Sediment tolerance of Sargassum algae inhabiting sediment-covered rocky reefs

Kawamata, Shigeru; Yoshimitsu, Satoshi; Tokunaga, Shigemitsu; Kubo, Satoshi; Tanaka, Toshihiro

doi:10.1007/s00227-011-1849-6

Cited by 15 publications

(6 citation statements)

References 23 publications

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“…However, it is difficult to judge the relative role of these factors without known environmental tolerances of Sargassum populations to these variables. We suggest further investigation into the specific thresholds of tropical Sargassum populations to these and other factors, such as sediment load (Kawamata et al 2012), to clarify their relative role and seasonal importance in future quantitative models.…”

Section: Discussionmentioning

confidence: 99%

Sea temperature shapes seasonal fluctuations in seaweed biomass within the Ningaloo coral reef ecosystem

Fulton

Depczynski

Holmes

et al. 2014

Limnology & Oceanography

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Environmental drivers of seaweed biomass were investigated at Ningaloo, Western Australia, a coral reef ecosystem with negligible anthropogenic influences on seaweeds from fishing, farming, or eutrophication. Periodic surveys of benthic macroalgae occupying seaweed-dominated beds within the lagoon at two locations (Coral Bay, Tantabiddi) were made during winter, spring, and late summer over a 26 month period. Canopyforming Sargassum spp. biomass fluctuated over a seasonal growth-decay cycle, with highest values in the warm summer months (up to 1013 g fresh weight 0.25 m 22 at Coral Bay) and lowest values in winter (down to 155 g fresh weight 0.25 m 22 at Tantabiddi). Conversely, prominent understory seaweed genera Dictyopteris and Lobophora reached peak biomass in winter, when the Sargassum spp. canopy was lowest. Sargassum spp. biomass variation could be attributed largely to time (52%), location (21%), and site (26%), with low variation within individual seaweed beds (1%). Statistical analysis of the influence of five environmental variables (temperature, light, wind-driven upwelling, rainfall, significant wave height) indicated that location and sea temperature (1 month antecedent to biomass) provided the best explanation for Sargassum spp. biomass fluctuations. While sea temperature is a key driver of seaweed temporal dynamics, heterogeneity at the kilometer scale suggests that spatial context is also important. Given the important role of seaweeds in many ecosystem processes, this strong biophysical coupling between Sargassum spp. biomass and sea temperature suggests that thermal climate change will significantly affect coral reef productivity and biodiversity.

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Section: Discussionmentioning

confidence: 99%

Sea temperature shapes seasonal fluctuations in seaweed biomass within the Ningaloo coral reef ecosystem

Fulton

Depczynski

Holmes

et al. 2014

Limnology & Oceanography

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“…may have been more abundant at sandy sites due to greater tolerance to sedimentation than Sargassum spp. [61] , [62] , although some species of Sargassum are capable of recruiting to cobbles covered with fine sediment [63] . Macroalgae that are able to trap and bind sediments can benefit from sedimentation [55] , [58] .…”

Section: Discussionmentioning

confidence: 99%

Mechanisms Influencing the Spread of a Native Marine Alga

et al. 2014

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Like invasive macrophytes, some native macrophytes are spreading rapidly with consequences for community structure. There is evidence that the native alga Caulerpa filiformis is spreading along intertidal rocky shores in New South Wales, Australia, seemingly at the expense of native Sargassum spp. We experimentally investigated the role physical disturbance plays in the spread of C. filiformis and its possible consequences for Sargassum spp. Cleared patches within beds of C. filiformis (Caulerpa habitat) or Sargassum spp. (Sargassum habitat) at multiple sites showed that C. filiformis had significantly higher recruitment (via propagules) into its own habitat. The recruitment of Sargassum spp. to Caulerpa habitat was rare, possibly due in part to sediment accretion within Caulerpa habitat. Diversity of newly recruited epibiotic assemblages within Caulerpa habitat was significantly less than in Sargassum habitat. In addition, more C. filiformis than Sargassum spp. recruited to Sargassum habitat at some sites. On common boundaries between these two macroalgae, the vegetative growth of adjacent C. filiformis into cleared patches was significantly higher than for adjacent Sargassum spp. In both experiments, results were largely independent of the size of disturbance (clearing). Lastly, we used PAM fluorometry to show that the photosynthetic condition of Sargassum spp. fronds adjacent to C. filiformis was generally suppressed relative to those distant from C. filiformis. Thus, physical disturbance, combined with invasive traits (e.g. high levels of recruitment and vegetative growth) most likely facilitate the spread of C. filiformis, with the ramifications being lower epibiotic diversity and possibly reduced photosynthetic condition of co-occurring native macrophytes.

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“…Further, these effects appear to be context dependent, as one study showed sediments provided nutrient benefits (Schaffelke 1999), while another demonstrated negative impacts across demographic parameters (Umar et al 1998). On temperate reefs, where the consequences of sediment loads for macroalgae are better studied, the effects on growth are primarily negative (e.g., Kawamata et al 2012) by blocking light and gas or nutrient exchange (reviewed by Airoldi 2003; but see Kawamata et al 2011). Yet one study (Gorgula and Connell 2004) showed that nutrient enrichment in the sediments increased algal turf cover.…”

Section: Introductionmentioning

confidence: 99%

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

et al. 2016

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Despite increasing concern that sediment loads from disturbed watersheds facilitate algal dominance on tropical reefs, little is known of how sediments interact with two primary drivers of algal communities, nutrients and herbivory. We examined the effects of sediment loads on the thalli of two increasingly abundant genera of macroalgae, Galaxaura and Padina, in a bay subject to terrestrial sediment influx in Mo'orea, French Polynesia. Field experiments examining (1) overall effects of ambient sediments and (2) interacting effects of sediments (ambient/removal) and herbivores (caged/uncaged) demonstrated that sediments had strong but opposite effects on both species' biomass accumulation. Sediment removal increased accumulation of Padina boryana Thivy 50% in the initial field experiment but had no effect in the second; rather, in a novel interaction, herbivores overcompensated for increases in tissue nutrient stores that occurred with sediments loads, likely by preferential consumption of nutrient-rich meristematic tissues. Despite negative effects of sediments on biomass, Padina maintained rapid growth across treatments in both experiments. In contrast, positive growth in Galaxaura divaricata Kjellman only occurred with ambient sediment loads. In mesocosm experiments testing interactions of added nutrients and sediments on growth, Galaxaura grew at equivalent rates with sediments (collected from thalli on the reef) as with additions of nitrate and phosphate, suggesting sediments provide a nutrient subsidy. For Padina, however, the only effect was a 50% reduction in growth with sediment. Overall, retention of thallus sediments creates a positive feedback that Galaxaura appears to require to sustain net growth, while Padina merely tolerates sediments. These results indicate that sediments can modify nutrient and herbivore control of algae in ways that differ among species, with the potential for strong and unexpected effects on the abundance and composition of tropical reef macroalgae.

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Sediment tolerance of Sargassum algae inhabiting sediment-covered rocky reefs

Cited by 15 publications

References 23 publications

Sea temperature shapes seasonal fluctuations in seaweed biomass within the Ningaloo coral reef ecosystem

Sea temperature shapes seasonal fluctuations in seaweed biomass within the Ningaloo coral reef ecosystem

Mechanisms Influencing the Spread of a Native Marine Alga

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

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