TEMPERATURE INDUCED HISTOLOGICAL CHANGES IN THE FEMALE GONAD OF FRESHWATER BIVALVE, INDONAIA CAERULEUS (PRASHAD, 1918) DURING DIFFERENT SEASONS

The adult freshwater bivalve molluscs, Indonaia caeruleus (47-51 mm in shell-length) were collected and brought to laboratory from banks of Godavari river at Paithan, during different seasons. After 24 h laboratory acclimatization, they were exposed to normal water temperature of 28.5-31.0°C (served as control) during summer, 25.5-26.0°C during monsoon and 21.5-23.0°C during winter. For experimentation, the animal were exposed to the elevation of water temperature 34.0°C, 30.0'c and 27.0°C during summer, monsoon and winter respectively for 15 days. The histological study of the female gonads were made after 15 days. During different seasons, in control group the study revealed dominance of gametogenic phase during summer, developmental stages of oogonia during monsoon and maturation and release of oocytes during winter seasons. Due to elevation of temperature during different seasons, enlargement (growth) of oocytes as well as release of oocytes were observed at the expense of lipid globules and nutritive cells. The follicles of the female gonads expanded more and ovarian interfollicular connective tissue was observed to reduced, which was more pronounced at 34.0°C during summer compared to 30.0"C during monsoon and 27.0°C during winter season. However, in experimental group, normal development of oocytes were observed and they were released during monsoon and winter. More release of oocytes were observed during winter at 27.0°C. The results are discussed in the light of effect of elevation temperature on the histological structure of female gonadal tissues of bivalve mollusks, Indonaia caeruleus.