不同培水方式对斜带石斑鱼育苗池中浮游生物群落的影响

 斜带石斑鱼在中国的养殖主要位于南方，养殖规模仍不及其他海水养殖鱼类，如卵形鲳鲹、海鲈、军曹鱼等。苗种培育成活率低是造成斜带石斑鱼养殖业发展滞后的主要“瓶颈”之一，这与石斑鱼仔鱼开口期缺乏适宜的生物饵料有关，尤其是浮游动物的缺乏。为此，文中设计了4种不同培水方式，研究其对斜带石斑鱼育苗池中浮游生物群落的影响。方式1中分别添加益生菌、虾片40 mL·m^-3和4 g·m^-3（组1），方式2中分别添加益生菌、虾片80 mL·m^-3和8 g·m^-3（组2），方式3中添加小球藻液2.5 L·m^-3（组3），方式4中添加小球藻液5 L·m^-3（组4）。每组设3个重复。育苗池规格2.5 m ×4.0 m×1.1 m（宽×长×高）。结果表明，组1和组2中浮游植物、浮游动物种类数高于组3和组4。益生菌和虾片的添加可显著提高育苗池中浮游植物及浮游动物密度。整个育苗过程中。组2所含浮游动物密度维持在较高水平(1.3 × 10.5~2.1 × 10.5 ind·L^-1)，组1和组2中浮游动物密度要显著高于组3和组4(P≤0.05)。从实验中可看出石斑鱼育苗池中添加一定量的益生菌和虾片，可获得较丰富的浮游动物群落，为石斑鱼仔稚鱼生长提供活饵料。

Effects of Various Water Cultivation Regimes on Plankton Community in Grouper Epinephelus coioides Larviculture Ponds

As a member of grouper family,Epinephelus coioides is one of the most commonly cage-cultured species in southern areas of China.Although groupers production are becoming more popular in worldwide markets,the aquaculture industry of this specie is still poorly developed when compared to other marine fish species aquacultured such as stripped bass,cobia,gilthead seabream.Despite of other factors affecting the expansion of cultured area for groupers,the price and steady provision of larvae are important determinants,which depend on effectiveness of the larval culture.Nowadays,grouper larvae for aquaculture in China are mostly from Hainan province due to its favorable conditions for larval culture such as good water quality,suitable temperature.However,mass production of grouper larvae is still encountering many difficulties,and high mortalities were often reported in grouper larvae culture,which affects its industry development.The low survival rate of grouper larvae cultured is due to the poor first-feeding conditions such as live prey deprivation or environmental stress.The aim of this paper is to compare and discuss effects of various water cultivation regimes on plankton community in grouper Epinephelus coioides larviculture ponds(2.5 m × 4.0 m ×1.1 m,W×L×H).Four cultivation regimes were designed.In group 1(G1) and group 2(G2),two different levels of prepared effective microorganisms solution(EMS)(40 mL·m-3 for G1 and 80 mL·m-3 for G2,respectively) and two different levels of shrimp chip(SC)(4 g·m-3 for G1 and 8 g·m-3 for G2,respectively) were daily added one week prior to hatching.Effective Microorganisms comprised of Clostridiums,Photosynthetic bacterium,Lactobacillus,Saccharomyces and Nitrobacteria species.In group 3(G3) and group 4(G4),only prepared Platymonus spp.solution(PS) was daily added one day prior to hatching at a level of 2.5 L·m-3 for G3 and a level of 5 L·m-3 for G4,respectively.Each group contained three replicates.Results showed that G1 and G2 had more species of phytoplankton and zooplankton than G3 and G4 did.Both phytoplankton and zooplankton populations’ density could be significantly improved by EMS and SC additions.G2 had a high density of zooplankton populations(1.3 × 105 ～2.1 × 105 ind·L-1) during the larval culture period.Zooplankton populations density in G1 and G2 were significantly higher than noted in G3 and G4 during the larval culture period(P≤0.05).In the present studies,high density of zooplankton populations observed in G2 indicates that effective microorganisms do have a positive role in improving zooplankton biomass of grouper experiment ponds.Additionally,a brown water environment came into being in ponds which been added shrimp chip and brown sugar.This may play a role in alleviating possible external stress to grouper larvae.Overall,abundant zooplankton biomass as live prey for grouper larvae growth would be constantly attained by additions of EMS and together with SC.