广西北海西村港互花米草对红树林湿地大型底栖动物群落的影响

为了解互花米草(Spartina alterniflora)入侵红树林的生态影响, 作者对位于北海市西村港的红树林湿地以及周边互花米草盐沼的大型底栖动物群落多样性和群落结构进行了研究。2012年10月至2013年9月连续4次取样, 按照取样时间研究大型底栖动物的种类、物种组成、生物量和生物多样性等群落特征的差异, 探讨互花米草入侵红树林湿地对大型底栖动物的影响。本研究共采集底栖动物16种, 隶属于5门7纲15科, 其中互花米草群落10种, 红树林湿地12种。研究发现互花米草入侵后中国绿螂(Glauconome chinensis)个体数量剧增, 导致不同采样时间互花米草盐沼的大型底栖动物生物量均显著高于红树林湿地; 除个别月份外, 红树林湿地大型底栖动物的Margalef丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数均显著高于互花米草群落。基于生境-采样时间的双因素方差分析结果表明, Shannon-Wiener多样性指数和Simpson指数在两种生境间差异显著; 两种生境的Margalef丰富度和Pielou均匀度指数在不同采样时间差异显著; 大型底栖动物生物量和物种数量在两种生境间和不同采样时间差异均显著。基于多元回归分析的研究结果表明, 互花米草密度是影响大型底栖动物生物量的关键因子, 而互花米草株高可以解释物种个体数量、Shannon-Wiener多样性指数和Simpson指数在两种生境的变化。对不同采样时间大型底栖动物群落结构的非度量多维度(non-metric multidimensional scaling, NMDS)分析结果表明, 红树林与互花米草群落的大型底栖动物群落相似性很低。总而言之, 在西村港地区, 互花米草入侵虽然增加了大型底栖动物的生物量, 但由于优势物种的凸显, 显著降低了大型底栖动物群落的多样性, 且种类组成与群落结构与红树林群落相比已有差异。由此可见, 互花米草入侵红树林对当地的大型底栖动物群落多样性造成影响。     

互花米草入侵对大型底栖动物群落垂直结构的影响

2012年8月,在浙江省玉环县漩门湾国家湿地公园,利用自制分层采样器,以5 cm为单位对0—25 cm泥层进行分层取样,研究潮间带互花米草滩涂和自然滩涂两种生境中大型底栖动物的垂直分布情况,以及互花米草入侵对大型底栖动物垂直结构的影响。两种生境中共获得大型底栖动物40种,其中软体动物18种,甲壳动物13种,环节动物4种,其他类群5种。在自然滩涂生境中获得的物种数为30种,互花米草生境为31种,两种生境的共有种有21种。互花米草和自然滩涂生境平均栖息密度分别为222.6株/m2和1052.8株/m2。研究结果表明:(1)大型底栖动物主要栖息在0—10 cm泥层深度;(2)大型底栖动物群落沿泥层深度存在分层分布现象;(3)互花米草入侵缩短了底栖动物的垂直分布距离,但对其主要栖息深度影响不大;(4)互花米草入侵改变了原来生境特征,导致大型底栖动物的群落结构发生变化。     

长江口盐沼湿地不同亚生境的大型底栖动物群落组成和多样性差异

2015年7月—2016年6月每月在长江口盐沼湿地采集潮沟、光滩和盐沼(以海三棱藨草为主)三种亚生境的大型底栖动物样本,分析其群落组成和多样性差异。结果表明:共采集到大型底栖动物21种,隶属4门、5纲、15科,以软甲纲(7种)和多毛纲(4种)种类较多;潮沟和盐沼亚生境的优势种无差异;盐沼底栖动物物种数最高,潮沟次之,光滩物种数最低;盐沼底栖动物的密度和生物量均高于其他2种亚生境;三种亚生境的大型底栖动物密度两两间差异显著(P0.05),而生物量无显著差异(P0.05);盐沼底栖动物群落的Shannon多样性指数最高(1.08),光滩次之(1.03),而潮沟最低(0.63);光滩底栖动物群落的Simpson物种丰富度指数、Pielou均匀度指数值均高于潮沟和盐沼,反映光滩底栖动物群落种类密度的分布相比其他2种亚生境较为均匀;通过群落聚类和非度量多维标度分析发现,盐沼和潮沟亚生境的大型底栖动物群落结构较为相似,而与光滩差异较大,引起两者差异的主要贡献种是谭氏泥蟹、河蚬、背蚓虫等。     

灵昆岛围垦区内外滩涂大型底栖动物生物多样性

2006年2月至2006年11月在灵昆岛东滩湿地选择1997年围垦潮沟滩涂以及围垦区外的自然滩涂作为样地,开展了自然滩涂与围垦潮沟滩涂大型底栖动物群落生物多样性比较的调查研究.共发现大型底栖动物36种,隶属7门8纲22科,这些物种中软体动物、节肢动物和环节动物共占物种总数的83.33%.其中在围垦区内的4个样点共发现大型底栖动物27种,在自然滩涂上的4个样点共发现大型底栖动物32种.通过对定量取样获得的各群落大型底栖动物密度数据进行计算,得到了各种大型底栖动物的生态位宽度和围垦区内外不同生境中大型底栖动物群落生物多样性指数(Shannon-Weiner指数 H'、Pielou指数 J、Simpson指数 D),结果显示围垦滩涂潮沟上的光滩和边滩以及自然滩涂上的高潮带和中潮带滩涂的Shannon-Weiner多样性指数 H'较高,Simpson优势度指数D则相对较低,表明了这些位点的大型底栖动物的多样性程度较高,而长满互花米草(Spartina alterniflora)位点的Shannon-Weiner多样性指数 H'和Pielou均匀度指数 J都要小于受潮水作用相似的邻近滩涂,但Simpson优势度指数D却相对较高,这表明互花米草入侵已改变了原来的大型底栖动物群落结构.运用相似度指数Jc、成对t检验以及聚类和排序等多种统计学方法对围垦滩涂潮沟和自然滩涂上的各个位点进行了群落相似性分析,结果表明潮位是影响自然滩涂上大型底栖动物分布的一个重要因素,不同潮位之间的大型底栖动物群落差异比较明显.相对而言,围垦区内各生境之间的大型底栖动物群落分化程度较低,即围垦导致潮位因素对大型底栖动物的分布的影响降低.     

长江口互花米草生长区大型底栖动物的群落特征

2005年对长江口潮滩湿地互花米草(Spartina alterniflora)生长区不同季节大型底栖动物群落特征的研究表明:长江口互花米草生长区的大型底栖动物有21种,其中甲壳纲10种、多毛纲5种、腹足纲5种、辨鳃纲1种.主要种类有拟沼螺(Assiminea sp.)、背蚓虫(Notomastus latericeus)、尖锥拟蟹守螺(Cerithidea largillierli)、中国绿螂(Glauconome chinensis)、钩虾(Gammaridae sp.)等.食性功能群均以碎屑食者和植食者为主.大型底栖动物平均栖息密度为(650.5±719.2)个/m2,标准误主要是由于北湖的拟沼螺密度很大.栖息密度从大到小的顺序为沿河口梯度从内到外分布的北湖边滩、崇明东滩、金山卫边滩.大型底栖动物群落分布不均匀,沿河口梯度变化存在明显的空间差异.栖息密度和物种多样性在夏季最高,冬季最低.大型底栖动物平均生物量为(20.8±6.1)g/m2,季相变化为夏季＞秋季＞春季＞冬季.BIO-ENV分析表明沉积物粒径和盐沼高度是大型底栖动物群落特征的主要影响因素.不同研究结果的差异除了时空因素外可能与互花米草的种群动态有关.加强不同时间尺度的研究有助于正确评价互花米草对大型底栖动物的影响.     

长江口东滩湿地芦苇生境大型底栖无脊椎动物群落结构的月动态

2015年5月至2016年4月对长江口东滩湿地芦苇生境的大型底栖无脊椎动物群落结构进行监测,分析了该生境下底栖动物群落物种组成和多样性的月变化.结果表明: 芦苇株高和盖度均在3—8月逐渐增大,9月后逐渐降低;芦苇密度和地上生物量(干质量)均在7月达到最大值.调查期间,共发现大型无脊椎底栖动物20种(包括2种鉴定到属,2种鉴定到科).其中,腹足纲种类最多,有11种(包括1种鉴定到属);软甲纲有5种;昆虫纲和多毛纲均只有2种.以緋拟沼螺、堇拟沼螺和尖锥似蟹守螺等为主要优势种.从生活型来看,底上附着型种类数最多(11种),其次为穴居型(5种)和底内型(4种).大型底栖动物密度和生物量存在明显的季节或月变化,夏季(8月)出现全年最高值.Margalef物种丰富度指数(D)和Shannon指数(H)月份间差异显著,Pielou均匀度指数(J)月份间差异不显著(除11月).大型底栖动物群落在42%相似性水平上划分为3个群聚.从非度量多维标序(nMDS)排序图可知,5月、10—11月与其他月份差异较大.水温、芦苇地下生物量和盐度等环境因子对于底栖动物密度变化具有一定影响,但未达到显著水平(P>0.05).受人类活动的持续影响,长江口东滩湿地芦苇生境底栖动物群落物种多样性有所下降,芦苇生境价值急需重视.     

围垦对南汇东滩湿地大型底栖动物的影响

为评价围垦促淤工程对南汇东滩湿地大型底栖动物生态学的影响,根据2004年10月和2009年10月对南汇东滩湿地底栖动物的定量定性调查数据,进行对比分析。结果表明:2004年共采集到大型底栖动物32种,其中在经围垦促淤后形成的堤内、堤外两个区域分别采集到底栖动物20种和21种,2009年堤内外分别为9种和19种,共26种;2004年堤内和堤外优势种分别为8种和4种,共有优势种为中华蜾蠃蜚和谭氏泥蟹,2009年堤内优势种仅有摇蚊幼虫1种,堤外有4种,优势种种类组成也发生了很大变化;2004年大型底栖动物的平均丰度和生物量分别为44.15个/m2和38.80 g/m2,2009年为86.76个/m2和1.97g/m2,2009年堤内、堤外的生物量与2004年相比明显降低,丰度变化则相对较小;运用SPSS软件的单因素方差分析、群落聚类和MDS排序对南汇东滩湿地各断面进行群落结构分析,结果表明围垦是大型底栖动物群落结构改变的一个重要因素,围垦造成堤内底栖动物群落结构发生了明显差异,堤外群落结构变化相对较小。大型底栖动物的生物多样性指数(Shannon-Weiner指数H'、Pielou均匀度指数J'、Margalef物种丰富度指数d和Simpson指数D)受到围垦促淤工程的影响均降低,尤其以围垦圈淤的堤内湿地生物多样性指数最低。围垦促淤工程对盐度、潮汐动力、底质特征的改变以及人类活动等因素是影响大型底栖动物群落结构的主要原因,工程结束后的湿地生态修复十分必要。     

人工拔除互花米草对红树林大型底栖动物群落的影响

【背景】大型底栖动物群落是红树林生态系统结构与功能的重要组成部分。大型底栖动物群落及其所在的红树林生态系统正遭受严重的人类活动介导的多种侵扰,如烈性入侵植物互花米草的入侵。很多研究调查了红树林生态系统底栖动物群落对互花米草入侵的响应,但互花米草移除对生物群落的影响鲜有报道。【方法】选取位于山口国家级红树林保护区的3个断面(山角、永安和北界),分别在3个断面定量采集互花米草拔除前和拔除后的底栖动物,比较其物种组成、栖息密度和生物量,研究人工拔除互花米草对红树林大型底栖动物群落结构的影响。【结果】大型底栖动物群落在互花米草拔除前后发生了显著变化:在选取的3个断面上共观测到1~3种拔除前后共有的物种,且优势种在3个断面上均发生了变化;物种丰富度在2个断面(永安和北界)上略有增加,在一个断面(山角)上降低;在3个断面上,互花米草拔除后生物的栖息密度和生物量都显著降低。【结论与意义】底栖动物群落的这些显著变化会对其栖息地内以及周边红树林生态系统的食物网结构及红树林的生态功能产生重要影响,因此当大规模人工移除互花米草时,需充分考虑这些变化可能带来的负面影响,制定合理、有效的互花米草清除策略,保护脆弱的红树林生态系统。     

茅埏岛不同生境大型底栖动物生物多样性

2012年11月—2013年10月,对浙江台州茅埏岛不同生境下的大型底栖动物进行了4次取样调查,比较了红树林、互花米草和光滩生境下大型底栖动物的生物多样性及季节变化。共检出大型底栖动物48种,隶属8门9纲28科,其中软体动物、节肢动物和环节动物占总物种数的83.3%。用定量取样的密度数据计算大型底栖动物的Shannon指数、Pielou指数、Margalef指数、Simpson指数和G-F多样性指数,结果表明:互花米草生境在物种种数和栖息密度上均低于光滩和红树林生境,物种种数在季节上春夏两季高于秋冬两季;从Shannon指数和G-F多样性指数上看,红树林生境下大型底栖动物的多样性高于光滩与互花米草生境;红树林间,红树幼林大型底栖动物物种多样性低于6年生和8年生红树林,而科属多样性高于后两者。生境和季节是影响大型底栖动物分布的重要因素。     

长江口互花米草生长区大型底栖动物的群落特征

2005年对长江口潮滩湿地互花米草（Spartina alterniflora）生长区不同季节大型底栖动物群落特征的研究表明：长江口互花米草生长区的大型底栖动物有21种，其中甲壳纲10种、多毛纲5种、腹足纲5种、辨鳃纲1种。主要种类有拟沼螺（Assiminea sp.）、背蚓虫（Notomastus latericeus）、尖锥拟蟹守螺（Cerithidea largillierli）、中国绿螂（Glauconome chinensis）、钩虾（Gammaridae sp.）等。食性功能群均以碎屑食者和植食者为主。大型底栖动物平均栖息密度为(650.5±719.2)个/m²，标准误主要是由于北湖的拟沼螺密度很大。栖息密度从大到小的顺序为沿河口梯度从内到外分布的北湖边滩、崇明东滩、金山卫边滩。大型底栖动物群落分布不均匀，沿河口梯度变化存在明显的空间差异。栖息密度和物种多样性在夏季最高，冬季最低。大型底栖动物平均生物量为(20.8±6.1)g/m²，季相变化为夏季>秋季>春季>冬季。BIO-ENV分析表明沉积物粒径和盐沼高度是大型底栖动物群落特征的主要影响因素。不同研究结果的差异除了时空因素外可能与互花米草的种群动态有关。加强不同时间尺度的研究有助于正确评价互花米草对大型底栖动物的影响。     

洋山港潮间带大型底栖动物群落结构及多样性

2009-2010年在洋山港海域大洋山岛和圣姑礁进行四个季度潮间带大型底栖动物生态学研究。共采集到大型底栖动物61种,以广布种为主,部分为河口低盐种,其中软体动物22种,环节动物16种,节肢动物12种,苔藓动物5种,腔肠动物4种,星虫动物和棘皮动物各1种。优势种为短滨螺(Littorina brevicula)、多齿围沙蚕(Perinereis nuntia)、日本笠藤壶(Tetraclita japonica)、齿纹蜒螺(Nerita yoldii)和特异大权蟹(Macromedaeus distinguendus)。丰度和生物量在不同季节明显不同(P<0.05):丰度的最高值出现在春季,为(3204.9±837.84)个/m²,最低值出现在秋季,仅为(2213.2±731.27)个/m²;生物量的最高值则出现在夏季(2233.2±1493.42)g/m²,冬季最少,仅为(819.95±484.80) g/m²。大洋山岛和圣姑礁的丰度和生物量具有较大差异(P<0.05):年均丰度以大洋山断面较高,为(3090±742.74)个/m²,圣姑礁断面较低,为(2133±372.51)个/m²;而年均生物量则以圣姑礁断面较高,为(1711.1±1180.76) g/m²,大洋山断面较低,仅为(1028.5±627.61) g/m²。运用ABC曲线、等级聚类和MDS对大型底栖动物群落结构分析发现:大洋山潮带间大型底栖动物群落尚未受到干扰或干扰较轻,群落结构相对稳定;而圣姑礁断面的潮间带大型底栖动物群落受到了中度的干扰,群落结构稳定性下降。与15年前的研究相比,圣姑礁大型底栖动物的密度和生物量均有大幅度的降低,这与洋山港海域盐度的升高、生态环境变化和人为干扰强度增加等有关。     

2011—2020年长江口大型底栖动物群落结构变化趋势

对2011—2020年夏季长江口48个站位的大型底栖动物定量监测数据进行统计分析,研究长江口海域底栖生物群落时空结构演变特征。结果表明,近10年长江口海域共鉴定大型底栖动物284种,其中多毛类128种,占总种数的45.1%,甲壳类64种占22.2%,软体动物56种占19.7%,棘皮动物16种占5.6%,其他类合计20种。平均生物密度为(79.5±45.9)个/m²(年份变幅14.7—195个/m²)。平均生物量为(5.20±3.25)g/m²(年份变幅1.01—10.11g/m²),多毛类、软体动物、甲壳类是生物密度和生物量组成的主要类群。十年期间种类数、生物密度和生物量均呈现明显上升趋势,口外区贡献最突出。四个监测区域(南支、北支、杭州湾、口外)的优势种差异大。丝异须虫Heteromastus filiformis在各年份的优势种中出现的频度显著最大。总体来看,长江口监测区域大型底栖动物群落自然演变趋势向好。三项多样性指数统计结果表明,口外区大型底栖动物种类组成多样性水平显著高于口内三个区。生物群...     

Peculiarities of the population of <Emphasis Type="Italic">Bythotrephes brevimanus</Emphasis> lilljeborg, 1901, in lake pleshcheevo (the Upper Volga Basin)

The morphological and biological features of Bythotrephes—a relatively rare crustacean in Lake Pleshcheevo—have been identified on the basis of vast material (several hundreds of individuals) collected in August 2010. The individuals were distinguished by a minimal body size, short caudal appendix, absence of a loop, and very small caudal claws and were identified as Bythotrephes brevimanus Lilljeborg, 1901. The morphology of the crustacean corresponds to the high water mineralization in the lake and the relative stability of the environment. Some peculiarities of molt and growth of the crustacean were distinguished. A chitinous integument of the caudal appendix formed during embryogenesis has a different structure than chitin formed during further molts. In August, the population of B. brevimanus in different areas of the lake was stable and consisted only of juveniles and parthenogenetic females (80%) (4–6 eggs). The largest number of crustaceans (150 ind./m³) was recorded in the periphery of the depression above depths of 6–7 m; 80 ind./m³ were recorded above depths of 11–12 m; and, above the depression, there were less than 30 ind./m³. The small density of crustaceans in the pelagial depends on the intensive grazing of this food object selected by fish in especially transparent water (color 15–20 and transparency 300–600 cm).     

Food supply in intertidal area for shorebirds during stopover at Chongming Dongtan, China

The wetland in Chongming Dongtan, China is an important stopover site for migratory shorebirds along the East Asian-Australasian Flyway. The high-abundance macrobenthos in Chongming Dongtan allow migratory birds to refuel during the stopover. This study analyzed the distribution and density of macrobenthos in the intertidal zone. Results showed that the macrobenthos mainly consisted of gastropods, bivalves, polychaetes, crustaceans and insect larvae. The density of gastropods [(2805 ± 360) ind./m²] was the highest, accounting for up to 80% of the total macrobenthos density. Meanwhile, bivalves [(51.4 ± 7.8) g/m²] and gastropods [(38.7 ± 5.1) g/m²] together accounted for more than 90% of the total biomass. On the other hand, there were significant differences in the distribution of macrobenthos among different intertidal zones. Gastropods were mainly confined to the Scirpus zones, and bivalves to the outer Scirpus zone and the muddy and sandy flats. In terms of the spatial distribution of density, the gastropod density was higher in the north but lower in the south. However, no significant difference was found in the density and biomass of macrobenthos groups between spring and autumn, except that the density of bivalves in autumn was significantly higher than that in spring (P < 0.001).     

Impact of long-term alternations of discharge and spate on the chironomid community in the lowland Widawka River (Central Poland)

Spatial and temporal distribution, abundance and production of macroinvertebrate communities were estimated over two years in a fifth-order section of the Widawka River. Discharge of this river has been increased artificially by coal mine water inputs. Additionally, during the second year, one of the highest discharges of the current 20-year period was recorded. Chironomidae were co-dominant in macrobenthos, both in a straight reach (WIA) and in a meandering site (WIB). More mosaic habitats resulted in higher densities of midges, reaching 6215 ind.m^–2 in year 1 and 1141 ind.m^–2 in year 2 at WIA, while at WIB 896 densities were ind.m^–2 and 257 ind.m^–2, respectively. Flooding affected the distribution and abundance of the chironomid assemblages. Recolonization by psammophilous Polypedilum began after the various microhabitats were buried with sand. Chironomid production was estimated on a species-specific basis for the dominant taxa. In year 1 (mean annual water temperature 10.0° C) chironomid production was 12.4 g dry wt m^–2 yr^–1 1 at WIA and 1.9 g dry wt m^–2 yr^–1 at WIB. These values sharply decreased in year 2 (mean annual water temperature 9.8° C) reaching 1.9 g dry wt m^–2 yr^–1 at WIA and 0.4 g dry wt m^–2 yr^–1 at WIB, as effects of the high spate.     

Production and population dynamics of Tubifex tubifex in the profundal zone of a freshwater reservoir in N. Italy

During a study of a pumped storage system from May 1979–June 1980 the profundal macrobenthos of the upper reservoir (Lago di S. Maria Valvestino) was sampled at a fixed station and the population of the tubificid Tubifex tubifex studied in detail. Eggs, embryos and the individuals living in an extra-cocoon stage were counted and individually weighed from monthly samples, according to the methods described in Bonomi & Di Cola (1980). Numerical recruitment during the study period was estimated as 257 000 ind m^–2 yr^–1; of which 110 000 died either as eggs or as embryos, i.e. inside the cocoons, and a further 128 000 died before they attained sexual maturation. The data seem to confirm the typical demographic strategy of T. tubifex i.e. high fecundity and high mortality in the early life stages. The total annual production of the species was estimated at 91.7 g (w.w.) m^–2. The low P/B ratio (2.0 yr^–1) is considered to be mainly due to high population densities.     

Distribution and abundance of postlarval and juvenile Pleuragramma antarcticum (Pisces, Nototheniidae) off Terra Nova Bay (Ross Sea, Antarctica)

During the Italian Antarctic Expedition of 1987–1988 zooplankton was collected in Terra Nova Bay (Ross Sea) by a multinet BIONESS (250-μm or 500-μm net mesh size). The early life history of Pleuragramma antarcticum was described from 268 samples. More than 98% of a total of 34,436 fish larvae belonged to P. antarcticum. The mean relative abundance in the whole area for positive 0 to 150-m hauls was 434 ind./100 m³ (±720 SD). Postlarvae were most abundant and frequent in the samples (99.8%) while low concentrations of juveniles were found (n=67). Length of age group 0 ranged from 8 to 20 mm and age group 1+ were from 36 to 53 mm. Average growth rate over a period of 1 year was 0.08 mm per day. Based on modal values, the mean daily increment of P. antarcticum postlarvae in the period 5 January to 2 February (29 days) was about 0.21 mm. Highest abundances occurred near Cape Washington (mean: 2,108 ind./100 m³) while lower densities were recorded in the northern basin of the self (31 ind./100 m³). Horizontal and vertical distribution patterns in Terra Nova Bay seem to be strictly correlated to hydrographic features and different water masses with highest densities associated with the westward flowing current of the limb of the Antarctic coastal current and southern limb of the Ross Sea Gyre. These currents become part of the clockwise gyre in Terra Nova Bay. More than 62% of the postlarvae were collected in well-stratified warm surface water (0–50 m) near the summertime thermocline (20–70 m). The northern part of Terra Nova Bay seems to represent nursery ground of early stages of P. antarcticum and the presence of permanent polynya could provide favourable food conditions for development of the first stages of life. Differing distribution patterns probably reflect an interaction of various parameters including bathymetry, floating ice shelf, hydrographic features such as currents, local eddies and frontal systems, with P. antarcticum postlarval biology (spawning) and ecology (feeding, horizontal and vertical distribution patterns). Received: 10 June 1996 / Accepted: 19 July 1997     

The influence of coastal upwelling on the distribution of Calanus chilensis in the Mejillones Peninsula (northern Chile): implications for its population dynamics

A field experiment was carried out in October 1998 during active upwelling in a coastal area off the Mejillones Peninsula (23° S). Zooplankton was sampled at day and night, during two subsequent days at 4 stations inside and outside of the upwelling plume. Three depth strata were sampled: 0–20 m, 20–80 m and 80–200 m. Oceanographic data were obtained in a grid of 23 stations using a CTDO, a fluorometer and a Doppler current meter. Calanus chilensis was mostly represented by late stages, i.e. copepodid C5 and adult males and females. There were no day/night effects on vertical distribution, and abundance was significantly higher inside the upwelling plume in the upper 20-m layer at nearly 14 ind. m^–3, compared to ca. 5 ind. m^–3 outside the upwelling plume. Temperature at 10 m depth and biomass, estimated from stage numbers and their mean dry weights, were used to estimate growth and daily production of Calanus at temperature-dependent rates. The potential loss of biomass from the upwelling center because of advection in the upwelling plume was estimated from current data in the Ekman layer and biomass density. The mean cross-shelf component of the current was estimated at 10.4 km d^–1 within the upwelling plume. This yielded a loss of biomass of 9.7 mg dry weight m^–2 . Production, estimated by a temperature-dependent approach, ranged between 44 and 35 mg dry weight m^–2 d^–1, at mean temperatures of 14.6 °C and 15.8 °C inside and outside of the upwelling plume respectively. Within the plume, as much as 22% of daily production may be advected offshore. However, a higher concentration of biomass in the upwelling plume allowed a greater production compared to surrounding areas. A mass balance approach suggests that advective losses may not have a major impact on the C. chilensis population, because of very high daily production at temperature-dependent rates.     

Distribution and special traits of naturalization of new and rare zooplankton species in waterbodies of the Upper Volga basin

More than ten new zooplankton species were registered in reservoirs of the Upper Volga during 2002–2005. Since 2003, the cladoceran Diaphanosoma orghidani Negrea, had intensively settled in different biotopes of Ivankovo, Uglich, Rybinsk, and Sheksna reservoirs and is the most abundant (16 000 ind./m³) in the latter one. The rotifer Asplanchna henrietta Langh. was found for the first time in Rybinsk Reservoir in 1985, and by 2004, this species had also occurred in Ivankovo, Uglich reservoirs, Lake Nero, and some small waterbodies of the basin. In Lake Nero its density reaches especially high values (>1 million ind./m³). Causes, mechanisms, and ecological consequences of the expansion of new zooplankton species are discussed.