Study On Artificial Breeding Of Reef-Building Corals In Land-Based Systems

Under the background of large-scale degradation of coral reef ecosystems worldwide,the artificial breeding of reef-building corals has been the key research direction of coral reef ecological restoration and biodiversity conservation in recent years.In this study,the asexual splintering and sexual breeding process of reef-building corals were studied by constructing different land-based coral cultivation systems.The asexual splintering coral of Montipora digitata,Pavona decussata and Porites lutea were cultivated under the conditions of micro-land-based coral cultivation system respectively.Asexual branching cultivation of Porites lutea,Favia favus,Pavona frondifera and Echinopora lame was carried out in large land-based coral culture systems.Specific sexual breeding system of land-based coral cluster helmet coral Galaxea fascicularis sexual breeding process of the research,the experimental results are as follows:1.The growth rate of larva of the three types of corals increased from highto low under the conditions of the microland-based coral culture system:M.digitata > P.decussata > P.lutea.The volume and weight growth multiples of the three types of coral branches were positively correlated with the Fv/Fm values of the symbiotic algae.Symbiosis with D1 a,C1 type zooxanthella of M.digitata coral production growth rate is significantly higher than just type with C1 zooxanthella of Pavona decussata coral symbiotic cross snags,the Fv/Fm the mean difference was not significant,but only with C1 type zooxanthella symbiotic cross Pavona decussata coral growth rate is significantly higher than only type with C15 zooxanthella of P.lutea coral symbiotic,Fv/Fm mean significant difference.The results show that the growth of different types of coral cuttings is closely related to their symbiotic algae species and Fv/Fm values,which can provide theoretical support for coral species selection and cuttings cultivation in coral reef restoration work.2.The large-scale land-based coral cultivation system with the treatment of circulating water system as the core can construct the environment conditions suitable for coral growth,under which the survival rate of the four types of corals is higher than 80%.The mean Fv/Fm values of symbiosis with C1 type zooxanthella of F.favus,P.frondifera,E.lame,and symbiosis with type zooxanthella C15 of P.lutea were 0.58,0.61,0.62 and 0.39 respectively.The growth rates were as follows: E.lame > P.frondifera > F.favus > P.lutea.The results showed that the suitable environmental physicochemical factors,the symbiotic algae and their photophysiological characteristics were importantparameters for the artificial asexual pruning of corals under the conditions of land-based system.3.Land-based coral sexual breeding system of artificial cultivation to sexual maturity stage of the G.fascicularis coral as a hermaphrodite,in vitro fertilization and early embryo development stage experience cleavage,blastula,gastrula stage and floating wave larva stage,the oocyte nonexistent zooxanthella,floating wave larvae in beginning to find environment zooxanthella adhesion after 5 days.The cement base with micro-pore structure and covered with zooxanthellae is beneficial to the development of coral larvae attachment metamorphosis.It takes about 48 hours for a fertilized egg to develop into a club-shaped buoy larva.In 30 days,it can develop into a coral larva with complete bone structure and active tentacles.In 90 days,it can develop into a coral larva with multiple cups and begin asexual proliferation to form a community.The results showed that the embryo and larva of clumped galea coral had the reproductive biological characteristics of fast development,high attachment rate and fast growth.The results show that the land-based coral culture system can maintain stable and suitable conditions for different growth and development of corals,and can be used to study the artificial asexual branching cultivation and artificial sexual breeding of corals.The results of this study provide a theoretical basis for coral reef ecological restoration by further utilizing the artificial breeding technology of reef-building corals and have important guiding significance forthe application of coral reef artificial breeding technology.