Utilization of holdfast fragments for vegetative propagation of Macrocystis integrifolia in Atacama, Northern Chile

Abstract

We attempted to propagate Macrocystis integrifo lia (giant kelp) by fragmentation and regeneration of holdfasts, which consist of creeping stolons with lateral haptera. Stolons from a natural kelp population in Bahia Chasco (Atacama, North Chile) were cut into fragments, each containing one or more lateral stipe and frond initials. Fragments were attached to longlines with elastic bands. We used two additional types of inoculants as controls: (1) natural recruits from the local parent population and (2) laboratory-cultured young sporophytes. Length, reproductive phenology, and mortality were determined monthly. Our results confirmed the feasibility of M. integrifolia propagation by reattachment of stolon fragments, and we obtained up to eight new individuals from one parent holdfast. Individuals from holdfast regeneration formed sporangial sori 3 months earlier than control specimens from recruits and laboratory culture, while all three types gave similar values for mortality. Holdfast morphology of regenerates differed strongly depending on their origin: stolon fragments continued growth and developed new haptera except in the cut surfaces, natural recruits formed typical M. integrifolia holdfast morphs, and sporophytes originating from laboratory culture produced minor stolons with many haptera. Implications of our results on ecology, repopulation, and aquaculture are discussed.

Giant kelp (Macrocystis) fishery in Atacama (Northern Chile): biological basis for management of the integrifolia morph

“…The survival of old plants can be explained by vegetative propagation. The integrifolia morph has a stonoliferous holdfast (Westermeier et al 2012(Westermeier et al , 2013a. New individuals spread and colonize nearby substrata starting from the holdfast (Westermeier et al 2013b).…”

“…New individuals spread and colonize nearby substrata starting from the holdfast (Westermeier et al 2013b). This strategy has been rarely mentioned in the literature (Druehl and Kemp 1982;Graham 1996;Westermeier et al 2013a), but it is probably the most important factor responsible for fast recovery in integrifolia populations, especially in northern Chile. Thus, apart from adverse extrinsic factors, adult integrifolia sporophytes will be apt to live as long as they remain attached to their substratum, which means two years or even much longer.…”

“…Since this procedure did not satisfactorily work for the integrifolia morph, individual fishermen in Bahia Chasco have developed their own harvesting and management systems. Bahia Chasco, Atacama, supports one of the most important Macrocystis populations in northern Chile (Westermeier et al 2013a). With an area of 280 -380 ha (Zavala et al 2010), this kelp forest offers habitat, substratum, food and wave protection for a highly diverse marine ecosystem of fishes, invertebrates and understory marine algae (Westermeier et al 2012 unpublished).…”

Genetic and morphological diversity in sympatric kelps with contrasting reproductive strategies

“…The occurrence of unique asexual lineages in marine algae is often correlated with marginal habitats (Tatarenkov et al 2005), limits of distribution (Oppliger et al 2014), favourable conditions (Demes & Graham 2011), range expansions (e.g. Kruger-Hadfield et al 2016) or senescence (Westermeier et al 2013, Murúa et al 2017). Under such conditions, asexual reproduction is thought to be more advantageous, i.e.…”

Repopulation techniques for Macrocystis integrifolia (Phaeophyceae: Laminariales) in Atacama, Chile

“…Natural recruitment depends mainly on season of the year and substratum availability (Westermeier et al 2012b). In addition, Westermeier et al (2013a) found that M. integrifolia holdfast fragments easily regenerate and the authors suggested a technique on this basis for recovery projects of kelp beds. Only few reports describe repopulation experiments with the intertidal kelp Lessonia nigrescens in Chile (Vásquez and Tala 1995;Correa et al 2006), and no studies are known for M. integrifolia.…”