PEREZ Alejandra patricia
congresos y reuniones científicas
Bioaccumulation of photoprotective compounds and mortality patterns in cold-adapted calanoid Copepods from North Patagonia: synergetics effects of UV radiation and temperature.
Norrtälje, Suecia
Workshop; GLEON VII; 2008
Climate change is likely to impact aquatic ecosystems in the Patagonia region ofSouthern South America through different mechanisms: (i) direct increase in UV due toozone depletion, (ii) direct effect on water temperature and (iii) indirect effects oftemperature on tolerance of organisms to UV and changes in the radiation environmentmediated by changes in DOC levels. The identification of biological processesinfluenced by UV exposure and temperature in predictable ways will improve ourappreciation of their combined effects on freshwaters. Cold adapted populations of thegenus Boeckella are common in freshwaters of South America and may be suitablesentinels of climate change since they also occur in lakes and ponds highly exposed toRUV. In this work we focus in two species of Boeckella, B. antiqua that is restricted toa few sites in Northwestern Patagonia and B. gracilis, which has a broad distributionfrom 31ºS 64ºW to 49ºS 72ºW. We analyse the combined effects of RUV and warmingon the bioaccumulation of the photoprotective compounds MAAs (mycosporine-likeamino-acids) and on species survivorship. Our results indicate that photoprotection byMAAs in B. antiqua and B. gracilis increases with temperature and exposure to UVradiation. The accumulation of MAAs could be dissected out into uptake andelimination processes, both of which are strongly and predictably influenced by UV andtemperature. Bioaccumulation rates of MAAs increase with temperature. The patternsfound in both species seem to point out alternative photoprotective strategies. B.gracilis bears high amounts of constitutive MAAs which are stable while MAAsconcentration in B. antiqua is more plastic perhaps compensating its lower amounts ofconstitutive pigments. These patterns may reflect also specific adaptation toenvironmental seasonality. In fact, B. antiqua inhabits semi and permanent ponds andmust adjust photoprotection to a wide temperature gradient B. gracilis dwells in pondswith a winter hydroperiod bearing high levels of constitutive MAAs which readilyprovide photoprotection at a narrower temperature range. Survivorship of Boeckellaantiqua and B. gracilis was found to be significantly conditioned by temperature andUV radiation. Temperatures beyond 12°C pose a bottleneck for both species andincrease UV impact. The bioaccumulation of photoprotective compounds and thesurvivorship of cold adapted zooplanktonic species could be used to assess the potentialeffects of warming and increased UV exposure due to climate change.