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Journal of Plankton Research Vol.22 no.11 pp.2095-2104, 2000
© Oxford University Press 2000
UV-induced mortality of zoea I larvae of brown shrimp Crangon crangon (Linnaeus, 1758)
Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, PO Box 2503, D-26111 Oldenburg, Germany
Zoea I larvae of the brown shrimp Crangon crangon (Decapoda) were exposed to varying levels of UV radiation in a sunshine simulator. ‘Short-term exposures’ (0–8 h) were used to determine the highest UV dose with no significant effect (NOEC; defined by limit of detection) and the lethal dose of 10 and 50% mortality (LD10 and LD50). Crangon crangon showed a relatively high sensitivity to UVB radiation (NOEC = 10 kJ m–2, LD10 = 15 kJ m–2, LD50 = 24 kJ m–2) compared to other crust-acean species. LD values (1997–1998) showed no adaptation to seasonal light regimes. ‘Long-term exposures’ (0–10 days) were carried out to assess the range where the ‘law of reciprocity’ is valid. The larvae were exposed to UV levels of 0.2, 0.4 and 0.7 J m–2 for appropriate time intervals, always cumulating in a sublethal dose of 5 kJ m–2 day–1. Results reflect a possible threshold (0.2–0.4 J m–2 UVB) in the effect of the different UVB doses used; thus, a proportional relationship of intensity and exposure time can only be shown at UVB levels above this threshold intensity.