UVR for the health of fish and coral
- Thread starter kiel
- Start date
Two schools? I've never seen anyone in the literature claim it was needed for health (but I could easily have missed such claims). Almost everything I've read suggests it has negative effects, if any at all. Certain color generation, sure, but that isn't health.
Many live well below the zone where UV penetrates in any reasonable amount.
This may be of interest:
Effects of solar ultraviolet radiation on coral reef organisms. Banaszak, Anastazia T.; Lesser, Michael P. Unidad Academica Puerto Morelos, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico, Puerto Morelos, Mex. Photochemical & Photobiological Sciences (2009), 8(9), 1276-1294.
Abstract
Organisms living in shallow-water tropical coral reef environments are exposed to high UVR irradiances due to the low solar zenith angles (the angle of the sun from the vertical), the natural thinness of the ozone layer over tropical latitudes, and the high transparency of the water column. The hypothesis that solar UV radiation (UVR, 290-400 nm) is an important factor that affects the biol. and ecol. of coral reef organisms dates only to about 1980. It has been previously suggested that increased levels of biol. effective UV B radiation (UVB, 290-320 nm), which is the waveband primarily affected by ozone depletion, would have relatively small effects on corals and coral reefs and that these effects might be obsd. as changes in the min. depths of occurrence of important reef taxa such as corals. This conclusion was based on predictions of increases in UVR as well as its attenuation with depth using the available data on UVR irradiances, ozone levels, and optical properties of the water overlying coral reefs. Here, we review the exptl. evidence demonstrating the direct and indirect effects of UVR, both UVB and UV A (UVA, 320-400 nm) on corals and other reef assocd. biota, with emphasis on those studies conducted since 1996. Addnl., we re-examine the predictions made in 1996 for the increase in UVB on reefs with currently available data, assess whether those predictions were reasonable, and look at what changes might occur on coral reefs in the future as the multiple effects (i.e. increased temp., hypercapnia, and ocean acidification) of global climate change continue.
and
UV effects on aquatic ecosystems. Hader, D.-P.; Kumar, H. D.; Smith, R. C.; Worrest, R. C. Institut fur Botanik und Pharmazeutische Biologie, Universitat Erlangen-Nurnburg, Erlangen, Germany. Journal of Photochemistry and Photobiology, B: Biology (1998), 46(1-3), 53-68.
Abstract
A review with 185 refs. Regarding the effects of UV-B radiation on aquatic ecosystems, recent scientific and public interest has focused on marine primary producers and on the aquatic web, which has resulted in a multitude of studies indicating mostly detrimental effects of UV-B radiation on aquatic organisms. The interest has expanded to include ecol. significant groups and major biomass producers using mesocosm studies, emphasizing species interactions. This paper assesses the effects of UV-B radiation on dissolved org. matter, decomposers, primary and secondary producers, and briefly summarizes recent studies in freshwater and marine systems. Dissolved org. carbon (DOC) and particulate org. carbon (POC) are degrdn. products of living organisms. These substances are of importance in the cycling of carbon in aquatic ecosystems. UV-B radiation has been found to break down high-mol.-wt. substances and make them available to bacterial degrdn. In addn., DOC is responsible for short-wavelength absorption in the water column. Esp. in coastal areas and freshwater ecosystems, penetration of solar radiation is limited by high concns. of dissolved and particulate matter. On the other hand, climate warming and acidification result in faster degrdn. of these substances and thus enhance the penetration of UV radiation into the water column. Several research groups have investigated light penetration into the water column. Past studies on UV penetration into the water column were based on temporally and spatially scattered measurements. The process of spectral attenuation of radiant energy in natural waters is well understood and straightforward to model. Less known is the spatial and temporal variability of in-water optical properties influencing UV attenuation and there are few long-term observations. In Europe, this deficiency of measurements is being cor.
by a project involving the development of a monitoring system (ELDONET) for solar radiation using three-channel dosimeters (UV-A, UV-B, PAR) that are being installed from Abisko (North Sweden, 680N, 19E) to Tenerife (Canary Islands, 270N, 17W). Some of the instruments have been installed in the water column (North Sea, Baltic Sea, Kattegat, East and Western Mediterranean, North Atlantic), establishing the first network of underwater dosimeters for continuous monitoring. Bacteria play a vital role in mineralization of org. matter and provide a trophic link to higher organisms. New techniques have substantially changed our perception of the role of bacteria in aquatic ecosystems over the recent past and bacterioplankton productivity is far greater than previously thought, having high division and turnover rates. It has been shown that bacterioplankton play a central role in the carbon flux in aquatic ecosystems by taking up DOC and remineralizing the carbon. Bacterioplankton are more prone to UV-B stress than larger eukaryotic organisms and, based on one study, produce about double the amt. of cyclobutane dimers. Recently, the mechanism of nitrogen fixation by cyanobacteria has been shown to be affected by UV-B stress. Wetlands constitute important ecosystems both in the tropics and at temperate latitudes. In these areas, cyanobacteria form major constituents in microbial mats. The organisms optimize their position in the community by vertical migration in the mat, which is controlled by both visible and UV-B radiation. Cyanobacteria are also important in tropical and sub-tropical rice paddy fields, where they contribute significantly to the availability of nitrogen. Solar UV radiation affects growth, development and several physiol. responses of these organisms. On a global basis, phytoplankton are the most important biomass producers in aquatic ecosystems.
The organisms populate the top layers of the oceans and freshwater habitats where they receive sufficient solar radiation for photosynthetic processes. New research strengthens previous evidence that solar UV affects growth and reprodn., photosynthetic energy-harvesting enzymes and other cellular proteins, as well as photosynthetic pigment contents. The uptake of ammonium and nitrate is affected by solar radiation in phytoplankton, as well as in macroalgae. Damage to phytoplankton at the mol., cellular, population and community levels has been demonstrated. In contrast, at the ecosystem level there are few convincing data with respect to the effects of ozone-related UV-B increases and considerable uncertainty remains. Following UV-B irradn., shifts in phytoplankton community structure have been demonstrated, which may have consequences for the food web. Macroalgae and sea-grasses are important biomass producers in aquatic ecosystems (but considerably smaller than phytoplankton). In contrast to phytoplankton, most of these organisms are sessile and can thus not avoid exposure to solar radiation at their growth site. Recent investigations showed a pronounced sensitivity to solar UV-B radiation, and effects have been found throughout the top 10-15 m of the water column. Photoinhibition can be quantified by oxygen exchange or by PAM (pulse amplitude modulated) fluorescence. Surface-adapted macroalgae, such as several brown and green algae, show a max. of oxygen prodn. at or close to the surface; whereas algae adapted to lower irradiances usually thrive best when exposed deeper in the water column. Mechanisms of protection and repair are being investigated. UV effects on aquatic animals are of increased interest. Evidence for UV effects has been demonstrated in zooplankton activity. Other UV-B-sensitive aquatic organisms include sea urchins, corals and amphibians. Solar UV radiation has been known to affect corals directly.
In addn., photosynthesis in their symbiotic algae is impaired, resulting in reduced org. carbon supply. Amphibian populations are in serious decline in many areas of the world, and scientists are seeking explanations for this phenomenon. Most amphibian population declines are probably due to habitat destruction or habitat alteration. Some declines are probably the result of natural population fluctuations. Other explanations for the population declines and redns. in range include disease, pollution, atm. changes and introduced competitors and predators. UV-B radiation is one agent that may act in conjunction with other stresses to affect amphibian populations adversely. The succession of algal communities is controlled by a complex array of external conditions, stress factors and interspecies influences. Freshwater ecosystems have a high turnover and the success of an individual species is difficult to predict, but the development of general patterns of community structure follows defined routes. There is a strong predictive relationship between DOC concn. and the depth to which UV radiation penetrates in lakes. Since DOC varies widely, freshwater systems display a wide range of sensitivity to UV penetration. In these systems, increased solar UV-B radiation is an addnl. stress factor that may change species compn. and biomass productivity. The Arctic aquatic ecosystem is one of the most productive ecosystems on earth and is a source of fish and crustaceans for human consumption. Both endemic and migratory species breed and reproduce in this ocean in spring and early summer, at a time when recorded increases in UV-B radiation are maximal. Productivity in the Arctic ocean has been reported to be higher and more heterogeneous than in the Antarctic ocean. In the Bering Sea, the sea-edge communities contribute about 40-50% of the total productivity. Because of the shallow water and the prominent stratification of the water layer, the phytoplankton are more exposed and affected by solar UV-B radiation.
In addn., many economically important fish (e.g., herring, pollock, cod and salmon) spawn in shallow waters where they are exposed to increased solar UV-B radiation. Many of the eggs and early larval stages are found at or near the surface. Consequently, reduced productivity of fish and other marine crops is possible but has not been demonstrated. There is increased consensus, covering a wide range of aquatic ecosystems, that environmental UV-B, independent of ozone-related increases, is an important ecol. stress that influences the growth, survival and distribution of phytoplankton. Polar ecosystems, where ozone-related UV-B increases are the greatest and which are globally significant ecosystems, are of particular concern. However, these ecosystems are characterized by large spatial and temporal variability, which makes it difficult to sep. out UV-B-specific effects on single species or whole phytoplankton communities. There is clear evidence for short-term effects. In one study a 4-23% photoinhibition of photosystem II activity was measured under the ozone hole. However, extrapolation of short-term effects to long-term ecol. consequences requires various complex effects to be accounted for and quant. evaluation remains uncertain.
Many live well below the zone where UV penetrates in any reasonable amount.
This may be of interest:
Effects of solar ultraviolet radiation on coral reef organisms. Banaszak, Anastazia T.; Lesser, Michael P. Unidad Academica Puerto Morelos, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico, Puerto Morelos, Mex. Photochemical & Photobiological Sciences (2009), 8(9), 1276-1294.
Abstract
Organisms living in shallow-water tropical coral reef environments are exposed to high UVR irradiances due to the low solar zenith angles (the angle of the sun from the vertical), the natural thinness of the ozone layer over tropical latitudes, and the high transparency of the water column. The hypothesis that solar UV radiation (UVR, 290-400 nm) is an important factor that affects the biol. and ecol. of coral reef organisms dates only to about 1980. It has been previously suggested that increased levels of biol. effective UV B radiation (UVB, 290-320 nm), which is the waveband primarily affected by ozone depletion, would have relatively small effects on corals and coral reefs and that these effects might be obsd. as changes in the min. depths of occurrence of important reef taxa such as corals. This conclusion was based on predictions of increases in UVR as well as its attenuation with depth using the available data on UVR irradiances, ozone levels, and optical properties of the water overlying coral reefs. Here, we review the exptl. evidence demonstrating the direct and indirect effects of UVR, both UVB and UV A (UVA, 320-400 nm) on corals and other reef assocd. biota, with emphasis on those studies conducted since 1996. Addnl., we re-examine the predictions made in 1996 for the increase in UVB on reefs with currently available data, assess whether those predictions were reasonable, and look at what changes might occur on coral reefs in the future as the multiple effects (i.e. increased temp., hypercapnia, and ocean acidification) of global climate change continue.
and
UV effects on aquatic ecosystems. Hader, D.-P.; Kumar, H. D.; Smith, R. C.; Worrest, R. C. Institut fur Botanik und Pharmazeutische Biologie, Universitat Erlangen-Nurnburg, Erlangen, Germany. Journal of Photochemistry and Photobiology, B: Biology (1998), 46(1-3), 53-68.
Abstract
A review with 185 refs. Regarding the effects of UV-B radiation on aquatic ecosystems, recent scientific and public interest has focused on marine primary producers and on the aquatic web, which has resulted in a multitude of studies indicating mostly detrimental effects of UV-B radiation on aquatic organisms. The interest has expanded to include ecol. significant groups and major biomass producers using mesocosm studies, emphasizing species interactions. This paper assesses the effects of UV-B radiation on dissolved org. matter, decomposers, primary and secondary producers, and briefly summarizes recent studies in freshwater and marine systems. Dissolved org. carbon (DOC) and particulate org. carbon (POC) are degrdn. products of living organisms. These substances are of importance in the cycling of carbon in aquatic ecosystems. UV-B radiation has been found to break down high-mol.-wt. substances and make them available to bacterial degrdn. In addn., DOC is responsible for short-wavelength absorption in the water column. Esp. in coastal areas and freshwater ecosystems, penetration of solar radiation is limited by high concns. of dissolved and particulate matter. On the other hand, climate warming and acidification result in faster degrdn. of these substances and thus enhance the penetration of UV radiation into the water column. Several research groups have investigated light penetration into the water column. Past studies on UV penetration into the water column were based on temporally and spatially scattered measurements. The process of spectral attenuation of radiant energy in natural waters is well understood and straightforward to model. Less known is the spatial and temporal variability of in-water optical properties influencing UV attenuation and there are few long-term observations. In Europe, this deficiency of measurements is being cor.
by a project involving the development of a monitoring system (ELDONET) for solar radiation using three-channel dosimeters (UV-A, UV-B, PAR) that are being installed from Abisko (North Sweden, 680N, 19E) to Tenerife (Canary Islands, 270N, 17W). Some of the instruments have been installed in the water column (North Sea, Baltic Sea, Kattegat, East and Western Mediterranean, North Atlantic), establishing the first network of underwater dosimeters for continuous monitoring. Bacteria play a vital role in mineralization of org. matter and provide a trophic link to higher organisms. New techniques have substantially changed our perception of the role of bacteria in aquatic ecosystems over the recent past and bacterioplankton productivity is far greater than previously thought, having high division and turnover rates. It has been shown that bacterioplankton play a central role in the carbon flux in aquatic ecosystems by taking up DOC and remineralizing the carbon. Bacterioplankton are more prone to UV-B stress than larger eukaryotic organisms and, based on one study, produce about double the amt. of cyclobutane dimers. Recently, the mechanism of nitrogen fixation by cyanobacteria has been shown to be affected by UV-B stress. Wetlands constitute important ecosystems both in the tropics and at temperate latitudes. In these areas, cyanobacteria form major constituents in microbial mats. The organisms optimize their position in the community by vertical migration in the mat, which is controlled by both visible and UV-B radiation. Cyanobacteria are also important in tropical and sub-tropical rice paddy fields, where they contribute significantly to the availability of nitrogen. Solar UV radiation affects growth, development and several physiol. responses of these organisms. On a global basis, phytoplankton are the most important biomass producers in aquatic ecosystems.
The organisms populate the top layers of the oceans and freshwater habitats where they receive sufficient solar radiation for photosynthetic processes. New research strengthens previous evidence that solar UV affects growth and reprodn., photosynthetic energy-harvesting enzymes and other cellular proteins, as well as photosynthetic pigment contents. The uptake of ammonium and nitrate is affected by solar radiation in phytoplankton, as well as in macroalgae. Damage to phytoplankton at the mol., cellular, population and community levels has been demonstrated. In contrast, at the ecosystem level there are few convincing data with respect to the effects of ozone-related UV-B increases and considerable uncertainty remains. Following UV-B irradn., shifts in phytoplankton community structure have been demonstrated, which may have consequences for the food web. Macroalgae and sea-grasses are important biomass producers in aquatic ecosystems (but considerably smaller than phytoplankton). In contrast to phytoplankton, most of these organisms are sessile and can thus not avoid exposure to solar radiation at their growth site. Recent investigations showed a pronounced sensitivity to solar UV-B radiation, and effects have been found throughout the top 10-15 m of the water column. Photoinhibition can be quantified by oxygen exchange or by PAM (pulse amplitude modulated) fluorescence. Surface-adapted macroalgae, such as several brown and green algae, show a max. of oxygen prodn. at or close to the surface; whereas algae adapted to lower irradiances usually thrive best when exposed deeper in the water column. Mechanisms of protection and repair are being investigated. UV effects on aquatic animals are of increased interest. Evidence for UV effects has been demonstrated in zooplankton activity. Other UV-B-sensitive aquatic organisms include sea urchins, corals and amphibians. Solar UV radiation has been known to affect corals directly.
In addn., photosynthesis in their symbiotic algae is impaired, resulting in reduced org. carbon supply. Amphibian populations are in serious decline in many areas of the world, and scientists are seeking explanations for this phenomenon. Most amphibian population declines are probably due to habitat destruction or habitat alteration. Some declines are probably the result of natural population fluctuations. Other explanations for the population declines and redns. in range include disease, pollution, atm. changes and introduced competitors and predators. UV-B radiation is one agent that may act in conjunction with other stresses to affect amphibian populations adversely. The succession of algal communities is controlled by a complex array of external conditions, stress factors and interspecies influences. Freshwater ecosystems have a high turnover and the success of an individual species is difficult to predict, but the development of general patterns of community structure follows defined routes. There is a strong predictive relationship between DOC concn. and the depth to which UV radiation penetrates in lakes. Since DOC varies widely, freshwater systems display a wide range of sensitivity to UV penetration. In these systems, increased solar UV-B radiation is an addnl. stress factor that may change species compn. and biomass productivity. The Arctic aquatic ecosystem is one of the most productive ecosystems on earth and is a source of fish and crustaceans for human consumption. Both endemic and migratory species breed and reproduce in this ocean in spring and early summer, at a time when recorded increases in UV-B radiation are maximal. Productivity in the Arctic ocean has been reported to be higher and more heterogeneous than in the Antarctic ocean. In the Bering Sea, the sea-edge communities contribute about 40-50% of the total productivity. Because of the shallow water and the prominent stratification of the water layer, the phytoplankton are more exposed and affected by solar UV-B radiation.
In addn., many economically important fish (e.g., herring, pollock, cod and salmon) spawn in shallow waters where they are exposed to increased solar UV-B radiation. Many of the eggs and early larval stages are found at or near the surface. Consequently, reduced productivity of fish and other marine crops is possible but has not been demonstrated. There is increased consensus, covering a wide range of aquatic ecosystems, that environmental UV-B, independent of ozone-related increases, is an important ecol. stress that influences the growth, survival and distribution of phytoplankton. Polar ecosystems, where ozone-related UV-B increases are the greatest and which are globally significant ecosystems, are of particular concern. However, these ecosystems are characterized by large spatial and temporal variability, which makes it difficult to sep. out UV-B-specific effects on single species or whole phytoplankton communities. There is clear evidence for short-term effects. In one study a 4-23% photoinhibition of photosystem II activity was measured under the ozone hole. However, extrapolation of short-term effects to long-term ecol. consequences requires various complex effects to be accounted for and quant. evaluation remains uncertain.
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here's a specific reference for corals:
Spatial and temporal variability of solar ultraviolet exposure of coral assemblages in the Florida keys: Importance of colored dissolved organic matter. Zepp, Richard G.; Shank, G. Christopher; Stabenau, Erik; Patterson, Karen W.; Cyterski, Mike; Fisher, William; Bartels, Erich; Anderson, Susan L. Ecosystems Research Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Athens, GA, USA. Limnology and Oceanography (2008), 53(5), 1909-1922. Abstract
Solar UV radiation can have deleterious effects on coral assemblages in tropical and subtropical marine environments, but little information is available on UV penetration into ocean waters surrounding corals. Here we provide an extensive data set of optical properties in the UV domain (280[en]400 nm) that were obtained during 1998-2005 at sites located in the Lower and Middle Keys and the Dry Tortugas. Absorption coeffs. of the colored component of the dissolved org. carbon (DOC; colored dissolved org. matter [CDOM]) were 6 to 25 larger than particulate absorption coeffs. in the UV region, indicating that CDOM controls UV penetration in the inshore coastal waters and reef tract. CDOM absorption coeffs. (aCDOM) and DOC were highly correlated to diffuse attenuation coeffs. (Kd) in the UV spectral region. Measurements using moored sensors showed that UV penetration at the reef tract in the Lower Keys varies significantly from day to day and diurnally. The diurnal variations were linked to tidal currents that transport CDOM over the reef tract. Summertime stratification of Case 1 bluewaters near the reef tract during periods of low wind resulted in higher temps. and UV penetration than that obsd. during well-mixed conditions. This result suggests that higher UV exposure accompanying ocean warming during low-wind doldrums conditions significantly contributes to coral bleaching. Modeling results indicate that changes in underwater sunlight attenuation over the coral reefs can affect UV-induced DNA (DNA) damage and inhibition of coral photosynthesis much more strongly than changes in the stratospheric ozone layer.
Spatial and temporal variability of solar ultraviolet exposure of coral assemblages in the Florida keys: Importance of colored dissolved organic matter. Zepp, Richard G.; Shank, G. Christopher; Stabenau, Erik; Patterson, Karen W.; Cyterski, Mike; Fisher, William; Bartels, Erich; Anderson, Susan L. Ecosystems Research Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Athens, GA, USA. Limnology and Oceanography (2008), 53(5), 1909-1922. Abstract
Solar UV radiation can have deleterious effects on coral assemblages in tropical and subtropical marine environments, but little information is available on UV penetration into ocean waters surrounding corals. Here we provide an extensive data set of optical properties in the UV domain (280[en]400 nm) that were obtained during 1998-2005 at sites located in the Lower and Middle Keys and the Dry Tortugas. Absorption coeffs. of the colored component of the dissolved org. carbon (DOC; colored dissolved org. matter [CDOM]) were 6 to 25 larger than particulate absorption coeffs. in the UV region, indicating that CDOM controls UV penetration in the inshore coastal waters and reef tract. CDOM absorption coeffs. (aCDOM) and DOC were highly correlated to diffuse attenuation coeffs. (Kd) in the UV spectral region. Measurements using moored sensors showed that UV penetration at the reef tract in the Lower Keys varies significantly from day to day and diurnally. The diurnal variations were linked to tidal currents that transport CDOM over the reef tract. Summertime stratification of Case 1 bluewaters near the reef tract during periods of low wind resulted in higher temps. and UV penetration than that obsd. during well-mixed conditions. This result suggests that higher UV exposure accompanying ocean warming during low-wind doldrums conditions significantly contributes to coral bleaching. Modeling results indicate that changes in underwater sunlight attenuation over the coral reefs can affect UV-induced DNA (DNA) damage and inhibition of coral photosynthesis much more strongly than changes in the stratospheric ozone layer.
kiel
New member
if my experience is anything to go by i don't think there would be too much available at this poing randy, my curiosity was only sparked recently by a researcher from here in melbourne tasked with captively breeding a now extremely endangered species of freshwater fish (details for anyone interested) since it's already limited population was hit very hard by a big fire we had recently
needless to say he was taking his work exceptionally seriously.....we got talking about lighting, and UV came up. he wasn't keen on completely removing it from the environment he provided for the fish he was trying to breed
the impression i got from my conversation with him was that there's an emerging pro-UV crowd down here.....mybe we'll hear more of it in future
needless to say he was taking his work exceptionally seriously.....we got talking about lighting, and UV came up. he wasn't keen on completely removing it from the environment he provided for the fish he was trying to breed
the impression i got from my conversation with him was that there's an emerging pro-UV crowd down here.....mybe we'll hear more of it in future
OK, sounds good. 
kiel
New member
well...having considered this a little bit more from my permanent position on the fence i have decided to let my perspective loose in cyberspace and see what comes back
currently, i would be inclined to agree with the pro-uv crowd in that there seems to be some real potential for health issues stemming from uv deficit.....
although ultraviolet light is known to be damaging at higher intensities, and particularly at higher frequencies, as with humans it appears that ultra violet light does play a constructive role in the process of the condition of marine organisms
this is intuitive to myself and correlates with what is known by most aquarists regarding the potential harm to marine organisms if there is any sort of drastic chemical or physical change to their aquatic environment. although on a smaller and less easily comprehensible scale, i would liken it to removing salt from the water, although obviously far less dramatic in reality
from a physiology perspective it would make sense to believe that abruptly ceasing any sort of metabolic process is likely to lead to cellular degeneration which will have a snowball effect on the health of the organism, as the survival of cells depends on movement, or use (think "use it or loose it")
if any part of this cellular network falls into disuse, it begins to degenerate. to a limited extent this is healthy and even beneficial, however if too great can lead to problems in that degenerating tissue within a living organism is going to produce toxic byproducts which carry potential to not only cause harm within the affected region, but also spread to other similarly comprised regions of the anatomy
bringing this back to marine organisms the metabolic process in question as far as i can understand here is the production of mycosporine-like amino acids (MAA), which basically act to absorb ultra-violet generated energy/potential damage in the same way as melanin does for us humans
from what limited information i have gone through thus far, as with the production of vitamin D in humans, MAA appears to have a secondary function in that it acts as an anti-oxidant both within the organisms which produce it and to the benefit of organisms in the surrounding environment
i don't think this is something that is going to cause any real immediate issues for the hobby aquarium (although could reduce the lifespan of your livestock), however thinking longer term - and particularly with regards to long term captive coral propagation if it is to succeed harvesting said organisms from the wild - the accumulative effect of this abrupt and continuous environmental difference could lead to hereditary disease in captive fish and coral lineages...
this is by no means a comprehensive study, but a point of interest for myself non the less, and i can only see benefits for all concerned arising from the discussion of matters such as this :fish1:
from here i will personally probably be looking into upgrading my current LED lighting system with some degree of UV-A/B capacity....
currently, i would be inclined to agree with the pro-uv crowd in that there seems to be some real potential for health issues stemming from uv deficit.....
although ultraviolet light is known to be damaging at higher intensities, and particularly at higher frequencies, as with humans it appears that ultra violet light does play a constructive role in the process of the condition of marine organisms
this is intuitive to myself and correlates with what is known by most aquarists regarding the potential harm to marine organisms if there is any sort of drastic chemical or physical change to their aquatic environment. although on a smaller and less easily comprehensible scale, i would liken it to removing salt from the water, although obviously far less dramatic in reality
from a physiology perspective it would make sense to believe that abruptly ceasing any sort of metabolic process is likely to lead to cellular degeneration which will have a snowball effect on the health of the organism, as the survival of cells depends on movement, or use (think "use it or loose it")
if any part of this cellular network falls into disuse, it begins to degenerate. to a limited extent this is healthy and even beneficial, however if too great can lead to problems in that degenerating tissue within a living organism is going to produce toxic byproducts which carry potential to not only cause harm within the affected region, but also spread to other similarly comprised regions of the anatomy
bringing this back to marine organisms the metabolic process in question as far as i can understand here is the production of mycosporine-like amino acids (MAA), which basically act to absorb ultra-violet generated energy/potential damage in the same way as melanin does for us humans
from what limited information i have gone through thus far, as with the production of vitamin D in humans, MAA appears to have a secondary function in that it acts as an anti-oxidant both within the organisms which produce it and to the benefit of organisms in the surrounding environment
i don't think this is something that is going to cause any real immediate issues for the hobby aquarium (although could reduce the lifespan of your livestock), however thinking longer term - and particularly with regards to long term captive coral propagation if it is to succeed harvesting said organisms from the wild - the accumulative effect of this abrupt and continuous environmental difference could lead to hereditary disease in captive fish and coral lineages...
this is by no means a comprehensive study, but a point of interest for myself non the less, and i can only see benefits for all concerned arising from the discussion of matters such as this :fish1:
from here i will personally probably be looking into upgrading my current LED lighting system with some degree of UV-A/B capacity....
currently, i would be inclined to agree with the pro-uv crowd in that there seems to be some real potential for health issues stemming from uv deficit.....
Do you have any scientific articles that suggest marine organisms need or benefit from UV? I've not seen any.
Do you have any scientific articles that suggest marine organisms need or benefit from UV? I've not seen any.
kiel
New member
no, it's just my own homology driven perspective at work i'm easily persuaded.....
http://www.annualreviews.org/doi/abs/10.1146/annurev.physiol.64.081501.155802
this article explores MAAs role in marine organisms in a bit more depth both as a byproduct of uv stimulation and a secondary metabolite, but only the extract is available free. not entirely sure but i don't think i'd be allowed to publicly share the contents...
another variable in all of this of particular interest with regards to the hobby aquarium is ambient uv
if uv is required at all i imagine it's only going to be in trace amounts, and given that most hobby aquariums are going to be situated in a room with some ambient sunlight, that might just be enough to satisfy any potential requirements
for my own aquarium situated immediately in front of a north facing window with ambient sunlight exposure basically all day, i'd hazard a guess that this may indeed be sufficient if the requirement existed....
i'm easily persuaded.....http://www.annualreviews.org/doi/abs/10.1146/annurev.physiol.64.081501.155802
this article explores MAAs role in marine organisms in a bit more depth both as a byproduct of uv stimulation and a secondary metabolite, but only the extract is available free. not entirely sure but i don't think i'd be allowed to publicly share the contents...
another variable in all of this of particular interest with regards to the hobby aquarium is ambient uv
if uv is required at all i imagine it's only going to be in trace amounts, and given that most hobby aquariums are going to be situated in a room with some ambient sunlight, that might just be enough to satisfy any potential requirements
for my own aquarium situated immediately in front of a north facing window with ambient sunlight exposure basically all day, i'd hazard a guess that this may indeed be sufficient if the requirement existed....
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greenbean36191
Premium Member
You seem to think that the UV would be beneficial because it induces production of MAAs, which are anti-oxidants. What you're forgetting though is that UV is a major source of oxidative stress- the reason you need the anti-oxidants in the first place. Without that extra source of oxidative damage there is less need for anti-oxidants. I'm not sure why you expect there to be a net benefit. It's kind of like realizing that the insurance company will give you money to fix your car, but you have to wreck the car to get the money to fix it.
kiel
New member
no i hadn't forgotten that
over-exposure of uv-a is a major source of oxadative stress, however acceptable (relative to the requirements of the organism) uv exposure is both beneficial and necessary
uv exposure is a source of oxadative stress....so is nutrition.....much more so than acceptable levels of uv exposure. ROS are a natural metabolite, they're meant to happen
you can't think of uv as an artifical addition, or environmental supplement in the context of "you think it will be benficial because it would..."
it's a matter of it is necessary because it does....the environment the orgnisms have come from does include uv exposure
the basic biological principle is sound, removing any factor from an environment which maintains an existing biological condition is going to disrupt the metabolic processes which occur within that organism
that organisms condition depends on all these things happening, take part of it away and you could be opening pandoras box
it's not at all like wrecking a car for insurance money....
it's like not oiling your car and expecting it to run as it should
put too much oil in that car: fiill the gas tank, cylinders, block, and cabin with motor oil, and that car no longer functions the way it was intended to.....
too much oil damages the car, but so does not enough
is this biological factor significant enough to warrant attention? possibly. currently, i think it's possible
maas have been identified as an anti-oxidant, but that's just all they've been identified as so far. they're secondary functions as highlighted in the synopsis of the article link i provide above could be as wide ranging as:
and that's on top of the fact that the cellular structures which produce these substances may also become a health hazard if not appreciated, in the same was our bodies can if we sit around all day and don't use them
the simple fact is, the environment these animals have come from does include uv exposure. that's the environment which produces and maintains healthy organisms, that's the environment i think we should be modelling ours on
there's not a lot of info or research on this subject out there are the moment, but there's lots of disoveries yet to be made, unspeakable numbers of things we're yet to learn. it starts with an idea, and i got this idea from a marine researcher if that's more an indication of it's credibility to some....i'm just adding my thoughts to it
over-exposure of uv-a is a major source of oxadative stress, however acceptable (relative to the requirements of the organism) uv exposure is both beneficial and necessary
uv exposure is a source of oxadative stress....so is nutrition.....much more so than acceptable levels of uv exposure. ROS are a natural metabolite, they're meant to happen
you can't think of uv as an artifical addition, or environmental supplement in the context of "you think it will be benficial because it would..."
it's a matter of it is necessary because it does....the environment the orgnisms have come from does include uv exposure
the basic biological principle is sound, removing any factor from an environment which maintains an existing biological condition is going to disrupt the metabolic processes which occur within that organism
that organisms condition depends on all these things happening, take part of it away and you could be opening pandoras box
it's not at all like wrecking a car for insurance money....
it's like not oiling your car and expecting it to run as it should
put too much oil in that car: fiill the gas tank, cylinders, block, and cabin with motor oil, and that car no longer functions the way it was intended to.....
too much oil damages the car, but so does not enough
is this biological factor significant enough to warrant attention? possibly. currently, i think it's possible
maas have been identified as an anti-oxidant, but that's just all they've been identified as so far. they're secondary functions as highlighted in the synopsis of the article link i provide above could be as wide ranging as:
and more...
and that's on top of the fact that the cellular structures which produce these substances may also become a health hazard if not appreciated, in the same was our bodies can if we sit around all day and don't use them
the simple fact is, the environment these animals have come from does include uv exposure. that's the environment which produces and maintains healthy organisms, that's the environment i think we should be modelling ours on
there's not a lot of info or research on this subject out there are the moment, but there's lots of disoveries yet to be made, unspeakable numbers of things we're yet to learn. it starts with an idea, and i got this idea from a marine researcher if that's more an indication of it's credibility to some....i'm just adding my thoughts to it
greenbean36191
Premium Member
You haven't offered any evidence to support this assertion. You're working backwards from the conclusion that this must be true.
As far as normal amounts of UV being necessary, as Randy already pointed out, many of the species we keep in the hobby occur down to depths where there is essentially no UV exposure, which would suggest that UV is not necessary for them. One of my study animals, the good old BTA occurs down to at least 140 ft (as deep as we've looked for them). Several Acropora, faviids, mussids, and corallimorphs also occur at those depths. At that depth they're receiving about 0.1% of surface UV levels. Anything deeper than about 95 ft is getting less than 1% of surface UV. In Hawai'i, even at 70 ft, the noon UV is less than 7 watts/m^2.
They are a natural consequence of metabolism, but that doesn't mean they're meant to happen. They're damaging to cellular machinery and cells have multiple mechanisms in place to control and destroy them. They don't want them around. They may perform an important signalling role, but the jury is still out on that one. Even so, there is no lack of ROS without UV exposure. They're inevitably produced in fairly large amounts as a normal part of photosynthesis and cellular respiration. Without UV there is no reason to believe the animals are suffering from lack of either ROS or the normal, non-MAA antioxidants that control them.
...for some of them. It still does not follow that exposure to UV is beneficial to them simply because it's part of nature. The environment these organisms come from also include tropical cyclones, extreme low tides, predators and parasites, hypoxia, hyperoxia, floods and runoff. These all play important roles in structuring the ecology of the reef as a whole, but all are harmful to individual corals (except corals that are reliant on fragmentation by storms for reproduction). You're assuming natural= benevolent and from there progressing on to the assume necessity and benefit, which is an astronomical leap.
In deep reef corals, MAA concentrations are essentially undetectable. That seems to indicate that the zoox's cellular machinery doesn't get bogged down if it's not making MAAs. The zoox and the corals do just fine without them.
Unless he's got evidence to support his position, I'm unimpressed by the fact that he's a marine researcher. I'm a marine ecologist too and I don't think the idea has any legs. There's a similar thread going on at Ron Shimek's (another marine biologist) forum on Marine Depot and he seems to think the idea is equally baseless.
kiel
New member
nature is evidence
the biological principles are proven relative to specific non-marine organisms, however specific to marine organisms, as i have said, i am simply using homological molecular biology as reason to believe. i'm not claiming it's absolute evidence the principles can be applied to all marine organisms...
the answer is probably somewhere in the middle
in that it is probably different specific to different organisms, relative to the type of uv they are exposed todiscussing the question with all marine or non-marine organisms grouped as a whole is obviously going to be problematic given the variable conditions from which they have emerged
i'm not working backwards from a claim, i am not making a claim at all. nature is making the claim, i am listening and trying to understand
removing a natural variable and stating it is not necessary is the claim beyond what actually exists in nature
uv exists at variable levels in nature from which the subject matter originates
uv is a constant (although obviously variable on day to day basis) in the molecular mechanics which shape the condition of individual marine organism, even if it's in variable or trace amounts
it's not like a storm, run off, or predators and parasites. the former are fluctuations in the movement of large quantities of these constants, and the latter constants which shape the larger variable of species as a single unit
everything is meant to happen, but i agree that doesn't mean we absolutely need to replicate it, or that it isn't actually a biological villain relative to particular organisms
if we can improve the health of our fish and coral by removing a damaging factor (something which alters the permanence of the structure of their condition) from their environment, that's great, but until such time as someone can show us that it's going to improve upon nature and not mess things up i'm going to set my bench mark at natural life cycles
the anti-uv crowd are the folks with something to prove....
nature is pro-uv in naturally occurring quantities, it isn't wiping out species, it's always been there and they are surviving. anything beyond that is up to someone who claims to know better to prove....
fair enough
i'm of the same position regarding tertiary straight jackets however to some people it is more important than reason....
