Reproductive biology of Durvillaea antarctica (Chamisso) Hariot in the sub-Antartic ecoregion of Magallanes (51–56° S)

Abstract

Durvillaea antarctica (Chamisso) Hariot is a large kelp commonly found on the exposed rocky shores of the Chilean coastline. It is endemic to the Southern Hemisphere and is used for direct consumption in the human diet and for alginate extraction; it is commonly known as “cochayuyo” (word from Chilean indigenous population “Mapudungun” language). The species occurs in the sub-Antarctic region and is found from Coquimbo (30° S) to Cape Horn (56° S). This study investigates and describes the seasonal reproductive strategies of D. antarctica located in the far south of the Chilean coast, in the region of the Magallanes (51–56° S), Chile, during the period of a year. Samples were taken in quadrants of 10 m2 parallel to the coastline in the intertidal zone of three locations during consecutive seasons. Both the phenological stages and the different states of maturity in individuals were determined. These findings were used to describe the main characteristics of the reproductive cycle and the spatial heterogeneity that may exist between the reproductive processes within each studied area. The results indicate that in all three studied localities of D. antarctica reproductive individuals are present throughout the year. The largest amount of reproductive individuals tends to exist in autumn and winter, with the numbers subsequently decreasing in spring and summer. In all studied localities, it was possible to identify male and female non-reproductive individuals. The largest number of male and female plants in the studied populations was found from autumn to winter; however, there were shifts in the proportions during these periods that lead to an increase in male over female fronds. In all localities, both male and female individuals in different stages of maturity were found, with the level of maturity depending on locality and season. Mature fronds were found more frequently during autumn and winter although the measures of maturity vary between different localities. Based on these results we conclude that D. antarctica is a species with present reproductive individuals throughout the year, similar to populations of this species described for other sub-Antarctic latitude. It is possible that there could be a cryptic species in the region, presenting morphological and reproductive variability that did not agree well with the circumscription of the species. Therefore, studies of ecophysiological and molecular aspects are needed to clarify the taxonomic status of this species in the sub-Antarctic region of Magallanes.