渤海水母类生态的初步研究——种类组成、数量分布与季节变化

水母类是海洋生态系统中非常重要的一个类群。根据 1 959年以来在渤海进行的几次较为全面的调查资料 ,对渤海水母类的种类组成、数量分布与季节变化作了较为详细的研究。共记录到水母类 4 1种 ,其中水螅水母 35种 ,钵水母 4种 ,栉水母 2种。主要以近岸低盐类型为主 ,高盐种类少并且出现时间短。渤海水母类密度的季节变化有 3个高峰 ,出现在冬季 ,夏季和秋季 ,分别由八斑芮氏水母、酒杯水母属、和平水母属、五角水母构成。渤海水母类的分布具有一定的季节特点 ,冬季和夏季以莱州湾密度最高 ,春季为渤海湾最高 ,秋季为中央海区最高。辽东湾水母类的密度在各个季节都不算高     

渤海浮游动物群落生态特点Ⅲ.部分浮游动物数量分布和季节变动

用1959年全国海洋普查中网浮游动物标本,分析渤海水母类,枝角类,糠虾,毛虾和幼虫类的数量分布和季节变化,结果表明,水母类以近岸低盐种为主,主要出现在莱州湾,渤海湾和辽东湾近岸水域,冬季出现的种类较少,优势种为八斑芮氏水母;夏季种类较多,优势种为半球杯水母和嵊山多胃水母等,鸟喙尖头蚤为近岸高温低盐种,主要出现在莱州湾,数量在6月份达到最大值,箭虫是海主要肉食性种类之一,其数量高峰期出现在9月份,长住囊虫的季节变化呈双峰型变化,第1次数量高峰出现在5月份,第2次数量高峰出现在8月份。该种大部分时间主要分布在莱州湾,渤海湾和辽东湾近岸水域,渤海出现的糠虾有长额刺糠虾和漂浮囊糠虾,其中长额否则糠虾受温度的影响较小,在春,夏秋,各有一个数量高峰;漂浮囊糠虾在秋末数量明显增加,这两种糠虾主要分布在渤海湾和辽东湾近岸水域。／三叶针尾涟虫属于低温种类,主要出现在秋季和冬季,细长脚绒属夏季高温种,在6,7月份数量较高,该种的分布受盐度影响比较大,主要出现在受黄海海流影响的谪盐水域,数量较大的幼虫有桡足类的六肢幼体,多毛类海稚虫科的幼体,以壳类幼体和腹足类幼体,其中桡足类六肢幼体和海稚虫科的幼体在5月份出现较多,腹足类幼体在6．7月份数量较高,双壳类幼体在8月份数量较高。     

北部湾北部水母类群集结构与数量分布

根据"908"专项北部湾2006—2007年四个季节的调查数据,分析了北部湾北部(20°N以北海域)水母类的种类组成、数量分布、优势种和群集结构特征及其环境影响因子。该区共记录水母类4类125种,分别为水螅水母类99种、管水母类17种、钵水母类4种和栉水母5种;以沿岸暖水种为主,占本区水母总种数的61.6%,其次是大洋暖水种,占37.6%,沿岸暖温种仅占0.8%。种数季节变化呈单峰型,夏季83种,冬季56种,秋季和春季各49种,四季均以水螅水母类为主。周年丰度变化呈单峰型,夏季(943.0个/m3)春季(572.4个/m3)冬季(548.2个/m3)秋季(427.6个/m3)。拟细浅室水母、双生水母、球型侧腕水母、四叶小舌水母、半口壮丽水母、两手筐水母、异摇篮水母、双小水母、单囊美螅水母、疣真囊水母、半球美螅水母、六幅和平水母、八囊摇篮水母、刺胞真囊水母、黑球真唇水母、端粗范式水母和细颈和平水母共17种全年出现,为四季种;其中,前7种为四季优势种,优势度(Y)分别为0.25、0.19、0.09、0.08、0.05、0.03和0.03,各季节的优势种演替模式不尽相同。依据水母种类和数量分布情况,北部湾北部水母类可划分2个群集:栖息在受沿岸流影响的20 m以浅的低盐群集,代表种有拟细浅室水母和双生水母等;栖息在受外海水影响的20 m以深的高盐群集,代表种有四叶小舌水母、半口壮丽水母和两手筐水母等。海流与水团的消长是影响水母类群集结构和水平分布格局的重要影响因素。     

莱州湾水母种类多样性及群集结构的季节变化

基于2011年5月至2012年4月(除冰期12月和翌年1—2月外)在渤海莱州湾逐月采集的数据资料,系统地开展水母种类组成、数量分布的周年季节变动,弥补自20世纪90年代以来该区域相关资料的不足,有利于掌握该水域水母(主要是小型水母)主要种类数量时空分布特点,促进莱州湾生物类群对生境改变响应的相关研究。结果显示:所有调查中,共出现水母30种,无全年出现的种类。各月中,莱州湾水母以8月种数最多,5月数量居多。各月水母总数量的80%多由1—2种优势种贡献所致;水母优势种类组成季节更替明显。3—5月优势种为八斑唇腕水母;6月为嵊山秀氏水母和贝氏真囊水母;7月为贝氏真囊水母、9月有细颈和平水母;10月为细颈和平水母和大西洋五角水母,8月和11月无明显的优势种,但8月细颈和平水母和曲膝薮枝螅水母数量较多。莱州湾小型水母聚集结构主要呈现季节性时间格局上的变动。春季有八斑唇腕水母为代表、在湾内分布的聚集组;夏季有以嵊山秀氏水母和贝氏真囊水母为代表、在湾口西侧和湾中部分布的聚集组,以及细颈和平水母为代表、在湾中底部分布的聚集组;秋季有四枝管水母和大西洋五角水母为代表、在湾口和中部分布的聚集组。水温对小型水母聚集结构分布具有较为重要的影响作用。大型水母在本调查出现较少。海蜇和沙海蜇出现于6—8月个别站位;海月水母7—10月均有出现,但高密集区出现在10月紧邻莱州湾的湾底水域。     

水母和海蜇

介绍了水母和海蜇的生物学特性、我国海域水质母类的种类组成、分布特点、水母与人类的关系以及母类的研究动态。     

我国的水螅水母

关于我国水螅水母的调查研究,已发表不少的报告。徐锡藩(1928)曾记载了厦门港的水母一新种;费鸿年(1937)记录了海南岛管水母2种;林绍文(l937)报告了浙江嵊山沿海的水母10种;丘书院(1954)发表了厦门的水母18种;高哲生等(1958)记载了山东沿海(主要是青岛)的水母33种;周太玄等(1958)发表了烟台水母33种;魏崇德(1959)报告了舟山水母10种;高哲生等(1962)又报告了舟山水母22种;许振祖等(1962)发表了福建沿海水母类,其中水螅水母有18种;Bigelow(1918)曾述及Vanhoffen记载了香港水母8种;本文作者自秦皇岛采得水母5种。在淡水水母调     

东海栉水母(Ctenophora)生态特征

根据1997~2000年东海23°30′~33°00′N、118°30′~128°00′E海域4个季节海洋调查资料,对东海栉水母数量变化和地理分布特征作了探讨。结果表明,东海栉水母平均丰度秋季(6.3 ind.(100m3)-1)>春季(1.6 ind.(100 m3)-1)>冬季(1.4 ind.(100 m3)-1)>夏季(0.6 ind.(100 m3)-1)。调查海域鉴定到种的栉水母共有6种,其中球型侧腕水母(Pleurobrachia globosa)是东海的主要种类;掌状风球水母(Hormiphora palnata)和瓜水母(Beroe cucumis)是常见种;带水母(Cestumsp.)是次常见种;蝶水母(Ocyropsis crystalline)和卵型瓜水母(Beroe avata)是稀有种。东海栉水母系暖水性浮游动物类群,其数量变化与东海暖流势力活动过程中的携带有密切的联系。球型侧腕水母分布较为广泛,是适应环境能力较强的种类;掌状风球水母、蝶水母和卵型瓜水母相反,仅适应有限的环境;瓜水母和带水母适应能力介于以上两类栉水母之间。     

黄渤海漁業敌害之一——霞水母

在我国沿海出产的腔肠动物水母类中,与国民经济有关的,首先要数海蜇,其次便是这里所要叙述的霞水母。海蜇是东海和黄、渤海的丰产食用水母;霞水母体型虽大,却没有食用价值,但是由于它在黄、渤海的渔汛时期的大量出现,却成为当地渔业很大的一种敌害。在它大量出现时期,可使渔获量锐减乃至停止,所以它是一种可注意的有害水母。本文把它的形态构造、生活习性和为害情况作一简要     

长江口及临近海域夏季水母类分布特征

采用1998年8月,1999年8月长江口及其临近海域（121°15′E-122°41′E,30°00′N-31°30′N）的调查资料,对采集到的水母样品进行分析,探讨水母的分布特征以及影响因素。结果表明：调查海域共出现水母21种,其中水螅水母15种,管水母4种,栉水母2种;可分为近岸低盐性、低盐河口性和大洋暖水性3个生态类群,其中近岸低盐物种达60％以上,分布范围广,低盐河口类群仅出现于受长江冲淡水影响明显的低盐水域,而大洋暖水类群分布于受外海水影响较大、盐度较高、离岸较远的区域;优势种为贝氏拟线水母、球型侧腕水母、单囊美螅水母、五角水母、拟细浅室水母和双生水母。总体分布特征为：从长江口向外伴随着盐度的逐渐增大．丰度逐渐升高,在长江）中淡水与外海水交汇的舟山渔场西部水域,丰度最大;水母的出现种类、丰度均与东海外海水、长江冲淡水2大水系的配置有关：外海水越强,整个区域平均盐度较高,出现的水母种类、丰度均高;反之,长江冲淡水势力控制范围大,平均盐度明显降低,物种少且丰度低。     

拟柄突和平水母在中国的首次发现及其生活史观察

报道青岛海洋科技馆培养的和平水母属(软水母亚纲,和平水母科)一种我国的新纪录--拟柄突和平水母西 Eirene lacteoides Kubota and Horita,1992.首次提供该种水母水螅体的形态,并对各期水母体的特征进行描述,为编写水螅水母动物志提供参考.     

中国近海浮游动物群落结构及季节变化

2006年7-8月、12月-2007年2月、2007年4-5月、2007年10-12月,对中国近海进行了4个航次生物、化学和水文等专业综合调查.根据采集的浮游动物样品分析鉴定结果,对中国近海浮游动物群落结构、种类组成及优势种的季节变化进行研究.结果表明,中国近海浮游动物有1330种,隶属于7门19大类群,浮游幼体47类,其中,节肢动物为最优势类群,有782种,占58.80％,其次为刺胞动物,有324种,占24.36％.在浮游动物群落结构中,4个海区均以桡足类和水母类的种类和数量占绝对优势.中国近海4个海区浮游动物种类数有明显季节变化,渤海和黄海,浮游动物种类数夏、秋季多于春、冬季;东海和南海,浮游动物种类数春、夏季多于秋、冬季.中国近海浮游动物群落大体可划分为6个主要生态类群:近岸低盐类群、低温高盐类群、高温高盐类群、低温广盐类群、高温广盐类群和广温广盐类群.结合同步调查的其它生物、水文、化学环境参数的分析结果,对中国近海浮游动物群落种类丰度与环境因子进行生物与环境变量关系分析,结果表明,浮游动物群落结构与水温、盐度、水深、溶解氧、硝酸盐和pH存在明显相关关系.水温和盐度是影响浮游动物群落结构最重要的两个环境因子.     

Spatial and seasonal distribution patterns of fish assemblages in the Río Champotón, southeastern Mexico

Río Champotón in the Yucatán Peninsula is within the Usumacinta Province, the most diverse in fish fauna in Mexico, and is part of the Mesoamerican hotspot, with high endemism and exceptional habitat loss. The spatial and seasonal variability of its fish fauna and their relation to physical habitat characteristics were studied, finding 53 taxa. Canonical correspondence analysis shows salinity, distance from the river mouth, and substratum type differentiate an estuarine and a freshwater region. Fish fauna replacement was observed, with taxa exclusive to each region: 26 estuarine and 27 freshwater species. Six freshwater species enter the estuarine region when the high river flow depletes salinity. Estuary showed greater seasonal differences in specific richness than the freshwater region, which have sites with higher local specific richness. Despite its small drainage, Río Champotón has a highly diverse fish fauna and some areas are affected by human activity and the hurricane season. Its conservation is of critical importance.     

Salt marsh vegetation of the Western Mediterranean desert of Egypt

The extensive salt marshes in the plains and depressions of the western Mediterranean desert of Egypt were classified into three habitat types: A with shallow water table and high salinity, B with relatively deep water table and high salinity, and C transitional habitats in which salinity and water table are no controlling factors. Fourteen vegetation types were distinguished, each dominated by one or two species.The dominating life forms are chamaephytes in sites of high salinity, and therophytes in sites of low salinity. Spatial and temporal variations in the standing crop biomass were pronounced. The accumulation of material started during spring and reached a maximum in autumn, when photosynthetic activity was maintained to account for transpiration losses.There was a general trend of increasing salinity and concentration of different ions from habitat type A to habitat type C through habitat type B. The periodical variation in the water table was insignificant, while a significant drop in salinity and the concentration of different ions was detected in spring, which was attributed to the diluting effect of rain water during that season.Most species exhibited clear distribution patterns and their a bundance varied significantly along gradients of different factors. Simple correlations between the compositional gradients or the distributional behaviour of species and salinity or the concentration of individual ions were generally low, while correlations with combinations of ions in the form of ratios (notably sodium and potassium adsorption ratos) were higher.During the early stages of succession the building up of soil and the decrease in salinity are the most important factors while at more advanced stages, soil texture and calcium carbonate content become more decisive.Nomenclature follows Täckholm (1974)     

A study of the Werewilka Inlet of the saline Lake Wyara, Australia – a harbour of biodiversity for a sea of simplicity

Lake Wyara receives most of its water from Werewilka Creek, with the area between the two forming Werewilka Inlet which is highly variable in area, and salinity and has high habitat heterogeneity. Over 12 years, 84 species of macroinvertebrate were found in the inlet, but only 34 in the lake. Halobiont and halophilic species were the same in each, but there were many fewer salt-tolerant species in the lake and no freshwater species. The latter were excluded by salinity, but habitat homogeneity due to strong wave action in the lake seems to limit many salt-tolerant species to the inlet. Species richness in large saline lakes in inland Australia is limited by salinity, poor speciation opportunities engendered by their episodic nature, and habitat homogeneity.     

Fishes of a subtropical Australian saltmarsh and their predation upon mosquitoes

Synopsis The fishes occurring in a subtropical Australian saltmarsh were studied from January to December 1984 to determine the seasonal abundance and feeding of the most common species. Wide variations in pool water levels and salinity were recorded. Eight species of fish were collected, four of which are of economic importance to fisheries. Three taxa, Gambusia affinis, Pseudomugil signifer, and gobiids predominated in terms of abundance and occurrence. The abundance of fishes fluctuated markedly on a seasonal basis with few fish being taken in winter and spring (June–November) when pool water levels were low. Diets of the most common species were similar with terrestrial foods forming an important component of all diets. Feeding activity was highest in summer (December to February) when mosquito larvae, copepods, and larval coleopterans formed a large proportion of the fishes' diets. Results from the present study indicate that fish important to commercial fisheries rarely utilise the upper littoral saltmarsh habitat and that resident fishes are unlikely to effectively control mosquito larvae in saltmarsh.     

Seasonal dynamics of the helminths of bluegill (Lepomis macrochirus) in a subtropical region

Seasonal prevalence and abundance of the helminths of bluegill sunfish in a Louisiana oligohaline bayou were measured by a survey and a field "live-box" experiment. The survey took place from the spring of 1997 to the summer of 1998 and examined fish that were <7 cm. Three trematode species, Phagicola nana (Heterophyidae), Ascocotyle tenuicollis (Heterophyidae), and Posthodiplostomum minimum (Diplostomatidae), and 2 nematode species, Camallanus oxycephalus (Camallanidae) and Spinitectus carolini (Cystidicolidae), were examined. Camallanus oxycephalus was the only helminth that showed a distinct seasonal pattern. Abundance and prevalence peaked in summer, which was likely driven by concerted reproductive cycles of females. The survey data indicated that the other helminths fluctuated over time but did not seem to follow a distinct seasonal pattern. The fluctuations could be attributed to the variable nature of the habitat or to the stochastic events that influence transmission dynamics, particularly isolated events such as tropical storms, which cause dramatic changes in salinity. The live-box experiment successfully measured recruitment of A. tenauicollis and suggested a seasonal component of the distribution of this species, which was possibly caused by temperature-dependent emergence of cercariae from the snail intermediate host.     

A comparison of the macrobenthic faunas of permanently open and temporarily open/closed South African estuaries

Thirteen estuaries in the Eastern Cape Province, South Africa, were broadly categorised according to size and salinity distribution and were assigned to one of the following categories: permanently open estuaries having a strong salinity gradient between mouth and upper estuary, freshwater-deprived permanently open estuaries, medium-sized temporarily open/closed estuaries, and small, temporarily open/closed estuaries. The macrobenthos collected during surveys was then compared in terms of the following parameters: species composition, salinity, sediment mud content, density of macrobenthic animals, Hill's N0 (species richness), and Hill's N1 (diversity). Mud content was found to be the most important environmental variable responsible for biotic patterns found, and sites were consequently assigned to either a sand zone fauna, or a mud zone fauna. Both types of fauna are present in all estuaries sampled, with upper sites of river dominated estuaries having an additional oligohaline fauna, and freshwater-deprived estuaries providing habitat for many marine species. Small, temporarily open/closed estuaries have the highest macrobenthic density, whereas N0 and N1 are highest in freshwater-deprived permanently open systems. River-dominated permanently open estuaries tend to have lower macrobenthic densities, species richness, and diversities compared to estuaries in the other categories. No seasonal differences in these ecological indices were found within any of the estuarine categories.     

Fish abundance and species richness across an estuarine–freshwater ecosystem in the Neotropics

We investigated the distributional patterns of shallow-water fish and their environmental correlates along a broad spatial scale encompassing estuarine and freshwater ecosystems. Marine-vagrant species were restricted to the sites under the influence of salinity intrusion, whereas estuarine-related and freshwater guilds were found along the entire estuarine–freshwater gradient. Primary- and secondary-freshwater fish guilds had the most widespread spatial distribution and comprised a major fraction of the total abundance and species richness. Abiotic factors correlated with fish abundance and composition along two main environmental axes, one related with variation in salinity, water transparency, and sediment granulometry and the other with the slope gradient. Species richness was significantly higher at the natural channel linking the estuarine- and freshwater-ecosystem, which probably was due to: (a) a steeper slope that favored the confluence of fish from the littoral (<2 m) and limnetic (>2 m) zones and (b) the sporadic inflow of saltwater that carried into this region several marine-related species. Although estuarine–freshwater ecotones are known to support few species, mainly salinity tolerant, our results suggest that habitat features and seasonal fish movement associated with salinity intrusion could lead to more diverse fish assemblages in this transitional zone.     

The role of salinity tolerance and competition in the distribution of an endangered desert salt marsh endemic

Rare plants are often associated with distinctive soil types, and understanding why endemic species occur in unique environments is fundamental for their management. At Ash Meadows National Wildlife Refuge in southern Nevada, USA, we evaluated whether the limited distribution of endangered Amargosa niterwort (Nitrophila mohavensis) is explained by this species’ tolerance of saline soils on salt-encrusted mud flats compared with the broadly distributed desert saltgrass (Distichlis spicata var. stricta). We simultaneously explored whether niterwort distribution is restricted from expanding due to interspecific competition with saltgrass. Surface soils collected throughout niterwort’s range were unexpectedly less saline with lower extractable Na, seasonal electroconductivity, and Na absorption ratio, and higher soil moisture than in adjacent saltgrass or mixed shrub habitats. Comparison of niterwort and saltgrass growth along an experimental salinity gradient in a greenhouse demonstrated lower growth of niterwort at all but the highest NaCl concentrations. Although growth of niterwort ramets was similar when transplanted into both habitats at the refuge below Crystal Reservoir, niterwort reproductive effort was considerably higher in saltgrass compared to its own habitat, implying reallocation of resources to sexual reproduction to maximize fitness when the probability of ramet mortality increases with greater salinity stress. Saltgrass was not a demonstrated direct competitor of niterwort; however, this species is known to increase soil salinity by exuding salt ions and through litterfall. Niterwort conservation will benefit from protecting hydrological processes that reduce salinity stress and preventing saltgrass colonization into niterwort habitat.