Seasonal variations in phytoplankton productivity in a shallow cove in the eastern Seto Inland Sea,Japan

Fisheries Science - We examined phytoplankton productivity in Shido Bay, an active oyster farming area in the eastern Seto Inland Sea, Japan, by an in situ 13C method from March 2016 to January...     

Spawning grounds of red sea bream in the east Seto Inland Sea

We surveyed the distribution of red sea bream eggs between 2006 and 2010 in the east Seto Inland Sea to determine the location of the spawning grounds and the characteristics of preferred spawning habitats. We identified early-development stage red sea bream eggs using a monoclonal antibody assay. The early-development stage eggs were present in waters around Awaji Island (AW area) and around Ieshima Island, Shodo Island, and Bisan Seto (collectively the ISB area). The mean red sea bream egg density in the AW area was not significantly different from that in the ISB area. Based on the locations where we observed early-development stage eggs and the density of eggs, the ISB and AW areas appeared to be the primary spawning grounds in the east Seto Inland Sea during the survey period. A quotient analysis suggested that spawning fish had clear preferences for physical conditions. The areas suitable for spawning appear to be those with sandy substrate at a depth of 30–70 m. The temperature range suitable for spawning was between 16.5 and 21.5 °C.     

长牡蛎壳金选育群体性腺发育与营养成分的周年变化

为了评估长牡蛎(Crassostrea gigas)壳金选育群体的繁殖周期及营养价值,自2013年11月至2014年10月,对山东省刘公岛海区长牡蛎第三代壳金选育群体的性腺发育、营养成分(总蛋白、总脂肪、糖原)季节变化及其与环境因子的关系进行了研究,并比较了与普通养殖群体营养成分的差异。结果表明,长牡蛎壳金选育群体雌雄比例接近1︰1,性腺同步发育;配子发生开始于2月,全年只有1个产卵季节(6―8月),7月为两性配子排放高峰期。配子成熟及排放期间,水温处于较高水平,食物充足,可为性腺发育提供能量,也有利于幼体的存活和生长。卵母细胞直径从配子发生开始逐渐增大,并在产卵前达到最大值(36.88μm),产卵后则降低。营养成分分析表明,脂肪含量在性腺–内脏团中随配子发育积累储存,产卵后显著降低;糖原在性腺发育到4月时开始下降,为配子的发育提供能量;蛋白质在配子发育过程中大量合成,与繁殖活动存在密切联系。长牡蛎壳金选育群体外套膜的总蛋白含量显著高于普通养殖群体(P0.05),糖原和总脂肪含量显著低于普通养殖群体(P0.05),其他组织的一般营养成分未出现显著差异。研究表明,长牡蛎在壳金群体选育过程中营养成分已表现出分化,这为长牡蛎壳色选育提供了重要参考依据。     

Daily growth rate model of Japanese anchovy larvae Engraulis japonicus in Hiuchi-nada Sea, central Seto Inland Sea

In the present study, we developed a larval anchovy growth model in relation to sea temperature and food availability via food consumption and metabolic process terms, based on biological data from previous laboratory experiments and field surveys from 2003 to 2006 in Hiuchi-nada Sea, central part of Seto Inland Sea, Japan. To investigate when food shortage for larval anchovy and then recruitment failure occur in Hiuchi-nada Sea, anchovy food requirements were estimated by using the growth model, and we compared the food requirement with anchovy food availability. We applied an estimation method for growth model parameters, Hewett?CJohnson p and Q ₁₀, by minimizing the sum of squares of difference between mass-specific growth rates estimated by the models and those by otolith growth analysis. Parameter p was 0.86, slightly higher than typical values, and Q ₁₀ was 2.11, close to the value used for the biological model of larval northern anchovy. Food shortage for anchovy larvae did not occur in Hiuchi-nada Sea, although it was indicated that low food availability led to a low reproductive success rate. The newly developed growth model is considered optimal at present and useful to link environmental conditions and larval growth.     

山东沿海褶牡蛎与太平洋牡蛎等位基因酶的遗传变异

采用水平淀粉凝胶电泳技术研究了山东沿海莱州 (LZ)、俚岛 (LD)和青岛 (QD)三地褶牡蛎自然群体以及荣成的太平洋牡蛎 (TP)养殖群体的等位基因酶遗传变异。进行测试的 9种酶中共检测到 2 0个位点。LZ与QD群体的多态位点比例为 6 0 .0 % ,其余两群体均为 5 5 .0 %。LZ、LD、TP和QD各位点平均有效等位基因数分别为 1.42 2± 0 .16 5、1.2 38± 0 .0 85、1.2 0 7± 0 .0 86和 1.32 6± 0 .119。平均杂合度观察值分别为 0 .2 16± 0 .0 5 0、0 .16 5± 0 .0 36、0 .139± 0 .0 34和 0 .195± 0 .0 42。结果表明 ,LZ和QD群体的遗传变异水平高于LD和TP群体。同时 ,各群体中普遍存在杂合子缺失现象。太平洋牡蛎群体与其它三个褶牡蛎群体的遗传距离很小 ,甚至小于莱州和青岛的两个褶牡蛎群体间的遗传距离 0 .0 5 0 0 ,尤其是与俚岛褶牡蛎群体遗传相似度最大 ,遗传距离小于其它各群体之间的距离 ,仅为 0 .0 0 99。     

Correlation of extractive components and body index with taste in oyster Crassostrea gigas brands

Fisheries Science - We investigated the free amino acid (FAA) composition, glycogen content, and body index of 31 brands of oyster Crassostrea gigas to evaluate their taste graphically using a...     

Winter longitudinal variation in the body size of larval fishes in the Seto Inland Sea,Japan

This study revealed the spatial variation in abundance and body size of larval fishes in the Seto Inland Sea, Japan, in January 2014 and 2015. Fish larvae were collected by a 1.3-m-diameter ring net towed at the surface and at 10-m depth at 21 stations. The most dominant species was the sandlance Ammodytes japonicus, constituting 82% of total larval fish caught. The body size of A. japonicus was greater [ca. 9 mm total length (TL) in 2014] in eastern areas than in western areas (ca. 5 mm TL in 2014). This trend was also observed in rockfishes (Sebastiscus marmoratus and Sebastes inermis species complex), suggesting a common phenomenon in this region. Because the water temperature was lower in eastern areas, it is likely that the longitudinal differences in larval body size are attributable to earlier spawning in eastern areas caused by different temperature conditions.     

Spatial and temporal variations of sediment quality in and around fish cage farms: A case study of aquaculture in the Seto Inland Sea, Japan

ABSTRACT: Fish cage farming generates large amounts of organic waste in the form of unconsumed feed and fecal matter, resulting in sediment deterioration and a threat to its own sustainability. Field studies analysed the scale of the impact of fish cage farming on sediment quality, variability of impact and spread of sediment enrichment in the vicinity of a fish farm. Two fish culture sites near the Fukuyama area of the Seto Inland Sea of Japan were chosen for the study. There was a significant difference between the quality of the sediment in aquaculture and non-aquaculture areas. The sediment underlying the fish cage farms was found to be extremely reducing, acidic and sulfidic. Sediment ignition loss did not vary markedly with the season. However, the redox potential and acid volatile sulfide content of aquaculture areas did show some seasonal variation. Sediment encircling a 165 m radius from the center of a farm in Yokota was judged as organically enriched by fish farming. A variation in sediment quality within the two sites and also within the stations was observed. Based on sediment quality, the stations could be categorized as less affected, highly affected or moderately affected.     

关于太平洋牡蛎的养殖技术之二太平洋牡蛎工厂化育苗技术的研究

本文是对太平洋牡蛎工厂化育苗技术的总结,论述了太平洋牡朗工厂化育苗技术以及在水质、饵料、固着基的选用中应注意的事项,并就生产中遇到的问题进行讨论。一、材料太平洋牡蛎亲贝来源于福建省漳浦县竹屿虾池,壳长平均95cm,幼虫固着基为太平洋牡蛎壳中间打了孔,光滑面相对,用45丝聚乙烯穿成串,每串100片,4串为一组,青苗有效水体560m3,饵料池水体150m3,使用经二级沙滤沉淀过后的海水。二、方法1亲贝培育：于今年元月上旬购进个体大、生长正确、无病害亲贝放人虾池育肥促熟．加强虾池饵料生物培养,调节好水质。2人工授精孵化：从…     

Seasonal variations in the immunological and physiological parameters of the Pacific oyster Crassostrea gigas cultured in Bahía de Macapule (Sinaloa,Mexico)

Triploid Crassostrea gigas were cultured during 13 months in Nestier‐type oyster trays. The impact of environmental parameters on the physiological and immunological parameters was evaluated. Temperature, salinity and seston were recorded monthly. Seventeen oysters were sampled monthly for immunological and condition index (CI) analyses. Samples were obtained as a haemolymph lysate supernatant (HLS). Protein content was determined using the Bradford method. The activity of hydrolytic enzymes was determined using the API ZYM kit and the lysoplate assay. Seston showed different patterns throughout the cycle. Condition index showed a positive correlation with the protein content of HLS. Protein showed a negative correlation with temperature. Eleven hydrolytic enzymes were detected in samples and higher enzymatic activity corresponded to leucine arylamidase and esterase. Leucine arylamidase and lysozyme activity showed a positive correlation with temperature. Oyster mortality was 28% in our modules and 70% in the oyster farm. Oysters showed low values of CI and haemolymph protein content in summer–autumn when mortalities were observed in the culture system. This finding suggests that these stressed oysters may have insufficient energy to invest in their immune system. It appears that oyster mortality in the culture system resulted from a combination of animal overcrowding, high temperature and low salinity.     

水溶性牡蛎多糖的降血压活性

牡蛎中含有丰富的多糖。从牡蛎中制备的水溶性多糖经HPLC测定,其单糖组成为葡萄糖,以葡聚糖分子筛测定其分子量为(3.93~10.84)×106 Da。以牡蛎多糖(7g/kg)对高血压模型大鼠灌胃均具有较明显的降低收缩压和舒张压作用。     

乳山湾水体重金属含量的季节变化与养殖贝类对水体重金属的生物富集效应

为了解乳山湾近岸海域重金属污染情况及养殖贝类对重金属富集情况,按春、夏、秋、冬四个航次采集湾内和湾外的表层海水,并于秋季采集湾内养殖的太平洋牡蛎(Crassostrea gigas)分析海水及牡蛎体内Cu、Pb、Zn、Cr、Cd、As、Hg等7种重金属含量,评价海水质量与养殖贝类的食用安全。结果表明:乳山湾湾内湾外海域水质较好,除冬季Zn以及春、秋两季的Hg符合二类海水水质标准,其余点位均符合一类海水水质标准,海水水质为"清洁"。乳山湾湾内和湾外沉积物中各重金属的含量均低于第一类海洋沉积物标准,没有受到明显的污染。乳山湾内养殖牡蛎体内Cd和Zn的浓度远远高于湾内水体中重金属的浓度,表明太平洋牡蛎对重金属具有较强的富集作用,但仍符合二类海洋生物质量标准。     

关于太平洋牡蛎的养殖技术之一太平洋牡蛎三倍体育苗技术措施

三倍体技术是国际上一项先进的生物技术。通过技术手段,使正常的二倍体生物的染色体加倍,以达到倍化效果。经过倍化处理得到的三倍体品种具有不育性及许多优良性状,使它体现出了很高的商业价值和生物学价值。目前,这一领域已成为海洋生物技术研究和开发的热点,国内外对这一技术的发展都极为重现,在不同领域都得到应用,尤其在水产领域的开发更为突出。以美国为首的一些发达国家,已利用先进的三倍体技术有力的推动了水产业的发展,创造了巨大的经济效益,而且一些品种已实现了产业化生产。我区由于近几年二倍体太平洋牡蛎夏季大批死亡…     

Re-examination of age and growth of daggertooth pike conger Muraenesox cinereus in the western Seto Inland Sea, Japan

Age determination and growth using otolith rings in Muraenesox cinereus was re-examined in the western Seto Inland Sea, Japan. Previous study in this area indicated that new rings were formed annually from March to May, and then from September to October once individuals had achieved four or five rings. In this study, monthly changes in marginal growth rate indicated that the first ring was formed before November in the year following hatching, and from then on another ring was formed annually in July or August. The birth month was determined to be August based on a peak in monthly change in the gonad somatic index. Estimated von Bertalanffy growth functions were L = 806.6{1 ? exp[? 0.33(t + 0.06)]} and L = 1264.0{1 ? exp[? 0.19(t + 0.15)]} for males and females, respectively. Lengths after 3 years of age in this study were 100 mm longer than those in a previous study for both sexes.     

Elemental analysis of otoliths of Japanese anchovy: trial to discriminate between Seto Inland Sea and Pacific stock

The ability to discriminate local stocks of Japanese anchovy Engraulis japonicus was assessed based on data from four elements (K, Na, P, and Sr) using an electron probe micro analyzer (EPMA) and data from three elements (Ba, Mn, and Sr) using inductively coupled plasma mass spectrometry (ICP-MS) from the otoliths of 40 anchovy (23.6–47.0 mm body length). Anchovy were caught at three sites (Aki-nada, Hiuchi-nada, and Osaka Bay) in the Seto Inland Sea, and one site (Kuroshio extension) in the Pacific Ocean in 2002. In order to discriminate different spawning grounds, EPMA data from the core portion (from core to 30 μm in the core-posterior axis) were used. Results showed that it was difficult to discriminate between the Seto Inland Sea and the Pacific anchovy by EPMA data. Conversely, it was possible to discriminate between the Seto Inland Sea and the Pacific anchovy by ICP-MS data from bulk otoliths. Our results showed that Mn contents of otoliths using ICP-MS discriminate between spawning grounds most, and Ba and Sr discriminate less. The difference in elemental compositions in anchovy otoliths between the Seto Inland Sea and the Pacific Ocean might be reflected by cumulative experienced elemental composition of ambient sea water during life history between the Seto Inland Sea and the Pacific anchovy.     

Spawning season,spawning grounds,and egg production of red sea bream in Hiuchi-nada,Seto Inland Sea

The spawning season and grounds of red sea bream in Hiuchi-nada, the central part of the Seto Inland Sea, were described using a new method based on monoclonal antibodies for identifying Pagrus major eggs, and the daily egg production (standardized by the incubation time and survival rate) was estimated. At the peak of spawning (May), the ranges of sea temperature, salinity, and chlorophyll a where red sea bream eggs occurred were 14.8–17.4°C, 32.0–33.0, 0.5–4.4 μg/L, respectively. The main spawning grounds of the red sea bream were confirmed as being the areas near the Geiyo Islands, Misaki Peninsula, Saijyo, Niihama. The spatial spread of red sea bream eggs increased with the egg developmental stage. The ranges of daily egg production in 2005 and 2006 were 0.3–19.3 and 0.2–6.7 × 10⁹ eggs/day, respectively. In Hiuchi-nada, aquaculture farms are located close to the spawning grounds, and the potential spawning population from the aquaculture farms equaled or exceeded that of the estimated spawning population obtained by the egg production method. Red sea bream eggs in Hiuchi-nada might be produced by both wild and aquaculture-based spawning populations.     

利用扇贝育苗车间繁育太平洋牡蛎技术

目前我国北方有许多大型的扇贝育苗场,利用率较低,这些育苗车间主要在春季进行虾夷扇贝、海湾扇贝育苗。由于扇贝育苗行业竞争十分激烈,各育苗单位已经开始综合利用扇贝育苗车间,由单一扇贝育苗转为多品种的育苗,而牡蛎育苗正好可以在扇贝育苗结束之后进行,这将可以充分的利用扇贝育苗车间。牡蛎是一种营养价值很高的海洋贝类,广东称蚝、福建称蛎房、江浙称蛎黄、     

三倍体长牡蛎(Crassostrea gigas)不育性研究

三倍体长牡蛎(Crassostrea gigas)雌性怀卵量在0～2000万,雄性精量在0～1亿,大大低于正常二倍体。三倍体生殖腺发育受阻,大部分停留在增殖期和休止期,一部分虽发育至生长期和成熟期,但与同期的二倍体比较,生殖腺发育差。部分三倍体配子能完成受精作用,并发育至D形幼虫,但不能继续正常发育。卵子减数分裂后为含14～16条染色体的非整倍体。因此,三倍体长牡蛎是不育的。     

Pacific oysters,Crassostrea gigas,established in Scotland

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