Annual changes in macrobenthos abundance in Funka Bay,Japan

The temporal variation in macrobenthos abundance was studied in Funka Bay in the periods 2001–2004 and 2007–2010. Dissolved oxygen just above the sea floor of the basin was lower and ignition loss at the level of the sea floor was higher in 2007–2010 than in 2001–2004. Macrobenthic species were categorized into three groups: long-lived species, sedental polychaeta Notomastus latericeus, and short-lived species. Ignition loss was the most influential factor affecting macrobenthos abundance as this variable restricts the recruitment of macrobenthos. The abundance of both long-lived species and N. latericeus was lower between 2007 and 2010 than between 2001 and 2004. Supplementation of oxygen from outside the bay by the Tsugaru Warm Current may be an important factor impacting the increase in the abundance of long-lived species. The abundance of N. latericeus barely increased between 2007 and 2010, possibly because dissolved organic matter, which is their food item, may have become limited due to a narrow chink between sediments with eutrophication. The abundances of short-lived species did not differ between the periods 2001–2004 and 2007–2010 due to the organisms having a low tolerance to hypoxia. The current conditions in Funka Bay are on the verge of turning the bay into an azoic zone.     

Transport of subarctic large copepods from the Oyashio area to the mixed water region by the coastal Oyashio intrusion

The lateral transport of organic carbon in large grazing copepods ( Neocalanus cristatus, Neocalanus flemingeri, Neocalanus plumchrus and Eucalanus bungii ) from the Oyashio area to the mixed water region (MWR) by the coastal Oyashio intrusion was estimated using the data of VMPS (vertical multiple plankton sampler) and 1500 dbar-referred geostrophic transport from the CTD (conductivity temperature depth sensor) data of five cruises during June 2001 to April 2002 on a repeat observation section OICE (Oyashio Intensive observation line off Cape Erimo), which extends southeastward from Hokkaido Island, Japan. The transport to MWR by the coastal Oyashio intrusion was estimated to be 5.3 × 10¹¹ g C for the four species. Data from profiling floats also indicated that the copepods were advected from OICE to MWR by the coastal Oyashio intrusion within about 2 months. This transport is considered to be one of the significant sources of organic carbon in MWR as it is larger than the amount of large zooplankton consumed by Pacific saury ( Cololabis saira ) in MWR, one of the dominant copepod predators in this region.     

Annual and seasonal dynamics of fish in the brackish-water Matsalu Bay, Estonia

Abstract –  Matsalu Bay in the Väinameri (West-Estonian Archipelago Sea) is a relatively shallow but large bay. It is the only real delta estuary in the northern Baltic Sea. The fish fauna is strongly dominated by freshwater species such as perch Perca fluviatilis , roach Rutilus rutilus , white bream Blicca bjoerkna and rudd Scardinius erythrophthalmus . The study presents CPUE data describing annual and seasonal variations in the species composition, abundance and spatial distribution, based on 1 year of monthly samplings from August 2001 to August 2002 and routine coastal monitoring (in late July–early August) between 1994 and 2003. The bay can be divided into three rather distinct parts. The fish fauna of the inner part (salinity 0–2 p.p.t.) is different from two open parts and resembles that of freshwater lakes. In the openmost part (salinity usually 4–6 p.p.t.) some marine species, such as herring Clupea harengus membras , flounder Platichthys flesus and eelpout Zoarces viviparus may seasonally be abundant. Species composition and abundance of most species varies seasonally and interannually. Only the abundance of few species such as pike Esox lucius and pikeperch Stizostedion lucioperca was not impacted by seasonality. The most dynamic period in the bay is spring, when several species (some of them very rare in summer, such as herring and smelt Osmerus eperlanus ) enter the bay for spawning.     

Annual variation in otolith increment widths of walleye pollock (Gadus chalcogrammus) larvae in Funka Bay,Hokkaido, Japan

To clarify relationships between year‐class strength and larval growth of walleye pollock (Gadus chalcogrammus), and oceanographic conditions in the Pacific stock off Hokkaido and Tohoku, Japan, we undertook conductivity/temperature/depth (CTD) observations and investigated larval densities, larval otolith increment widths and larval prey densities (of copepod nauplii) of the 2008, 2009, 2010 and 2011 yr classes in Funka Bay. Oyashio Coastal Water (OCW) flowed into the bay in late February in 2008, 2010 and 2011, and the mean water temperatures decreased to 1.9–3.1 °C in March. OCW was not observed in 2009, and it was warm in late February (≥3.4 °C). Increment widths of lapillar otoliths during the yolk‐sac stage were wide in 2009 and 2011, medium in 2010 and narrow in 2008. Increment widths during the first‐feeding stage tended to become wider as the hatch month progressed, and the annual variation during the first‐feeding stage was larger than that of the yolk‐sac stage. The densities of the primary food for the larvae were high in 2008 when larval increment widths were narrowest, so the effect of prey abundance on larval growth appeared to be small. The ranking of the larval abundance in March was nearly coincident with that of the increment width during the larval stage. We, therefore, suggest that the larval growth rate is associated with the mortality rate and that the growth–mortality hypothesis may be applicable to walleye pollock in Funka Bay. Feeding success under warm water conditions may be an important factor that contributes towards high growth rates.     

Growth of the brittle star Ophiura sarsii sarsii in Funka Bay,Hokkaido, Japan

Fisheries Science - The brittle star Ophiura sarsii with a disc diameter (DD) of less than 9 mm is an important prey item for flathead flounder Hippoglossoides dubius in Funka...     

Long-term changes in the assemblage of demersal fishes and invertebrates in relation to environmental variations in Tokyo Bay, Japan

Abstract Long-term changes in the demersal assemblage, including both fishes and invertebrates, in Tokyo Bay, Japan, were examined between 1977 and 1995. A total of 255 species were collected, of which 113 were regarded as representative in terms of occurrence. Multivariate analyses of the representative species showed that fluctuations in the catch were related to three periods that reflected changes in relative abundance and species composition. In particular, mantis shrimp, Oratosquilla oratoria (de Haan), whipfin dragonet, Repomucenus valenciennei (Temminck & Schlegel), and marbled sole, Pleuronectes yokohamae Günther, showed high dominance in the mid-1980s. Discriminant analysis suggested that the demersal assemblage changed synchronously with environmental conditions. Causes of the temporal changes in the demersal assemblage in relation to variations in environmental factors are discussed.     

杭州湾北部安氏白虾体长与体重关系的季节变化特征

为掌握安氏白虾（Palaemon annandalei）的生长特性,根据2018年2月、5月、8月和11月于杭州湾北部（30°37''N~30°47''N,121°26''E~121°59''E）进行的张网调查数据,利用幂函数、相对体重和单因素方差分析等方法对其体长与体重关系、肥满度等进行研究。结果显示,安氏白虾的体长、体重组成均具有显著的季节变化特征,从春季至冬季,平均体长和平均体重均呈现逐渐下降的趋势,平均体长和平均体重的季节差异显著（P<0.05）。体长与体重关系参数a为条件因子,反映出安氏白虾种群所处环境的优劣,a值夏季最高,冬季最低,从春季到冬季呈现先升高后又逐渐降低的变化趋势,参数b为异速生长因子,可用来判断安氏白虾种群是否处于匀速生长,b值表现出与a值相反的变化趋势。协方差分析表明,安氏白虾体长与体重关系参数仅春季和夏季间无显著性差异（P>0.05）,其余季节之间均存在显著性差异（P<0.05）。安氏白虾的肥满度从春季到秋季逐渐上升,秋季达到最高值,冬季又降至最低值。方差分析显示,春季和夏季间的肥满度无显著性差异（P>0.05）,其余季节间肥满度均具有显著性差异（P<0.05）。研究表明,杭州湾北部安氏白虾体长与体重关系参数a和b具有显著的季节变化特征,并且这个变化受捕食关系、捕捞压力和环境因子等方面影响。     

海州湾及其邻近海域鱼类群落结构冗余度

过度捕捞、环境污染等人类活动以及气候变化等影响着海洋鱼类群落动态及其稳定性。为深入研究海州湾海域鱼类群落结构及其变化,根据2011年、2013—2016年春、秋两季在该海域进行的渔业资源与环境调查数据,应用多元统计分析和结构冗余度分析方法,研究了海州湾海域春、秋季鱼类群落结构冗余度。结果显示,海州湾及邻近海域春、秋季鱼类均可划分为南北两个群落。春季北部群落的典型种包括方氏云鳚、细纹狮子鱼、黄鮟鱇和大泷六线鱼;南部群落的典型种为小黄鱼、短吻红舌鳎、方氏云鳚和星康吉鳗。秋季北部群落的典型种为棘绿鳍鱼、长蛇鲻和星康吉鳗;南部群落典型种包括短吻红舌鳎、棘头梅童鱼、鮸、矛尾虾虎鱼、小黄鱼和皮氏叫姑鱼。春、秋季鱼类群落响应单元数均为1,群落结构冗余度水平低;响应单元中种类与南、北鱼类群落典型种组成相似,表明海州湾春、秋季鱼类群落空间结构特征主要受方氏云鳚、细纹狮子鱼、小黄鱼、棘绿鳍鱼和长蛇鲻等少数种类决定。决定海州湾及邻近海域鱼类群落结构特征的可替代种类较少,当主要种类受损时,群落结构会发生较大变化,鱼类群落结构稳定性较低。     

莱州湾和桑沟湾养殖海区主要营养盐的周年变动及限制因子

于2001年3月至2002年3月在2个典型养殖海湾——莱州湾和桑沟湾,对其海水中主要营养盐进行了周年监测。结果显示,在莱州湾,总无机氮(TIN)浓度春季最低,冬季最高;活性磷酸盐(PO_4~(3-)-P)浓度春季最高,冬季最低;活性硅酸盐(SiO_3~(2-)-Si)浓度夏季最高,春季和秋季最低;N与P的浓度比[C(N)/C(P)]变化范围为1.145～128.61,年平均值为21.066±22.712。Si与N的浓度比[C(Si)/C(N)]的变化范围为0.000～0.922,年平均值为0.241±0.280。说明Si有可能是该湾主要的限制性元素。在莱州湾,总无机氮(TIN)浓度春季最低,夏季最高;活性磷酸盐(PO_4~(3-)-P)浓度冬季最高,夏季最低;活性硅酸盐(SiO_3~(2-)-Si)浓度夏季最高,最低值出现在春季和秋季;C(N)/C(P)的变化范围为1.482～149.935,年平均值为18.080±28.854;除夏、秋季部分月份外,N限制的可能性较大。C(Si)/C(N)的变化范围为0.000～2.840,年平均值为0.387±0.609,但大部分时间为0.5以下,表明Si也可能是桑沟湾的主要限制性营养盐。     

Effects of hypoxia on principal prey and growth of flathead flounder Hippoglossoides dubius in Funka Bay, Japan

ABSTRACT:   Effects of hypoxia on the principal prey and growth of flathead flounder Hippoglossoides dubius were studied in Funka Bay. Of the three dominant year-classes that occurred in recent years, the 1995 year-class was small in total length at age ≥ 3 and low in condition factor at age ≥ 2. Ophiuroids (almost Ophiura sarsi ), which were the dominant prey in the 1980s, were of little importance and instead, crustaceans such as mysids, natant decapods and pelagic amphipods, bivalves and fish were important prey items for H. dubius in 2000–2001. In addition, the feeding intensity of H. dubius in 2000–2001 was lower than that in the 1980s. These facts are closely related to a reduction of prey abundance, particularly ophiuroids. It seems that the hypoxia that occurred in the central part of the bay during the summer and autumn of 1995–1997 caused the poor food supply and low growth rate at ages 2–4 of the 1995 year-class.     

三峡水库175 m蓄水前后香溪河库湾浮游植物的群落结构

2011年9-11月三峡水库175 m蓄水期前后,在香溪河库湾沿程布点和采样,监测分析库湾浮游植物群落结构及水体环境的时空动态。结果表明,蓄水期前后香溪河库湾共鉴定浮游植物7门、42属,主要为绿藻和硅藻;浮游植物密度随时间变化呈降低趋势,浮游植物成分空间差异不显著,时间上则由绿藻向硅藻演替;营养物质、光热条件等环境因子时间差异明显,空间差异不显著。利用物种多样性指数评价香溪河库湾水质,蓄水期前后库湾水质较好,为中污染状态。利用冗余分析(redundancy analysis,RDA)浮游植物群落结构与环境因子之间的关系,水位、表底温差、溶解性硅酸盐浓度ρ(SiO2-3-Si)、真光层深度/混合层深度(Zeu/Zmix)、水位日变幅、硝酸盐氮浓度是浮游植物群落结构的主要影响因子。     

渤海湾近岸海域浮游纤毛虫丰度和生物量的季节变化

2015年春季(5月)、夏季(7月)和秋季(9月)在渤海湾近岸海域进行浮游纤毛虫丰度和生物量的调查。浮游纤毛虫丰度、生物量及种类组成均表现出明显的季节变化。春、夏和秋季纤毛虫的平均丰度分别为(1016±868)、(2011±1327)和(2456±1776)ind./L,平均生物量分别为(1.91±2.53)、(5.78±4.45)和(3.11±2.40)μg?C/L。3个季节砂壳纤毛虫占纤毛虫丰度的比例平均为(26.7±23.3)%,夏季最高,为(43.4±25.1)%,秋季最低,为(12.3±8.1)%。无壳纤毛虫和砂壳纤毛虫丰度和生物量的水平分布特点不同,无壳纤毛虫在3个季节中没有表现出明显的分布规律,在近岸和远岸都有丰度和生物量高值的出现;砂壳纤毛虫丰度和生物量则一般在近岸较高。3个季节共鉴定出砂壳纤毛虫8属25种,其中,拟铃虫属(Tintinnopsis)种类最多。春季砂壳纤毛虫优势种为波罗的拟铃虫(Tintinnopsis baltica)、百乐拟铃虫(Tintinnopsis beroidea)和原始筒壳虫(Tintinnidium primitivum);夏季砂壳纤毛虫优势种为妥肯丁拟铃虫(Tintinnopsis tocantinensis)、原始筒壳虫和厦门拟铃虫(Tintinnopsis amoyensis);秋季砂壳纤毛虫优势种为原始筒壳虫。春季砂壳纤毛虫群落口径较小,为(31.5±2.5)μm,夏季和秋季较大,分别为(35.9±8.2)和(34.8±5.2)μm。夏季砂壳纤毛虫群落Shannon指数及Pielou指数均较春季和秋季大。本研究可为该海区浮游纤毛虫分布的长期变化、浮游生态系统的研究及渔业资源的发展提供基础数据。     

渤海湾鱼类早期资源群落结构特征及其时间变化研究

渤海湾历史上为黄渤海多种主要经济鱼类的重要产卵和育幼场。基于历史调查资料和补充调查,构建渤海湾鱼卵、仔稚鱼调查数据集,通过数理统计分析阐述1982年以来渤海湾鱼类早期资源(浮性鱼卵和仔稚鱼)群聚特性和演替过程。结果显示,渤海湾鱼类早期资源结构、产卵和育幼场重心位置处于持续更替过程中,不同时期早期资源的种类组成、资源丰度、优势种类和物种多样性水平等呈明显季节更替,118º30ʹE以西湾中底部海域一直为产卵和育幼场集中分布区。相较1980s,渤海湾鱼类早期资源已发生结构性改变,且渤海湾作为传统经济鱼类的产卵和育幼场所的功能下降明显。渤海湾鱼类早期资源种数和资源丰度均在2010s前期跌至历史低值,近年来又显著回升。鱼类早期资源种数由1980s的39种,1990s前期的31种、后期的34种,2000s—2010s初期的22 种,逐次下降至2010s前期的21种,2010s中后期开始逐步回升,至2020s初期已达40种。2020—2021 年鱼卵种数约为1980s的80%左右,资源丰度约为彼时的88%;仔稚鱼种数与1980s大致相当,资源丰度则为彼时的1.33倍。鱼卵、仔稚鱼物种多样性水平呈年际和年代际剧烈波动,鱼类早期资源种类年际更替现象明显,且近年来呈明显加快趋势。产卵类型、栖息类型和适温类型亲体种数均呈先下降后上升的变动趋势,全年综合浮性卵种数比例下降,黏性卵和具卵膜丝卵种数比例升高;陆架浅水中上层鱼类种数所占比例升高,中底层和底层鱼类所占比例降低。斑 (Konosirus punctatus)、青鳞小沙丁鱼(Sardinella zunasi)、小黄鱼(Larimichthys polyactis)、带鱼(Trichiurus japonicus)、花鲈(Lateolabrax maculatus)和半滑舌鳎(Cynoglossus semilaevis)等渤海湾传统经济鱼类早期资源密度显著降低;鳀(Engraulis japonicus)、蓝点马鲛(Scomberomorus niphonius)、赤鼻棱鳀(Thryssa kammalensis)和少鳞 (Sillago japonica)等鱼类早期资源密度显著增高。渤海湾鱼类早期资源发生量主要取决于产卵场的环境条件、捕捞强度和对鱼类早期资源的损害程度,渤海湾鱼类早期资源结构及其动态变化是环境和捕捞双重扰动下鱼类群落内生态位错位交替和结构性渔业资源衰退的具体体现。     

莱州湾东部养殖水域氮、磷营养盐的分布与变化

根据1997年5月－1998年6月对莱州湾的6次调查资料，研究了莱州湾氮，磷营养盐的平面分布和季节变化规律，结合历史资料讨论了莱州湾氮，磷营养盐的历史演变。提出在研究近岸海生态体系中氮，磷营养盐限制性，应该对氮，磷营养盐的周转速进行研究。     

渤海莱州湾硬骨鱼类早期资源群落结构及演变

莱州湾作为黄渤海众多渔业生物关键栖息地,其鱼类早期发生量和补充量直接影响渤海乃至黄海渔业资源动态及其可持续性。实验基于历史调查资料并结合补充调查,构建莱州湾鱼卵、仔鱼调查数据集,通过数理统计和时间序列分析阐述近40年来莱州湾鱼类早期资源(浮性鱼卵、仔稚鱼)群聚特性和演替过程。结果显示,莱州湾鱼类早期资源结构处在持续更替过程中,不同时期早期资源的种类组成、资源丰度、优势种类和物种多样性水平等呈明显季节更替。鱼卵和仔稚鱼种类数和资源丰度均在2010s (2010—2019,以下同此表示)初期跌至历史低值,近年来均又呈现一定程度回升。鱼卵和仔稚鱼种类数由1980s的44种,1990s前期的34种、后期的40种,2000s的35种,逐次下降至2010s前期的24种,2010s中后期开始逐步回升至38种。当前鱼卵种数仅为1980s的60%左右,资源丰度不足彼时三分之一;仔稚鱼种数为1980s的四分之三左右,资源丰度约为彼时的90%。生命周期短、性成熟早、处于食物链低端的中上层和底层小型鱼类为莱州湾鱼类早期资源的主体成分。长期变化,相同季节优势种种类更替现象明显,且近年来呈明显加快趋势;鱼卵仔稚鱼...     

Effect of environmental factors and prey species on daytime and nighttime vertical distribution of juvenile walleye pollock in and around Funka Bay

We examined factors affecting the vertical distribution of juvenile walleye pollock during “the second critical period” (i.e. the transition period of prey size) in and around Funka Bay, Hokkaido, Japan. During the day, small juveniles (<30 mm) were distributed mainly in shallow, warm, and low-salinity water within the bay, whereas larger ones (≥30 mm) occurred in deeper, cold and saline water. During the night, the large juveniles migrated to shallower depths. Outside the bay, small- and large-sized juveniles were distributed in water masses of similar physical properties during the daytime, whereas during the nighttime, most of the juveniles moved to shallower depth, and some juveniles dived to deeper water mass. Dietary analysis revealed that large juveniles fed on large copepods (≥0.5 mm in body width) more than small juveniles did. The composition of zooplankton in our survey area showed that large-sized copepods often occurred in deeper saline water. From these results, there is a possibility that juvenile pollock inside and outside Funka Bay occupied different water masses preferable for each feeding advantage.     

陵水湾浮游动物群落结构特征及其季节变化

为了探明陵水湾浮游动物饵料情况,本研究依据2014年11月(秋季)、2015年5月(春季)、8月(夏季)和2016年1月(冬季)陵水湾4个航次的调查资料,分析了该海湾浮游动物的种类组成、优势种、丰度和生物量、生物多样性等群落结构特征及其影响因素。调查共发现浮游动物94种和浮游幼虫21类,其中桡足类(Copepoda)最多,有38种,其次是水螅水母类(Hydromedusae)11种,毛颚类(Chaetognatha)8种,其余类群种类数在1～6种之间。浮游动物群落主要由广温广盐类群、暖水沿岸类群和暖水外海类群组成,优势种主要分布在前两个类群,无全年优势种;浮游幼虫是陵水湾的重要类群,丰度呈现为冬季(低温)高于春季(高温)。与亚热带海域不同,低温已不再是制约陵水湾海洋生物生长的主要因子。浮游动物丰度和生物量均呈现为秋季最高,春季最低,冬季高于夏季。浮游动物群落物种Shannon-Wiener指数(H￠)和均匀度指数(J￠)的变化趋势一致,表现为春夏季高,秋冬季低,湾外高,湾内低。聚类分析结果表明,陵水湾浮游动物可分为湾内和湾外两个群落,主要受地形阻隔所致。盐度与浮游动物丰度和生物量均呈显著负相关关系,是浮游动物季节变化的主要影响因子之一。根据陵水湾浮游动物年均生物量估算出浮游动物提供的渔产潜力为2.24×10~4 kg。陵水湾浮游动物丰度呈现剧烈的季节变化,有必要对其进行长期的跟踪监测。     

同安湾浮游动物数量的平面分布和季节变动

本文主要研究2000年同安湾浮游动物的种类组成和数量分布，并就其与环境因子的关系进行了初步探讨。结果表明，在同安湾共记录到浮游动物69种及12种浮游幼虫，以近岸低盐种类为主。浮游动物数量季节分布呈现春季高，冬、夏季居中，秋季最低的特点。种类数的季节分布与水温的季节变化一致。浮游动物数量与养殖贝类、浮游植物细胞数密切相关，并与浮游植物数量呈显著的正相关关系。同安湾浮游动物的数量与邻近养殖水域西海域的相当，比马銮湾的低。与历史资料比较，同安湾浮游动物的次级生产力水平比1995年的有所上升，但恢复得较慢。