INDUCTION OF TESTIS-OVA IN PIKEPERCH (SANDER LUCIOPERCA (L.)) EXPOSED TO 4-NONYLPHENOL
Krystyna Demska-Zakęś*, Zdzisław Zakęś**
*Department of Ichthyology, University of Warmia and Mazury in Olsztyn, Poland
**Department of Aquaculture, The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of the study was to evaluate the effect of nonylphenol (NP) administered in feed (trout pellets) on the growth rate, mortality, and morphological and histological gonad development of pikeperch. The oral administration of NP (0.0, 0.1, 1.0, 10.0, or 100.0 mg kg-1 feed) to pikeperch juveniles (initial body weight of approximately 0.3 g; fish age 28 days post hatch (28 DPH)) for 7 to 63 days (35-91 DPH) did not affect fish mortality, growth, or condition. Histological and morphological studies revealed that the administration of NP (time of exposure over 28 days (fish age above 63 DPH)) at a dose 0.1-100 ppm significantly decreased the percentage of males and produced intersex fish. Abnormal gonads contained numerous small spaces resembling the ovocell of ovaries. Testis-ova contained both female and male germ cells. An increase in treatment dose and time of duration increased the percentage of intersex fish and decreased the percentage of males.
Key words: PIKEPERCH (SANDER LUCIOPERCA), 4-NONYLPHENOL, TREATMENT DURATION, SEX DIFFERENTIATION, TESTIS-OVA