In situ rates of DNA damage and abnormal development in Antarctic and non-Antarctic sea urchin embryos

Abstract

To understand the in situ effects of ultraviolet radiation (UV-R) on the development of planktonic embryos from a range of latitudes, we quantified rates of DNA damage (cyclobutane pyrimidine dimer [CPD] production) and abnormal development in embryos of 4 sea urchin species: Sterechinus neumayeri (Antarctica), Evechinus chloroticus (New Zealand), Diadema savignyi and Tripneustes gratilla (Cook Islands). Quantifications were made using in situ experimental techniques that were standardised to allow direct comparisons among species. Captive embryos were held on moored experimental racks for 2 to 5 d and exposed to one of 3 light treatments: (1) full ambient light; (2) visible light but no UV-R; or (3) visible light and UV-A but no UV-B. Each treatment was repeated at 3 depths (0.5, 1.0, and 4 or 5 m). Ambient UV-R irradiance was highest during the tropical exposures, although UV-R dose during experiments was greatest in Antarctica. DNA damage (CPD concentration) was significantly higher in Antarctic embryos (up to 30.8 CPDs Mb -1 DNA) compared to New Zealand (16.5 CPDs Mb -1 DNA) and tropical species (2.2 and 3.0 CPDs Mb -1 DNA, respectively), with damage decreasing with depth. DNA damage was positively related to total UV-B dose accumulated during each experiment. Exposure to UV-R increased abnormal development, with rates generally higher in Antarctic embryos. High abnormality rates were associated with both UV-B and UV-A exposure. The greater sensitivity of Antarctic embryos to UV-R is consistent with their slow metabolism, low concentrations of sunscreens, and slow rates of DNA repair compared with temperate and tropical species. © Inter-Research 2007.