Embryonic Development Of Acropora Hyacinthus And Corals Were Cultivated Under Indoor Condition

With the environmental degradation and increasing number of human activities in recent years, number of corals are shrinking and the worldwide coral reef ecosystems are facing a serious degradation. In order to protect coral reefs and understand factors influencing coral growth and reproduction, more and more researchers set out to breed corals. This research established recirculating aquaculture system for coral under indoor condition. The Montipora foliosa and Acropora hyacinthus were cultivated in recirculating aquaculture system, then the DIN, DIP, COD, DO were monitored and plankton (including the phytoplankton and zooplankton) were investigated in recirculating aquaculture system before or after breeding coral. We collected dioecious Acropora hyacinthus sperm and spawn for artificial insemination, observed the embryo processes, and tried to raise the coral larvae. The results were as following:1. Embryonic and larval development of Acropora hyacinthus showed, A. hyacinthus were hermaphrodites, vitro fertilization, and spwaned on the second to third day after full moon. Its embryonic development was divided into six stages:zygote stage, cleavage, blastula, gastrula, planula and coral larvae. The embryonic developed to the planula larva at48hours later. Then, the planula larva quickly settled down and metamorphosize to form coral larvae about7days later.2. The results about using Trichlorfon to kill the Harpacticoida which feed on the coral larva showed that, the remaining of Harpacticoida became less while the concentration of trichlorfon increased; the remaining Harpacticoida decreased with the increased time when concentration of trichlorfon was the same; lethal effect of0.05mg/L trichlorfon is best after being treated for19h with no effect on growth and development of the coral larvae.3. The study results about using Moinidae mongolica to raisie A.hyacinthus in the tank established by RAS showed that A.hyacinthus can ingest M. Mongolica, and A. hyacinthus feeding on M. Mongolica grew significantly faster than no feeding.4. From September5,2014to February5,2015, we feeded M.foliosa in the tank established by RAS, then studied the growing rate of M.foliosa in different depths. The results showed:the area and the weight of the corals in10cm and20cm depths were on the rise, and those in10cm depths increased greater than those in20cm depths.5. Before and after feeding M. Mongolica, we monitored the sea water quality in RAS for8months. Before feeding,the survey results showed, DIN, COD and DIP were decreased from1.251mg/L to6.18mg/L, from0.37mg/L to0.65mg/L, from0.0544 mg/L to0.0158mg/L, respectively.While the DO increased from6.83mg/L to7.88mg/L.4kinds of changed water quality factor conform to the second category of seawater quality standards. Organic pollution index A fell to-0.771from4.743, the water quality turned good from the serious pollution; eutrophication index fell to0.004from0.561, the nutrition level reached the poor nutrition which conform to the growth condition of coral. After raisied Mfoliosa, the quantity of DIN, COD, DIP and DO conform to the second category of seawater quality standards; organic pollution degree reached1; the nutrition level was poor. In conclusion, the RAS can regulate water quality effectively.6. From July5,2014to February5,2015,we invested phytoplankton in RAS for8months before and after feeding M. Mongolica, we identified27species among4phytoplankton phylum, in which10species of bacillariophyta accounted for37%in total and ranked first. The density andspecies of phytoplankton ranged from0.16×103cell/L-14.7X103cell/L and from3-8. From cell density and species change before and after feeding, the front feeder cell density was significantly higher than after feeding. Compared to the density, the former breeding species number changes of phytoplankton little difference.7. From July5,2014to February5,2015,we invested zooplankton in RAS for8months before and after feeding M. Mongolica, The survey results implied,8species among3zooplankton phylum were identified. The density and species of zooplankton ranged from1ind/L to17.15ind/L and from1-8,respectively. From cell density and species change before and after feeding, the front feeder density and species number was significantly higher than after feeding.