Survival and growth of ex-situ coral recruits under different grazing treatments

Co-culture of coral recruits with different species of grazing herbivores was tested as a method of improving the corals’ survival and growth in ex-situ grow-out facilities. Coral recruits from Acropora millepora, A. tenuis, A secale, Porites lobata and Platygyra daedalea were cultured for 6 months in 50L flow-through tanks under one of five grazing treatments:(1) Thalotia, coral cultured with 30 Calthalotia strigata per tank,(2) Turbo, 30 Turbo haynesi per tank,(3) COTS, 40 Acanthaster cf. solaris per tank,(4) Mix, 10 Calthalotia strigata, 10 Turbo haynesi, 20 Acanthaster cf. solaris and(5) Control, with no grazers.Survival was tracked by photographs of plugs with coral recruits taken at Day 0, Day 7. Day 14 and subsequently fortnightly until Day 182 when the experiment was ended. Growth from Day 0 to Day 56 and Day 182 was the basal growth of the recruits, measured using the ImageJ program. Parameters:Size and growth of corals is measured in mm2In growth datafiles, the fused parameter indicated which recruits had fused on the designated measurement date. Different groups of fused corals on the same plug are indicated by different numbers.Survival is recorded under Dead_time 0 for no mortality occurring within the time frame and 1 for when mortality occurred, and time_Survival for time of event (either 182 for no mortality or the day mortality was observed).本研究以迁地繁育养殖设施中提升珊瑚幼体存活率与生长速率为目标，测试了不同植食性牧食生物与珊瑚幼体共培养的应用效果。实验所用珊瑚幼体采自微孔鹿角珊瑚（Acropora millepora）、精致鹿角珊瑚（A. tenuis）、A. secale、团块滨珊瑚（Porites lobata）以及雕形平脑珊瑚（Platygyra daedalea），将其置于50L流水养殖桶中培养6个月，并设置5种牧食处理组：(1) 板齿螺组（Thalotia）：每桶投放30只条纹板齿螺（Calthalotia strigata）；(2) 蝾螺组（Turbo）：每桶投放30只Haynes蝾螺（Turbo haynesi）；(3) 棘冠海星组（COTS）：每桶投放40只cf.太阳长棘海星（Acanthaster cf. solaris）；(4) 混合组（Mix）：每桶投放10只条纹板齿螺、10只Haynes蝾螺及20只cf.太阳长棘海星；(5) 对照组（Control）：不添加任何牧食生物。 存活率通过定期拍摄附着有珊瑚幼体的珊瑚断枝进行追踪，拍摄时间点为第0天、第7天、第14天，后续每两周拍摄一次，直至实验结束的第182天。珊瑚幼体的生长量以第0天至第56天、第0天至第182天的基部生长量为指标，采用ImageJ软件完成量化测量。 相关参数说明如下： 1. 珊瑚的尺寸与生长量计量单位为mm²； 2. 生长数据文件中，"fused（融合）"参数用于标记指定测量日期已发生融合的珊瑚幼体，同一珊瑚断枝上的不同融合珊瑚群落将以不同数字加以区分； 3. 存活率数据通过两个字段记录：Dead_time字段用于标记死亡发生情况，取值为0代表该周期内未出现死亡，取值为1代表发生了个体死亡；time_Survival字段记录死亡事件的具体发生日期，未出现死亡的个体记为182。