Allometric scaling of seagrass form and productivity

Abstract

The implications of differences in plant size for seagrass productivlty were examined based on an extensive compilation of data on architecture and growth of seagrass species. The analysis revealed strong allometric relationships between the size of different components, particularly a close scaling of the size of leaves, shoots, and fruits to rhizome diameter, as well as strong relationships between shoot size and the dynamics (e.g turnover rate, plastochrone interval, and longevity) of seagrass leaves and rhizomes of different species. The decrease in rhizome elongation rates and leaf turnover rates with increasing seagrass size demonstrates the importance of architecture for seagrass productivlty, and also provides explanations for the different ecological roles of small, colonizing species, and large, climax seagrass species. In addition, these results demonstrate that while habitat conditions have important Influences on seagrass productivity, differences in size may explain the vast range of turnover tlmes, plastochrone intervals, and module longevities, encountered among seagrass species.

Shoot organization in the seagrass zostera noltii: implications for space occupation and plant architecture

“…Fig. 8 shows the correlation between the PI-A/PI-5 index and the number of shoots per rhizome internode (SPI), using data derived from Duarte (1991) and the assumptions outlined previously. Unfortunately, data on branching frequency are limited (Marba´and Duarte 1998) precluding the exploration of the relationship between the PI-L/PI-5 index and branching frequency, which will deserve future research efforts.…”

“…to branch or to become a vertical shoot) ( Table 1). This hypothesis was checked by comparing the architecture of several seagrass species with the values for the cited indexes derived from Duarte (1991) under the following assumptions: (1) shoot plastochrone interval (SPI) was equivalent to PI-5, since PI-5 determines the appearance of a lateral shoot. (2) Leaf plastochrone interval (LPI) corresponded to PI-L and (3) rhizome plastochrone interval (RPI) was equivalent to PI-A, since internode growth takes place during one PI-A.…”

“…8 Correlation between the number of shoots per rhizome internode (SPI) and PI-A/PI-5 index in 14 seagrass species. Data were modified from Duarte (1991). Letters inserted indicate the species: Aa…”

“…phenotypic plasticity) may influence the plant ability to evolve under favourable conditions and to avoid the unfavourable ones (Slade and Hutchings 1987;Hemminga and Duarte 2000). Morphological and/or architectural variability may be a symptom of the high phenotypic plasticity of seagrasses to cope with stressful and changing environments where they thrive (Duarte 1991;Hemminga and Duarte 2000;Nelson 2000).…”

Presencia de Cistenides Elhersi Hessle, 1917 (Polychaeta Perctinariidae) en aguas someras magallánicas habitadas por praderas de Ruppia Filifolia: Evidencia de Euribatia, Eurihalididad y Euritermia?

“…El género ruppia (Potamogetonaceae) reúne aproximadamente 10 especies que conforman praderas submareales someras en ambientes de salinidad típica de agua de marinas costeras como en lagos andinos hipersalinos (Verhoeven, 1979;Bigley & Harrison, 1986;Duarte, 1991). Los representantes del género se caracterizan por tener aspecto de pasto ("seagrass") con hojas delgadas típicas de monodicotiledóneas o acutiformes las que tienden a ser perennes y a estar sostenidas por una matriz de raíces y rizomas (Bigley & Harrison, 1986), con floraciones apicales y permanecen siempre sumergidas (De la Barra, 2003).…”