Aspects of gametogenesis, oocyte morphology and maturation of the lugworm Arenicola marina (Annelida: Polychaeta) in relation to commercialised procedures to extend the breeding season

Environmental manipulation is a common method of extending the spawning season of aquaculture species including the polychaete worm Arenicola marina. Temperature synchronises autumn spawning populations and so its manipulation was used to advance and delay spawning. Females were exposed to a minimum period of 3 weeks at 5 °C in conjunction with the injection of prostomial homogenate to induce spawning up to 4 weeks prior to the natural spawning date. We also maintained individuals at 15–17 °C starting 4 weeks prior to, and then continuing after the natural spawning date, delaying spawning for up to 4 months. Both sexes can be manipulated, but males suffered higher mortalities and a greater rate of spontaneous spawning within the tanks. In ‘advanced’ females, mean oocyte diameters (measured in September, one month prior to spawning) were significantly larger and more homogenous compared to ambient individuals, whilst ‘delayed’ females produced a second cohort of oocytes approximately 8 weeks into the treatment. Delaying and advancing spawning induced significant changes in the ultrastructural morphology of prophase and metaphase oocytes, and delayed prophase oocytes showed a significant increase in the number with cracks on the surface of the vitelline membrane. Although, SDS-PAGE and Western blots confirmed that Maturation Promoting Factor (MPF) activity was not different from ambient controls, there were significant changes in MPF activity levels (measured by histone kinase activity) in manipulated oocytes. A. marina has the plasticity for spawning to be delayed and advanced by a number of months; this is essential for the continued development of aquaculture of this species. However, the maturational ability of the oocytes is compromised and this may have significant implications for production and quality of the offspring from manipulated individuals.     

多毛类沙蚕在沿岸海洋污染环境中的生物修复作用

随着经济社会的快速发展,人类对海洋生态环境的负面效应逐渐显现出来,海洋污染环境影响了人类的正常生活.为了防止沿岸海洋环境污染和海洋生态环境的持续恶化,各国都采取积极的响应措施.为了减少有害污染物和避免生态环境恶化,国内外的许多专家和学者提出利用多毛类的生物修复能力来有效地缓解沿岸海洋环境污染的压力.     

马氏珠母贝不同地理种群内自繁和种群间杂交子一代感染多毛类寄生病的分析

选用我国马氏珠母贝 3个地理种群 ,北海野生种群 (BW ) ,大亚湾野生种群 (DW)和三亚野生种群 (SW)作为亲本 ,通过不同地理种群内自繁产生了 3个子一代群体 (BB1 、DD1 、SS1 )和不同地理种群间杂交产生了 3个子一代群体 (BD1 、BS1 、DS1 )。比较分析 6个子一代群体感染多毛类寄生病的情况表明 ,马氏珠母贝是多毛类寄生虫的易感贝类 ,多毛类寄生虫基本上是凿贝才女虫 ;子一代的感染率在 66 7%～ 75 5 %之间 ,雌、雄贝之间的感染率无显著差异 (P >0 0 5) ,双壳同时感染多毛类寄生虫的感染率大于仅单壳(左壳或右壳)感染的感染率(P <0 0 5) ,在同一个群体内 ,感染多毛类寄生病与未感染多毛类寄生病贝的形态性状指标 (壳长、壳宽、总体重和壳重 )无显著差异 (P >0 0 5) ,说明多毛类寄生病并未影响马氏珠母贝的生长。多毛类寄生病的主要危害是导致马氏珠母贝的大量死亡。杂交子一代群体DS1 和BD1 的多毛类寄生病率与自繁群体BB1 相比 ,分别降低了 8 4%和8 8% (P <0 0 5) ,表明种群间杂交一代初步提高了马氏珠母贝抗多毛类寄生虫病的能力。     

Formation of periphyton biofilm and subsequent biofouling on different substrates in nutrient enriched brackishwater shrimp ponds

Periphyton grown on substrates is known to improve water quality in aquaculture ponds. Five different substrates, (i) bamboo pipe (ii) plastic sheet (iii) polyvinylchloride (PVC) pipe (iv) fibrous scrubber, and, (v) ceramic tile were evaluated for the formation of biofilm in this experiment. The substrates were suspended 25 cm below the water surface. Each type of substrate was collected fortnightly to analyze the abundance and biomass of different periphytic algae and of the biofouling organism. The study was terminated after 60 days due to severe fouling by polychaete. Results showed that pond water nutrients were high on day 60 with mean total ammonia-N, nitrite-N and soluble reactive phosphorus concentrations of 309.6 ± 8.6 μg L^− 1, 26.0 ± 2.7 μg L^− 1 and 87.2 ± 7.1 μg L^− 1 respectively. During the first two weeks the substrates were colonized by 19 periphytic algae. The most abundant family was Bacillariophyta (8 genera) followed by Chlorophyta (7 genera) and Cyanophyta (4 genera). Periphyton colonization on bamboo pipe showed the highest (p < 0.05) biomass in terms of chlorophyll a amongst all the substrates used. The biomass varied from 179 to 1137 μg m^− 2 with mean values of 1137.2 ± 0.6, 929.6 ± 0.6, 684.2 ± 1.2, 179.1 ± 0.6 and 657.0 ± 0.6 μg m^− 2 on bamboo pipe, PVC pipe, plastic sheet, fibrous scrubber and ceramic tile respectively for the first 15 days. From 3rd week, polychaetes began to form tubes on the substrate. By day 60, the whole surface of all substrates was covered with tightly packed polychaete tubes with mean densities of 168.0 ± 15.4, 121.0 ± 13.5, 72.8 ± 9.8, 72.4 ± 7.4 and 56.0 ± 6.8 polychaete tubes cm^− 2 for bamboo, PVC, plastic, fibrous scrubber and ceramic tile respectively. This study illustrated the invasive nature of attached polychaete thus hampering the formation of periphyton biofilm on substrates which could have been used for improving water quality in enriched brackishwater shrimp ponds.     

广东雷州流沙湾养殖企鹅珍珠贝多毛类寄生虫病的调查

对流沙湾养殖的企鹅珍珠贝(Pteria penguin)多毛类寄生虫病进行了调查。结果显示,锥形笼养殖2~4年的企鹅珍珠贝母贝多毛类寄生虫病感染率为39.13%~44.98%,开放式养殖2~4年为26.6%~35.63%,同一养殖方式各龄母贝多毛类寄生虫病感染率之间差异不显著(P>0.05);养殖时间两年时,多毛类寄生虫病的感染率与养殖方式之间存在极显著差异(P<0.01);养殖时间3年和4年时,多毛类寄生虫病的感染率与养殖方式之间存在显著差异(P<0.05)。锥形笼养殖的企鹅珍珠贝左壳较易感染多毛类寄生虫病。企鹅珍珠贝感染多毛类寄生虫病后,其生长与健康贝相比,无显著差异(P>0.05)。