Abstract
We investigated the presence and ecology of Chirocephalus croaticus (Steuer, 1899) during three successive seasons (spring and autumn 2018, spring 2019) at Lake Petelinje (SW Slovenia). ...Although the presence (duration, abundance) of this fairy shrimp strongly differs among different seasons and both years, we showed that in a season with favourable conditions (spring 2018) its abundance increases rapidly at the end of the season as the shrimps persist in small pools until the water dries out. The species may appear again during the autumn, however, its abundance and persistence seem to be much lower and shorter than during the spring, respectively. Nevertheless, persistence and abundance may also differ strongly among the two successive spring seasons (less shrimps found during the shorter season of 2019 than in 2018). Larvae appear first, and are most abundant at the beginning of the season, and are followed by adult males (protandry) and females, which become most abundant at the end of the season. Also, larvae seem to be more abundant on exposed bottom (gravel path), while adults are much more abundant in the shelter of a submerged meadow. Ovigerous females had 9-37 cysts (fertilized eggs) in their brood pouch, and the position of differently developed eggs changed during the season; the presence of females without eggs during mid- and at the end of season indicates the production of thin-shelled summer, and thick-shelled winter cysts, respectively. In contrast with the water decrease that is in strongly negative association with the abundance of the fairy shrimps (lake size — abundance:
r
=
−
0.56,
P
<
0.001), no other environmental parameters were highly associated (
r
⩽
|
0.38
|) with species abundance. Although the local population (one of only two currently known) seems to be in good condition, appropriate conservation action should be taken to prevent the decrease of this population in the future.
Numerous specimens of Chirocephaluswere found repeatedly over the last eight years in an intermittent lake in SW Slovenia. They were first identified as Chirocephalus spinicaudatusSimon, 1886. Later ...it turned out that they fit the diagnosis of Chirocephalus croaticus (Steuer, 1899), a species described from a small lake in Southern Croatia, about 300 km from Slovenia. It was considered as endemic of its type locality only. Now its range expands into NW direction. The population in Slovenia is in good condition and, if there is no change in land use, could persist for a long time. A small population of the same species in a small puddle near the intermittent lake Cerknisko Jezero (about 30 km from lake Petelinjsko Jezero) was destroyed a few years ago. A detailed description of specimens of both sexes is given and some information on their ecology is added. Particular attention is given to the male legs which could provide good diagnostic characters. For comparison, legs of Chirocephalus diaphanus Prévost, 1803 are shown.PUBLICATION ABSTRACT
Electron transport system (ETS) activity was measured in Chirocephalus croaticus from the intermittent lake, Petelinjsko Jezero. The ETS activities were measured at 5, 10, 15, 20, and 25 °C, and were ...studied separately in juveniles, females and males. Juveniles had significantly higher activity than adults at a standard temperature of 20 °C. The mass-specific ETS activity decreased with increasing size of the animals; the value b was 0.787. Respiration rates (R) were determined at 20 °C and the ratio ETS/R (±standard deviation) for C. croaticus was 1.43±0.46 (n=38). ETS activity increased with temperature. Females had higher Q^sub 10^ than males in higher temperature range (t-test; t=2.50; d.f.=8; p<0.05). Activation energy E^sub a^ was higher for females than males (t-test; t=2.35; d.f.=8; p<0.05). Females exhibited lower ETS activity than males over the lower temperature range, but their ETS could function more efficient at higher temperature.PUBLICATION ABSTRACT
