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The short-term effects of crude oil on the survival of different size-classes of cladoceran Daphnia magna (Straus, 1820)

Lennuk L., Kotta J., Taits K., Teeveer K.

Oceanologia

2015

No. 57 (1)

71--77

We studied the acute effects of crude oil on the size-class population structure of the cladoceran Daphnia magna. D. magna were tested in three size-classes: small (1.4 mm, SE = 0.013), medium (2.5 mm, SE = 0.026), and large (3.1 mm, SE = 0.022) with six concentrations of crude oil (10, 50, 100, 400, 600, and 1700 mg L-1). The most important results of our experiment were as follows: (1) Crude oil had no significantly effect on D. magna below concentration 100 mg L-1. (2) An increasing crude oil concentration above 100 mg L-1 sharply decreased the survival of D. magna, (3) and survival varied among size classes. Being in contact with the concentration of 400 mg L-1 and above, all cladoceran specimens died after 96 h.

Survival chances of ground nests in a meadow habitat : a case study in Vrana Lake Nature Park (Mediterranean region, Croatia)

Purger J., Muzinić J., Purger D.

Polish Journal of Ecology

2012

Vol. 60, nr 1

207-212

The number of ground-nesting bird species in meadows, one of the most vulnerable habitats in the ornithological reserve of Vrana Lake Nature Park has decreased in recent decades. Nest survival rates were investigated in meadows and reed beds using nest predation experiments in late March and in May 2005. Predators damaged 18% of the 50 artificial nests placed in the pasture meadow habitat in March and 22% in May. Daily survival rate of nests were found to be similar in March (97%) and May (96%). In May, 64% of 25 nests located in the reed bed were discovered by the predators, with the daily survival rate of nests (90%) being significantly lower than that of nests in the nearby meadow. The results suggest that the reasons for the decreasing number of nesting bird species may be - instead of the pronounced presence and activity of predators in the area - the shrinkage of meadow area, the lack of buffer zone, the proximity of agricultural lands, and disturbance caused by intensive grazing.