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Inter-species variability in morphological traits creates a need to know the range of variability of characteristics in the species for taxonomic and ecological tasks. Copepoda Arctodiaptomus salinus, which inhabits water bodies across Eurasia and North Africa, plays a dominant role in plankton of different water bodies-from fresh to hypersaline. This work assesses the intra- and inter-population morphometric variability of A. salinus in the Mediterranean-Black Sea region and discusses some observed regularities. The variability of linear body parameters and proportions was studied. The impacts of salinity, temperature, and population density on morphological characteristics and their variability can manifest themselves in different ways at the intra- and inter-population levels. A significant effect of salinity, pH and temperature on the body proportions was not found. Their intra-population variability is dependent on temperature and salinity. Sexual dimorphism of A. salinus manifests in different linear parameters, proportions, and their variability. There were no effects of temperature, pH and salinity on the female/male parameter ratio. There were significant differences in the body proportions of males and females in different populations. The influence of temperature, salinity, and population density can be attributed to 80%-90% of intra-population variability of A. salinus. However, these factors can explain less than 40% of inter-population differences. Significant differences in the body proportions of males and females from different populations may suggest that some local populations of A. salinus in the Mediterranean-Black Sea region are in the initial stages of differentiation.

Artemia (Anostraca) is among the most primitive and ancient groups of crustaceans. Artemia spp. play a dominant role in the ecosystems of hypersaline waters, and often they are the only animals in these extreme biotopes. Most ethological studies on Artemia have been conducted on nauplii and metanauplii. We made ethological observations on Artemia under laboratory conditions and in the natural waters of Crimea, where we studied growth and ontogenetic changes of swimming behavior. Growth occurred during the first 50 days up to a size of 9.5-10.5mm, after which time the size did not increase (some females lived up to 6.5 months). A strong positive relation was found between maximal speed and individual length, which varied between 0.4 and 10.5mm; it may be approximated by the power equation: Vmax=1.205·K(0.820), where Vmax is the maximal speed of Artemia (in mms(-1)) of the length K (in mm). There is no similar relation between average speed and length of Artemia. The average speed of adults was 40-60% lower in environments with microalgae compared to media without food. The duration of the "riding position" for mating pairs of Artemia urmiana in our experiments varied from 10 to 27 days. In lakes we observed different Artemia aggregations varying in size and form. We conclude that the swimming behavior of Artemia is quite complex and diverse, and develops during ontogeny., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Arctodiaptomus salinus inhabits water bodies across Eurasia and North Africa. Based on our own data and that from the literature, we analyzed the influences of several factors on the intra- and inter-population variability of this species. A strong negative linear correlation between temperature and average body size in the Crimean and African populations was found, in which the parameters might be influenced by salinity. Meanwhile, a significant negative correlation between female body size and the altitude of habitats was found by comparing body size in populations from different regions. Individuals from environments with highly varying abiotic parameters, e.g. temporary reservoirs, had a larger body size than individuals from permanent water bodies. The changes in average body mass in populations were at 11.4 times, whereas, those in individual metabolic activities were at 6.2 times. Moreover, two size groups of A. salinus in the Crimean and the Siberian lakes were observed. The ratio of female length to male length fluctuated between 1.02 and 1.30. The average size of A. salinus in populations and its variations were determined by both genetic and environmental factors. However, the parities of these factors were unequal in either spatial or temporal scales.