渤海中部海域水体中Hg、As的时空分布特征

本研究分析了2013年5月(春季)、7月(夏季)、11月(秋季)、12月(冬季)渤海中部海域表、中、底层海水中汞(Hg)、砷(As)两种元素的时空分布特征。结果显示,Hg 的含量范围为0.0029–0.3926μg/L,平均含量为0.0676μg/L。从垂直分布来看,水体中Hg的含量呈现底层>中层>表层的变化特点;从四季的变化特点看,水体中Hg的含量呈现春季>冬季>秋季>夏季的变化规律,其中,仅有夏季表层水体达到国家海水水质标准(GB3097–1997),其余水体中 Hg 的含量均有超标现象发生。As的含量范围为0.65–10.83μg/L,平均含量为1.50μg/L,除夏季表层水体中的As含量较高外,水体中的As均呈现均匀的分布模式。从垂直分布来看,As在四季的平均含量均表现为表层>中层>底层,且均未超出国家海水水质标准。研究表明,渤海中部海域水体中,As 的含量均达到Ⅰ类水质标准(20μg/L),而Hg含量却频频超出Ⅰ类水质标准(0.05μg/L)或Ⅱ类水质标准(0.20μg/L)。渤海中部海域水质已经受到了重金属的污染,推测该现象主要源于人类活动的影响。     

渤海中部COD的时空分布特征及其对富营养化的贡献分析

以2013年春、夏、秋、冬4个季节对渤海中部海区的调查数据为依据,对调查海域表、中、底层水体的化学耗氧量(Chemical oxygen demand, COD)的时空分布、来源及其对富营养化的贡献等进行了分析。结果显示,调查海域COD平均含量以夏季最高,秋季次之,春季最低。垂直分布差异表现为春季表层最高,中层最低;夏季表层最高,底层最低;秋季和冬季均为中层最高,底层最低。各站位 COD 平均浓度水平分布在春季无明显的高值出现,含量分布较均匀,夏季 COD从西向东呈降低趋势,高值主要分布于西部海域;秋季和冬季COD从北向南呈递减趋势,高值分布于调查海域北部。调查海域各站位营养指数E值变化范围为0.088–2.995,平均值为0.337±0.403,大于1的站位有25个,其中,秋季20个,冬季5个,表明大部分调查海域水质未达到富营养化状态,处于较低营养水平。COD 对调查海域富营养化的贡献率为46.15%–141.41%,平均值为(71.36±14.98)%,表明COD在渤海海区富营养化中占据了主要地位。     

长江口外海域夏末温跃层与底层水低氧现象研究

基于长江口外海域2009年夏末调查的温盐和溶解氧(DO)资料,采用垂向梯度法对夏末长江口外海域温度垂向结构类型进行划分,计算了温跃层深度、强度和温跃层处DO垂向梯度等参数。长江口外海域夏末水温垂向结构类型及其温跃层强度的分布表现为长江冲淡水、黄海沿岸流、台湾暖流表层暖水和台湾暖流深层冷水交汇、混合的态势。相关性分析表明,温跃层深度与温跃层处DO垂向梯度之间为负相关,温跃层深度与垂向最小DO浓度之间为正相关,温跃层强度与温跃层处DO垂向梯度之间为正相关。最接近DO供给源的上温跃层强度与温跃层处DO垂向梯度具有较强的相关性(r=0.69)。温跃层越浅、强度越大,对底层水低氧现象的影响越大。温跃层、特别是上温跃层引起的水体层化阻碍DO向底层输运,起到了物理隔氧的作用,与低氧现象具有紧密的联系,是低氧现象在长江口外海域从春末到秋季发生、发展、维持和消亡过程的重要环境控制因素。     

獐子岛邻近海域悬浮颗粒物的时空分布特性

根据2015年秋季(10月)和2016年冬季(1月)、春季(4月)、夏季(7月)4个航次的调查研究,分析了獐子岛养殖海域表、底层水体中总悬浮颗粒物(TPM)、颗粒有机物(POM)和颗粒有机物比例(PCOM,%)的时空分布特征,结合POM与叶绿素a(Chl-a)及环境因子的相关性分析,探讨了悬浮颗粒物的影响因素及其与虾夷扇贝(Patinopecten yessoensis)底播养殖之间的潜在联系。结果显示,獐子岛海域TPM和POM的浓度变化范围分别为16.76~97.54、2.20~17.20 mg/L,年平均浓度分别为(31.65±9.58)、(6.97±2.08)mg/L。PCOM值的变化范围为8.69%~37.09%,平均值为(22.25±4.18)%。TPM浓度的季节变化趋势为秋季春季夏季冬季,最大值出现在秋季表层。而POM和PCOM的最高值出现在夏季,冬季的值最低。POM与TPM的平面分布趋势相似,大部分海域的平面分布比较均匀;春、夏季POM的分布呈现中部略高、四周略低的特点,秋、冬季与之相反;夏季底层显著高于表层(P0.01),其他季节表、底层无显著差异(P0.05)。4个季节中,獐子岛海域的POM与Chl-a的含量呈极显著正相关关系(P0.01);其中,春季底层和夏季表层的POM与Chl-a均存在极显著正相关关系(P0.01)。另外,只有夏季表层POM与盐度之间存在显著负相关关系(P0.05),说明夏季陆源输入对该海域的悬浮颗粒有机物有显著影响。     

不同地区三角帆蚌养殖水体理化环境的季节变化

分别于2006年9月、2006年12月、2007年3月和2007年7月调查了分布在江苏省苏州市、浙江省杭州市和绍兴市、湖北省荆州市、江西省九江市的10个三角帆蚌(Hyriopsis cumingii)养殖水体的理化环境。结果表明调查期间上述水体水温为6.5~34.0℃,Ca2+为17.89~66.54 mg/L,总硬度为61.02~217.78 mg CaCO3/L,总碱度为43.30~218.24 mg CaCO3/L,总氮(TN)为0.46~2.78 mg/L,总磷(TP)为0.01~0.35 mg/L,高锰酸盐指数(COD Mn)为4.36~17.98 mg/L。从地点上看:苏州、杭州、绍兴的水体水温和透明度高于九江和荆州的水体,但表层溶氧(DO)、pH和总碱度低于后者;苏州的水体盐度、Ca2+和总硬度高于九江、荆州、杭州和绍兴的水体;杭州、绍兴的水体TN和TP高于九江、荆州和苏州的水体;荆州的水体COD Mn高于杭州、绍兴、九江和苏州的水体。从时间上看:7月和9月水温、TP和COD Mn高于3月和12月,而表层DO、pH、Ca2+、总硬度和TN低于后者;透明度、盐度和总碱度季节变化趋势不明显。所调查的水体DO、COD Mn与水温相关,TN、TP与DO相关,表明DO、COD Mn、TN、TP随水温变化而变化。     

渤海中部海区水域夏季环境质量综合评价

基于2012年夏季渤海中部海域21个站点的调查数据,采用内梅罗(Nemerow)指数、富营养指数(EI)和潜在富营养化法对渤海中部海域水体环境质量现状进行了评价.内梅罗指数评价结果显示,对参与评价的酸碱度、溶解氧、无机氮、活性磷酸盐、化学耗氧量、石油类、重金属(Cu、Zn、Pb、Cd、Hg和As)等12项指标而言,表层、10m层、底层受污染站位比例分别为57.1％、33.3％、23.8％.表层海水石油类浓度超标率为57.1％,10 rn层水体超标率为42.9％,底层水体超标率为14.3％,石油类是主要污染因素.从分布位置看,受污染站位主要集中在调查区域的西南部,中部海域水质等级较高.海水环境质量呈现出由沿岸水域向中央海盆逐渐升高的趋势.渤海中部海域无明显富营养化状态,除表层13号站位外,表层、10m层、底层海水富营养状态指数法EI均小于l,表现为贫营养级水平.绝大部分海域氮磷比值高于Redfield比值,但未呈现富营养化水平,无机氮浓度升高,活性磷酸盐浓度降低,渤海中部水域营养盐结构由氮限制向磷限制转变,已经开始转变成磷限制中度营养状态.     

夏季和冬季辽东湾海域水体中叶绿素a含量分布特征

为研究辽东湾海域水体中叶绿素a含量的分布特征,于2013年8月(夏季)和12月(冬季)在辽东湾设置38个站位,分别采集了表、中、底层的海水样品,检测夏季和冬季两个航次水体中叶绿素a的含量,分析该海域叶绿素a的季节分布与空间变化特征。同时利用相关性统计分析的方法,将各水质因子对叶绿素a含量影响的差异显著性进行了分析。结果显示,调查海域夏季的叶绿素a平均质量浓度为6.90μg/L,冬季为1.26μg/L,时间分布上夏季质量浓度明显高于冬季;空间水平分布上,夏季辽东湾湾口的平均叶绿素a质量浓度明显高于湾内的平均质量浓度,而冬季则越靠近湾口处叶绿素a的平均质量浓度越低,与夏季规律正好相反;空间垂直分布上,夏季表层叶绿素a的质量浓度最高,10m层次之,底层的质量浓度最低;而冬季的叶绿素a质量浓度则呈现10m层最高,底层次之,表层质量浓度最低的趋势。说明辽东湾叶绿素a含量存在明显的时间和空间分布特征;结合同期的温度、盐度、溶解氧等环境因子的调查结果,统计分析结果表明调查海域中环境因子温度、盐度、溶解氧和营养盐的季节性变化是导致叶绿素a含量趋势变化的最可能原因之一。     

南海中部海域夏季叶绿素a浓度垂向分布特征

根据2014年7月~8月南海中部海域(12°N~18°N,110°E~117°E)调查获得的水柱方向上连续的叶绿素a浓度(Chl-a)数据,分析了南海中部海域夏季Chl-a垂向分布特征。结果表明:1)南海中部海域Chl-a垂向分布呈现先增加后减小的趋势,在30~70 m水层出现Chl-a高浓度区;2)次表层Chl-a最大值(subsurface chlorophyll a concentration maximum,SCM)强度变化为0.94~4.69 mg·m-3,平均为1.90 mg·m-3,是遥感表层Chl-a平均值的18.10倍,SCM深度变化为4~75.36 m,SCM厚度变化为19.01~80.36 m;3)从断面分布来看,局部海域Chl-a垂向分布受到上升流的显著影响,断面A上沿岸上升流区表现出明显的SCM强度大、深度浅和厚度大的特征,而断面B上中沙群岛岛礁上升流区同样表现出SCM强度大、深度浅的特征,但是厚度相对较小。     

夏季桑沟湾养殖水域有机碳的平面分布特征及其来源分析

根据2012年8月对桑沟湾养殖海域18个站位取得的溶解有机碳(DOC)、颗粒有机碳(POC)和叶绿素a(Chl-a)数据,基于不同区域的养殖特点,分析了DOC和POC的平面分布特征,并对POC的来源进行了初步探讨。结果表明,整个调查海域表层DOC的浓度范围为1.70～2.82mg/L,平均值为2.03mg/L,大致呈自西向东递减的趋势。表层POC的浓度范围为0.04～1.33mg/L,平均值为0.55mg/L,大致呈自南向北逐渐递增的趋势。网箱养殖区表层DOC和POC含量最高,其次为桑沟湾近岸海域,而海带养殖区最低,这表明有机碳的含量与养殖品种和模式有直接的关系。根据POC/Chl-a比值对POC来源进行初步分析,表明贝类养殖区、海带养殖区、贝藻混养区、桑沟湾近岸海域以及外海对照点的POC主要来自活的浮游植物,而网箱养殖区存在降解的有机物质。     

河口及近岸海域低氧环境对水生动物的影响

水体溶解氧浓度低于2 mg/L时,通常称水体为低氧或缺氧(hypoxia)。目前,中国的长江口等许多河口及近岸海域的底层水体出现了季节性低氧区,这些低氧区对鱼类等水生动物及海洋生态环境的影响目前仍不十分清楚,这应引起政府及研究部门的关注。本文综述了低氧区的成因,分析了低氧对水生动物的影响,特别是近年来研究较多的水生动物对低氧的分子响应研究进展,最后综述了低氧对海洋生态系统的影响。我国未来的研究应注重低氧区海洋物理、海洋生物等基础数据的收集,同时,要加强低氧区对我国主要渔场影响的研究。     

Habitat use of cownose rays (Rhinoptera bonasus) in a highly productive,hypoxic continental shelf ecosystem

Highly productive surface waters and hypoxic (dissolved oxygen, DO ≤ 2.0 mg L^?1) bottom waters develop seasonally on the northwestern Gulf of Mexico continental shelf due to nutrient and freshwater inputs from the Mississippi‐Atchafalaya River system. We investigated the spatial distribution of the cownose ray (Rhinoptera bonasus), a highly mobile, bentho‐pelagic species that is a seasonal resident of the shelf, in relation to surface chlorophyll, bottom‐water hypoxia, and other environmental variables (salinity, temperature, depth). We used synoptic trawl and aerial surveys to investigate ray distributions at both shelfwide (100–1000s km) and local (5–50 km) spatial scales. Shelfwide sampling indicated that rays were associated with regions of high surface chlorophyll and low bottom salinity and DO, conditions characterizing the Mississippi‐Atchafalaya plume region. Local sampling in and around the hypoxic zone indicated that rays preferred habitats where bottom waters were hypoxic but they primarily occupied normoxic (DO > 2.0 mg L^?1) waters above the bottom hypoxic layer. Stomach fullness and diet composition were similar between rays sampled in habitats with hypoxic versus normoxic bottom waters. These results indicate that cownose rays are strongly associated with riverine‐influenced regions of the shelf and preferentially use habitats with hypoxic bottom waters, perhaps for benthic foraging. Collectively, our results highlight the importance of considering the responses of mobile species to enhanced productivity and to hypoxia‐induced habitat degradation, which are both the products of coastal eutrophication.     

Demersal fish and invertebrate biomass in relation to an offshore hypoxic zone along the US West Coast

In August 2007, as part of the NOAA National Marine Fisheries Service (NMFS) West Coast Groundfish Bottom Trawl Survey, we examined the biomass of demersal organisms in a known hypoxic area off the Oregon coast. Although observed each summer, the intensity of hypoxia has varied annually (2002–2007) with the greatest temporal and spatial extent noted in 2006. In 2007 we identified the geographic extent of the hypoxic zone and sampled 17 stations along two depth contours (50 and 70 m) within the area. A Sea-Bird SBE 19 plus equipped with a dissolved oxygen (DO) sensor was attached to the bottom trawl to monitor oxygen concentration during each tow. Bottom DO concentrations at all stations were hypoxic with means along the tow tracts ranging from 0.43 to 1.27 mL L⁻¹. Total catch per unit effort (ln CPUE, kg hectare⁻¹) and species diversity (number of species, N ) were significantly and positively related to oxygen concentration along the hypoxic gradient. In addition, CPUE (natural log-transformed) for eight fish species and five benthic invertebrate species were significantly and positively related to bottom oxygen concentration within the hypoxic region. Condition factors for five fish species, as well as Dungeness crab ( Cancer magister ) increased with increased bottom oxygen levels along the hypoxic gradient. Historical catch (2003–2006) within the hypoxic zone indicates that biomass was significantly lower in 2006, the year with the lowest bottom DO levels, relative to other years.     

深型水库溶解氧分层规律及其机制探究——以万安水库为例

溶解氧（DO）是衡量生态状况的重要指标,对生态系统的平衡至关重要。为探究深型水库DO分层的规律及其影响机制,于2022年监测了九龙江万安水库的理化指标及营养元素的垂向分布,并分析库区的DO分层规律及影响因素。结果表明：2月属万安水库混合期,呈贫营养状态,DO垂向平均浓度高达6.70 mg/L,DO变化受浮游植物分布及“翻库”影响;5月属热分层形成期,处中营养状态,水体在内源产氧减少和原位DO消耗驱动作用下出现温跃层溶解氧极小值,36 m以下水体处于缺氧状态;8月为热分层稳定期,处中度富营养化,表层DO最大浓度达12.00 mg/L以上,在35 m深度出现DO极大值,水体热分层阻碍DO补充、内源产氧减弱是造成热分层稳定期水体上层大范围缺氧的主要原因;10月为热分层消退期,呈中营养状态,DO垂向平均浓度仅为0.77 mg/L,水深2.79 m以下水层皆处于缺氧状态。热分层时期DO垂向变化受到水体热分层、营养水平、污染状态及浮游植物生长分布等因素的影响,热分层从物理角度影响DO分层,营养水平及污染状态可以影响DO的产耗机制,而库区水体浊度通过影响浮游植物的垂向分布进而对DO浓度产生影响。本研究探明了水层缺氧及变温层DO极小值等现象出现的原因,深入探讨了DO变化规律与营养元素生物地球化学循环间的关系,为维护库区水生态健康提供科学依据。     

威海双岛湾人工鱼礁区刺参大面积死亡原因初探

2013年9月4日开始,威海双岛湾人工鱼礁区15 m以深水域,刺参出现大面积死亡.为了解致死原因,于9月6日开展了相关调查.结果表明,有害浮游生物与刺参死亡的相关性较小,缺氧水层的出现可能是刺参死亡的主要原因.在所调查的海区,缺氧水层的上界约为13 m～15.5 m,下界至海底.夏季的高温、多雨和少风导致温跃层和盐跃层出现,水体垂直循环受阻后在海底形成缺氧层.建议增殖生产中合理安排增殖放养密度,对海区增殖生物状况和底层溶解氧进行实时监测,开展预警、预报,合理安排采捕生产,以减少因底层缺氧造成的经济损失.     

溶解氧对团头鲂耐低氧新品系F5代的鳃组织形态及各组织酶活性的影响

为研究不同浓度溶解氧(DO)对团头鲂(Megalobrama amblycephala)耐低氧新品系F5代鳃组织形态以及各组织酶活性的影响,本研究将团头鲂在低氧[DO为(1.7±0.2) mg/L]和高氧[DO为(19.3± 0.5) mg/L]条件下分别处理0、4和7 d,恢复常氧[DO为(7.8±0.3) mg/L] 7 d后,通过石蜡切片观察鳃组织的形态,并测定了鳃、肝胰腺、肠道、肌肉中过氧化氢酶(CAT)、琥珀酸脱氢酶(SDH)及乳酸脱氢酶(LDH)活性和丙二醛(MDA)含量。石蜡切片结果显示,随着低氧处理时间的延长,团头鲂新品系鳃丝的层间细胞团体积减小,鳃小片表面积增加,恢复常氧7 d后又有所恢复。高氧条件下,层间细胞团体积增大,鳃小片表面积减小,恢复常氧7 d后也会恢复。酶活性检测结果显示,在低氧和高氧2种条件下,随着处理时间的延长,CAT活性和MDA含量在各组织中的变化无明显规律,但均有显著差异(P<0.05)。低氧条件下,LDH活性显著增高,SDH活性显著降低(P<0.05)。高氧条件下,LDH活性显著降低,SDH活性显著增高(P<0.05)。本研究可为溶解氧对团头鲂的鳃组织以及各组织酶活性的影响提供基础资料,并为团头鲂新品系的养殖与选育奠定基础。     

Influences of dissolved oxygen on juvenile largemouth bass foraging behaviour

Summer stratification often leads to large areas of hypolimnetic hypoxia in lakes and reservoirs. These areas of hypoxia alter fish behaviours and distributions as well as restrict access to valuable prey resources, yet few studies have examined foraging behaviour of fish in response to low dissolved oxygen (DO) concentrations. We observed foraging behaviour of juvenile largemouth bass, Micropterus salmoides, in response to varying DO concentrations in tanks that simulated a stratified lake water column during the summer: 28°C oxygenated epilimnion, 15°C deoxygenated hypolimnion. Compared with saturated concentrations (8.0–9.0 mg/L), hypolimnetic oxygen concentrations of 3.0 mg/L and 1.5 mg/L resulted in a drastic decrease in prey consumption, handling efficiency and time spent below the thermocline mainly due to avoidance behaviour of hypoxic conditions. However, we found at high hypolimnetic prey densities, individual fish were more willing to venture into reduced oxygen concentrations. Several unique behaviours including transporting prey above the oxycline for consumption, aquatic surface respiration and gill flaring were employed by largemouth bass foraging in low oxygen environments. Reduced hypolimnetic oxygen concentrations may influence and alter feeding strategies, especially for fish that rely on benthic prey resources.     

Effects of Limited Dissolved Oxygen Supply on the Growth and Energy Allocation of Juvenile Chinese Shrimp,Fenneropenaeus chinensis

Information about the effect of hypoxia exposure on energy allocation is helpful for better understanding how aquatic animals tolerate and adapt to a hypoxic environment. The growth, molting, and energy allocation were investigated in juvenile Fenneropenaeus chinensis exposed to five different dissolved oxygen (DO) seawaters (2.09 ± 0.15, 3.10 ± 0.29, 4.13 ± 0.25, 4.73 ± 0.12, and 5.48 ± 0.09 mg/L DO) for 30 d. When DO was below 4.13 mg/L, the growth of shrimp was depressed. Feed ingestion and feed conversion efficiency decreased with the decrease of DO. Less feed ingestion was caused by lower daily metabolic energy. Higher proportion of ingested energy lost in metabolism, exuviations, and nitrogen excretion caused lower feed conversion efficiency. More energy lost in exuviations, lower survival rate, soft carapaces of dead shrimp, and cannibalism were found in oxygen deficient groups and it implicated that hypoxia could delay the shrimp recovering from molting and cause cannibalism and higher mortality. The results indicated that hypoxia was an important factor affecting the amount and fitness of shrimp stock because it could cause a high rate of mortality and growth depression.     

Effect of Sublethal Hypoxia on the Immune Response and Susceptibility of Channel Catfish, Ictalurus punctatus, to Enteric Septicemia

The effect of sublethal hypoxia exposure on stress and immune responses and susceptibility to Edwardsiella ictaluri infection in juvenile channel catfish, Ictalurus punctatus, was investigated. Fish were monitored for temporal changes in glucose and cortisol concentrations before, during, and after 2 h exposure to sublethal hypoxia (<2 mg/L dissolved oxygen [DO]) and when maintained under normoxic conditions (6.0 ± 0.3 mg/L DO). Both blood glucose and plasma cortisol increased significantly in response to hypoxic conditions. Fish exposed to hypoxic or normoxic conditions were challenged with a high dose (1.3 × 10⁷ colony‐forming units [CFU]/mL) or a low dose (1.3 × 10⁵ CFU/mL) of E. ictaluri or sterile culture broth by 30‐min immersion bath. Approximately 1% of fish in both the normoxic and the hypoxic groups died when challenged with the low dose of E. ictaluri. However, when challenged with the high dose of E. ictaluri, catfish exposed to hypoxic conditions had significantly higher cumulative mortality (36 ± 12.1%) than those maintained under normoxic conditions (12 ± 1.1%). Total hemolytic complement and bactericidal activities and antibody response were lower in hypoxia‐exposed channel catfish, indicating that increased susceptibility of channel catfish to E. ictaluri may be the result of the immunosuppressive effects of the stress response to hypoxia.     

黄海绿潮（浒苔）暴发区温盐、溶解氧和营养盐的分布特征及其与绿潮发生的关系

根据2008年7月9～14日对黄海绿潮暴发区生态环境要素的调查数据,重点研究了调查海域温盐、溶解氧和营养盐的分布特征及其与绿潮发生的关系。结果表明,溶解氧的平均值为9.22mg/L,整体处于过饱和状态,呈北高南低,西高东低的分布趋势。溶解无机氮的平均值为9.07μmol/L,呈现出南高北低,苏北沿岸向离岸方向逐渐降低的趋势;活性磷酸盐的平均值为0.19μmol/L,呈现出东高西低,自外海向海洲湾方向递减的趋势。在调查海域的东部出现营养盐高值区。通过分析温度、盐度、溶解氧、营养盐与绿潮发生的关系发现,温度、盐度和溶解氧均处于浒苔藻体生长和孢子释放的适应范围内。大面积浒苔聚集区的表层海水DIN和PO34--P的平均含量分别为14.89和0.27μmol/L,营养盐含量要明显高于调查海域其他海区营养盐的含量,表明充足的营养盐是绿潮发生的物质基础。同时调查海区表层、10m层和底层N/P（摩尔比）比值的平均值分别为702、194和411,均远大于Redfield值,由此可见,该调查水域主要受到磷的潜在限制。