Movatterモバイル変換

[0]ホーム
URL:

Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
Thehttps:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log inShow account info
Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation
pubmed logo
Advanced Clipboard
User Guide

Full text links

Frontiers Media SA full text link Frontiers Media SA Free PMC article
Full text links

Actions

Share

.2012 Aug 27:3:316.
doi: 10.3389/fmicb.2012.00316. eCollection 2012.

Light gradients and optical microniches in coral tissues

Affiliations

Light gradients and optical microniches in coral tissues

Daniel Wangpraseurt et al. Front Microbiol..

Abstract

Light quantity and quality are among the most important factors determining the physiology and stress response of zooxanthellate corals. Yet, almost nothing is known about the light field that Symbiodinium experiences within their coral host, and the basic optical properties of coral tissue are unknown. We used scalar irradiance microprobes to characterize vertical and lateral light gradients within and across tissues of several coral species. Our results revealed the presence of steep light gradients with photosynthetically available radiation decreasing by about one order of magnitude from the tissue surface to the coral skeleton. Surface scalar irradiance was consistently higher over polyp tissue than over coenosarc tissue in faviid corals. Coral bleaching increased surface scalar irradiance by ~150% (between 500 and 700 nm) relative to a healthy coral. Photosynthesis peaked around 300 μm within the tissue, which corresponded to a zone exhibiting strongest depletion of scalar irradiance. Deeper coral tissue layers, e.g., ~1000 μm into aboral polyp tissues, harbor optical microniches, where only ~10% of the incident irradiance remains. We conclude that the optical microenvironment of corals exhibits strong lateral and vertical gradients of scalar irradiance, which are affected by both tissue and skeleton optical properties. Our results imply that zooxanthellae populations inhabit a strongly heterogeneous light environment and highlight the presence of different optical microniches in corals; an important finding for understanding the photobiology, stress response, as well as the phenotypic and genotypic plasticity of coral symbionts.

Keywords: bio-optics; coral photobiology; ecophysiology; microenvironment; microgradients; microsensor; tissue optics; zooxanthellae.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1
Micro-scale scalar irradiance measurements on corals. (A) Overview showing a small fragment ofPlatygyra lamellina with the scalar irradiance microprobe positioned at the coral tissue surface at a 45° angle,(B) the spherical microsensor tip (white bulb; 100 μm) at the surface of coenosarc tissue, and(C) the microprobe inserted into coral tissue.
FIGURE 2
FIGURE 2
Micro-scale spectral scalar irradiance at the tissue surface of different corals. Data were normalized to the incident downwelling spectral irradiance,Ed. Note that scale begins at 100%Ed. Dark and light color tones represent measurements made on polyp and coenosarc tissue, respectively. Arrows show major absorption wavelengths of peridinin (480–490 nm), chlorophyllc (460 nm) and chlorophylla (435–440, 675 nm), and emission/reflectance of host pigments (480–590 nm).
FIGURE 3
FIGURE 3
Integrated scalar irradiance (in % of downwelling irradiance) at the tissue surface of corals.(A) PAR (photosynthetically available radiation, 400–700 nm) and(B) NIR (near-infrared radiation, 700–800 nm). Data are means ± SD (n = 9). Measurements were done at the surface of the coenosarc (white bars) and polyp (blue bars) tissue, respectively.
FIGURE 4
FIGURE 4
Mapping of spectral scalar irradiance heterogeneity along one coral polyp inPlatygyra lamellina.(A) Photograph detailing the five different measurement positions along a horizontal tissue surface gradient (indicated as arrow or sensor tip, 1–5). Black scale bar is 2 mm.(B) Single scalar irradiance spectra (400–800 nm) at the measurement points (1–5).
FIGURE 5
FIGURE 5
Effect of bleaching on the tissue surface scalar irradiance of a coral. The figure shows spectral scalar irradiance for coenosarc (black) and polyp (blue) tissue of a bleachedGoniastrea aspera, expressed as percentage of healthy coral.
FIGURE 6
FIGURE 6
Microprofiles of spectral scalar irradiance within coral tissue. Representative profiles measured in the coralMontastrea curta within(A) coenosarc (tissue thickness ~400 μm) and(B) polyp tissue (tissue thickness ~1200 μm). Scalar irradiance was normalized to the incident downwelling spectral irradiance,Ed; dotted line represents 100%Ed. The uppermost spectrum (black) represents measurements taken at the coral surface and subsequent spectra correspond to increments of 100 μm with the lowermost spectrum equaling measurements over the coral skeleton. Spectra are colored in an alternating fashion (black–red) for clarity.
FIGURE 7
FIGURE 7
Microgradients of light, O2, and photosynthesis within coral tissue. Microprofiles were measured within ~400 μm thick coenosarc tissues of the coralMontastrea curta from just above the skeleton (depth 400 μm) to the coral surface (depth 0 μm). Data points are mean values (±SE;n = 4)(A) Mean photosynthetically available radiation (PAR, 400–700 nm; closed symbols) and near-infrared radiation (NIR, 700–800 nm; open symbols) scalar irradiance profiles. Scalar irradiance was normalized to the incident downwelling irradiance.(B) Average O2 concentration (μM; open symbols) and gross photosynthesis (nmol O2 cm-3 s-1; blue bars). For clarity error bars of O2 concentration and photosynthesis are only + and -, respectively. The downwelling photon irradianceEd (PAR) was 640 μmol photons m-2 s-1.
FIGURE 8
FIGURE 8
Effect of incident photon irradiance on within tissue photon scalar irradiance (400–700 nm). The microsensor was positioned at a depth of 1000 μm within the polyp tissue just above the skeleton of the coralPlatygyra lamellina. Black line illustrates a linear fit (r2 > 0.99) and dashed lines represent ±95% confidence intervals.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Al-Horani F. A., Ferdelman T., Al-Moghrabi S. M, De Beer D. (2005). Spatial distribution of calcification and photosynthesis in the scleractinian coral Galaxea fascicularis. Coral Reefs 24 173–180
    1. Alieva N. O., Konzen K. A., Field S. F., Meleshkevitch E. A., Hunt M. E., Beltran-Ramirez V., Miller D. J., Wiedenmann J., Salih A., Matz M. V. (2008). Diversity and evolution of coral fluorescent proteins. PLoS ONE 3 e2680 10.1371/journal.pone.0002680 - DOI - PMC - PubMed
    1. Anderson R. R., Parrish J. A. (1981). The optics of human skin. J. Invest. Dermatol. 77 13–19 - PubMed
    1. Anthony K. R. N., Hoogenboom M. O., Connolly S. R. (2005). Adaptive variation in coral geometry and the optimization of internal colony light climates. Funct. Ecol. 19 17–26
    1. Brown B. E. (1997). Coral bleaching: causes and consequences. Coral Reefs 16 129–138

LinkOut - more resources

Full text links
Frontiers Media SA full text link Frontiers Media SA Free PMC article
Cite
Send To

NCBI Literature Resources

MeSHPMCBookshelfDisclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

[8]ページ先頭
©2009-2025 Movatter.jp