An allometric method for measuring leaf growth in eelgrass, Zostera marina, using leaf length data

Abstract

The rate of production of leaf biomass in eelgrass (Zostera marina L.) is an indicator variable for environmental influences on the growth of this important seagrass species. The efforts to restore eelgrass meadows from the harmful human influences make the use of nondestructive evaluations essential. We present, here, an indirect procedure for the estimation of the growth rates of eelgrass leaves by using easily obtained measurements of leaf length and increases in leaf length, and allometric parameters linked to the scaling of leaf biomass and leaf length. This allometric method includes criteria that allow the estimation of leaf growth rates even when the sizes of some of the leaves cannot be determined because of herbivory or other environmental factors. To validate the proposed method, we performed simulation studies and analyzed data from two natural eelgrass populations in the East Pacific (México). These allometric projections of leaf growth rates displayed a high level of correspondence with observed values. We show that whenever the allometric parameters for the scaling of eelgrass leaf dry weight in terms of leaf length have been previously fitted, the method proposed here can provide an alternative for estimating biomass production that is both accurate and nondestructive and uses easily obtained data on leaf length and increases in leaf length between the sampling periods.

Form–function relationships in a marine foundation species depend on scale: a shoot to global perspective from a distributed ecological experiment

“…(At one site (San Diego), the distance between each shoot base and the original mark in the leaf sheath was used as a surrogate for sheath length.) Body size was determined as the sum of all leaf lengths (from meristem to distal tip), multiplied by sheath width; this should index above-ground biomass since only leaves project above the sediment, and they are flat and can be assumed rectangular (Echevarría-Heras et al 2013). Allometric relationships among traits were examined for maximum length (= canopy height), number of leaves, sheath width, and sheath length, with this last trait serving a unique role as it remained intact even when leaves were damaged or some abscised.…”

“…1B). This morphology lends itself to several simple metrics of plant size based on measuring the length of each leaf, the sheath width and length (Echevarría-Heras et al 2013). Leaf extension derives from a leafpunching method, tracked as these holes move away from the basal meristem, and this absolute growth rate is used to calculate productivity (RGR, relative growth rate) as daily leaf extension relative to the summed length of all standing leaves (Dennison 1990, Herbert andFourqurean 2009).…”

The effect of parameter variability in the allometric projection of leaf growth rates for eelgrass (Zostera marina L.) II: the importance of data quality control procedures in bias reduction

“…Even though the elimination of eelgrass shoots linked to a typical evaluation activity does not infringe damage to natural populations, the effects of shoot removal could be severe for transplanted plots. Therefore, in an overall program that leads to eelgrass conservation it is important to include nondestructive assessment methods [ 1 , 2 ].…”

“…The parameter α is named allometric exponent and β termed normalization constant. Particularly, Echavarria-Heras et al [ 1 ] and Echavarria-Heras et al [ 2 ], stressed the significance of the model in the adaptation of an allometric proxy for L g ( t , ∆ t ). This allometric surrogate will be here denoted by means of the symbol L ga ( α , β , t , ∆ t ), and its explicit formulae derived in Appendix A .…”

Using the value of Lin’s concordance correlation coefficient as a criterion for efficient estimation of areas of leaves of eelgrass from noisy digital images

“…Although traditional assessment methods do not cause damage to natural populations, their invasive nature could significantly alter the development of transplanted populations. Echavarria-Heras et al [ 29 ] and Echavarria-Heras et al [ 30 ] propose allometric methods that reduce eelgrass biomass and leaf growth rate estimations to measurements of leaf length or area. Besides, the use of digital imagery could provide leaf area estimations which avoid invasive effects.…”