Study toxicity of green algae Lyngbya martensiana Menegh. Ex Gomont and its Histopathological effects on gills of swordtail fish Xiphophorus helleri


The toxicity of the blue green algae Lyngbya martensiana Menegh. ex Gomont which isolated from some water floats in Basrah city was studied on fishes Xixiphorus hellari . The algae used as food for fishes to study the effects left by it on gills of them . The effect of toxicity were studied at successive periods started from 5, 10, 15 20 ,25 , 30, 40, 50, 60 , 70 and up to 80 days. The toxic chemical compounds [Thioura trimethyl, 7- Hexadecenoic acid and Cyclohexasilioxane, dodecamethyl] were isolated and identified from algae by used gas chromatography - mass technique [GC- Mass] . Histopathological changes were studied using tissue sections in the gills of different periods . It did not show any changes after 5 days, but after 10 days showed some changes represented by detachment of epithelial layer of the secondary gill lamellae and change in the straight shape of the secondary gill lamellae which have form of the letter L. The changes increased after 15, 20 and 25 days and subsequent periods , they were represented by hyperplasia in secondary gill lamellae , aneurism and congestion of blood capillary of secondary gill lamellae, adhesion of secondary gill lamellae from free ending , adhesion separated epithelial tissue of one secondary gill lamellae with separated epithelial tissue of neighboring secondary gill lamellae , aggregation and hypertrophy of chloride cells , presence of oedema , necrosis of the blood capillary And changes included osteoporosis in the bone which surrounds the pulp cartilage and osteomitosis.