Variations in the body shape of the rotifer Keratella quadrata (Müller, 1786) in selected Albanian lagoons


1Agricultural University of Tirana, Email:

2University of Zagreb, Zagreb, Croatia,

*Corresponding author  e-mail:;        

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Seasonal/temporal variation in body shape, often termed cyclomorphosis, occurs in several zooplankton groups, including rotifers. Such variation is common within the genus Keratella, mainly involving changes in body and spine lengths. Changes in body shape of the rotifer Keratella quadrata in three important brackish water bodies (Karvasta, Narta and Butrinti)  were recorded over the course of half a year (mid-November 2013 to mid-June 2014).  Specimens of Keratella from samples were removed, mounted in 40 % glycerol on microscope slides under cover slips, and measured at a magnification of 1,000, with oil immersion, using an ocular micrometer with a graduation interval of 1.33 µm. Following our data records body and caudal spine lengths increased from November until the end of February, and then decreased until June. Such changes were not significantly correlated consistently positively or negatively to water temperature, pH, conductivity, food levels or total number of copepod numbers. Following individuals recoded during investigations during the winter season individuals corresponded most closely to the literature descriptions of the group or subspecies quadrata, while those present during the spring-summer shows the form, group or variety dispersa. The first half of the study period was characterized by water of relatively low temperature, low pH and high conductivity, while, for the second half, temperature and pH increased and conductivity decreased. Standard methods for sampling and analyses for physical and chemical parameters were implemented. Further elaboration of the existing data and further works will enable a deeper and more detailed knowledge on the situation of different living community clusters and the environmental state of the lagoons of Albania.

Keywords: Albanian lagoons; zooplankton; rotifer; cyclomorphosis; transitional water.




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