Effects of flow and colony morphology on the thermal boundary layer of corals

Jimenez, Isabel M.; Kühl, Michael; Larkum, Anthony W. D.; Ralph, Peter J.

doi:10.1098/rsif.2011.0144

Cited by 75 publications

(100 citation statements)

References 62 publications

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“…The mass-transfer resistance imposed by the DBL has been correlated with nutrient limitation in the giant kelp Macrocystis pyrifera [16], and a considerable spatial variation of the DBL over the thallus and cryptostomata of Fucus vesiculosus has been observed [17]. However, current knowledge of the DBL characteristics of aquatic plants is largely based on point measurements with O 2 microsensors [15], while it is known from boundary layer studies in biofilms [4], corals [18][19][20] and sediments [4,21 -23] that the DBL exhibits a spatio-temporal heterogeneity that is modulated by both flow velocity and surface topography. Similar studies of DBL topography are very limited in aquatic plant science [24], and the aim of this study was to explore how the DBL thickness and the local O 2 flux varied spatially over the thallus of F. vesiculosus with and without tufts of hyaline hairs.…”

Section: Introductionmentioning

confidence: 99%

Diffusion or advection? Mass transfer and complex boundary layer landscapes of the brown algaFucus vesiculosus

Lichtenberg

Nørregaard

Kühl

2017

J. R. Soc. Interface.

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The role of hyaline hairs on the thallus of brown algae in the genus Fucus is long debated and several functions have been proposed. We used a novel motorized set-up for two-dimensional and three-dimensional mapping with O 2 microsensors to investigate the spatial heterogeneity of the diffusive boundary layer (DBL) and O 2 flux around single and multiple tufts of hyaline hairs on the thallus of Fucus vesiculosus. Flow was a major determinant of DBL thickness, where higher flow decreased DBL thickness and increased O 2 flux between the algal thallus and the surrounding seawater. However, the topography of the DBL varied and did not directly follow the contour of the underlying thallus. Areas around single tufts of hyaline hairs exhibited a more complex mass-transfer boundary layer, showing both increased and decreased thickness when compared with areas over smooth thallus surfaces. Over thallus areas with several hyaline hair tufts, the overall effect was an apparent increase in the boundary layer thickness. We also found indications for advective O 2 transport driven by pressure gradients or vortex shedding downstream from dense tufts of hyaline hairs that could alleviate local mass-transfer resistances. Mass-transfer dynamics around hyaline hair tufts are thus more complex than hitherto assumed and may have important implications for algal physiology and plant -microbe interactions.

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Section: Introductionmentioning

confidence: 99%

Diffusion or advection? Mass transfer and complex boundary layer landscapes of the brown algaFucus vesiculosus

Lichtenberg

Nørregaard

Kühl

2017

J. R. Soc. Interface.

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“…Coral tissue microtopography affects the thickness of the diffusive boundary layer, that is the thin layer of water covering the coral tissues where diffusion is the prime transport mechanism, which can be rate limiting for respiration and photosynthesis [12]. The buildup of a thermal boundary layer controls the heat exchange of corals and is likewise affected by flow and tissue surface topography [13]. Additionally, coral tissue properties strongly modulate the optical microenvironment of coral photosymbiotic microalgae known as zooxanthellae, where, for example, tissue thickness and opacity control Symbiodinium light exposure via formation of distinct light gradients [14] that are further affected by the presence and distribution of coral host pigments, such as the green fluorescent protein (GFP) containing chromatophore system [15,16].…”

Section: Introductionmentioning

confidence: 99%

In vivo imaging of coral tissue and skeleton with optical coherence tomography

Wangpraseurt

Wentzel

Jacques

et al. 2017

J. R. Soc. Interface.

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Application of optical coherence tomography (OCT) for in vivo imaging of tissue and skeleton structure of intact living corals enabled the non-invasive visualization of coral tissue layers (endoderm versus ectoderm), skeletal cavities and special structures such as mesenterial filaments and mucus release from intact living corals. Coral host chromatophores containing green fluorescent protein-like pigment granules appeared hyper-reflective to near-infrared radiation allowing for excellent optical contrast in OCT and a rapid characterization of chromatophore size, distribution and abundance. In vivo tissue plasticity could be quantified by the linear contraction velocity of coral tissues upon illumination resulting in dynamic changes in the live coral tissue surface area, which varied by a factor of 2 between the contracted and expanded state of a coral. Our study provides a novel view on the in vivo organization of coral tissue and skeleton and highlights the importance of microstructural dynamics for coral ecophysiology.

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“…The increase of Symbiodinium cells directly at the base of colonies suggests that a portion of the cells expelled by the adult colony are retained in close proximity. This may be due to cells becoming trapped within the flow-reduced boundary layer that exists to varying extents around all corals (Nakamura and Van Woesik 2001;Jimenez et al 2011), followed by the eventual settling of cells into the nearby sediment. The significant increase of Symbiodinium cells up to 25 cm from the base of the colony (at 1.08 × 10 4 cells/mL) suggests that the diffusion of non-motile cells from the base of the colony through the interstitial spaces of the sediment is not detectable beyond this distance.…”

Section: Free-living Symbiodinium Cellsmentioning

confidence: 99%

The free-living Symbiodinium reservoir and scleractinian coral symbiont acquisition

Nitschke¹

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The genus Symbiodinium (Dinophyceae, Suessiales), a group of geographically widespread marine dinoflagellates, comprises numerous ecologically and genetically distinct taxa. Symbiodinium spp.establish intracellular symbioses with cnidarians, infecting hosts such as jellyfish, sea anemones, octocorals and reef-building corals. The energetic demands of hosts can be met at varying levels by Symbiodinium through translocation of photosynthetically-fixed carbon, assisting in the formation of coral reefs. The cnidarian-dinoflagellate symbiosis is relatively well studied. In contrast, empirical data for population dynamics, distribution, and physiology of free-living Symbiodinium are limited.Therefore this thesis aims to characterise the dynamics between free-living Symbiodinium cells, hosts, and their habitat.Free-living Symbiodinium cells have been identified in reef sediment, and this study investigated whether adult coral colonies are a significant source of benthic Symbiodinium cells. Acropora millepora colonies were translocated to bare patches of sediment (Heron Reef, Great Barrier Reef, Australia), and the surrounding sediment was sampled for Symbiodinium cells over a period of 18 months. An 8-fold increase in visually-identified cells relative to the background population was recorded from the sediment at the immediate base of coral colonies. Symbiodinium abundance returned to background levels after the removal of the coral. These fine-scale changes in the distribution of cells suggests that hard-coral may be an important 'passive' source of Symbiodinium.The 'active' supply of Symbiodinium cells to the benthos was investigated through direct contact of coral tissue with sediment. Symbiont loss was induced in the coral Pocillopora damicornis through burial of coral branches. Peak cell abundance in the sediment occurred after four days, but the photophysiology (F v /F m ) of the Symbiodinium cells was significantly impaired. By day 12, Symbiodinium cells were present only in low concentrations in sediment samples, and the majority of cells were substantially degraded. In this study, Symbiodinium appeared to survive only transiently following expulsion, with an approximate window of viability of seven days. Such a period may be sufficient for coral recruits to make contact with potential symbionts in situ.Elevated temperatures induce a range of serious, deleterious effects in Symbiodinium. The potential amelioration of these effects was investigated, testing the hypothesis that Symbiodinium cells find refuge from stress when cultured within sediment. An exclusively free-living clade A (not known to form symbioses) and the symbiosis-forming type A1 were grown with or without a microhabitat of carbonate sediment at 25°C, 28°C or 31°C. The exclusively free-living clade A was physiologically superior to symbiosis-forming A1 across all measured variables and treatment combinations: it iii reproduced faster within the sediment, exhibited high levels of motility and maintained a stable maximum quantum yield (F ...

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Effects of flow and colony morphology on the thermal boundary layer of corals

Cited by 75 publications

References 62 publications

Diffusion or advection? Mass transfer and complex boundary layer landscapes of the brown algaFucus vesiculosus

Diffusion or advection? Mass transfer and complex boundary layer landscapes of the brown algaFucus vesiculosus

In vivo imaging of coral tissue and skeleton with optical coherence tomography

The free-living Symbiodinium reservoir and scleractinian coral symbiont acquisition

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