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Abstract

Length-weight relationships and morphological variability were assessed for black-striped pipefish Sygnathus abaster Risso, 1827 that has successfully spread in freshwater ecosystems of Ponto-Caspian basin. Ninety females and ninety males were analyzed. Their standard length was 10.65±0.9 cm, ranged 6.90-14.10 cm and the wet weight -0.71±0.02 g (0.15 -1.53 g) respectively. The length-weight relationships were significant (P≤ 0.05) for all samples. The R 2 values ranged from 0.869 to 0.949. In terms of growth, males in all observed areas were positively allometric (b > 3), while females showed isometry (b = 3). Poled samples (males + females) were positively allometric. In addition, measurements of thirteen morphometric characters allowed indicating several morphological differences of individuals from several samples. They manifested in body and head proportions, fins position and body heights with P≤0.05. Furthermore, principal components analysis allowed us to differentiatefish from lacustrine and stream habitats into two separate scatters by external morphology that proved the availability of some different ckreods (ontogenetic channels) of black-striped pipefish. One of them was implemented in lotic ecosystems of the lacustrine parts and another in lentic stream parts of Dnieper reservoirs.