The Baikalian genus Rhyacodriloides in Europe: phylogenetic assessment of Rhyacodriloidinae subfam. n. within the Naididae (Annelida)

Martin, P., Martínez‐Ansemil, E. & Sambugar, B. (2010). The Baikalian genus Rhyacodriloides in Europe: phylogenetic assessment of Rhyacodriloidinae subfam. n. within the Naididae (Annelida). —Zoologica Scripta, 39, 462–482. Two new species of the oligochaete genus Rhyacodriloides Chekanovskaya, Rhyacodriloides aeternorum sp. n. and Rhyacodriloides latinus sp. n., are described from subterranean water bodies of Italy and Slovenia. A comparison with the known species of this genus, Rhyacodriloides abyssalis Chekanovskaya, 1975 and Rhyacodriloides gladiiseta Martin & Brinkhurst, 1998, both from Lake Baikal, shows that the enigmatic ‘cellular masses’ of the latter two species must be interpreted as different, not homologous structures. As a result, R. gladiiseta is to be ascribed to the Phallodrilinae, a primarily marine naidid subfamily, mentioned for the first time in Lake Baikal, and placed in its own genus, Phallobaikalus gen. n. The two new species are morphologically very similar, but their penial setae differ slightly. The phylogenetic relationships of R. latinus sp. n. and R. abyssalis within the Naididae (formerly the Tubificidae) were investigated using a combination of three genes, one nuclear (18S rDNA) and two mitochondrial (12S rDNA and 16S rDNA). A fragment of the mitochondrial COI gene, used as a barcode, also genetically characterized all Rhyacodriloides species. Sequences of 34 Naididae were obtained from EMBL, representative of five naidid subfamilies, and including five oligochaete outgroups. The data were analysed by parsimony, maximum likelihood and Bayesian inference. Taken in combination, the three genes investigated confirm that the two Rhyacodriloides species analysed are closer to each other than to any other naidid species. However, they are separated by 16S and COI distances that amount to 18.5% and 27.2%, respectively, suggesting an ancient separation between species, in good accordance with their present biogeographic distribution. Rhyacodriloides cannot be considered as a rhyacodriline, as assumed so far, as they never appeared related to this subfamily in any analysis considered. In contrast, they appear at the base of a naidid group, including the Tubificinae, the Phallodrilinae, the Limnodrilinae, as well as Branchiura sowerbyi, a species whose phylogenetic association with the rhyacodrilines has been questioned for a long time. Despite a lack of phylogenetic support, this position is congruent with a morphological reassessment of the Rhyacodrilinae, and strongly supports the erection of a new naidid subfamily to accommodate Rhyacodriloides.     

A review of the biology of British Naididae (Oligochaeta) with emphasis on the lotic environment

SUMMARY. Naidids live in a wide range of aquatic habitats but are particularly important numerically as part of the benthic fauna of rivers with stony substrates. In general they graze on bacteria and algae although some, particularly Chaetogaster spp., are mainly predaceous, and C. limnaei vaghini is a parasite of molluscs, chiefly Gastropoda. Food selection seems to be based largely on particle size although the food quality of the particles within the appropriate size-range influences rates of growth and reproduction. Major factors determining the distribution and abundance of naidid species are the nature of the substratum and the presence and kind of vegetation. Plants with a highly dissected form, a thick growth habit, and which permit the greatest periphyton development generally support the most abundant naidid populations. The oligochaete fauna of coarse substrates (stones and gravels) is often dominated by the Naididae but both species-richness and abundance of naidid populations are generally reduced where fine substrates (silts and muds) occur. The occurrence of worms within the substratum is also determined by its nature; naidids penetrate to depths of 20–70 cm in coarse substrates but rarely penetrate below 6 cm in mud. The principal factor limiting both depth penetration and the dominance of naidids in fine substrates is probably oxygen availability. Naidids reproduce both asexually and sexually, the former method predominating for most of the year. Asexual reproduction usually involves the budding-off of zooids but a few species fragment. Sexual reproduction is often infrequent; populations of some species produce few or no sexually mature individuals. In mature worms asexual reproduction virtually ceases. In populations that produce mature individuals there is apparently one sexual generation a year, usually occurring during the summer and autumn. Adults die soon after laying their cocoons. In general, naidids are most abundant during the summer months when rates of growth and asexual reproduction are stimulated by higher temperatures and a plentiful supply of food. A few species, however, e.g. Nais elinguis and Paranais litoralis, are more abundant in the spring. The response of naidid species to different kinds of pollution is varied but generally organic enrichment of rivers which have stony substrates results in a considerable (ten- to twenty-fold) increase in naidid abundance. Nais elinguis, N. barbata, N. communis, N. variabilis, and Chaetogaster diaphanus are often abundant in such rivers, the foremost species reaching densities of 200 000 m^?2. Nais alpina, N. bretscheri, and N. pardalis appear to be relatively intolerant of organic enrichment. A substantial increase in naidid abundance is also promoted by the deposition of biologically inert particles (coal dust, china clay, sand) on the river bed. The importance of Naididae in relation to pollution surveillance of fresh waters is discussed.     

Meiobenthic naidid and aeolosomatid oligochaetes from the profundal zone,and relations of species to eutrophication

Oligochaetes were sampled using meiobenthos methods from depths of between 20 and 94 m in Lake Päijänne in 1986. Individuals belonging to several species of the Naididae and Aeolosomatidae, which are generally considered to include mainly littoral or lotic species, were found more or less regularly at these profundal depths. The naidid species Chaetogaster langi and Amphichaeta leydigii were more abundant in the deepest areas than at 20 m. Species also appeared to react differently to water quality. The naidid species Chaetogaster langi and the aeolosomatid species Aeolosoma quaternarium, A. hemprichi and Rheomorpha neiswestnovae were most abundant on average at oligotrophic, unpolluted stations, naidid species Amphichaeta leydigii, Specaria josinae and Vejdovskyella comata were more abundant at eutrophicated stations and Dero digitata was more abundant in organically loaded areas. The observations of Amphichaeta leydigii, Chaetogaster setosus and Rheomorpha neiswestnovae were new for Finland.     

Opportunist rotifers: colonising species of young ponds in Surrey,England

Quantitative substrate samples were collected at a newly constructed gravel bar habitat in the Tombigbee River, Mississippi, to characterize oligochaete (naididae and tubificidae) species richness and community composition. A total of 28 species of naidid and tubificid worms were indentified during the three-year study; Nais pardalis, Dero nivea, D. obtusa, Pristina aequiseta (naididae), and Branchiura sowerbyi (Tubificidae) were dominant. In June, 1985, three months after construction, 30 samples yielded seven taxa of oligochaetes; naidid and tubificid densities (± standard deviation) were 12.9 (± 29.7) and 10.1 m^–2 (±39.6), respectively. In October, 1985, 20 taxa were identified, and naidid and tubificid densities were 387.9 (± 300.5 and 22.9 m^–2 (± 50.7), respectively. Tubificid densities were highest in the spring, except during the first year, and naidid densities showed their highest densities in the fall during all years. Dominance changed from Nais pardalis and Dero nivea during the first year to Pristina aequiseta and D. nivea during the last year. The naididae, which typically inhabit gravel, exhibited more uniform colonization patterns than did the tubificidae. Comparatively low densities characterized the oligochaete community during the first year and high naidid densities during the last. Because this gravel bar is relatively isolated from similar substrates, and since oligochaetes disperse only via drift or crawling, colonization processes have been slow.     

Lacustrine,profundal meiobenthic oligochaetes as indicators of trophy and organic loading

Meiobenthic and macrobenthic oligochaetes were collected from two depths in Lake Päjänne and examined together with environmental data in which two environmental gradients can be seen. Numbers of Piguetiella blanci, Aeolosoma quaternarium and Aeolosoma hemprichi were positively correlated with oxygen saturation and negatively correlated with total phosphorus and COD suggesting that these species are indicators of oligotrophic conditions. Numbers of Amphichaeta leydigii, Specaria josinae and Vejdovskyella comata were positively correlated with total phosphorus which implies that these species prefer eutrophic conditions. The last three species and Dero digitata showed positive correlations with COD and organic sedimentation, which suggests that they also indicate organic loading. A decrease in aeolosomatid biomass was seen with increasing phosphorus and organic loading. The average body size of detritus-feeding naidids in the upper part of the profundal zone was reduced by organic loading, and more clearly eutrophication, which emphasizes the importance of including meiobenthic oligochaetes in pollution investigations. Of the naidid and aeolosomatid species, Chaetogaster langi preferred the greatest depths of the profundal zone while most of the other species were more abundant at 20 m rather than at the maximum depth. Clustering of the oligochaete taxa supported these observations and clustering of sampling stations based on oligochaete variables generally corresponded to clustering based on environmental data.     

Seasonal dynamics of aufwuchs Naididae (Oligochaeta) on Phragmites australis in a eutrophic lake

The Oligochaeta and Aphanoneura in the aufwuchs on Phragmites australis in a eutrophic hardwater lake were studied at two sites over a period of one year, in order to elucidate the structure and dynamics of this assemblage. The naidids Chaetogaster diastrophus, Nais spp., and Stylaria lacustris dominated the assemblage at any season. At both sites these taxa showed the same distinct pattern of successive population maxima in spring and summer: Chaetogaster diastrophus reached its peak density first, followed by Nais species, and eventually by Stylaria lacustris. Differences in temporal dynamics between sites were small apart from a second Stylaria maximum which was only observed at one site. Total naidid densities reached peak values of 3.8 individuals per cm² reed stem surface area. With mean individual biomass of 2.2 µg dry mass for Chaetogaster diastrophus, 13.3 µg for Nais, and 86 µg for Stylaria lacustris, respectively, maximum total naidid biomass on reed stems was 44 µg dry mass per cm². The biomass peak occurred later than that of total naidid density because in summer larger naidids dominated the assemblage. The observed succession appears to be consistent with seasonal changes in periphytic algal communities on the reed stems.     

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...     

Einnischung von fünf Grundeln (Teleostei, Gobiidae) der Ostsee und ihre Deutung mit Hilfe der Präadaptationstheorie

Niche occupation by 5 goby species (Teleostei, Gobiidae) in the Baltic Sea and its interpretation by means of the theory of pre-adaptation The habitats and prey of five goby species were investigated near the shore of the Lübeck Bight (SW Baltic) during the period 1989–1991. Observations showed that Gobius niger is a macrobenthos feeder, Pomatoschistus microps a meiobenthos feeder; Pomatoschistus pictus prefers meiobenthos as well as plankton while Pomatoschistus minutus feeds on benthos of every size, as well as planktonic cope-pods when offered in surplus; Gobiusculus flavescens is generally a plankton feeder but, when this component is in short supply in the summer, changes to macrobenthos. P. pictus and P. microps existed at different depths; G. flavescens and P. minutus presented countercurrent densities in shallow habitats during the course of a year. This adaptability of behaviour in habitat and prey choice can be explained by the modification ability of pre-adaptional genes in the goby genomes. After having invaded species-poor habitats such as the brackish Baltic Sea, wide niche dimensions are initially occupied. The niche is here considered to be an attribute of the species as well as of the habitat according to GÜNTHER (1950). Hence, innidation is defined as a process which implies specialization by loss of most preadaptations and leads to the optimal use of the ecosystem by the species. This process of a single species corresponds to the maturation of successions of whole biocoenoses.     

青弋江流域大型底栖动物群落结构及水质评价

研究河流大型底栖动物群落结构特征及水环境质量对水生态的保护与修复具有重要意义。以青弋江流域为研究对象,于2020年9月进行了大型底栖动物及水体理化因子的调查,采用相对重要性指数、生物多样性指数及Jaccard相似性系数分析了大型底栖动物群落结构特征,运用丰度/生物量比较曲线法及冗余分析法探究了底栖动物群落受到的干扰程度及其主要影响环境因子,最后利用水生态环境质量综合指数对河流水质进行评价。研究结果表明：(1)共采集鉴定大型底栖动物61种,隶属于3门6纲17目,平均丰度为265.9个/m~2,平均生物量41.6 g/m~2。相对重要性指数分析显示,日本沼虾(Macrobrachium nipponensis)、中国圆田螺(Cipangopaludina chinensis)、羽摇蚊(Chironomus plumosus)及扁蜉(Ecdyrus)为群落中的主要优势种。(2)由群落相似性分析知,Jaccard相似性系数较低,调查点位之间存在较强的空间异质性。(3)冗余分析表明,电导率、氨氮浓度及流速是影响底栖动物群落结构的主要环境因子。(4)生物指数分析结果显示该流域水质为轻度污染或中度污...     

莱州湾小清河口近岸海域底栖生境健康评价

于2019年7月、8月和9月对莱州湾小清河口近岸海域的大型底栖动物进行调查,对该海域大型底栖动物群落的种类组成和群落结构等进行研究,利用丰度/生物量比较曲线法、AMBI指数法和M-AMBI指数法对研究海域大型底栖动物群落健康和底栖生境健康状况进行评价。研究结果表明,2019年7月、8月和9月共采集到大型底栖动物64种,其中多毛类24种,甲壳类19种,软体动物17种,其他类群4种。该海域的优势种为光滑河蓝蛤（Potamocorbula laevis）、彩虹明樱蛤（Moerella iridescens）、半褶织纹螺（Nassarius semiplicatus）、四角蛤蜊（Mactra veneriformis）,寡鳃齿吻沙蚕（Nephthys oligobranchia）、中蚓虫（Mediomastus californiensis）、东方长眼虾（Ogyrides orientalis）、尖齿拳蟹（Philyra acutidens）和短角双眼钩虾（Ampelisca brevicornis）,其中彩虹明樱蛤和寡鳃齿吻沙蚕在三次调查中均为优势物种,优势度明显。群落结构聚类分析和多维尺度分析表明,7月研究海域的大型底栖动物群落以10%的相似性可以分为3组,8月以18%相似性可以分为4组,9月以19%的相似性可以分为3组,三次调查的群落结构相似度均较低。丰度/生物量比较曲线法研究结果显示,底栖动物群落生物量优势显著,群落处于未干扰状态。AMBI指数及M-AMBI指数分析结果表明,莱州湾小清河口近岸海域底栖生境处于未干扰或者轻度干扰的状态,健康状况处于高等或者优良的状态。     

Composition and distribution of bottom oligochaete fauna of a north Italian eutrophic lake (Lake Ledro)

The profundal macroinvertebrates, particularly the oligochaetes, of Lake Ledro (Trento, Italy), that has recently undergone eutrophication, were studied.A statistical approach of random sampling was used to study the distribution and abundance of the oligochaete species. The optimum sample number was calculated from a preliminary sample series. The oligochaete community was made up of five tubificid species, one naidid and one lumbriculid species that on average represents more than 80% of the macrobenthic community. Population density was correlated with depth and decreasing oxygen concentration. The role of Tubifex tubifex as a eutrophic, tolerant species was confirmed; and in fact it was the only species found (although at low density) in the deepest and anoxic zone. No comparable data are available for the lake prior to eutrophication, but these data will be valuable for future comparison once a remediation program for the lake has been implemented.     

Half a century of oligochaete research in Estonian running waters

About 51500 specimens from 1542 samples, collected over the years 1954–1975 and 1986–1999 in different running water bodies throughout Estonia, were identified. Tubificidae prevailed in the material, with Limnodrilus hoffmeisteri forming about 40%. This species was followed by the tubificids Tubifex tubifex, Potamothrix hammoniensis, Psammoryctides barbatus, L. udekemianus and Spirosperma ferox, the naidid Stylaria lacustris, and the lumbriculid Stylodrilus heringianus. Two main ecological assemblages were distinguished: the pelophilous assemblage, dominated by L. hoffmeisteri, and the psammophilous one, where usually P. barbatus was dominant. The relationships between different species and the chemical parameters of water were usually weak but in contrast, correlated well with sediment preferences. In organically enriched reaches, L. hoffmeisteri usually dominated. The fauna of the streams of the islands was poorer in species due to their small size rather than geographical isolation. Some recent antropochorous Ponto-Caspian invaders have only reached the lowermost reaches of the two largest rivers. Some brackish water species were found in the mouth of the Pärnu River. No essential differences were found between the comparable sets of oligochaete samples collected in 1954–1975 and 1987–1997 in the Estonian running waters.     

Meiofaunal emergence from intertidal sediment measured in the field: significant contribution to nocturnal planktonic biomass in shallow waters

Field studies on the occurrence of meiobenthos in the water column above intertidal sandflats have been performed near the Island of Sylt in the northern Wadden Sea. Swimming meiobenthos was strongly dominated by harpacticoid copepods. Many of them have a semiplanktonic life-style. They rest in superficial sediment layers at low tide and swin in the water column at high tide. Swimming activity correlated negatively with light. The abundance in the water column was one order of magnitude higher during the night. Strong currents caused by storm tides significantly decreased meiobenthic abundance in the water column. Light and flow being constant, no significant changes of meiobenthic abundance per unit area occurred over a tidal cycle. Since holoplankton and meroplankton abundances correlated positively with the height of the water column, semiplanktonic meiobenthos may dominate the mesozooplankton in shallow waters. On an average, emergence of meiobenthos increased the mesozooplanktonic biomass by about 2% during diurnal high tides over the entire tidal cycle, and by about 50% during nocturnal high tides. Because of seasonal cycles of the dominant harpacticoids, this high contribution to planktonic biomass may be a summer phenomenon.     

近岸典型生态系统大型底栖动物的次级生产力——以瓯江口、洞头列岛为例

为更好了解和估算河口及岛屿生态系统大型底栖动物次级生产力的情况,以近岸两个典型生态系统河口-瓯江口、岛屿-洞头列岛为例,于2015年4月和10月在该海域进行大型底栖动物调查,采用3种Brey经验模型对大型底栖动物次级生产力进行估算,并分析次级生产力与环境因子的关系。结果表明:(1)以去灰干重(ash-free dry weight,AFDW)计,Brey经验公式估算瓯江口和洞头列岛海域年均次级生产力分别为0.48 g(AFDW)m~(-2)a~(-1)和0.70 g(AFDW)m~(-2)a~(-1),Brey模型估算瓯江口和洞头列岛海域年均次级生产力分别为0.51 g(AFDW)m~(-2)a~(-1)和1.55 g(AFDW)m~(-2)a~(-1),Brey模型估算瓯江口和洞头列岛海域年均次级生产力分别为0.25 g(AFDW)m~(-2)a~(-1)和0.99 g(AFDW)m~(-2)a~(-1)。(2)3种经验模型反映大型底栖动物年均次级生产力空间分布趋势一致:瓯江口海域有1高值区,位于瓯江口南部;洞头列岛海域有2高值区,分别位于洞头本岛东北部的三盘岛与花岗岛之间和东黄岛东南部的岛屿之间。(3)瓯江口海域大型底栖动物年均次级生产力主要贡献种为双鳃内卷齿蚕Aglaophamus dibranchis、长吻沙蚕Glycera chirori、异蚓虫Heteromastus filiforms、焦河篮蛤Potamocorbula ustulata、薄云母蛤Yoldia similis、圆筒原盒螺Eocylichna braunsi,它们对次级生产力的贡献率超54.2%;洞头列岛海域大型底栖动物年均次级生产力主要贡献种为双鳃内卷齿蚕、异蚓虫、薄云母蛤、绒毛细足蟹Raphidopus ciliatus、隆线强蟹Eucrate crenata、脑纽虫Cerebratulina sp.、红狼牙鰕虎鱼Odontamblyopus rubicundus,它们对次级生产力的贡献率超57.1%。(4)次级生产力与环境因子的相关性分析显示化学需氧量、悬浮物和表层沉积物中值粒径是影响瓯江口海域大型底栖动物年均次级生产力的重要环境因子,而环境因子与洞头列岛海域大型底栖动物年均次级生产力相关关系不显著。(5)瓯江口海域Brey经验公式与Brey模型估算结果基本一致,洞头列岛海域Brey经验公式与Brey模型估算结果基本一致。     

The effect of organic pollution on the abundance and distribution of aquatic oligochaetes in an urban water basin, Taiwan

Aquatic oligochaetes are abundant in polluted areas and are, therefore, commonly used as bioindicators to study organic pollution in rivers and streams. In order to develop a species-level oligochaete biotic index to reflect the River Pollution Index (RPI) in the Taichung Water Basin in Taiwan, we conducted a systematic sampling scheme to collect aquatic oligochaetes from the sediment samples of watercourses in the Taichung Water Basin, Taiwan. We evaluated the relationships between aquatic oligochaetes and the sewage pollution using statistical methods. The distribution of aquatic oligochaetes in relation to environmental variables, such as water quality and sediment characteristics of the regional urban contaminated streams was expressed by Canonical Correspondence Analysis (CCA). We identified 17 species of aquatic oligochaetes (Annelida, Clitellata) including 3 species of Tubificidae, 13 species of Naididae, and 1 species of Enchytraeidae from the watercourses of an urban region in the Taichung Water Basin in Taiwan, during the summer and winter of 2005 and 2006. A positive correlation was found between the total abundance of aquatic oligochaetes and the RPI (r = 0.58, P < 0.05). However, only population density of the most abundant tubificid, Limnodrilus hoffmeisteri, increased with increasing RPI values and a significantly negative correlation was found between the population density of the naidid, Nais communis, and RPI values. The results of CCA indicated that certain naidids, such as Aulophorus furcatus and Allonais gwaliorensis also tolerated extremely polluted environments in upper stream or stony habitats, implying that tubificids should not be the sole representation of simple biotic indices but should also include pollution-tolerant naidids. We found that the community structure of aquatic oligochaetes was influenced by short-term variations in microhabitat rather than according to seasonal factors in our study region. The results proved that aquatic oligochaetes were sensitive enough to provide a supplement for the regional urban pollution assessment applications for biotic indicators at the species-level.     

Bottom Communities of Semyachik Lagoon (Kronotskii Biosphere Reserve, Eastern Kamchatka)

Bottom communities of Potamogeton filiformis,Zostera marina+ Z. japonica+ Macoma balthica, Enteromorpha prolifera, and a stony block–boulder intertidal community were distinguished in Semyachik Lagoon. The macrobenthos associated with these communities is described. Generally, the biomass and occurrence frequency indices of the macrozoobenthic communities of the lagoon are an order of magnitude lower than those of macrophytobenthic communities (Kafanov, Plekhov, 1998); therefore, they do not play a significant role in bottom community structure. With the exception of the stony block–boulder intertidal community, their spatial distribution is entirely determined by the distribution of underwater vegetation, which is completely controlled by the geomorphological and hydrological features of the lagoon.     

Impacts of cultivation of red algae Kappaphycus alvarezii on planktonic and benthic faunal density in relation to environmental and hydrobiological parameters in tropical coastal ecosystem

The experimental cultivation of Kappaphycus alvarezii was done to investigate its daily growth rates and biomass yields, and their impacts on planktonic and benthos population densities were evaluated by floating raft culture method. Biomass yields and daily growth rates of K. alvarezii were observed. The phytoplankton and zooplankton densities varied from 25,250 to 319,033 cells/m³ and 12,060 to 207,893 individuals/m³, respectively. Similarly, macrobenthos and meiobenthos densities varied from 11,105 to117061 nos/m² and 14,740 to 727,000 nos/m², respectively. The maximum values of plankton and benthos were recorded in the control site compared with the culture sites. Pearson correlation suggests that growth rate of K. alvarezii is negatively correlated with zooplankton density (r = ?0.9); macrobenthos (r = ?0.9) and meiobenthos density (r = ?0.8) at P < 0.01 level. The crop yield negatively correlated with macrobenthos density (r = ?0.7) at P < 0.01 level and with meiobenthos density (r = ?0.6) at P < 0.05 level for the two culture sites. One- way ANOVA revealed the differences in the growth rates and crop yields. Among the two culture sites, culture site 1 showed significant variation (P < 0.01), whereas culture site 2 showed statistically insignificant (P > 0.01). The conclusion suggests that water nutrient declined at both culture sites than control site. So, the plankton and benthic fauna were declined in the culture sites.     

Associations between macrobenthos and invasive cordgrass, Spartina anglica, in the Danish Wadden Sea

We conducted a survey to provide knowledge on mechanisms controlling spatial and temporal variability of macrobenthos in an intertidal Wadden Sea area partly covered by invasive Spartina anglica. Benthic macrofauna was collected seasonally at seven stations along a transect covering non-vegetated mudflat and vegetated marsh areas. Shannon diversity index was consistently higher for macrobenthos in the open mudflat compared to the marsh area. Infaunal species, like Arenicola marina, Tubificoides benedeni and Macoma balthica, were more abundant in the mudflat than the marsh, while the opposite was evident for epifaunal species, like Hydrobia ulvae and Littorina littorea. The infaunal crustacean, Corophium volutator, on the other hand, appeared particularly attracted to the mudflat–marsh boundary. The biomass of below-ground plant materials and macrodetritus was positively correlated with the total macrofaunal abundance, while the biomass of dead below-ground plant materials alone showed a significant negative correlation with infaunal abundance. Total macrofaunal abundance was highest during summer in the mudflat, while no seasonal pattern was evident in the marsh. The negative influence of S. anglica invasions on infaunal abundance may have serious implications for higher trophic levels, such as waterbirds, that forage in Wadden Sea areas and thus for the overall biodiversity and ecosystem functioning.     

Oligochaete communities at the mouth of the Neva and their relationship to anthropogenic impact

Changes in the oligochaete community of the Neva Mouth for the period 1982–1993 are discussed in relation to anthropogenic impacts. A number of community parameters such as species composition, biomass and diversity were generally stable, although local changes were noted. Predominance of eutrophic species, i.e. L. hoffmeisteri, T. tubifex, P. hammoniensis was enhanced, whereas mesotrophic and oligotrophic species — L. isoporus, S. heringianus, T. newaensis disappeared or became less numerous at some stations. The reverse trend was observed at other stations. These phenomena were accompanied by a sharp increase in the variability of biomass and/or diversity, which is regarded as exceeding normal annual fluctuations. The oligochaete community is recognized as a promising indicator of the ecological situation in the Neva Mouth.     

长江口潮间带底栖生物生态及变化趋势

基于长江口3个区域潮间带(崇明东滩、南汇边滩和嵊山岛)监测数据,对长江口区域潮间带底栖生物生态现状及变化趋势进行评价。结果表明,2019年长江口海域泥相和岩相潮间带共鉴定大型底栖生物9门57种,软体动物、甲壳类和多毛类构成主要类群。崇明东滩、南汇边滩两个泥相潮间带底栖生物平均栖息密度分别为96.4个/m~2和160.4个/m~2,平均生物量分别为68.42 g/m~2和45.71 g/m~2;嵊山岛岩相潮间带平均栖息密度和生物量分别为488.9个/m~2和763.72 g/m~2。各断面多样性、丰富度和均匀度指数分别位于1.36—3.24、0.75—2.88和0.48—0.77,泥相潮间带低潮区生物多样性优于中潮区和高潮区,岩相潮间带中潮区生物多样性最好。聚类分析可见长江口海域潮间带底栖生物分为泥相和岩相2个大组群,物种分布存在明显的分潮区现象,高潮区站位成群或与个别中潮区站位成群,低潮区站位成群或与个别中潮区站位成群,表明底质类型和潮汐是影响潮间带大型底栖生物群落结构的主要因子。近30年来,崇明东滩和南汇边滩底栖生物种类数存在一定波动,嵊山后陀湾断面生物种类数明显下降;3个区域潮间带...