岩虫室内养殖的初步研究

为推动岩虫Marphysa sanguinea室内养殖,采用体质量为(6.26±1.68)g的岩虫进行了人工养殖方法(铺沙水槽和塑料箱)、养殖密度(50~250条/m~2)和饲料配方选择(藻粉、鱼粉和虾粉)的研究。结果表明:采用悬挂式养殖方法的养殖效果较好,养殖30 d后岩虫的成活率为88.6%;经过60 d的养殖,50、100条/m~2密度组岩虫的成活率为86.7%,与150、200、250条/m~2密度组有显著性差异(P0.05),113~125条/m~2(705~750 g/m~2)是比较适合的岩虫室内人工养殖密度;饲料中添加动物蛋白30%~70%或投喂新鲜卤虫可以满足岩虫的生长要求。本研究结果可为岩虫的人工促熟及增养殖提供基础数据。     

岩虫室内人工繁育的初步研究

通过人工培育方法,在岩虫亲体3种培育密度(100、200、300尾/m2)于水温(25±0.6)℃、盐度(31±0.5)条件下,获得幼体0.58×104～1.5×104尾;由3种幼虫培育密度(0.2×104尾/m2、0.5×104尾/m2和1.0×104尾/m2)经50 d后获得幼虫0.09×104～0.43×104尾/m2,幼虫体长2.10～2.68 cm,成活率达42%～57%。     

Survival,growth and biomass of mud polychaete Marphysa iloiloensis (Annelida: Eunicidae) under different culture techniques

Polychaetes are commercially exploited as fishing bait and supplemental diet to crustacean and finfish broodstock. However, scarcity of supply and biosecurity issues limits its use. Polychaete aquaculture has become the best alternative to wild resources. In this study, two different culture techniques (1‐sediment tank throughout the culture period and 2‐nursery tank with bioflocs for 30 days; thereafter, juveniles were transferred to sediment tank until harvest) using two diets [bioflocs (BF) and feed mill sweepings (FS)] were tested to determine the survival, growth and biomass of polychaete Marphysa iloiloensis (Glasby et al., Zootaxa, 2019, 4674) in the grow‐out. The 180‐day trial was conducted in 16 tanks (0.20 m²) stocked with 5,066 ± 575 M. iloiloensis trochophore larvae/tank which were assigned randomly into four culture treatments with four replicates each. The treatments were labelled as: (a) BFS – fed BF in sediment tank for 180 days; (b) BF + BFS – fed BF in nursery tank for 30 days, juveniles were transferred in sediment tank and fed BF for another 150 days; (c) FSS – fed FS in sediment tank for 180 days; and (d) BF + FSS – fed BF in nursery tank for 30 days, juveniles are transferred in sediment tank and fed FS for another 150 days. Results showed that polychaetes in BF + FSS had significantly higher survival than BFS. Polychaetes in both BF + FSS and FSS had significantly higher body weight than BF + BFS and BFS, while biomass in BF + FSS (175.73 ± 42.25 g/tank) was significantly higher compared to other treatments (p < .05). Polychaetes fed with FS had 61%–64% protein and 12%–13% fat, while those fed with BF exclusively had 66%–70% protein and 3.50%–4.50% fat. The findings indicate that FS whether or not BF is included in the diet can improve both survival and growth of polychaetes but significantly higher biomass can be achieved with the combination of BF and FS. Additionally, polychaetes in BF + FSS contained 64% protein and 13% fat. Therefore, BF can be used as an alternative diet to FS in the early life stages of M. iloiloensis and nursery rearing using BF is imperative to increase its biomass in the grow‐out production.     

岩虫的性腺发育和生殖周期

根据性腺发育的组织切片观察，岩虫（Marphysa sanguinea）性腺发育可分为增生期、成熟期、排放期和休止期4个阶段。通过连续两年每月对岩虫性腺组织切片观察可以确定，在山东省乳山海区的岩虫性腺发育为1年1个周期。12月至翌年6月为增生期；7～8月为成熟期；7月下旬至8月为排放期；9～11月为休止期，其中7月下旬至8月中旬为繁殖盛期。岩虫的性腺起源于体腔腹面生殖上皮。生殖细胞发生时不出现滋养细胞。除休止期外，生殖细胞持续发生，成熟时多次排放。雄性生殖细胞形成合胞体（syncytium），精子为原始类型。雌性生殖细胞不形成合胞体，卵母细胞在发育的早期阶段，卵黄发生期问从卵巢（生殖上皮）排入体腔中，并在体腔中发育。卵细胞成熟时，有卵外膜，结构复杂。