scholarly journals Red fluorescence of the triplefin Tripterygion delaisi is increasingly visible against background light with increasing depth

2017 ◽  
Vol 4 (3) ◽  
pp. 161009 ◽  
Author(s):  
Pierre-Paul Bitton ◽  
Ulrike K. Harant ◽  
Roland Fritsch ◽  
Connor M. Champ ◽  
Shelby E. Temple ◽  
...  
Keyword(s):  
Colour Vision ◽  
Red Light ◽  
Field Measurements ◽  
Light Environment ◽  
Natural Light ◽  
Ambient Light ◽  
Red Fluorescence ◽  
As Species ◽  
Tripterygion Delaisi ◽  
Red Coloration

The light environment in water bodies changes with depth due to the absorption of short and long wavelengths. Below 10 m depth, red wavelengths are almost completely absent rendering any red-reflecting animal dark and achromatic. However, fluorescence may produce red coloration even when red light is not available for reflection. A large number of marine taxa including over 270 fish species are known to produce red fluorescence, yet it is unclear under which natural light environment fluorescence contributes perceptively to their colours. To address this question we: (i) characterized the visual system of Tripterygion delaisi, which possesses fluorescent irides, (ii) separated the colour of the irides into its reflectance and fluorescence components and (iii) combined these data with field measurements of the ambient light environment to calculate depth-dependent perceptual chromatic and achromatic contrasts using visual modelling. We found that triplefins have cones with at least three different spectral sensitivities, including differences between the two members of the double cones, giving them the potential for trichromatic colour vision. We also show that fluorescence contributes increasingly to the radiance of the irides with increasing depth. Our results support the potential functionality of red fluorescence, including communicative roles such as species and sex identity, and non-communicative roles such as camouflage.

scholarly journals Acclimatization of symbiotic corals to mesophotic light environments through wavelength transformation by fluorescent protein pigments

2017 ◽  
Vol 284 (1858) ◽  
pp. 20170320 ◽  
Author(s):  
Edward G. Smith ◽  
Cecilia D'Angelo ◽  
Yoni Sharon ◽  
Dan Tchernov ◽  
Joerg Wiedenmann
Keyword(s):  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Environmental Gradients ◽  
Red Light ◽  
Spectral Composition ◽  
Light Environment ◽  
Homogeneous Distribution ◽  
Red Fluorescent Proteins ◽  
Ecological Importance ◽  
Colour Morphs

The depth distribution of reef-building corals exposes their photosynthetic symbionts of the genus Symbiodinium to extreme gradients in the intensity and spectral quality of the ambient light environment. Characterizing the mechanisms used by the coral holobiont to respond to the low intensity and reduced spectral composition of the light environment in deeper reefs (greater than 20 m) is fundamental to our understanding of the functioning and structure of reefs across depth gradients. Here, we demonstrate that host pigments, specifically photoconvertible red fluorescent proteins (pcRFPs), can promote coral adaptation/acclimatization to deeper-water light environments by transforming the prevalent blue light into orange-red light, which can penetrate deeper within zooxanthellae-containing tissues; this facilitates a more homogeneous distribution of photons across symbiont communities. The ecological importance of pcRFPs in deeper reefs is supported by the increasing proportion of red fluorescent corals with depth (measured down to 45 m) and increased survival of colour morphs with strong expression of pcRFPs in long-term light manipulation experiments. In addition to screening by host pigments from high light intensities in shallow water, the spectral transformation observed in deeper-water corals highlights the importance of GFP-like protein expression as an ecological mechanism to support the functioning of the coral– Symbiodinium association across steep environmental gradients.

Light and the Optical Environment

2014 ◽  
Author(s):  
Thomas W. Cronin ◽  
Sönke Johnsen ◽  
N. Justin Marshall ◽  
Eric J. Warrant
Keyword(s):  
Deep Sea ◽  
Natural Light ◽  
The Sun ◽  
Ambient Light

This chapter explains how humans, and nearly all animals on Earth, witness astonishing variation in their optical environment. Brightness changes by many orders of magnitude each day, and colors also shift dramatically. Those animals that enter forests and especially the water experience even larger changes. Given this, it is surprising that nearly all the natural light on Earth ultimately comes from two sources, the sun and bioluminescence. A final source of light that is potentially relevant to vision is mechanoluminescence. In this process, light is produced by mechanical processes, including deformation (piezoluminescence), fracturing (triboluminescence), and crystallization (crystalloluminescence). The latter two have been suggested as being at least partially responsible for ambient light at deep-sea vents.

scholarly journals Role of elemental carbon in the photochemical aging of soot

2018 ◽  
Vol 115 (30) ◽  
pp. 7717-7722 ◽  
Author(s):  
Meng Li ◽  
Fengxia Bao ◽  
Yue Zhang ◽  
Wenjing Song ◽  
Chuncheng Chen ◽  
...  
Keyword(s):  
Light Absorption ◽  
Elemental Carbon ◽  
Red Light ◽  
Field Measurements ◽  
Light Irradiation ◽  
Photochemical Oxidation ◽  
Chemical Mechanism ◽  
Strong Light ◽  
Electron Transfer Pathway ◽  
Photochemical Aging

Soot, which consists of organic carbon (OC) and elemental carbon (EC), is a significant component of the total aerosol mass in the atmosphere. Photochemical oxidation is an important aging pathway for soot. It is commonly believed that OC is photoactive but EC, albeit its strong light absorption, is photochemically inert. Here, by taking advantage of the different light absorption properties of OC and EC, we provide direct experimental evidence that EC also plays an important role in the photochemical aging of soot by initiating the oxidation of OC, even under red light irradiation. We show that nascent soot, in addition to undergoing photochemical oxidation under blue light with a wavelength of 440 nm, undergoes similar oxidation under red light irradiation of λ = 648 nm (L648). However, separated OC (extracted from soot by n-hexane) and EC exhibit little reactivity under L648. These observations indicate that EC plays a pivotal role in photoaging of soot by adsorbing light to initiate the oxidation of OC. Comparison of in situ IR spectra and photoelectrochemical behaviors suggests that EC-initiated photooxidation of OC proceeds through an electron transfer pathway, which is distinct from the photoaging induced by light absorption of OC. Since the absorption spectra of EC have a much larger overlap with the solar spectra than those of OC, our results provide insight into the chemical mechanism leading to rapid soot aging by organic species observed from atmospheric field measurements.

Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) III. Effects of light

1967 ◽  
Vol 18 (1) ◽  
pp. 23 ◽  
Author(s):  
RC Rossiter ◽  
AB Beck
Keyword(s):  
Light Intensity ◽  
Subterranean Clover ◽  
Substantial Effect ◽  
The Other ◽  
Light Environment ◽  
Natural Light ◽  
Ecological Studies ◽  
Other Hand ◽  
Isoflavone Content ◽  
Per Se

Isoflavone levels in subterranean clover leaves were higher in 13 hr days of natural daylight than in 6 hr days, but length of photoperiod per se had no substantial effect on these levels. In the field, reduction of light intensity (by shading) to 40% daylight caused no decline in isoflavone levels compared with full daylight; even at 24% daylight the reduction in levels was ill defined. On the other hand, in young seedlings there was a marked fall in isoflavone content, especially in the unifoliate leaf, as light intensity fell from 950 to 320 f.c. However, appreciable isoflavone formation was found in dark-grown clover seedlings. Possible light reactions connected with the promotion of isoflavone synthesis are discussed. Changes in isoflavone levels resulting from variation in the natural light environment are unlikely to be sufficient to affect "clover disease".

scholarly journals Nuptial coloration varies with ambient light environment in a freshwater fish

2010 ◽  
Vol 23 (12) ◽  
pp. 2718-2725 ◽  
Author(s):  
J. R. MORRONGIELLO ◽  
N. R. BOND ◽  
D. A. CROOK ◽  
B. B. M. WONG
Keyword(s):  
Freshwater Fish ◽  
Light Environment ◽  
Ambient Light ◽  
Nuptial Coloration

scholarly journals Differential responses of coral larvae to the colour of ambient light guide them to suitable settlement microhabitat

2015 ◽  
Vol 2 (10) ◽  
pp. 150358 ◽  
Author(s):  
Marie E. Strader ◽  
Sarah W. Davies ◽  
Mikhail V. Matz
Keyword(s):  
Fluorescent Protein ◽  
Critical Role ◽  
Red Light ◽  
Green Light ◽  
Ambient Light ◽  
Coral Larvae ◽  
Acropora Millepora ◽  
Light Sensing ◽  
Natal Habitat

Reef-building corals produce planktonic planula larvae that must select an appropriate habitat to settle and spend the rest of their life, a behaviour that plays a critical role in survival. Here, we report that larvae obtained from a deep-water population of Pseudodiploria strigosa settled more readily under blue light and in the dark, which aligns well with the light field characteristics of their natal habitat. By contrast, larvae of the shallow-water coral Acropora millepora settled in high proportions under blue and green light while settlement was less in the dark. Acropora millepora larvae also showed reduced settlement under red light, which should be abundant at shallow depth. Hypothesizing that this might be a mechanism preventing the larvae from settling on the exposed upwards-facing surfaces, we quantified A. millepora settlement in manipulated light chambers in situ on the reef. While A. millepora larvae naturally preferred settling on vertical rather than exposed horizontal surfaces, swapping the colours of upwards-facing and sideways-facing light fields was sufficient to invert this preference. We also tested if the variation in intrinsic red fluorescence in A. millepora larvae correlates with settlement rates, as has been suggested previously. We observed this correlation only in the absence of light, indicating that larval red fluorescent protein is probably not directly involved in light sensing. Our study reveals previously under-appreciated light-sensory capabilities in coral larvae, which could be an important axis of ecological differentiation between coral species and/or populations.

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