EcologyofmacrobenthosinthesouthofZhejiangcoastalwaters

为了解浙江南部近岸海域海洋生态环境质量的现状及其变化趋势，2009年4月对浙江南部近岸海域的12个站位进行了大型底栖生物的分类、组成、丰度、生物量以及多样性的研究．应用Bray—Curtis相似性系数聚类和多维尺度排序，对浙江南部近岸海域的大型底栖生物进行群落划分；采用丰度生物量比较法分析群落的稳定性；并研究了对大型底栖生物产生影响的主要环境因子．本次调查共鉴定大型底栖生物109种，多毛类、软体动物和甲壳动物构成主要类群．平均生物量为23．38g／m^2，平均丰度为335．5ind／m^2，平均生物多样性指数为2．69．数量组成：生物量以软体动物居首（13．29g／m^2），鱼类次之（3．68g／m^2）；丰度以多毛类居首（268．0ind／m^2），软体动物次之（51．7ind／m^2）．浙江南部近岸海域可划分为3个群落．与环境因子进行相关性分析表明，有机污染含量、深度、溶解氧含量、盐度和悬浮物含量是对浙江南部近岸海域大型底栖生物产生影响的主要环境因子．总体上，除了瓯江口和乐清湾海域受到一定扰动，浙江南部近岸海域大型底栖生物环境质量较好，群落结构较为稳定．

Study on sea water intrusion into palaeochannels on south coastal plain of the Laizhou Bay by the Bohai Sea

The palaeochannel evolution in the study region is divided into four stages by such methods as 14C dating. Sea water intrusion through palaeochannels has been studied as a focal point. Palaeochannels are the main passageways through which the sea water intrudes at a higher speed, through many means and in a changeable dynamic state.

Ecological thresholds of phytoplankton community across environmental gradients in the harmful algal blooms-frequently-occurring,subtropical coastal waters,East China Sea

Phytoplankton communities can response immediately and directly to environmental changes,and thus have been applied as reliable biotic indicators in aquatic systems.This study provided insights into the relationships concerning ecological thresholds of phytoplankton communities and individual taxon in response to environmental changes in coastal waters of northern Zhejiang Province,East China Sea.Results demonstrated that there existed seasonal variations of phytoplankton community ecological thresholds of which spring being higher than those in summer.As for individual species,Prorocentrum donghaiense and Noctiluca scintillans were identified as the most tolerant and sensitive indicator species in spring and summer,respectively.They exhibited strong indications in response to environmental changes.These findings highlighted that phytoplankton community structure in this region was stable when environmental gradients were below the thresholds of sensitive species,whereas potential harmful algal blooms may occur when environmental gradients exceeded the thresholds of tolerant species.

Environmental evolution in the salt-water intrusion area south of Laizhou Bay since late Pleistocene

The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP： 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.

Distribution of fouling bryozoans in the northern South China Sea

This paper reports the species composition and distribution of fouling bryozoans in the northern SouthChina Sea. 34 species identified belong to 23 genera, 22 families of fouling bryozoa, of which most of 24 species on thebuoys attached to concrete sinkers. The 13 species on platforms mainly included Schizoporella errata and Membranipora savartii. Depth distribution of species, larval settlement behaviour and larvae type of fouling bryozoa are discussed.

The westward intrusion of south Pacific water at the western tip of the New Guinea Island

From the eastern Indonesian cruise from November 14 to 23, 2007, CTD （conductivity, temperature, depth profiler）/ADCP （acoustic Doppler current profiler）casting and seawater sampling were done at 25 stations around Waigeo Island near New Guinea Island. It was found overall westward intrusion of the south Pacific waters into the Seram Sea and southward spreading of the north and south Pacific waters into the Seram Sea. There is westward residual flow along the channel between Waigeo and New Guinea within upper 200 m with the maximum speed up to 50 cm/s, and much weaker eastward flow in the lower layer （〈 10 cm/s） due to blocking by the shallow sill at the west of the Dampier Strait. The abrupt change of bottom topography induces active horizontal and vertical mixing which results in a three-layered current system with a major through-flow of-0.99 Sv （Sv = 106 ma/s） into the Seram Sea; the transports in the upper and the lower layers are -1.14 Sv and -0.24 Sv （westward）, respectively, and in the middle there is a return flow with the transoort of ＋0.39 Sv （eastward）.

Phaeocystis globosa Scherffel,a harmful microalga,and its production of dimethylsulfoniopropionate

The production of dimethylsulfoniopropionate （DMSP） and its cleavage products （DMS） are well studied in phytoplankton worldwide. However, less is known about their sources, distributions, and impacts in the coast of China. We examined the production of DMSP and DMS in Phaeocvstis globosa Scherffel and other benthic macroalgae from the South China coast in relation to environmental conditions. P. globosa was a harmful marine microalgal species and its bloom took place in the eutrophic waters along the South China Sea frequently. It also produced high content of DMSP at different growth stages, with the highest concentration usually observed in the stationary period. Moreover, the production of DMSP in P. globosa was significantly affected by salinity and temperature with the highest contents associated with high salinity （e.g. 40） and low temperature （e.g. 20℃）. In field benthic macroalgae, there was also a marked difference in the DMSP of various species or different samples of the same species. Chlorophyll a contents were also determined for each macroalgal species. The highest chlorophyll a （238.7 ng/g fresh weight） was recorded in Chlorophyta Ulva lactuca at Guishan Island （Zhuhai）, while the lowest value （1.5 ng/g fresh weight） was found in Rhodophyta Gracilaria tenuistipitata in Zhanjiang. Further correlation analysis indicated that there was no significant relationship between the content of DMSP and chl-a in macroalgae samples （P〉 0.05）. All the results suggested that the production of DMSP in marine algae was not only species- and stage-related, but also greatly affected by various environmental factors.

Tidal analysis in the venturi-shaped area between Zhenhai and Shenjiamen in the East China Sea

In order to better understand the general tidal features in the venturi-shaped area between Zhenhai and Shenjiamen in the northern coastal region of Zhejiang Province in the East China Sea, the tidal data were obtained from both the three permanent tide stations of Zhenhai, Dinghai and Shenjiamen, and four temporary tide stations of Mamu, Chuanshan, Guoju and Liuheng, along with the current speed being observed at Luotou Waterway. Results from harmonic analysis show that: (1) The area was dominated by shallow water tides with irregular semi-diurnal features, and the smallest tidal range occurred in the area near a crossing line between Zhenhai and Dinghai stations, indicating that a tidal node existed in the southern Hangzhou Bay; (2) Formulae, HS2/HM2 >0.4 and gM2-(gK1+gO1)=270° (where H and g are harmonic constants), could be used as judging criteria for high and low tidal level diurnal inequalities; (3) The duration difference between ebb and flood tides could be roughly assessed by the ratio of HM4 vs. HM2; and the larger the ratio is, the bigger the duration difference is. At the same time, the duration period could be assessed by 2gM2-gM4, the epoch difference between M2 and M4 tidal constituents. If 2gM2-gM4 <180°, then the ebb duration is longer than the flood duration; if 180°< 2gM2-gM4 <360°, the result is reversed; (4) Taking Dinghai station as a center point, the highest tidal levels and the average high tidal levels, as well as the average tidal ranges at all stations became higher and larger both southeastwards and northwestwards, while the lowest tidal levels and the average low tidal levels appeared to be lower both southeastwards and northwestwards; and (5) The tidal patterns were not all in line with the tidal current patterns. As a conclusion, the smallest tidal range occurred in the narrow part of the venturi-shaped area. Along the both sides of the area, the highest tidal level and tidal range became higher and larger, while the lowest tidal level became lower with the increase of the distance from the narrow throat area. This is somehow different from the theory that the tidal level increases gradually when it moves towards the top narrow area of a V-shaped bay or estuary.

Implementing geostatistical analysis to study spatio-temporal distribution patterns of swimming crabs(Portunus trituberculatus)

This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was used to select the optimum method to get distribution results,and kriging was used for making spatial variability analysis.Data were collected from 87 sampling stations in November of 2015(autumn)and February(winter),May(spring)and August(summer)of 2016.Results indicate that swimming crabs widely distributed in autumn and summer:in the summer,they were more spatially independent,and resources in each sampling station varied a lot;in the winter and spring,the abundance of crabs was much lower,but the individual crab size was bigger,and they showed the patchy and more concentrative distribution pattern,which means they were more spatially dependent.Distribution patterns were in accordance with ecological migration features of swimming crabs,which were affected by the changing marine environment.This study could infer that it is applicable to study crab fishery or even other crustacean species using geostatistical analysis.It not only helps practitioners have a better understanding of how swimming crabs migrate from season to season,but also assists researchers in carrying out a more comprehensive assessment of the fishery.Therefore,it may facilitate advancing the implementation in the pilot quota management program of swimming crabs in northern Zhejiang fishing grounds.

Late Quaternary upper-water column structure in upwelling areas of the South China Sea

Based on a quantitative analysis of planktonic foraminifera in two gravity cores (17928 and 17954), the history of the upper-water structure of the eastern and western slopes of the South China Sea (SCS) over the last 220 Ka was reconstructed using the transfer function technique. Our results show that lower sea surface temperature (SST) and shallower depth of thermocline (DOT) exist at Core 17928, off Luzon, in the glacial periods; on the contrary, the same situation turned up in the interglacial at Core 17954, off Vietnam. These changes of the upper-water column structure in the two areas are induced by coastal up-welling, which in turn is driven by monsoons, namely, winter monsoon leads to upwelling at the eastern slope, and summer monsoon gives birth to upwelling on the western slope. Moreover, the intensity of upwellings is also closely related to the evolution of the East Asian monsoon. Therefore, we assume that the changes of the upwelling in the two sites indicate strengthenning of winter and

浙江海域新纪录种——瓣叉鼻鲀的形态特征及其DNA条形码分析

2020年4月,在浙江海域采集到12尾鲀形目鱼类标本,鉴定结果显示其为浙江海域的新纪录种—瓣叉鼻鲀Arothron firmamentum。本研究对采集到的12尾瓣叉鼻鲀进行了形态学及DNA条形码分析。瓣叉鼻鲀具有以下主要形态特征:体色灰黑色,除眼周围与尾柄后部外,全身布满小刺,背鳍鳍条数14,臀鳍鳍条数13~14,胸鳍鳍条数15~16,尾鳍鳍条数11。测定了12尾标本的线粒体COI与12S rRNA基因片段序列,结合GenBank中所有学名为A.firmamentum的同源序列进行分析,基于COI与12S rRNA基因片段序列构建的邻接系统树表明COI与12S rRNA基因片段聚类结果完全一致,均与近缘种明显分开,证实本研究采用形态学与分子方法鉴定的鲀形目鱼类为瓣叉鼻鲀。

南海沿海港口航道图深度基准面计算与评估

《海道测量规范》(GB 12327—2022)正式实施,按照新规范评估南海沿海港口航道图深度基准面值,能为海洋垂直基准的维护提供数据支持。对广州海事测绘中心辖区17个长期水位站长于2年的水位数据、长期站邻近的28个短期、临时水位站数据进行潮汐分析,评估了长期水位站的L值及深度基准面保证率,分析了短期、临时水位站平均海面、深度基准面的传递精度。结果表明:17个长期水位站3种算法深度基准面保证率均超过98%,保证了航行的安全性;不同方法确定的深度基准面L值互差,53%的长期水位站超过10 cm,7%短期、临时水位站超过15 cm,11%短期、临时水位站两种方法L值中数与原采用值差值超过15 cm,亟需修正南海沿海港口航道图深度基准值。

浙江南部近海春季鱼类多样性分析

根据2011年春季(4月、5月与6月)对浙江南部近海进行的共3个航次的底拖网渔业资源调查资料,对该海域的鱼类多样性进行了分析。结果表明:所捕获的90种鱼分别隶属于2纲15目51科75属;暖水性鱼类无论在种类数量还是生物量与尾数密度方面均居主导地位;所有优势种均为暖水性鱼类,其中矛尾虎鱼为春季三个月的共同优势种;生物量、尾数密度与丰富度指数(D)5月与6月的差异均极显著(P<0.01);多样性指数(H′)与水深、底温与底盐三者之间均为线性正相关(P<0.05),而与生物量呈线性负相关(P<0.05),这表明浙江南部近海春季鱼类的多样性(H′)随水深、底温与底盐的增加而增高,但同时却随生物量的增加而降低。

浙江南部近岸海域春季口虾蛄(Oratosquilla oratoria)生物量的时空分布

根据2011年春季(4月、5月、6月)对浙江南部近岸海域进行的共3个航次的底拖网渔业资源调查资料,对该海域口虾蛄(Oratosquilla oratoria)生物量的时空分布进行了分析。结果表明,4—6月,在月间分布上口虾蛄的生物量呈逐月下降的趋势,但各月间不存在显著性差异;在空间分布上大多数站位的生物量均较低(<150kg/km2);生物量重心位于27°33′N—27°55′N、121°20′E—121°38′E之间海域。各月相对高生物量(>150kg/km2)的空间分布与该月底温与底盐的变化相关。另外,随着月平均底盐特别是平均底温的升高,口虾蛄呈现逐月由较深海域向较浅海域移动的趋势。

浙江南部近岸海域春季蟹类群落结构特征

根据2011年春季(4月、5月和6月)对浙江南部近岸海域进行的共3个航次的底拖网调查数据,分析了该海域蟹类的种类组成、数量分布、优势种和多样性等特征。结果表明,春季共捕获蟹类13种,隶属于1目4科7属;上述所有种类中,除3种不确定外,其余分别为广温广盐种4种、高温广盐种4种与高温高盐种2种;4月与6月蟹类的质量密度与尾数密度间均存在显著差异(P<0.05);4月与5月、6月间的多样性指数(H′)差异均显著(P<0.05);丰富度指数(D)与底盐、水深两者均呈线性正相关(P<0.05),而多样性指数(H′)、均匀度指数(J′)与质量密度均呈线性负相关(P<0.05)。浙江南部近海春季蟹类群落以中小型非经济种类为主,结构较简单,其丰富度(D)随底盐、水深的增加而增加,而多样性(H′)与均匀度(J′)随质量密度的升高而降低。另外,蟳双斑(Charybdis bimaculata)为春季的绝对优势种,且其对质量密度与尾数密度的总贡献率均超过50%,这可作为渔业生态功能区及重要渔业水域选划的依据之一。

浙南海域腹泻性贝毒分析

在浙南海域共采集了10种贝类40份样品。运用高效液相色谱方法检测腹泻性贝毒,共检出9份样品含有腹泻性贝毒。染毒样品检出的腹泻性贝毒（软海绵酸,OA）质量比为0.07~5.85μg/g,共有7个样品含量超标,超标率为17.5%。无论是检出率还是超标率,都呈现夏季〉春季〉秋季的规律。浙南海域的南部腹泻性贝毒检出率和超标率比北部和中部都高。紫贻贝、缢蛏、泥蚶和青蛤较其他种类易富集腹泻性贝毒。养殖的贝类检出率及超标率均高于野生的贝类。

浙江南部沿岸产卵场春季虾类群落结构特征分析

根据2011年春季(4—6月)对浙江南部沿岸产卵场进行的共3个航次的底拖网调查数据,分析了该海域虾类的群落结构特征。结果表明:春季共发现虾类22种,隶属于1目9科16属;虾类生物量与尾数密度的最小值与最大值均分别出现在5月与6月;细巧仿对虾、葛氏长臂虾与周氏新对虾为各月的共同优势种;5月与6月的多样性指数(H′)存在显著差异(P<0.05);多样性指数(H′)和水深、底盐与生物量均呈线性负相关(P<0.05)。浙江南部沿岸产卵场春季虾类群落以广温广盐种为主、结构简单,其多样性(H′)随水深、底盐与生物量的增加而降低,各月共同优势种对生物量与尾数密度的贡献率均超过四成。

浙北近海曼氏无针乌贼增殖放流效果评估

为修复浙北近海曼氏无针乌贼(Sepiella maindroni)资源,2013—2016年实施了大规模放流,累计增殖放流受精卵7835×104粒,同期还开展了跟踪监测调查。本研究利用放流前后的定点资料和补充采样数据,估算了生长参数和死亡系数等指标,并构建资源评估模型,模拟分析了渔获产量和残存率的变化趋势。结果表明,2013—2016年浙北海域放流曼氏无针乌贼极限体长为138 mm,年生长系数K为2.354,t0为–0.05237 a,年总死亡系数Z为2.83,年自然死亡系数M为1.74,年捕捞死亡系数F为1.09;现行捕捞强度下,每投放1×104粒受精卵,可形成137.3 kg产量,同时还补充了502 ind性成熟个体,增殖放流在一定程度上起到了种群修复和增产增收的目的。评估结果显示,将开捕时间推迟2个月,捕捞产量可增加10.0%,发育至性成熟个体增加27.5%;捕捞强度也是影响放流效果的重要因素之一,若将年捕捞死亡系数降至0.76,捕捞产量最高可达155.6 kg,发育至性成熟个体增加29.4%。最后,针对研究结果提出提高曼氏无针乌贼放流效果和合理利用资源的建议。

浙江近岸海域赤潮发生的趋势与特点

根据历史记载和近年调查实测资料,概述了浙江近岸海域赤潮的历史与现状,分析了赤潮的特点与发生趋势,研究结果表明:浙江近岸海域各种不同类型藻类引发的赤潮频率均呈上升趋势,其中甲藻赤潮的发生次数上升尤为迅速,赤潮出现的规模越来越大,有毒赤潮记录次数也显著增加。探讨了赤潮发生的一些原因,指出了建立科学评估有害赤潮影响体系和预警系统的意义并提出了一些对策措施与建议。

浙江沿岸休闲生态型人工鱼礁初选点的环境适宜性分析

根据对浙江沿岸拟投放休闲生态型人工鱼礁的17个测站34个航次的环境本底调查结果,从水质、底质、生物环境等方面分析了投礁的可行性,并对浙江沿岸北部的绿华、朱家尖,中部的渔山、大陈和南部的虎头屿5个已经开始投礁的试放点的环境适宜性进行了论证,用水质、底质、生物三大类14个指标进行了分析评估和排序。结果表明,浙江沿岸除局部海域水色较浑、水流较急、易发赤潮外,大部分水质、底质和生物指标适合投放人工鱼礁。经分析评估和排序后,5个试放点的环境适宜性排序依次为渔山、虎头屿、绿华、朱家尖和大陈。