Objective. To examine the reliability of human placentalalkaline phosphatase (hPlAP) in the mother’s serum as amarker of premature labour among pregnant women whohad no known risks for premature labour and to determinethe critical value of hPlAP in pregnancies which ended upas a premature labour. Patients and Methods. The researchwas conducted in the form of a prospective study of 200 pregnantwomen. All the pregnant women were divided into twogroups, the examinees and the control group. The value ofhPlAP in serum of all pregnant women determined in theperiod from week 20 to 24 of gestation. > 2 median valuewas taken as a critical value for hPlAP . Besides descriptivestatistical methods for the statistical data processing we usedthe χ² test, student t-test, Fishers test and Mann-Withneystest, logistic regression. Results. The number of prematurelabours in the examined group was 17 (11.3%), in the controlgroup 22 (44%). The probability of premature labour is6.1 times higher in the control group in relation to the examinedgroup. The mean value of hPlAP in the examinedgroup was 608.2 but in the control group 1115.6. The meanvalue of hPlAP in the pregnant women who gave birth prematurelywas 1195 but in those who gave birth on time 632.2.There was a statistical significant difference in mean values ofhPlAP. Conclusios. hPlAP can be used as a reliable markerof idiopathic premature labour. hPlAP values connected withthe development of premature labour is 990 mU/l.

The Vransko lake is an oligotrophic lake that covers 3000 ha in the southern Croatia. It is connected to the Adriatic sea by 1 km long channel and by several natural underwater karstic holes. Out of 24 registered fish species, only few are autochtonous ones (Knipowitchia caucasica, Rutilus basak, Salaria fluviatilis). The other species either come from the sea (Anguilla anguilla, Atherina boyeri, Chelon labrosus, Dicentrarchs labrax, Liza aurata, L. ramada, Mugil cephalus, M. saliens, Platichthys flesus, Solea solea, Sparus aurata) or have been introduced, mostly disorganized, from the northern Croatian freshwaters since the late 1940s (Esox lucius, Carassius gibelio, Cyprinus carpio, Leuciscus cephalus, Pseudorasbora parva, Scardinius erythrophthalmus, Lepomis gibbosus, Silurus glanis, Tinca tinca). One of them (Gambusia affinis) was introduced to fight mosquito larvae. However, as only few of these species are really important for fishing in the lake, the aim of this study was to look into the significance of those species.