Combined effects of temperature and UVR on the survival of Artemesia longinaris and Pleoticus muelleri from South American coastal waters

MARIA A. MARCOVAL; JORGE L FENUCCI; A.C DIAZ; L.ESPINO

New Orleans, Louisiana

Conferencia; Aquaculture America 2015; 2015

World Aquaculture Society

The shrimps Pleoticus muelleri and Artemesia longinaris are two important target species for aquaculture in the region of the Southwestern Atlantic Ocean, from Southern Brazil to Patagonia (23-50 ºS). High latitudes in the S. Hemisphere have experienced an increase of ultraviolet radiation due to ozone depletion, and in temperature for the release of greenhouse gases, these are two of the most important anthropogenic climatic changes. Under culture conditions individuals of these species are kept in ponds at less than 2 meters deep, so they are exposed to extreme environmental conditions. The aim of this study was to assess the combined impact of UVR (280?400 nm) and temperature on survival of both species after being feeding with a diet plus an extract of macroalgae having UV absorbing compounds (UVaCs). Shrimp (~ 3g) came from the University Mar del Plata?s hatchery and were incubated at 5 ind. in 24-L tanks under controlled conditions of pH and salinity. Previous to the trail animals were fed for 30 days with a standard diet supplemented with extract of Undaria pinnatifida 3g/100g diet. Shrimps were exposed during 7 days to two radiation treatments: a) UVR: received the total radiation spectrum (UVR 280-400nm + PAR 400-700nm); b) PAR: radiation source covered with Ultraphan film (50% transmission at 395 nm) to receive only PAR. Additionally, two temperature treatments were considered: 20 and 25°C. Survival and concentrations of both UVaCs and carotenoids in tissues were evaluated. Trails were run by triplicate.There was no mortality due to PAR, all the observed mortality was found with the UVR treatment. P. muelleri was more sensitive to UVR than A. longinaris. For both species, mortality was significantly lower at 25 °C than at 20 °C. Both species are rich in carotenoid. Under UVR-stressed scenario, the induction of the synthesis of UV-absorbing compounds in the tissues was detected. Higher concentration of UVaCs in A.longinaris, were observed than in P.muelleri.These results, suggested that UVR-stressed animals metabolize from carotenoids to UV absorbing compounds, when UVaCs are available through the diet, and this fact might have contributed to a more effective photo protection against UVR. Most of the resistance to UVR observed with the increase in temperature might be due to an increment in metabolic activity caused by a repair mechanism mediated by enzymes.