Análisis de la estructura de tamaños de un gorgonáceo a través de índices alométricos

Abstract

This study presents an evaluation of the allometric relationships between some morphometric traits of the gorgonian Pseudopterogorgia americana, with the intention of determine a size structure for colonies of this species through allometric indexes. Traditionally, the height of the gorgonians has been used with this porpouse, because a correlation exist between the total colony longitude and its height. This relationship is variable and the variability increases with the height, however, it has been used in spite of the incorporated error. Another way of determining the structure of sizes theses populations is through the morphometric traits of the branches. In this work the total longitude of colony tissue was estimated measuring all the branches of each colony. Also, data on number of total branches, number of bifurcations, number of primary ramifications and height average of the primary branches were obtained. The chosen traits to characterize the colonies were related by models of linear regression. The height, the number of main branches and the number of total branches aretraits that offer an adequate estimate of the amount of tissue of each colony. With thesetraits allometric indexes were elaborated, by adding theirlogarithms. In this way, it is possible to find a more accurate size structure for the population, and use it for the demographic characterization of this populations. Using traits of the branches, in order to elaborate allometric indexes, allows reduction of the errors of the estimation of colonies not very high but with mny brnches, that have a great longitude of tissue but that would be classified in minor classes, and the overestimation of high colonies with few branches that would be considered in major size classes.