Metabolic characteristics of sea cucumber Apostichopus japonicus (Selenka) during aestivation

Metabolic characteristics of the sea cucumber Aposticholpus japonicus (Selenka) during aestivation were studied in the laboratory. The effects of water temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate (AER) in A. japonicus were determined by the Winkler and Hypobromite methods, respectively. Mature (large, 148.5 +/- 15.4 g, medium 69.3 +/- 6.9 g) and immature (small, 21.2 +/- 4.7 g) individuals aestivated at water temperatures of 20 and 25 degrees C, respectively. The metabolic characteristics of mature individuals were different from immature individuals during this period. The OCR of mature sea cucumbers peaked at 20 degrees C, and then dropped significantly at higher temperatures, whereas the OCR of the immature animals continued to increase slightly, even beyond the aestivation temperature. The AER of mature individuals peaked at 20 T, while that of the immature animals peaked at 25 degrees C. The relationships between dry weight (DW) and absolute oxygen consumption (R) and absolute ammonia-N excretion (N) could be described by the regression equation R or N=aW(b). With the exception of 15 degrees C, the O/N ratios (calculated in atomic equivalents) of large size sea cucumbers was close to 20 across the temperatures used in this study, indicating that their energy Source was a combination of lipid and protein. Oil the other hand, apart from small individuals maintained at 10 degrees C, the O/N ratios of the medium and small sea Cucumbers were close to 10, indicating that protein was their major energy source. The O/N ratios in all size groups remained unchanged after aestivation was initiated. (c) 2005 Elsevier B.V. All rights reserved.

The influence of diets containing dried bivalve feces and/or powdered algae on growth and energy distribution in sea cucumber Apostichopus japonicus (Selenka) (Echinodermata : Holothuroidea)

In recent years, bivalve feces and powdered algae have been used as the food sources of holothurians in China. In this study, growth and energy budget for sea cucumber Apostichopus japonicus (Selenka) with initial wet body,veights of 32.5 1.0 g (mean +/- SE, n=45) when fed with five different granule diets containing dried bivalve feces and/or powdered algae in water temperature 13.2-19.8 degrees C and salinity 30-32ppt were quantified in order to investigate how diets influence growth and energy distribution and to find out the proper diet for land-based intensive culture of this species. Results showed that diets affected the food ingestion, feces production, food conversion efficiency and apparent digestive ratios, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalve showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; this could be because feces-drying process removed much of the benefits. Dried bivalve feces alone, therefore, were not a suitable diet for sea cucumbers in intensive cultivation. The mixed diets of feces and powered algae showed promising results for cultivation of sub-adult Apostichopus japonicus, while animals fed with powdered algae alone, could not obtain the best growth. According to SGR of tested animals, a formula of 75% feces and 25% powdered algae is the best diet for culture of this species. Extruded diets were used in the present experiment to overcome shortcomings of the traditional powdered feeds, however, it seems a conflict exists between drying bivalve feces to form extruded diets and feeding sea cucumbers with fresh feces which contain beneficial bacteria. Compared with other echinoderms, in holothurians the energy deposited in growth is lower and the energy loss in feces accounts for the majority of the ingested energy. Such detailed information could be helpful in further development of more appropriate diets for culture of holothurians. (c) 2006 Elsevier B.V. All rights reserved.

Acute peristome edema disease in juvenile and adult sea cucumbers Apostichopus japonicus (Selenka) reared in North China

Acute peristome edema disease (APED) is a new disease that broke out in cultured sea cucumber along the Shangdong and Liaoning province coasts in China, PR, and has caused a great deal of death in Apostichopus japonicus (Selenka) since 2004. Here we report virus-like particles found in intestine epithelium of sea cucumbers reared in North China. It is the first time that sea cucumbers are reported to be infected by virus. Histological examinations showed that the viral inclusion bodies existed in intestine epithelium cells. Electron microscopic examinations show that the virions were spherical, 80-100 nm in diameter, and composed of a helical nucleocapsid within an envelope with surface projections. Detailed studies on the morphogenesis of these viruses found many characteristics previously described for coronaviruses. Virus particles always congregated, and formed a virus vesicle with an encircling membrane. The most obvious cellular pathologic feature is large granular areas of cytoplasm, relatively devoid of organelles. Tubular structures within virus-containing vesicles, nucleocapsid inclusions, and double-membrane vesicles are also found in the cytopathic cells. No rickettsia, chlamydia, bacteria, or other parasitic organisms were found. (c) 2007 Elsevier Inc. All rights reserved.

Impact of CO2-driven acidification on the development of the sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea)

We evaluated the impact of ocean acidification on the early development of sea cucumber Apostichopus japonicus. The effect of pH-levels (pH 8.04, 7.85, 7.70 and 7.42) were tested on post-fertilization success, developmental (stage duration) and growth rates. Post-fertilization success decreased linearly with pH leading to a 6% decrease at pH 7.42 as compared to pH 8.1. The impact of pH on developmental time was stage-dependent: (1) stage duration increased linearly with decreasing pH in early-auricularia stage; (2) decreased linearly with decreasing pH in the mid-auricularia stage; but (3) pH decline had no effect on the late-auricularia stage. At the end of the experiment, the size of doliolaria larvae linearly increased with decreasing pH. In conclusion, a 0.62 unit decrease in pH had relatively small effects on A. japonicus early life-history compared to other echinoderms, leading to a maximum of 6% decrease in post-fertilization success and subtle effects on growth and development.

Bioenergetic trade-offs in the sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea) in response to CO2-driven ocean acidification

Ocean acidification (OA) caused by excessive CO2 is a potential ecological threat to marine organisms. The impacts of OA on echinoderms are well-documented, but there has been a strong bias towards sea urchins, and limited information is available on sea cucumbers. This work examined the effect of medium-term (60 days) exposure to three pH levels (pH 8.06, 7.72, and 7.41, covering present and future pH variability) on the bioenergetic responses of the sea cucumber, Apostichopus japonicus, an ecologically and economically important holothurian in Asian coasts. Results showed that the measured specific growth rate linearly decreased with decreased pH, leading to a 0.42 %/day decrease at pH 7.41 compared with that at pH 8.06. The impacts of pH on physiological energetics were variable: measured energy consumption and defecation rates linearly decreased with decreased pH, whereas maintenance energy in calculated respiration and excretion were not significantly affected. No shift in energy allocation pattern was observed in A. japonicus upon exposure to pH 7.72 compared with pH 8.06. However, a significant shift in energy budget occurred upon exposure to pH 7.41, leading to decreased energy intake and increased percentage of energy that was lost in feces, thereby resulting in a significantly lowered allocation into somatic growth. These findings indicate that adult A. japonicus is resilient to the OA scenario at the end of the twenty-first century, but further acidification may negatively influence the grazing capability and growth, thereby influencing its ecological functioning as an "ecosystem engineer" and potentially harming its culture output.

Feeding and growth on bivalve biodeposits by the deposit feeder Stichopus japonicus Selenka (Echinodennata : Holothuroidea) co-cultured in lantern nets

Suspension aquaculture of filter-feeding bivalves has been developing rapidly in coastal waters in the world, especially in China. Previous studies have demonstrated that dense populations of filter-feeding bivalves in shallow water can produce a large amount of faeces and pseudofaeces (biodeposits) that may lead to negative impacts on the benthic environment. To determine whether the deposit feeder Stichopus (Apostichopus) japonicus Selenka can feed on bivalve biodeposits and whether the sea cucumber can be co-cultured with bivalves in suspended lantern nets, three experiments were conducted, two in tanks in the laboratory and one in the field. In a 3-month flow-through experiment, results showed that sea cucumbers grew well with specific growth rate (SGR) reaching 1.38% d(-1), when cultured in the bottom of tanks (10 m(3) water volume) where scallops were cultured in suspension in lantern nets. Moreover, results of another laboratory experiment demonstrated that sea cucumbers could survive well on bivalve biodeposits, with a feeding rate of 1.82 +/- 0.13 g dry biodeposits ind(-1) d(-1), absorption efficiency of organic matter in biodeposits of 17.2% +/- 5.5%, and average SGR of 1.60% d(-1). Our longer-term field experiments in two coastal bays (Sishili Bay and Jiaozhou Bay, northern China) showed that S. japonicus co-cultured with bivalves also grew well at growth rates (0.09-0.31 g wet weight ind(-1) d(-1)) depending on individual size. The results suggest that bivalve lantern nets can provide a good habitat for sea cucumbers; and the co-culture of bivalve molluscs with sea cucumbers may provide an additional valuable crop with no additional inputs. (c) 2006 Elsevier B.V. All rights reserved.

刺参急性口围肿胀病和皱纹盘鲍肌肉萎缩症的病理学研究

本论文以大连沿海养殖刺参劾皱纹盘鲍为研究对象，利用组织学、超微病理学、病理生理学的方法，开展了患病病理学研究，并对可能诱发刺参和皱纹盘鲍病害的原因，以及病变过程进行了初步探讨。 中国北方养殖刺参[Apostichopus japonicus (Selenka)]幼参和成参的急性口围肿胀病。急性口围肿胀病是爆发于中国北方辽宁省和山东省沿岸养殖刺参群体中的一种新发现的疾病，并且从2004年开始已经引起刺参的大面积死亡现象，经济损失重大。 本文报道在养殖患病刺参的肠上皮细胞内发现大量的病毒样颗粒。这是首次报道病毒样粒子感染刺参。组织学检查表明该病毒具有包涵体结构，寄生于肠上皮细胞中。电镜检查的结果表明，该病毒粒子呈球形，直径80-100纳米，螺旋状核衣壳，具有囊膜结构且囊膜表面具有纤突结构。 进一步的形态学和病理学分析发现该病毒具有许多报道的关于冠状病毒的特征。细胞质内的 病毒颗粒大部分以团聚方式存在于一个完整的包膜内，形成典型的病毒包涵体结构。最明显的细胞病理学特征是细胞质内大面积的粒状物质的存在，该区域相对缺少相应的细胞器。在病毒包涵体内的管状结构，核衣壳包涵体以及双层膜囊泡也在病变细胞内发现。 在病参体内未发现立克次氏体，衣原体，细菌以及其他寄生生物。 中国北方养殖皱纹盘鲍(Haliotis discus hannai)的肌肉萎缩症病理研究 。 在2004年和2005年的中国北方海区，养殖皱纹盘鲍幼体和成体群体中爆发了严重的肌肉萎缩症。肌电图监测显示病鲍的肌肉萎缩是肌源性的而不是神经源性的。 与正常对照组对比结果显示，病鲍的肌纤维数量和肌纤维直径都显著降低。 肌酶谱测定结果显示，病鲍血清中的肌酸激酶水平，肌酸激酶—肌同工酶水平和乳酸脱氢酶水平，与正常血清对比，呈显著升高状态，说明病鲍体内发生了肌细胞损伤。超薄切片电镜检测结果显示在发生病变的肌细胞内存在双螺旋丝状结构的包涵体（Paired helical filaments, PHFs）, 该结构是人类患包涵体肌炎的主要的病理特征。 本文首次报道在无脊椎动物中发现双螺旋丝包涵体结构。 对损伤的肌纤维的进一步研究发现了异常增生的小圆柱体结构（Small Cylinder Structure, SCS）和致密小体(Dense colored particles, DCP),同时观察到这两种异常结构与肌纤维的损伤直接相关。本文还对该病的感染机制作了探讨。 中国北方皱纹盘鲍(Haliotis discus hannai)肌肉萎缩的病理生理研究。严重的足肌肉萎缩症是鲍的一种慢性致死性疾病。在中国北方的养殖皱纹盘鲍群体中第一次发现是在2000年，随后在各养殖海区，自然海区及实验室养殖过程中都发现了该病的暴发。 超微结构电镜检测显示肌肉纤维损伤严重，其内的大部分肌原纤维断裂或消失。 大量的花瓣状的糖原颗粒聚集在断裂的肌原纤维中，还有一些被包裹在包膜内。 这说明在病鲍体内的糖原代谢处于被抑制状态（或停止状态），随后的血清学检测表明病鲍血清中的葡萄糖含量与正常对照的含量显著降低，也证明了糖代谢途径的终止。病鲍血清中胆固醇和甘油三酯的量显著降低，伴随着高密度脂蛋白的水平显著升高，说明脂肪代谢途径的亢进状态。病鲍血清中的二氧化碳水平的显著降低说明出现了酸碱平衡紊乱，通过病因学分析可知该酸碱平衡紊乱应属于代谢性酸中毒。病鲍血清中的钠离子和钾离子浓度显著升高，无机磷和镁离子浓度显著降低说明出现了患病皱纹盘鲍体内出现了电解质紊乱。病鲍血清中蛋白质含量的检测表明患病皱纹盘鲍已出现低蛋白血症，说明病鲍出现了严重的营养不良。病鲍血清中的尿酸含量，胆碱酯酶水平和γ-转肽酶水平与正常对照组相比显著降低。各项指标检测的结果说明糖代谢途径的终止造成了病鲍一系列的调节体系的不平衡和各种生理功能的紊乱，甚至造成了鲍的最终死亡。

刺参遗传连锁图谱构建及卵母细胞成熟过程研究

第一部分 刺参遗传连锁图谱的构建 利用AFLP和微卫星标记以一个远缘地理杂交家系为作图群体，以拟测交理论为作图策略，构建了刺参Apostichopus japonicus的雌性和雄性遗传连锁图谱。利用62对AFLP引物组合，对亲本和93个个体进行了分离分析，共得到3572个标记，其中具有多态性的标记为点数为1133个，多态性比例为31.5%。平均每个引物对产生18.3个多态片段。1133个多态性位点中，294个标记在父母本中都出现并在后代中分离，839个标记在父本或母本中出现并在子代分离，其中母本443(52.8%)个分离标记，父本396(47.2%)个分离标记。卡方检验显示，556个标记符合孟德尔1:1分离。筛选微卫星标记中30个在家系中具有作图信息，其中19个可用于母本作图，19个可用于父本作图。 利用Mapmaker 3.0/EXP软件对分离标记进行连锁分析。358个分子标记用于雌性遗传连锁分析，其中包括19个微卫星标记，199个AFLP标记和11个微卫星标记定位在雌性框架图谱中。雌性框架图谱共有25个连锁群，总长度为3148.3 cM。标记之间最大间隔为37.5 cM，平均间隔为17.0 cM，连锁群的分子标记数最大为21个最小为4个。用于雄性连锁分析的分子标记共有332个，其中包含19个微卫星标记。207个标记定位于23个连锁群上，其中AFLP标记数为196个，微卫星标记数为11个。23个连锁群总长度为3059.8 cM，标记间最大间隔38.6 cM，平均间隔16.6 cM。每个连锁群的长度范围在40 cM到271.4 cM之间，标记数在18到4个之间，包括二、三连体在内的雄性连锁图谱共覆盖3227 cM。雌雄基因组的预测长度分别为4053.7 cM和3816.3 cM，因此，所构建的雌雄连锁图谱覆盖率分别为84.0%和84.5%。通过共有微卫星标记，有3个连锁群在两个图谱中对应。分子标记在两个图谱中呈均匀分布，没有成簇现象。 分子标记筛选、遗传图谱的构建为刺参分子标记辅助选择育种，经济性状QTL定位和比较基因作图打下基础，并且最终将促进中国刺参遗传改良和新品种的培育工作。 第二部分 卵母细胞成熟过程研究 对刺参卵母细胞的体外诱导成熟方法进行探索，并且通过透射电子显微镜、扫描电子显微镜和激光共聚焦显微镜结合超薄切片技术及间接免疫荧光染色技术研究卵母细胞成熟的生物学过程。 分别利用在海参中有诱导作用的海星神经提取液和二硫苏糖醇(DTT)对从成熟卵巢解剖出的刺参卵母细胞进行诱导成熟试验，结果显示，刺参的卵母细胞在海水中不会发生自发成熟，海星神经提取液以及神经提取液加滤泡悬浮液对卵母细胞没有诱导成熟的作用，而二硫苏糖醇处理可以诱导卵母细胞生发泡破裂，当DTT溶液的浓度处于10-1 mol/L到10-3 mol/L之间时，对刺参卵母细胞的促熟作用较为明显，在10-2 mol/L左右时，卵母细胞的诱导成熟率可以达到90%以上。未成熟的卵母细胞处于第一次减数分裂前期，不具备受精能力。经DTT诱导后，生发泡发生移动并破裂，染色体排列到赤道板上，然后第一、二极体先后排出，诱导成熟的卵母细胞排出极体的时间与自然受精的卵子一致。在卵母细胞成熟过程中有受精膜举起的现象，说明精子入卵不是受精膜举起的必要条件。卵母细胞只有在生发泡破裂之后才具有受精能力，从生发泡破裂到第二极体排出前的整个减数分裂过程中，卵母细胞都可以受精，但是只有在第一极体排出前受精的卵母细胞才能发生卵裂。人工促熟的卵母细胞受精后，形成的胚胎似乎并不能正常发育，试验过程中最多只得到了8细胞期的胚胎，之后细胞便产生畸形并停止分裂，最终裂解消失。 利用DTT诱导刺参卵母细胞成熟，综合运用光镜、电子显微镜及激光共聚焦技术观察卵母细胞成熟过程，分析了卵母细胞表面动物极突起在卵母细胞脱滤泡中的作用，以及卵母细胞动物极突起和微管组织在生发泡移动过程中所起的作用。卵母细胞通过动物极突起连接到滤泡上，在脱滤泡作用开始时，卵母细胞动物极突起刺入并穿过滤泡膜，使得滤泡膜表面形成一个缺口，然后整个卵母细胞开始从缺口处挤出。脱滤泡的作用力来源有两种：胶膜层的水合作用以及滤泡的收缩。通过激光共聚焦显微镜观察，未成熟的卵母细胞中存在5种类型的微管，并且有两个微管组织中心锚定在卵母细胞突起下方。减数分裂重新启动时，生发泡沿微管向动物极移动，至细胞膜下时破裂。微管解聚对照实验证明驱动生发泡移动的细胞结构为微管束。生发泡破裂后，两个微管组织中心组织形成减数分裂纺锤体，然后第一极体以“收缩-排出”的独特方式排出。 本研究填补了刺参繁殖生物学研究中的缺失环节，为刺参人工繁育技术提供理论基础和指导。

刺参生态增养殖原理与关键技术

针对目前刺参养殖业中面临的问题，系统研究了刺参的基础生物学、组织学，生理生态学和呼吸生理学特征，评估了刺参的养殖容量，优化了养殖模式，以嵊泗列岛为例，系统研究了刺参南移后的存活和生长等特征。研究结果如下： 1．刺参体腔液细胞存在于刺参的体腔中，体腔液细胞行使免疫防御、营养贮存和运输的功能。根据形态和功能上的特征可分为小淋巴细胞、桑葚细胞、吞噬细胞、结晶细胞、纺缍细胞和振动细胞。体腔液细胞的形态和结构与其功能密切相关。不同特征的细胞可能是同一类型体腔液细胞的不同发育阶段。体腔液细胞平均密度为(3.79 ± 0.65)×106 cells /ml-1. 刺参的血淋巴细胞可分为小淋巴细胞、桑葚细胞、吞噬细胞和结晶细胞。刺参体腔液细胞可分为小淋巴细胞、桑葚细胞、吞噬细胞、结晶细胞、纺锤细胞和振动细胞。刺参吞噬细胞的吞噬率与温度呈正相关，并呈现出强烈的凝集现象。 2．刺参的血管、呼吸树、肌细胞和体腔内皮细胞的超微结构复杂，与其功能密切相关。夏眠前后刺参消化道明显萎缩，上皮细胞重吸收现象显著，结果显示组织结构的改变与外界环境相适应。刺参夏眠时体腔液pH和PO2升高，PCO2降低。连续取样对刺参体腔液血气指标没有显著性影响。刺参体腔液的%Extrw和%EwO2与体重呈负相关。 3．刺参的扰动导致底质中有机物含量、TOC、TN、叶绿素和细菌含量降低，刺参粪便中有机物含量高于周围底质，刺参对摄食底质具有选择性。刺参的扰动能增强底质的稳定性，与对照组相比，硫化物含量和氧化还原电位降低。 4．根据水体理化指标变化和自然沉积有机物的供饵力，结合不同温度下大规格刺参对自然生物沉积物的吸收率，计算刺参的养殖容量。浅海典型水域刺参的养殖容量约为109.40 g y-1m-2。 5．前三岛近岛水域底质有机物含量高于离岸深水水域，且粒度较离岸水域细，大多在0.20 mm以下。刺参的放流浓度和参礁的放置深度应选择在5-12m。刺参的放养规格宜为经人工越冬后体长在8-10厘米的参苗，体重超过30克。 6．研究了三种规格的刺参笼养殖存活和生长特征，初步建立了刺参筏式笼养技术。投喂海带，存活率达到83%以上。密度对刺参的生长有着显著的影响，随着实验的进行，放养密度增加，刺参的体重减小。4月后，随着温度的升高和海况的改变，刺参的生长率下降。刺参南移养殖模式的适宜放养密度应控制在3-5头，放养规格应在40g以上，经过5-6个月的生长能达到100g左右。

滤食性贝类对浅海养殖系统生源要素动态的影响

在浅海养殖系统中，生源要素的形态和动态对滤食性贝类生长有着重要影响，与此同时，滤食性贝类对系统中的生源要素的动态也具有重要作用，国外学者对此研究的比较多，但在我国研究甚少。在本论文中利用室内模拟实验和海上调查的方法，研究滤食性贝类的生物过滤、生物沉积及排泄作用对浅海养殖系统中生源要素动态的影响。室内模拟实验部分：1998年4月至6月间，在烟台利用室内规格相同的水池，建立了栉孔贝扇（Chlamys farreri）不同养殖密度单养、栉孔扇贝和海带（Laminaria japonica）混养、栉孔扇贝和海带、刺参（Apostichopus japonicus）多元化养殖等三种养殖模式，九个养殖系统和一个对照系统，实验中各池的温度、光照、盐度和换水量基本一致，定期测定实验池中颗粒有机碳（POC）、颗粒氮（PN）和水体及沉积物中营养盐的含量。实验结果表明：1 栉孔扇贝大量滤食水体中的颗粒物质，导致水体中颗粒物质浓度的降低，水体中POC和PN的现存量与栉孔扇贝的放养密度负相关，水体中颗粒物的缺乏会限制栉孔扇贝的生长，当POC、PN的现存量分别降低到0.09mg/L、0.015mg/L时，就会限制栉孔扇贝的生长。2 栉孔扇贝排泄代谢产物增加了水体中无机营养盐的浓度，栉孔扇贝排泄的氮以NH_4~+-N为主，占三氮的93.5%；海带可为栉孔扇贝生长提供一部分饵料。3 实验期间硅浓度低于或近于2umol/L，限制了硅藻的生长，实验后期水体中氮盐浓度降低，氮磷比小于10，可能限制了浮游植物的生长，减少了栉孔扇贝的饵料生物，从而抑制了栉孔扇贝的生长。4 在栉孔扇贝单养和贝藻参混养系列中，沉积物中有机物、有机碳、有机氮、有机磷及总磷的含量随栉孔扇贝放养密度的增大而减少。5 在贝藻混养系列中的栉孔扇贝生长好于单养系列，在贝藻参混养系列中的海带生长速度快于贝藻混养系列；单养和贝藻参混养模式中栉栉孔扇贝的日产量均以放养密度中等的（20个/m~2）养殖系统较高。海上调查部分：于1997年冬季、1998年春季和夏季，在烟台四十里湾海区进行了三次野外调查，分别在养殖海区和非养殖海区取得沉积物柱状样，测定沉积物中有机质和间隙水中无机营养盐的含量。实验结果表明：6 养殖区沉积物中有机质的含量大于非养殖区，平均高约22%。7 养殖海区沉积物间隙水中营养盐的浓度大于非养殖海区，其中养殖区NH_4~+-N、PO_4~(3-)-P 的浓度分别高于非养殖区50%和200%-400%，NO_3~--N, NO_2~--N 的浓度差别不明显；沉积物间隙水中营养盐浓度冬季较小，而春夏季浓度较高；氮盐以NH_4~+-N 为主，占90%以上。8 养殖海区沉积物－海水界面间营养盐扩散通量大于非养殖海区，烟台四十里湾沉积物－海水界面间NH_4~+-N, PO_4~(3-)-P, NO_3~--N, NO_2~--N 冬、春、夏三季平均扩散通分别为249.99 umol/m~2/d、3.78 umol/m~2/d、5.24 umol/m~2/d、0.83mol/m~2/d。

Biology community and bottom sediments in the West Bay of the Furugelm Island, Sea of Japan

An experiment was carried out on the soft bottom in the sublitoral zone of the Furugelm Island (Peter the Great Bay, Sea of Japan) to study formation of benthic communities. Boxes with defauned sediments were placed on depths of 4, 6 and 13 m and exposed during 60 days in the summer period. Half of them were covered with a net with mesh size 2 cm to prevent effect of large predators. It was found that spatial pattern of invertebrates' sinking in the bay conforms to distribution of benthic communities. Larvae of benthic invertebrates sinks in general in places inhabited by their adult species. The main factors responsible for recolonzation are: sediment type and local hydrodynamic conditions. Heart-shaped sea urchin Echinocardium cordatum is numerically dominated in the bay on depth 3-4.5 m, but its larvae sinks in the deeper area. Community structure is supported by mature specimen migration to places inhabited by species. Predators affect largely on the species.