令人担忧的“美丽赤潮”

上图所显示的就是我们经常说起的赤潮现象。 进入21世纪以来，我国海洋赤潮灾害一直处于高发期。2001年全国海域共发现赤潮77次，累计面积达15，000多平方千米，比2000年增加49次，增加面积约5，000平方千米。其中，浙江海域发现赤潮26次，累计面积近7，000平方千米；赤潮灾害的特点是：发生时间提前、持续时间延长、主要赤潮生物种类增多、总次数和累计影响面积均有大幅度增加。     

河北省近海有害藻华灾害分级、时空分布和优势藻华生物变化特征

为研究1989—2013年河北省近海有害藻华灾害分级、时空分布和优势肇事生物变化特征,对河北省近海累计58次有害藻华记录的发生时间、位置与范围、面积和优势有害藻华生物种类进行了统计分析。结果表明:小型(面积0~100 km2)、中型(100~1 000 km2)、大型(≥1 000 km2)和面积不详的有害藻华中,小型藻华为多发性藻华,发生次数占全省海域累计发生次数的60.35%;5-8月份是藻华多发期,发生次数占累计发生次数的86.21%;2000年后藻华发生频率大增,由原来年均发生1次演变为年均发生4次;秦皇岛海域发生藻华次数最多,占全省海域累计发生次数的57.14%,沧州海域次之,唐山海域最少;秦皇岛海域发生藻华累计面积最大,占全省海域累计发生面积的64.25%,沧州海域次之,唐山海域最小。河北省优势海洋有害藻华生物共计15种,易发性藻华生物夜光藻Noctiluca scintillans引发藻华次数最多,占全省海域累计发生次数的44.83%,2009年前是河北省近海最主要的藻华肇事生物;高发性藻华生物抑食金球藻Aureococcus anophagefferens引发有害藻华累计面积最大,占全省海域累计发生面积的55.57%,2009年后该藻和夜光藻共同成为河北省近海优势藻华肇事生物。     

2005年春夏季东海赤潮过程中营养盐作用初探

自20世纪90年代以来,我国进入赤潮高发期,近岸海域赤潮的发生频率、波及范围和危害程度呈逐年上升趋势.受长江径流等陆源输入影响,东海海域形成了其特有的富营养环境,目前已经成为我国赤潮发生最严重的区域之一.该海域赤潮暴发呈现出发生时间不断提前、持续时间不断加长、发生面积不断扩大、有毒有害藻类逐渐增加的特点[1-2].据统计,自2000年以来,我国沿岸海域共发生赤潮约480次,累计面积超过104000km2.其中,仅在东海海域发生赤潮的次数就占全国记录总数的60%,发生面积更是达到了70%以上[3],其发生频率和规模均远远高于我国其他3个海区.     

制约我国洗涤剂禁磷的症结何在

赤潮已被世界公认为海洋中的三大灾害之一,近些年来我国的赤潮发生数量猛增了3倍多,已是世界上赤潮多发生率国家。由于海洋赤潮发生的突然性、面积大及其他复杂的原因所致,至今没有找到彻底根治的办法。目前能防止赤潮发生的有效措施是将洗涤剂禁磷,即禁止生产、销售、使用含有磷酸盐的各种洗涤剂,从而减少含磷洗涤剂废     

浙江近岸海域赤潮事件时空分布特征研究

利用浙江省海洋灾害公报中2006—2017年的赤潮灾害数据,分析了浙江近海赤潮的年、月和季节尺度的变化规律,同时分析了浙江近海赤潮的空间分布规律。将自适应带宽核密度分析方法应用于赤潮灾害研究,分析了浙江近海不同海域受赤潮影响的程度。研究结果表明:浙江海域赤潮高发于春末和夏季,5月是发生峰值期;从年际情况看,近年来赤潮发生的累计次数和面积呈上升趋势;浙江省赤潮主要发生在5个海域,按受赤潮影响的程度由高到低依次为舟山本岛、嵊泗列岛、温州、宁波和台州。     

苏北灌河口邻近海域氮、磷污染物环境容量研究

本文基于苏北灌河口近岸海域三维水质模型,按照江苏省海洋功能区划的水质要求,采用自净过程积分方法,计算了氮和磷营养盐的环境容量。结果表明,研究海域无机氮和活性磷酸盐年海洋环境容量分别约为6 000和6 00t/a,具有明显季节变化特征,夏季最高,环境容量分别约为2 900和260t,其次是春季,分别约为1 400和140t,冬季和秋季最低,分别平均约为1 000和90t。对比分析现状污染负荷,研究海域无机氮、活性磷酸盐总量削减率分别相当于当前无机氮、活性磷酸盐入海负荷的55%、73%以上,研究结果可为江苏省北部灌河口沿海城市陆源污染物总量控制提供科学依据。     

6-8月我国赤潮发生次数和面积大幅减少

国家海洋局近日发布的赤潮监测情况显示：今年6～8月，全国海域共发现赤潮15次，累计面积2874平方千米，与2007年同期相比，赤潮次数减少29次，累计面积减少2984平方千米。而且，今年的赤潮分布趋势有所不同。往年6—8月，全国赤潮主要分布于浙江沿岸海域，福建厦门、霞浦、黄岐近岸海域，广东深圳沿岸海域和青岛、秦皇岛、天津、黄骅等渤黄海沿岸海域。     

新世纪渤海污染新特点

渤海的污染状况,在新世纪呈现出若干新特点。从污染程度和区域变化来看,新世纪渤海污染总面积总体上呈波动减小趋势,但近岸海域的污染程度却显著加重。从赤潮发生情况来看,渤海赤潮年发生次数由20世纪90年代的1位数上升至2位数;进入21世纪以来虽然赤潮年发生次数在逐渐减少,但赤潮面积总体上呈增大趋势,而且有毒藻类引发的赤潮次数和面积大幅增加。从渤海的主要污染物——营养盐浓度和比例的变化来看,近年来渤海近岸海域营养盐浓度(N、P)则呈加速增大趋势,N/P比值增幅达50%,而Si/N比值已降至0.5左右。从污染源变化来看,海上污染源的增速明显高于陆源。     

我国海域赤潮发生与海温及厄尔尼诺的相关分析

分析2000年以来我国海域赤潮发生次数和面积,以及期间与厄尔尼诺指数关系,分析认为①海域表温对我国4个海域赤潮发生有较显著影响.②2000～2007年4个海域发生的赤潮次数:东海>渤海>南海>黄海;2000～2007年4个海域赤潮发生面积:东海>渤海>黄海>南海.③1986～2007年厄尔尼诺对赤潮发生次数有一定的影响,4个海域赤潮发生次数与厄尔尼诺的相关程度不同:东海>南海>渤海>黄海,其中1999年后厄尔尼诺对中国近海赤潮发生次数具有显著影响.④1977～2007年发生的10次厄尔尼诺事件对厄尔尼诺年的次年我国海域赤潮发生的次数有比较显著的影响.     

福建主要港湾的水质单项评价与综合评价

根据2000年和2001年福建主要港湾的水质监测资料，对福建16个港湾的海洋环境质量进行了评价．结果显示：福建部分港湾的无机氮和活性磷酸盐超过二类海水水质标准．局部海域已达到富营养化，要重视和防范赤潮的发生和危害．有些港湾还存在不同程度的污染，其综合评价指数在0．43～1．07之间．     

Letters to the editor

A preliminary scuba survey of oligotrophic Lake Rotoma in 1972 revealed a vegetation mainly composed of native hydrophytes in which exotics were at an early stage of colonisation. In 1973 the presence of species was recorded in 5708 quadrats (625 cm²) at 1 m intervals along a total of 50 line transects placed systematically around the lake. Water depth was measured, and quadrat cover and substrate type were subjectively estimated. Species frequency calculations showed that the dominant vegetation pattern was a characean meadow of Chara fibrosa f. acanthopitys (A.Br.) R.D.W., Nitella leptostachys var. leonhardii (R.D.W.) R.D.W., and N. pseudoflabellata var. mucosa (Nordst.) Bailey. The charophytes extended over a depth range of 1–17.5 m on a wide variety of substrates and gradients. Native vascular plants were absent from many transects, and had a depth range only from 0 to 4.5 m, with most occurring above 3.5 m. The Low Mixed Community, found in shallow water less than 1.25 m in depth at the northeast end of the lake, provided this area with a high species diversity. Exotic hydrophytes had established in many areas around the lake. The distribution of Lagarosiphon major (Ridley) Moss and Elodea canadensis Michx. appeared to coincide with boating access and fallen submerged trees over a depth range of 0–6.0 m, although much of the available habitat had not yet been exploited. Emergent species were most abundant within the southwest inlet and also in the lagoons surrounding the lake where sheltered conditions and shallow gradients prevail.     

Letter to the Editor

Many shortcomings in the recent paper by Muraleedharan, Rao, Kurup, Unnikrishnan Nair and Sinha [Coastal Engineering, 2007, in press] are pointed out.     

Letter to the editor

It is a common observation that the mean length in a fish population progressively decreases as the biomass is reduced by fishing. However, this has not happened with the population of orange roughy (Hoplostethus atlanticus) on the Chatham Rise, New Zealand, even though the biomass is estimated to have declined by almost 80%. Because orange roughy are slow growing it might be expected that mean age (or its proxy, mean otolith weight) would be a more sensitive indicator of biomass decline than mean length. A simulation study shows that this is not true. With equal sample sizes, all three indicators are equally sensitive; on an equal cost basis, mean length is more sensitive than the others. A log transformation increases the sensitivity of age and otolith weight, but it is not clear whether this increase is sufficient to outweigh the much greater costs of measuring age and otolith weight, compared to length. Under the assumption of constant recruitment, it is more likely than not (P = 0.55–0.8) that a change in mean length would have been detected in the Chatham Rise population, given the estimated biomass decline.     

Letters to the editor

Re: Kirby, D. S.; Abraham, E. R.; Uddstrom, M. J.; Dean, H. 2003: Tuna schools/aggregations in surface longline data 1993–98. New Zealand Journal of Marine and Freshwater Research 37: 633–644.     

Letters to the editor

Species composition and biomass of plankton samples taken on transects across an upwelling plume off Farewell Spit in February 1981 are presented. Copepods were numerically dominant, particularly Oithona similis and Paracalanus indicus. Also abundant were large phytoplankters (Chaetoceros sp. and Trichodesmium sp.), crustacean faecal pellets, and euphausiid larvae. The distribution of zooplankton species suggests mixing of inshore waters and neritic populations with upwelled waters. These data are discussed with respect to an interpretation of the upwelling system as a northwards transport of zooplankton and its enhanced productivity into the South Taranaki Bight.