important seagrass-herbivore interactions. Differences among species in the percentage of leaf production removed were associated with differences in SGR, pointing to herbivore selective feeding upon faster-growing species resulting from their higher nutritional quality. This selection seems to he independent of leaf nutrient concentrations suggesting that, in agreement with past reports, nutrient levels are a poor descriptor of seagrass nutritional quality as most nutrients can be bound to indigestible fibre. No relationship between herbivory intensity and SGR was found among populations of a single species. On the other hand differences among species in the areal flux of production transferred to herbivores seemed related to differences in the level of production attained. These results point out that whereas SGR should he a descriptor of the variability among species in the extent of herbivore pressure (i.e. percentage of production removed), the level of production should he indicative of differences among species in their capacity to support herbivore production (i.e. flux of production channelled).
|Original language||English (US)|
|Number of pages||16|
|State||Published - Jan 1998|
Bibliographical noteFunding Information:
This study was funded by the projects AMB 93-0118 from the Spanish Commission of Science and Technology (CICYT) and CI1 * -CT91-0952 from the European Community and a grant from the Ramon Areces foundation. J. Cebrián was supported by a fellowship from the Commissió Interdepartamental de Recerca i Innovació Tecnológica. J. Romero and several anonymous referees critically reviewed the manuscript, and the paper benefited from many useful comments and improvements. We thank N. Agawin, S. Enrı́quez, M. Fortes, M. Gallegos, N. Marbà, M. Merino, B. Olesen, J. Uri and J. Vermat for assistance during field work, M. Hemminga for providing the samples of T. ciliatum and the Direcció General de Parcs of the Generalitat Valenciana for providing access to their facilities in Calp.
- Leaf production
- Specific leaf growth rate
ASJC Scopus subject areas
- Aquatic Science
- Plant Science