Hydrological-Morphometric Characteristics of Danube Delta Branches in the Backwater Zone

2020 ◽  
Vol 47 (3) ◽  
pp. 366-373
Author(s):  
M. V. Mikhailova ◽  
M. V. Isupova ◽  
V. N. Morozov
2019 ◽  
Vol 53 (4) ◽  
pp. 325-334
Author(s):  
V. N. Peskov ◽  
N. A. Petrenko ◽  
V. Yu. Reminnyi

Abstract We study size-at-age and sexual variability of morphometric characteristics of the marsh frog. According to the size of the body, males were divided into three size-age groups (juvenis, subadultus, adultus), females — into four groups (juvenis, subadultus, adultus, adultus-I). We found that the chronological age of frogs (skeletochronology) does not always correspond to their biological age (size and proportions of the body). We noted that the semi-adult males are reliably larger than females by mean values of 26 studied morphometric characters. Males and females of “adultus” group do not differ by linear body size, significant differences were found in body proportions (7 characters). For the females of “adultus-I” group, the mean values of 26 characters are significantly larger than for “adultus” males. The results of our study showed that with the age of the marsh frog, the level of exhibition, directionality and structure of morphometric sex differences changes.


2021 ◽  
Vol 26 (1) ◽  
pp. 2269-2274
Author(s):  
IOAN PĂCEŞILĂ ◽  
EMILIA RADU

Phosphorus is one of the most important inorganic nutrients in aquatic ecosystems, the development and functioning of the phytoplankton communities being often correlated with the degree of availability in assimilable forms of this element. Alkaline phosphatase (AP) is an extracellular enzyme with nonspecific activity that catalyses the hydrolysis of a large variety of organic phosphate esters and release orthophosphates. During 2011-2013, AP Activity (APA) was assessed in the water column and sediments of several aquatic ecosystems from Danube Delta: Roșu Lake, Mândra Lake and their adjacent channels – Roșu-Împuțita and Roșu-Puiu. The intensity of APA widely fluctuated, ranging between 230-2578 nmol p-nitrophenol L-1h-1 in the water column and 2104-15631 nmol p-nitrophenol g-1h-1 in sediment. Along the entire period of the study, APA was the most intense in Roșu-Împuțita channel, for both water and sediment samples. Temporal dynamics revealed its highest values in summer for the water column and in autumn for sediment. Statistical analysis showed significant seasonal diferences of the APA dynamics in spring vs. summer and autumn for the water column, and any relevant diferences for sediment.


2017 ◽  
Vol 13 (61) ◽  
pp. 154 ◽  
Author(s):  
T. I. Shevchuk ◽  
R. P. Piskun ◽  
T. B. Vasenko

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