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congresos y reuniones científicas
UVR effects on nauplii from South-Atlantic coastal waters (Patagonia, Argentina): Does food with high concentration UV-absorbing compounds make a difference?
GONÇALVES, R.J.; SPINELLI,M.L.; HERNANDEZ MORESINO, R. D.; VILLAFAÑE, V. E.; CAPITANIO, F. L.; HELBLING, E. W.
Congreso; 5th International zooplankton production Symposium: Population connections, community dynamics and climate variability; 2011
Zooplankton larvae are commonly considered to be sensitive to ultraviolet radiation (UVR, 280-400 nm), which may cause mortality, impaired locomotion and feeding. However, zooplankton may obtain protection via bioaccumulation of UV-absorbing compounds from their preys. In order to test the importance of bioaccumulation of UV-absorbing compound in protecting copepods against UVR, nauplii were collected in surface waters and were feed, at in situ temperature for 24 hs, using four different food treatments: a) cells < 20 μm from natural phytoplankton; b) culture of Chaetoceros sp., c) culture of Prorocentrum micans, and d) control: filtered water (0.22 μm). After feeding, nauplii were exposed to UVR and PAR (400-700 nm) for 4 hs (irradiances of 0.7, 48 and 164 W m-2 for UVB, UVA and PAR, respectively), using two radiation treatments: UVR+PAR and PAR. Motility and behavior were recorded continuously before, during and after exposure. The concentration of UVR-absorbing compounds (estimated spectrophotometrically) had higher values in larvae feed with natural phytoplankton (< 20 μm) and P. micans than in the other two treatments. However, there were no significant effects of UVR on mortality or swimming speed in any of the four food treatments. Nevertheless, UVR-exposed nauplii showed less activity near the surface than those exposed only to PAR. In the field, short term events (i.e., 24 hs) of exposures to algae rich in UV-absorbing compound may not be enough for nauplii to bioaccumulate significant amounts of these substances, and thus they might rely on other alternatives such as swimming to deeper waters.