The Study And Application Of Carbon Addition In Florida Soft-shell Turtle(Apalone Ferox)Aquaculture

Aquatic animals can only use of 20 ~ 30% of the feed nutrition, the remaining are excreted in the form of residual baits and feces in aquaculture ponds, eventually leading to the deterioration of aquaculture water quality and causing water environment pollution.Bio-floc technology is a new type of water treatment technology, which can improve the water quality effectively and improve the feed utilization. At present, the bio-floc technology has already been studied and applied extensively in Litopenaeus vannamei, Oreochromis aureus, Ctenopharyngodon idellus, Aristichthys nobilis and Apostichopus japonicas culture.However, compared with gills-breathing aquatic animals, which demand high dissolved oxygen, bio-floc technology used in culture of aquatic reptiles with lung respiratory, such as turtle, which needs low demand of dissolved oxygen content, has not been reported. This study investigated the use of glucose as carbon source in culture of na?ve Florida soft-shell turtle(Apalone ferox) to regulate C/N rato, produce biological floccules and regulate water quality. Besides, the influence on the microbial community structure in water, the growth performance, the nutrient component, non-specific immune function, and intestinal microbial community structure of the turtles were studied. This study aimed to provide a theoretical basis for the application of bio-floc technology in turtle culture. The main results are as follows:1. Addition of glucose to the Florida soft-shell turtle breeding system can regulate the C/N rations at 10:1, 15:1 and 20:1 for effective formation of biological floccules. Under microscope, the biological floccules were observed to have typical structure characteristics of biological floccules.2. When carbon source is added to the Florida soft-shell turtle breeding system for biological floccule production, the dissolved oxygen content in water of the experimental group was significantly lower than in the control group(p < 0.05). Besides, the biological floccules can also reduce the p H value in aquaculture water, generally reduce the alkalinity in the bio-floc system, and can stabilize alkalinity in water during the later period. At the same time, after the formation of biological floccules, it can reduce the concentration of ammonia nitrogen and nitrite nitrogen effectively.3. The added carbon source in the Florida soft-shell turtle breeding system changed the microbial community structure in the aquaculture water, increased the diversity of microbial community structure, controlled the abundance of the microorganisms. The α-, β-, γ- and δ-proteobacteria were the major bacterial groups existing both in the control group and experimental group in aquaculture water. Actinobacteria, Firmicutes and Bacteroidetes were the mutual major bacterial groups existing in experimental group with added carbon source. Adding carbon source can inhibit the cyanobacterial microorganisms.4. Addition of carbon source promoted the growth of the Florida soft-shell turtles, improved their survival rate and the non-specific immune ability to some extent, as well as the diversity of intestinal microbial community, which also increased with increasing C/N ratio.5. The nutrients in muscle, skirt and fatty tissues of the Florida soft-shell turtles that were grown in bio-floc greenhouse and imitative ecological farming conditions were determined. The results showed that in the bio-floc greenhouse the turtles had relatively balanced nutrients and high quality proteins.