Impacts of UV radiation on marine biota Impacts of Global Change on marine biota Moira Llabrés Master of Global Change UMP-CSIC January 2010
INDEX 1. UV introduction 1.1. Concept and wavelengths 1.2. Factors influencing UV levels 1.3. Ozone history. Trends and global change 2. How do we measure UV radiation? 2.1. Instruments and units 2.2. UV index 2.3. UV penetration 2.4. Submarine UV levels 3. How UV affects marine organisms? 3.1. UV effects 3.2. Mechanisms to avoid UV and repair damage 4. Impacts of UV on marine organisms: a review 5. Some examples of UV studies
UV introduction Electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 100 nm to 400 nm UVR range UVC: 200-280 nm UVB: 280-315 nm UVA: 315-400 nm
UV introduction UV radiation levels are influenced by: 1. SUN ELEVATION UV levels vary with time of day and time of year 2. LATITUDE Highest UV levels closer to equatorial regions 3. CLOUD COVER Scattering can have the same effect as the reflectance by different surfaces 4. ALTITUDE At higher altitudes a thinner atmosphere absorbs less UV radiation 5. OZONE Absorbs part of UV. Ozone levels vary over the year and even across the day 6. GROUND REFLECTION UVR is reflected or scattered by different surfaces
Ozone history 1970- Crutzen described that NO, increased with fertilizers, destroyed ozone 1974- Rowland & Molina indicated that CFC’s destroyed ozone 1985- Farman, Gardiner, Shankin published the Antarctic ozone hole (Nature) Ozone loss in Antarctica Images and data courtesy NASA Ozone Hole Watch 2006 Record area: 26.6 million km -2 2009- 24 million km -2 Ozone lost 4 DU year -1 between 1979-1995 (Weatherhead & Andersen 2006)
Ozone history Not only ozone loss was measured in Antarctica Ozone levels in Arosa (Switzerland) started to reduce in 1980 Font: http://jwocky.gsfc.nasa.gov/multi/multi.html)
Ozone trends 1987- Montreal protocol got to stop the declining in stratospheric ozone levels. However, pre-1980 levels of ozone are not recovered yet Actual predictions based on the rhythm of CFC’s disappearance from the atmosphere, indicate that pre-1980 ozone levels will not be recovered before 2050-2065 (Weatherhead & Andersen 2006) Ozone recovery predictions have been questioned because: - Other substances able to destroy ozone (such as Nitrogen dioxide, methane and water vapour) are being emitted - Warming generated by Green house gases accumulation in the atmosphere could be influencing the ozone recovery Ozone loss Increased UV-B radiation reaching marine ecosystems
How we measure UVR? Instruments and units UV radiometers UV sensors Satellite data: ex. TOMS from NASA TOMS: Total ozone mapping spectrometer ( http://toms.gsfc.nasa.gov/ery_) UV radiation units: W m -2 UV doses units: W s -1 m -2 equivalent to J m -2 as J = W s
How we measure UVR? UV index UVI measures the intensity of UVR rising the earth surface, in each wavelength, weighted to the potential human damage Global Solar UVI is formulated using the International Commission on illumination (CIE) reference action spectrum for UV-induced erythema on the human skin (ISO 17166:1999/CIE S007/E-1998) E λ is the solar spectral irradiance expressed in W m -2 nm -1 at wavelength λ d λ is the wavelength interval used in the summation S er λ is the erythema reference action spectrum K er is a constant equal to 40 W m -2
UV index UV index shows the power of UV to produce damage in the skin As UVI varies depending of the latitude the WHO in collaboration with WMO, UNEP and ICNIRP created a standard system to measure UVI and presented it to the public with the following colour code: UVI: 1 equals to 25 mW m -2 WHO: World Health Organization WMO: World Meteorological Organization UNEP: United Nations Environment Programme ICNIRP: International Commission on Non-Ionizing Radiation Protection
UVI values
UV penetration Penetration of UVR in the water column depends DOM concentration and optical quality It is measured by the diffuse attenuation coefficient ( K d ) K d = K W + K P + K D K W = attenuation by pure water K P = attenuation by particles (phytoplankton and detritus) K D = attenuation by DOM
UV penetration Diffuse attenuation coefficient ( K d, m -1 ) is calculated from measurements of downwelling irradiance by fitting the following equation to irradiance versus depth data. Z: depth E z = E 0 e (-Kd *Z) E 0 : irradiance at depth 0 K d = ln (E 0 /E z ) / Z E z : irradiance at depth Z Z 10% corresponds to the depth where irradiance is attenuated to 10% of the value just beneath the surface. UV data Eastern Sambo, FL Keys (2000)
UV penetration Some examples of K d (m -1 )
Z 10% Font: Tedetti & Sempere 2006. Review
Submarine UV levels There are until few measurements of UV penetration in the Ocean because equipment used is recent and there are only few laboratories able to evaluate the submarine UV radiation Tropical waters Surface UV irradiance during the day 26/05/03 26ºN 18ºW Atlantic Font: Llabrés & Agustí 2006
Submarine UV levels Polar waters Surface UV irradiance 305 340 during the day 16/01/04. PAR 313 380 Spanish Antarctic Base 320 395 (Livingston Island) 60 0,14 0,12 Radiación UV ( ! W cm -2 nm -1 ) 50 PAR ( ! mol fotones cm -2 s -1 ) 0,1 40 0,08 30 0,06 20 0,04 10 0,02 0 0 100 1140 1320 1500 1640 1820 2000 2140 Hora local (h) Font: Llabrés & Agustí
Submarine UV levels Polar waters UV penetration Font: Agustí et al. ICEPOS-2005
UV effects on marine organisms Direct UV effects DNA damage Mortality of invertebrate larvae and eggs Photosynthetic inhibition Fish skin and ocular and growth damage Deficient nutrient Phytoplankton mortality uptake MAAs formation Denature proteins and pigments Loss of motility and orientation
UV effects on marine organisms DNA damage UV denature DNA molecules which induces failures in replication and consequent genetic mutations UV induces chemical alterations in DNA bases generating photoproducts known as CPD (cyclobutane pyrimidine dimers), in which we have bindings of adjacent pyrimidine dimers. CPD formation in Plankton & ice algae Seagrasses and macroalgae Invertebrates and fish eggs and larvae
UV effects on marine organisms Indirect UV effects Oxidative stress: ROS formation - UV reacts with DOM and other chemical compounds such as nitrate inducing reactive oxygen species (ROS) - ROS such as hydroxyl radical (OH - ) and hydrogen peroxide (H 2 O 2 ) are toxic because react with biomolecules (proteins, lipids, DNA) modifying and destroying them. ROS cause lipid peroxidation of cell membranes. - ROS can be formed in the water and inside organisms cells
Mechanisms to avoid UV Photoprotection systems * Cell structures or parasols - Mucus segregated from microalgae - Special cell walls with glass formations to reflect UVR as coccolithophores * Chemical substances which absorb UVR - Mycosporines (MAAS), aminoacids only produced by bacteria, fungi and algae - Pigments as scytomenine produced by ice algae or melanine synthesized by zooplancton organisms * Antioxidants which neutralize the toxic effect of ROS - Ascorbate, cleaning enzymes and carotenoids - Carotenoids only synthesized by photosynthetic organisms
Mechanisms to avoid UV Photorepair systems * DNA repair system - Photoreactivation: stimulated by blue light and UV. Enzymes as photolyases identifies CPD’s and repair bases - Dark repair- acts without light. Enzymes identify the damaged DNA zone, cut, synthetize the correct sequence and stick it in the damaged zone, cutting the damaged sequence Systems which are present in all kind of cells and are very important in mammals cells. Ex. Human cell suffers 500000 lesions/day in DNA molecule * Protein repair system
Although potential impacts of elevated UVB were experimentally assessed on marine biota in the past, a full quantitative assessment of the magnitude of these impacts was still pending Acute impacts of elevated UV radiation on marine biota: a metaanalysis Moira Llabrés, Susana Agustí, Miriam Fernández, Antonio Canepa, Francisco Vidal, Felipe Maurin, Carlos Duarte LINC-GLOBAL (PUC-CSIC) IMEDEA (CSIC-UIB) ECIM, PUC
UV impacts Objective To quantify the effects and relative sensitivity to UVB of marine organisms and processes to allow incorporation of elevated UVB levels in assessments of the response of marine biota to global change By a meta ‐ analysis of the published literature on experimental assessments of responses of marine organisms to increased and reduced UV Assessing the magnitude of these responses Quantifying the response of various taxa and processes to elevated UV
UV impacts Methods 1. Search of literature using Web of Science and Scholar Google 2. Database was performed using the following parameters: Specie Taxa Size Hemisphere origin: North or South Year Stage: adult or immature Function: Survival as % was converted to Mortality Growth Mortality rate Metabolism Cellular-Molecular using Demography Behaviour
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