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As a response to ocean warming, shifts in fish species distribution and changes in production have been reported that have been partly attributed to temperature effects on the physiology of animals. The Southern Ocean hosts some of the most rapidly warming regions on earth and Antarctic organisms are reported to be especially temperature sensitive. While cellular and molecular organismic levels appear, at least partially, to compensate for elevated temperatures, the consequences of acclimation to elevated temperature for the whole organism are often less clear. Growth and reproduction are the driving factors for population structure and abundance. The aim of this study was to assess the effect of long-term acclimation to elevated temperature on energy budget parameters in the high- Antarctic fish Trematomus bernacchii. Our results show a complete temperature compensation for routine metabolic costs after 9 weeks of acclimation to 4°C. However, an up to 84% reduction in mass growth was measured at 2 and 4°C compared with the control group at 0°C, which is best explained by reduced food assimilation rates at warmer temperatures. With regard to a predicted temperature increase of up to 1.4°C in the Ross Sea by 2200, such a significant reduction in growth is likely to affect population structures in nature, for example by delaying sexual maturity and reducing production, with severe impacts on Antarctic fish communities and ecosystems. [ABSTRACT FROM AUTHOR]

Legacy pollutants, including polycyclic aromatic hydrocarbons (PAHs) and metals, can occur in high concentrations in some Antarctic marine environments, particularly near scientific research stations. Oxidative stress is an important unifying feature underlying the toxicity of many chemical contaminants to aquatic organisms. However, the potential impacts of pollutants on the oxidative physiology of Antarctic marine invertebrates are not well documented. Sterechinus neumayeri is a common animal in the shallow subtidal benthos surrounding Antarctica, and is considered an important keystone species. The aim of the present study was to collect baseline oxidative biomarker data for S. neumayeri and to investigate the impacts of field exposure to chemical contaminants on gamete health and parent-to-offspring transfer of oxidative stress resilience. We analysed antioxidant enzyme activities, levels of the molecular antioxidant glutathione, protein carbonylation, lipid peroxidation and levels of 8-OHdG as oxidative stress biomarkers in S. neumayeri from a contaminant-impacted site near McMurdo Station and a relatively pristine site at Cape Evans. Biomarkers were analysed in adult gamete tissue and in early stage embryos exposed to AN8 fuel oil. PAHs were quantified as a proxy for contamination and were found to be elevated in urchins from the contaminated site (up to 231.67 ng/g DW). These contaminant-experienced adult urchins produced eggs with greater levels of a broad suite of antioxidants, particularly superoxide dismutase, catalase and glyoxalase-I, than those from Cape Evans. In addition, embryos that were derived from contaminant-experienced mothers were endowed with higher baseline levels of antioxidants, which conferred an enhanced capacity to minimize oxidative damage to lipids, proteins and DNA when exposed to AN8 fuel. This pattern was strongest following exposure to 900 ppm AN8, where lipid and protein damage was 5–7 times greater than baseline levels in contaminant-naïve female embryos in comparison to 3–4 times greater in contaminant-experienced female embryos. Despite this inherited resilience against oxidative stress, abnormal development was as high in these embryos when exposed to AN8 as in those derived from contaminant-naïve mothers (up to 80% abnormality), implying the conferred advantage may not translate to a fitness or survival gain, at least up to the blastulae stage. Our findings document the first evidence for parent-to-offspring transfer of oxidative stress resilience in an Antarctic marine invertebrate. [ABSTRACT FROM AUTHOR]

The 'ozone hole' has caused an increase in ultraviolet B radiation (UV-B, 280-320 nm) penetrating Antarctic coastal marine ecosystems, however the direct effect of this enhanced UV-B on pelagic organisms remains unclear. Oxidative stress, the in vivo production of reactive oxygen species to levels high enough to overcome anti-oxidant defences, is a key outcome of exposure to solar radiation, yet to date few studies have examined this physiological response in Antarctic marine species in situ or in direct relation to the ozone hole. To assess the biological effects of UV-B, in situ experiments were conducted at Cape Armitage in McMurdo Sound, Antarctica (77.06°S, 164.42°E) on the common Antarctic sea urchin Sterechinus neumayeri Meissner (Echinoidea) over two consecutive 4-day periods in the spring of 2008 (26-30 October and 1-5 November). The presence of the ozone hole, and a corresponding increase in UV-B exposure, resulted in unequivocal increases in oxidative damage to lipids and proteins, and developmental abnormality in embryos of S. neumayeri growing in open waters. Results also indicate that embryos have only a limited capacity to increase the activities of protective antioxidant enzymes, but not to levels sufficient to prevent severe oxidative damage from occurring. Importantly, results show that the effect of the ozone hole is largely mitigated by sea ice coverage. The present findings suggest that the coincidence of reduced stratospheric ozone and a reduction in sea ice coverage may produce a situation in which significant damage to Antarctic marine ecosystems may occur. [ABSTRACT FROM AUTHOR]

To determine if an Antarctic species repairs DNA at rates equivalent to warmer water equivalents, we examined repair of UV-damaged DNA in echinoid embryos and larvae. DNA repair by photoreactivation was compared in three species Sterechinus neumayeri (Antarctica), Evechinus chloroticus (New Zealand) and Diadema setosum (Tropical Australia) spanning a latitudinal gradient from polar (77.86°S) to tropical (19.25°S) environments. We compared rates of photoreactivation as a function of ambient and experimental temperature in all three species, and rates of photoreactivation as a function of embryonic developmental stage in Sterechinus. DNA damage was quantified from cyclobutane pyrimidine dimer (CPD) concentrations and rates of abnormal embryonic development. This study established that in the three species and in three developmental stages of Sterechinus, photoreactivation was the primary means of removing CPDs, was effective in repairing all CPDs in less than 24 h, and promoted significantly higher rates of normal development in UV-exposed embryos. CPD photorepair rate constant (k) in echinoid embryos ranged from 0.33 to 1.25 h-1, equating to a time to 50% repair of between 0.6 and 2.1 h and time to 90%repair between 3.6 and 13.6 h. We observed that experimental temperature influenced photoreactivation rate. In Diadema plutei, the photoreactivation rate constant increased from k=0.58 h-1 to 1.25 h-1, with a Q10=2.15 between 22°C and 32°C. When compared among the three species across experimental temperatures (-1.9 to 32°C), photoreactivation rates vary with a Q10=1.39. Photoreactivation rates were examined in three developmental stages of Sterechinus embryos, and while not significantly different, repair rates tended to be higher in the younger blastula and gastrula stages compared with later stage embryos. We concluded that photoreactivation is active in the Antarctic Sterechinus, but at a significantly slower (non-temperature compensated) rate. The low level of temperature compensation in photoreactivation may be one explanation for the relatively high sensitivity of Antarctic embryos to UV-R in comparison with non-Antarctic equivalents. [ABSTRACT FROM AUTHOR]