Investigation of Shrimp Farming Effluent Effects on vegetative and reproductive characteristics of mangrove forests (Avicennia marina (Forssk.) Vierh.)

The aim of this study was to investigate the effects of shrimp farming effluent on vegetative and reproductive characteristics of grey mangrove in Tiab region of Hormozgan province. For this purpose, two stands, control and another stands next to the shrimp farm as a contaminated to shrimp farming effluent were selected and a three-hectare stand was identified in each of these two sites and sampling was performed by line sampling method. In this way, three 300-meter transects were selected using a random- systematic method in each stand. Also three plots (10×10), 150 meter apart from each other, were selected along the transects and the vegetative and reproductive characteristics of Avicennia marina (Forssk.) Vierh for trees higher than one were measured and analyzed using T-test. Results showed that, in the control site, vitality of trees, and the average quantity of tree height, crown length and the number of seedlings, with the amount of 2.57, 3.53 m, 3.53 m and 8.55 seedlings/m2 were significantly higher than those at the contaminated site. On the basis of the results, in the forest sediment of the contaminated site, the amount of phosphorus and nitrogen were significantly higher than those at the control site. Although more research is needed in order to confirm the factors reducing mangrove growth, this study can emphasize the need for more detailed and specialized studies for correct location selection and also licensing for these farms in order to guarantee and minimize the impact of shrimp farm outputs on mangrove ecosystems.