VULNERABILITY OF PATAGONIAN PLANKTONIC COPEPODS TO FLUCTUATIONS IN TEMPERATURE AND UVR

PATRICIA ELIZABETH GARCIA AND MARÍA C. DIÉGUEZ

CRUSTACEANA

BRILL ACADEMIC PUBLISHERS

Lugar: Leiden; Año: 2014

0011-216X

The aim of this investigation is to address the impact of fluctuations in temperature and ultraviolet radiation (UVR) on three species of South American copepods, Boeckella antiqua, B. gracilis and B. brevicaudata. Due to their restricted distribution to high latitude lakes of South America and to mountain lakes in the Andes, these copepods are considered cold stenotherm. The forecasted scenarios for climate change in Southern South America anticipate raising temperature and UVR levels with the potential to impact different ecosystems, and particularly, high altitude and latitude lakes and their cold adapted biota, such as those in Patagonia. Laboratory experiments were set up to analyse: (i) the effect of temperature and, (ii) the combined effect of temperature (5, 8, 12, 16, 20°C) and the dose of UV-B radiation (61, 194 and 324 J m-2) on copepod mortality. Experiments consisted of 10 day and 2 day incubations, respectively. The results showed that temperature is a limiting factor for B. brevicaudata that did not survive above 12°C. B. antiqua and B. gracilis withstood the temperature range; however, their mortality was higher between 12°C and 16°C. The second set of experiments showed that the survivorship of the three copepod species depend on the UV-B dose applied, with higher mortality at the highest dose. The treatments combining the higher temperatures of the range and the highest UV-B dose increased copepod mortality. Overall, at least one Boeckella species showed an acute sensitivity to increasing temperature, and the three species studied withstood the exposure to UV-B. The tolerance levels observed in this study reflect the specific adaptation of the copepods to conditions ranging from temperate to cold, and the high exposure toelevated solar radiation prevailing in their natural environments.