The Ponto-Caspian cladocera Cercopagis pengoi invaded the Baltic Sea in 1992. For the first time it was recorded in the Gulf of Riga and three years later it appeared in the Gulf of Finland. In the summer of 1999 it had been also found in huge numbers in shallow areas (0.5 - 10 m) of the Gulf of Gdańsk.
New records of Cercopagis pengoi (Cladocera, Crustacea) are reported for the first time from the central and western part of the Polish zone of the Baltic Sea.
The current increase of penetration of natural ultraviolet radiation (UVR ) in southern South America affects water bodies because the UVR can penetrate the water column. In this scenario, the zooplankton develops photoprotective strategies such as vertical migrations against UVR or synthesis of photoprotective substances. The present study was done using a population of Ceriodaphnia dubia. that was collected from small shallow wetland near Temuco, Chile. The specimens were exposed for 7 to 9 hours to natural ultraviolet radiation, and with different colored nylon as protection against UVR , the experiment was done during the southern summer of 2006. The results revealed that in the presence of protection against UVR provided by colored nylon, the mortality was low, whereas under exposure to UVR and covering by transparent nylon total mortality was observed. The relation between mortality and the dose of UV that can penetrate the different colored nylon is represented by LC₅₀ in UV (280-400 nm) and UVB (280-320 nm), within intensities of 234.82 and 14.96 kJ/m², respectively.