Field testing of inter- and intraspecific coalescence among mid-intertidal red algae

Abstract

Although spores, sporelings and juveniles of many ecologically important and competitively dominant seaweed species inhabiting intertidal and shallow subtidal habitats may coalesce, it is unknown whether coalescence among holdfasts of well-established clumps occurs naturally in the field. Using a combination of field and ultrastructural studies, we evaluate if inter-and intraspecific coalescence occurs between clumps of Mazzaella laminarioides and Nothogenia fastigiata and, if so, whether such a process modifies clump shapes and sizes. Interspecific encounters always resulted in cell compression and destruction of the contacting tissues and in the eventual mortality of 1 of the partners (in this case N. fastigiata). In contrast, intraspecific encounters in both species always resulted in coalescence. In these field populations, coalescence seems to be frequent and dynamic and is probably modulated by other community structuring mechanisms such as grazing, abiotic extremes, and mussel recruitment. This field demonstration of coalescence suggests that many intertidal and subtidal populations of coalescing Rhodophyta might be chimeric.

Tissue Type Matters: Selective Herbivory on Different Life History Stages of an Isomorphic Alga

“…We haphazardly placed two 10-m transects at each site in the M. flaccida zone, and we collected the closest clump of blades (henceforth referred to as an individual; some species of this genus have been shown to exhibit coalescence [Santelices 2003], but this is unknown but not likely for M. flaccida) to the transect tape at each 0.5-m interval, resulting in 40 individuals per site. Piedras Blancas and Vandenberg Air Force Base (Vandenberg) during August 2000.…”

Effect of grazing on distribution and recovery of harvested stands of Lessonia berteroana kelp in northern Chile

“…Positive or negative interactions among algae (i.e. intra-or inter-specific) during early life stages can also affect recruitment success, thus de termining the spatial structure of adult individuals (Santelices et al 2003). In red algae, spore aggregations during settlement facilitate the coalescence process (or fusion) of sporelings and/or juvenile individuals, which has been suggested to reduce vulnerability of juveniles to grazing as compared to solitary individuals (Maggs & Cheney 1990).…”

DEMOGRAPHIC CONSEQUENCES OF COALESCENCE IN SPORELING POPULATIONS OF MAZZAELLA LAMINARIOIDES (GIGARTINALES, RHODOPHYTA)1

“…This kind of growth strategy occurs frequently in taxa from roughly half of the orders of the red algae (Santelices et al. 1999), many of which are dominant components of intertidal and shallow subtidal communities (Santelices et al. 2003a).…”