Effects of wave exposure and depth on biomass, density and fertility of the fucoid seaweedSargassum polyceratium(Phaeophyta, Sargassaceae)

Abstract

Sargassum polyceratium is widely distributed around the island of Curac¸ao (Netherlands Antilles) where it inhabits strongly contrasting habitats. Changes in population structure have been followed in three bays with increasing levels of wave exposure at two depths: shallow (0 m) and deep (18 m). The effects of increasing wave exposure were investigated by studying three deepwater populations; and the effects of depth by studying shallow-and deep-water populations in the two calmer bays. Total density and stage density (reproductive thalli, juvenile thalli) were determined and total and individual thallus biomass was estimated non-destructively. In the most wave-exposed deep-water population thalli were twice as long with more than twice the biomass than in the calmest deep-water population. Total density and juvenile density were highest in the bay with intermediate wave exposure. Depth was an important factor at both the individual and population level. Shallow-water thalli had basal holdfast areas that were four times larger than those from deep water, and thallus biomass was positively correlated with holdfast area. Shallow-water juveniles invested more in the development of a holdfast and lateral growth than deep-water juveniles. Total biomass per quadrat was up to 10-fold higher in shallow-than in deep-water populations. In shallow-water populations reproductive thalli were present throughout the year whereas in deep-water populations they were present only during autumn and winter. We conclude that both wave exposure and depth affect population structure. Thalli were generally bigger and total biomass higher in the more exposed bay(s) and in shallower water, contradicting the general pattern in macroalgae of reduced size and biomass with increasing wave exposure.

Phenology, TPC and size-fractioning phenolics variability in temperate Sargassaceae (Phaeophyceae, Fucales) from Western Brittany: Native versus introduced species

“…Based on our results, differences in the phenology of S. muticum between different sites in Brittany (France) were comparable with spatial differences already published by Plouguerné et al (2006) and Engelen et al (2005). Site was a random pseudo-replicated factor in our experiment; nevertheless, some tendencies could be observed for the three species in regard of measured variables with space and time.…”

Trade-off between vegetative regeneration and sexual reproduction of Sargassum thunbergii

“…The effects of different locations on reproduction have been documented for other macroalgal populations (Engelen et al, 2005a;Baer & Stengel, 2010). For example, a decrease in reproductive effort from 60% in exposed sites to 40% in sheltered sites has been observed for Ascophyllum nodosum in south-eastern Canada (Cousens, 1986).…”

Photosynthetic carbon acquisition in Sargassum henslowianum (Fucales, Phaeophyta), with special reference to the comparison between the vegetative and reproductive tissues

“…Given the ecological and economic importance and the world-wide distribution of Sargassum species, considerable investigations have been carried out on the taxonomy, distribution, reproduction and phenology, population dynamics and ecology for Sargassum (e.g. Rico and Fernandez 1997;Andrew and Viejo 1998;Steen 2004;Yoshida et al 2004;Engelen et al 2005Engelen et al , 2008Ang 2006;Rivera and Scrosati 2006;Sjøtun et al 2007;Mattio et al 2008a, b;Noiraksar and Ajisaka 2008;Monteiro et al 2009). Some author also concern the photosynthetic physiology of Sargassum.…”