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J. H. M. Kouwenberg H. I. Browman J. J. Cullen R. F. Davis J.-F. St-Pierre J. A. Runge 《Marine Biology》1999,134(2):269-284
In the Gulf of St. Lawrence, Canada, productivity-determining biophysical interactions occur in the upper 0 to 30 m of the
water column. The eggs and larvae of several commercially important marine invertebrates and fishes (e.g. Gadus morhua L.) are found in this layer. Measurements of the diffuse attenuation coefficients for ultraviolet-B radiation (280 to 320 nm,
UV-B) at various locations in this geographic region indicated maximum 10% depths (the depth to which 10% of the surface energy
penetrates at a given wavelength) of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer
mixed-layer water column: organisms residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp
based solar simulator revealed that cod embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest
effects occurred under exposures to wavelengths below 312 nm. This susceptibility was also dependent upon developmental stage;
mortality was particularly high during gastrulation. At the shorter wavelengths (<305 nm) UV-B-induced mortality was strongly
dose-dependent, and not significantly influenced by dose-rate. The biological weighting function (BWF) derived for UV-B-induced
mortality in cod eggs is similar to that reported for naked DNA – suggesting that the mortality is a direct result of DNA
damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to 400 nm). Calculations based upon
the BWF indicate that, under current noon surface irradiance, 50% of cod eggs located at or very near (within 10 cm) the ocean
surface will be dead after 42 h of exposure. Under solar spectral irradiance simulating a 20% decrease in ozone layer thickness,
this time drops to 32 h. These are first-order estimates based upon surface irradiance taken at a time of day during which
the values would be maximal. Nonetheless, they illustrate the relative changes in UV-B impacts that will result from ozone
layer depletions expected over the coming decades. It is also important to point out that variability in cloud cover, water
quality, and vertical distribution and displacement of cod eggs and larvae within the mixed layer, can all have a greater
effect on the flux of UV-B radiation to which fish eggs are exposed than will ozone layer depletion at these latitudes.
Received: 2 March 1998 / Accepted: 18 December 1998 相似文献
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J. H. M. Kouwenberg H. I. Browman J. A. Runge J. J. Cullen R. F. Davis J.-F. St-Pierre 《Marine Biology》1999,134(2):285-293
The copepod Calanus finmarchicus Gunnerus is a key component of the planktonic food web in the Gulf of St. Lawrence, Canada. In this region, productivity-determining
biophysical interactions occur in the upper 0 to 30 m of the water column. The eggs and nauplii of C. finmarchicus are found in this layer. Measurements of the diffuse attenuation coefficients for solar ultraviolet-B radiation (280 to 320 nm,
UV-B) at various locations in this region indicated maximum 10% depths (the depth to which 10% of the surface energy penetrates)
of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer mixed-layer water column: organisms
residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp based solar simulator
revealed that C. finmarchicus embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest effects occurred under exposures to
wavelengths below 312 nm. A significant percentage of nauplii hatched from eggs exposed to these wavelengths exhibited malformations
indicative of errors in pattern formation during embryogenesis. At the shorter wavelengths (<305 nm), UV-B-induced mortality
was strongly dependent on cumulative exposure. The biological weighting function (BWF) derived for UV-B-induced mortality
in C. finmarchicus eggs is similar to that reported for naked DNA. This suggests that the UV-B-induced mortality effect on C. finmarchicus embryos is a direct result of DNA damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to
400 nm). Calculations based upon the BWF indicate that, under current noon surface irradiance, 50% of C. finmarchicus eggs located at or very near (within 10 cm) the ocean surface will be dead after 2.5 h of exposure. Under solar spectral
irradiance simulating a 20% decrease in ozone layer thickness, this time drops to 2.2 h. These are first-order estimates based
upon irradiance taken at a time of day during which the values would be maximal. Nonetheless, they illustrate the relative
changes in UV-B effects that will result from ozone layer depletions expected over the coming decades. It is also important
to point out that variability in cloud cover, water quality, and vertical distribution and displacement within the mixed layer,
can all have a greater effect on the flux of UV-B radiation to which C. finmarchicus eggs are exposed than will ozone layer depletion at these latitudes.
Received: 2 March 1998 / Accepted: 18 December 1998 相似文献
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