Zooplankton biomass in the Oosterschelde (SW Netherlands) before,during and after the construction of a storm-surge barrier

The hydrodynamic consequences of large coastal engineering (barrier-construction) works in the Oosterschelde were: prolonged residence times of the water, increased sinking of particulate material, and higher water transparencies. This strongly influenced the phytoplankton (Bakker et al., 1990; 1994) and phytoplankton biomass increased in the shallow Eastern compartment of the Oosterschelde (Bakker & Vink, 1994) while phytoplankton concentration of the seston rose.Zooplankton biomass, especially of copepods (Temora) and meroplankton (barnacle larvae) increased during the post-barrier period in the eastern compartment. It is hypothesized that this is caused by the improved feeding conditions and the increased retention times in this area.The barrier years 1985 and 1986 were characterized by low current velocities. In the Eastern compartment, this may have favoured the development of the rotifer Synchaeta (Bakker, 1994) and of the important copepod predator Pleurobrachia (Ctenophora).In the Western compartment, zooplankton developments in the post-barrier years were rather similar to those in the pre-barrier period. This led to the disappearance of the previously existing biomass gradients West-East (maxima in West). At present a trend in the opposite direction (maxima in East) is observed.     

Consumption of benthic invertebrates by waterbirds in the Oosterschelde estuary,SW Netherlands

The number of waders in the Oosterschelde, S.W. Netherlands, declined after a reduction in intertidal area due to the construction of a storm surge barrier and secondary dams, suggesting that the carrying capacity had been reached (Schekkerman et al., 1993). In this paper we present data on consumption and predation pressure by birds to explore whether the reduction in their numbers is due to prey depletion or to other factors.The total annual consumption of benthic invertebrates by birds in the Oosterschelde amounted to 1573 × 10³ g ADW y^–1 in the period before the coastal engineering works (pre-barrier) and 1500 × 10³ kg ADW y^–1 in the post-barrier period. More than half of the total amount of biomass is eaten by the Oystercatcher, and only seven (pre-barrier) or even six (post-barrier) bird species together take 90% of the total.Although the consumption by individual species may vary considerably among years, the total consumption was remarkably stable, with a CV of only 3–4% of the mean, especially compared to the variability of the prey populations. In the pre-barrier period, consumption was lowest in mid summer, increased sharply from August onwards until a peak was reached in January. A sharp decrease took place in March. In the post-barrier period, consumption peaked in October.The total consumption per unit area per year does not differ much between different sectors of the Oosterschelde, apart from a distinctly lower value in the eastern part. Of the total amount of food taken by birds, only 0.1–0.4% is taken in the subtidal compartment. In several study plots on an individual tidal flat, there was a clear relation between consumption and benthic biomass.The predation pressure was 13 and 23% of the standing stock, in the post- and pre-barrier period respectively. When cockles, mussels and their main predator, the Oystercatcher, are excluded from the calculations, the predation pressure of the other species was 30 and 37% of the biomass, respectively.Predation pressure of Oystercatchers in individual study plots varied from less than 10% to more than 70% of the standing stock. On cockle beds the predation pressure was positively related to the average length of the cockles present.Based on these results and a comparison with the literature we conclude that, at least for several species that feed intertidally, carrying capacity could be limited by the stocks of food. This does not mean that birds face food shortage each season. As the variability of the benthos populations is much higher than that of the bird densities it is likely that at some times food is not limiting, at other times it is. On the other hand, consumption is very low in the subtidal compartment and species feeding here could potentially increase substantially in numbers in the Oosterschelde.     

Responses to fertility and disturbance in a low-diversity grassland

We examined variation in species composition in a low-diversity, anthropogenic grassland in response to 11 years of nitrogen (N) manipulation and disturbance. The species-poor grassland (2–3 species/0.5 m²) represents a wide spread vegetation type (>10 million ha in North America) dominated by the introduced perennial grasses Bromus inermis and Agropyron cristatum. Four levels of N and three of soil disturbance were applied in all combinations to plots (5 × 15 m, N = 120) in a completely randomized design each year. Seeds or transplants of 47 species were added to ensure that dispersal was not a barrier to changes in species composition. After 11 years of treatment, all but the most disturbed plots continued to be dominated by B. inermis. The cover of the second-most abundant species, A. cristatum, decreased with disturbance but did not vary significantly with N. Despite the lack of changes in the identity of the dominant species, our environmental manipulations strongly influenced ecosystem characteristics. Added N increased soil available N, and decreased the cover of bare ground and light availability. Soil disturbance decreased aboveground biomass, and increased the cover of bare ground and light availability. Sawdust application, designed to decrease N availability, significantly reduced community biomass, and increased light availability and the cover of bare ground, but did not alter nutrient availability or species composition. The results highlight the difficulty of restoring diversity in species-poor, anthropogenic communities dominated by introduced species, and thus the importance of conserving remnants of diverse natural grasslands.     

Labidocera aestiva and L. scotti in Tamiahua Lagoon,Veracruz, Mexico

Labidocera aestiva and L. scotti were found in the Tamiahua Lagoon, Veracruz, Mexico. Fleminger (1957) found that the populations of these species may overlap geographically, although L. aestiva has affinity to the Carolinian province and L. scotti to the Caribbean province. This study describes the seasonal behavior and succession of this species in the Tamiahua Lagoon, a brackish water system with a high marine influence. A qualitative and quantitative analysis of samples was made in March, July, and September 1985 and January 1986. L. aestiva was found in temperatures below 26 °C in a wide salinity range. At temperatures above 26 °C and up to 32 °C, L. aestiva was present also with euryhaline character. In the Tamiahua Lagoon these two species did not overlap during this study. Both species are considered temporary inhabitants of this estuarine system in the Western Gulf of Mexico.     

苦苣苔科植物Lysionotus bijantiae的名实订正

通过查阅相关文献和标本,作者发现近期发表的苦苣苔科吊石苣苔属植物一新种——Lysionotus bijantiae D. Borah & A. Joe实为鉴定错误,应是汉克苣苔属的长圆叶汉克苣苔[Henckelia oblongifolia(Roxb.)D. J. Middleton & Mich. Möller] [原长圆叶唇柱苣苔Chirita oblongifolia(Roxb.)Sinclair]。Lysionotus bijantiae的模式标本采集于中国西藏东南部地区的喜马拉雅南坡,该地区苦苣苔植物多样性较为丰富。作者因其花具2枚发育雄蕊而将其归于吊石苣苔属,花萼分裂不达基部而与吊石苣苔属其他相关种类比较,而忽略了其种子先端不具附属物的特征。通过电镜扫描观察到,该种在墨脱境内居群以及其模式产地居群的种子均无附属物,从而证实了该种不是吊石苣苔属的物种,而是属于汉克苣苔属。因此,作者将Lysionotus bijantiae处理为Henckelia oblongifolia的新异名,同时提供了长圆叶汉克苣苔的彩色图片(含种子扫描图)、选定模式标本,并给出了吊石苣苔属和汉克苣苔属的区分方法和主要识别特征,不仅为这两个属的物种鉴定提供了参考,而且避免更多的物种分类混淆问题出现。     

Alteration of microbial community composition and changes in decomposition associated with an invasive intertidal macrophyte

Data demonstrating the effects of biological invaders on microbial communities and microbial processes are scarce, especially in marine environments. Research was conducted at Padilla Bay, Washington, to examine the effect that an invasive intertidal eelgrass, Zostera japonica Aschers & Graebn, has on rates of decomposition, microbial community composition, and the possible implications for associated ecosystem processes in this estuarine environment. A series of observational and experimental studies were conducted in beds of Z. japonica, beds of its native congener, Zostera marina, and mixed eelgrass beds. These studies assessed decomposition of invasive and native eelgrass, enumerated bacterial abundance, and examined sole source carbon usage (SSCU) by microbial assemblages. Z. japonica decomposed more rapidly than its native congener throughout the study period although rates of decomposition were variable. Microbial abundance did not differ among different vegetation compositions although differences in SSCU by microbial assemblages were detected among beds of invasive, native, and mixed eelgrass. These results indicate that this abundant invasive species can accelerate rates of decomposition and alter the associative decomposer community, which may lead to higher carbon and nutrient turnover within Padilla Bay.     

Distribution of sawfishes (Pristidae) in the Queensland Gulf of Carpentaria,Australia, with notes on sawfish ecology

Synopsis Pristis microdon, P. zijsron, P. clavata and Anoxypristis cuspidata are distributed throughout the Queensland section of the Gulf of Carpentaria, Australia. In a survey of the four species, Anoxypristis cuspidata was the most abundant and was recorded in both the inshore and offshore set net fisheries. The size distribution and catch locations of A. cuspidata suggest that the inshore area to a depth of 10 m may be the preferred habitat for juveniles of this species, while adults primarily occur offshore. Pristis microdon, P. zijsron and P. clavata were recorded only in the inshore fishery with catches dominated by immature animals. Pristis microdon was caught in the inshore fishery late in the monsoonal wet season (February to April) and inhabited both freshwater and estuarine environments. Pristis zijsron occurred only on the sand and mud flats outside river mouths whilst P. clavata inhabited both the sand and mud flats and upstream estuarine habitats. Observations on reproductive staging and the capture of neonate specimens suggest that in all four pristids, pupping occurred through the wet season until the beginning of the dry season in May. A seasonal set net closure for the barramundi, Lates calcarifer and shark fisheries, which has been in place since 1980 in Queensland Gulf waters, therefore offers a measure of protection to breeding female sawfish and their offspring.     

Revised treatment of <Emphasis Type="Italic">Memecylon</Emphasis> sect. <Emphasis Type="Italic">Afzeliana</Emphasis> (<Emphasis Type="Italic">Melastomataceae: Olisbeoideae</Emphasis>), including three new species from Cameroon

Summary  Seven new names at species rank are proposed in Memecylon sect. Afzeliana Jacq.-Fél., a group of forest shrubs and small trees confined to Guineo-Congolian Africa. The group is centred in Cameroon, where 17 of the 20 species occur. A new flower type, the “star-flower” in Memecylon is revealed, and its taxonomic and ecological importance discussed. Three new, locally endemic species from the South West Province of Cameroon are described, mapped and illustrated: M. kupeanum R. D. Stone, Ghogue & Cheek, M. bakossiense R. D. Stone, Ghogue & Cheek, and M. rheophyticum R. D. Stone, Ghogue & Cheek. Two new names, M. accedens R. D. Stone, Ghogue & Cheek and M. hyleastrum R. D. Stone & Ghogue and one new combination, M. mamfeanum (Jacq.-Fél.) R. D. Stone, Ghogue & Cheek are provided at species level for three taxa originally proposed as varieties of M. afzelii G. Don. The taxon M. arcuatomarginatum var. simulans Jacq.-Fél. is also elevated to species status, as M. simulans (Jacq.-Fél.) R. D. Stone & Ghogue. Conservation assessments are provided for all the newly named taxa. A key is provided to the species of Memecylon sect. Afzeliana.     

Persistence of <Emphasis Type="Italic">Paranosema</Emphasis> (<Emphasis Type="Italic">Nosema</Emphasis>) <Emphasis Type="Italic">locustae</Emphasis> (Microsporidia: Nosematidae) among grasshopper (Orthoptera: Acrididae) populations in the Inner Mongolia Rangeland,China

Paranosema (Nosema) locustae Canning has persisted in grasshopper populations in the Inner Mongolia Rangeland since spore treatment was applied in 1993. In the treatment year, a 58.32–71.43% reduction of grasshoppers was recorded and 59.26–80.36% of surviving grasshoppers of various species were infected. In the years following application, prevalence of P. locustae varied from 13.65% to 60.71%, demonstrating that P. locustae remains in grasshopper populations for many years. Infection prevalence was more than 60.00% for Dasyhippus barbipes (F.-W.), Bryodema luctuosum luctuosoma (Stoll) and Angaracris barabensis (Pall.) in 1993 but was very variable, ranging from 20.00% to 60.71% over the subsequent nine years. Disease prevalence was 43.72–60.71% in 1993 and 1994 for Oedaleus asiaticus B.-Bienko and Myrmeleotettix palpalis (Zub.) but gradually declined to approximately 20%, where it remained. Persistence of P. locustae in grasshopper populations may be important in keeping densities below economic thresholds for a number of years after application. Handling Editor: Helen Roy.     

ThechlL (frxC) gene: Phylogenetic distribution in vascular plants and DNA sequence fromPolystichum acrostichoides (Pteridophyta) andSynechococcus sp. 7002 (Cyanobacteria)

We examinedchlL (frxC) gene evolution using several approaches. Sequences from the chloroplast genome of the fernPolystichum acrostichoides and from the cyanobacteriumSynechococcus sp. 7002 were determined and found to be highly conserved. A complete physical map of the fern chloroplast genome and partial maps of other vascular plant taxa show thatchlL is located primarily in the small single copy region as inMarchantia polymorpha. A survey of a wide variety of non-angiospermous vascular plant DNAs shows thatchlL is widely distributed but has been lost in the pteridophytePsilotum and (presumably independently) within the Gnetalean gymnosperms.The namefrxC was originally used to denote a gene encoding a product with probable Fe : S cluster binding activity. This activity was postulated due to the amino acid sequence similarity between this product and the Fe : S-binding nitrogenase iron proteinnifH. Fe : S-binding is a property shared by ferredoxins, which are denoted by the prefix frx. However, this gene does not encode a ferredoxin. It is much larger than any known ferredoxin, it binds its Fe : S cluster between two halves of a homodimer (Fujita & al. 1989,Burke & al. 1993 a, c) instead of within a single subunit, and it lacks the pattern of clustered cysteines present in all ferredoxins (Meyer 1988). Therefore, we use the namechlL to recognize the sequence and functional similarities to the bacterial PChlide reductase subunit,bchL. Similar usage has been adopted for this (Suzuki & Bauer 1992) and other (Choquet & al. 1992,Burke & al. 1993b) PChlide reductase subunits.     

Physical control of Eurasian watermilfoil in an oligotrophic lake

The introduction of Eurasian watermilfoil (Myriophyllum spicatum) into oligotrophic waters of high water clarity in temperate zones of North America has produced growth in excess of 6 m depth and yearly biomass approaching 1000 g m^–2 dry weight. From its initial observation in Lake George, New York, USA in 1985, by 1993 milfoil had spread to 106 discrete locations within the lake. A 7-year study of one site having no management showed milfoil to grow expansively, suppressing native plant species from 20 in 1987 to 6 in 1993 with the average number of species m^–2 quadrat declining from 5.5 in 1987 to less than 2 in 1993. Management of milfoil by means of hand harvesting, suction harvesting and benthic barrier has reduced the number of unmanaged sites from 106 in 1993 to 11. One year post-treatment at sites utilizing suction harvesting, showed a greater number of native species at all sites than pretreatment with a substantial reduction in milfoil biomass. At sites where benthic barrier was removed 1–2 years after installation, milfoil had recolonized 44% of grid squares within 30 days. Ninety days after barrier removal 74% of grid squares contained milfoil and one year later 71% of the grids supported milfoil. During the first year following mat removal, the average number of species m^–2 peaked at 4.7 and stabilized at 4.5 during the second year. Hand harvesting by SCUBA in areas of limited milfoil growth (new sites of infestation and sites of former treatment) was found to reduce the number of milfoil plants present in subsequent years. Hand harvesting did not eliminate milfoil at any of the sites and regrowth/colonization necessitated reharvesting every 3 or more years. Results of evaluations of physical plant management techniques indicate that (1) an integrated program utilizing different techniques based on plant density reduced the growth of milfoil and (2) long term commitment to aquatic plant management is necessary since none of the techniques employed singly were found to eliminate milfoil.     

Seasonal succession of Copepoda in the Bahía Blanca estuary

The abundance and species composition of Copepoda with respect to other mesozooplanktonic groups were studied at the harbour of Ingeniero White in the inner zone of the Bahfa Blanca estuary, between July 1990 and August 1991. Maximal copepod abundances of 4.7 × 10 m^–3 and 4.9 × 10 m^–3 were observed in January 1991 and May 1991, respectively. Minimal abundances of 6 m^–3 were found in June 1990. Acartia tonsa was present throughout the year with high dominance in summer-autumn (December to May). Eurytemora affinis was present from July to October 1990 (first pulse) and from July to September 1991 (second pulse). Euterpina acutifrons was most abundant during spring 1990, whereas Paracalanus parvus was most abundant during winter-spring (July–October) 1990 and April–May 1991. The rest of the copepods were observed during winter and spring 1990 and July–August 1991. Calanoides carinatus and Labidocera fluviatilis, both species from the outer estuarine waters, were only found on two sampling dates. The proportion of meroplanktonic forms was high in certain months of the annual period considered. Differences between the copepod seasonal succession studied here and those observed during several years in the 1980's are discussed.     

基于分子证据确认秦岭藤属与驼峰藤属(夹竹桃科)的系统位置

秦岭藤属(Biondia Schltr.)是中国特有属,约13种,驼峰藤属(Merrillanthus Chun&Tsiang)是仅在我国与柬埔寨分布的单种属,目前两个属均被归并到白前属(Vincetoxicum Wolf),由于取样和系统发育分析尚存一些欠缺,因此其系统位置和归属尚需进一步确认。该文使用2个核糖体基因序列片段(ITS、ETS)、5个叶绿体基因序列片段(psbA-trnH、trnG、trnL、trnL-F、trnT-L),以及二者的合并数据,重建娃儿藤亚族(Tylophorinae)(包含属的模式秦岭藤[B.chinensis Schltr.=V.shaanxiense(Schltr.) Meve&Liede]与驼峰藤[M.hainanensis Chun&Tsiang=V.hainanense(Chun&Tsiang) Meve, H. H. Kong&Liede])的系统发育树。结果表明：秦岭藤属与驼峰藤属均包含在白前属中,秦岭藤与青龙藤[B.henryi(Warb.) Tsiang&Li=V.henryi(Warb....     

A revision of the <Emphasis Type="Italic">Heterospathe elegans</Emphasis> (<Emphasis Type="Italic">Arecaceae</Emphasis>) complex in New Guinea

Summary  Three closely affiliated species of Heterospathe Scheff. (H. elegans (Becc.) Becc., H. humilis Becc. and H. versteegiana Becc.) from New Guinea are revised. They are reduced to a single species which is divided into two subspecies, and the new combination H. elegans subsp. humilis (Becc.) M. S. Trudgen & W. J. Baker is made. The subspecies can be readily distinguished by their growth habit. Epitypes are designated for the three previously published names, as informative material on the habit is not included in the existing type specimens. A new, potentially related species is described as H. pullenii M. S. Trudgen & W. J. Baker.     

Biology,distribution and ecology of <Emphasis Type="Italic">Didymosphenia geminata</Emphasis> (Lyngbye) Schmidt an abundant diatom from the Indian Himalayan rivers

Three years of studies on some Indian Himalayan rivers in Jammu & Kashmir, Himachal Pradesh, and Sikkim revealed the presence of Didymosphenia geminata (Lyngbye) M. Schmidt, a large diatom, hitherto unreported from these areas. This is first report on the occurrence of this diatom in some Indian Himalayan rivers: Kishanganga in Jammu & Kashmir, Ravi in Himachal Pradesh in Western Himalaya and in Teesta river and its two tributaries, Lachen Chhu and Lachung Chhu from Sikkim in the Eastern Himalaya. D. geminata is the most abundant taxon in both suspended and benthic algal communities in these rivers. The species exhibits wide ecological amplitude, allowing it to inhabit both cold and warm waters. We also recorded the exotic brown trout, Salmo trutta fario in these Himalayan rivers. However, in Central Himalayan rivers, Alaknanda, Bhilangana, Mandakini and Dhauliganga in Uttarakhand, where this diatom was absent the trout were absent too. Our studies indicate that D. geminata may extend its distribution range to other Himalayan rivers, hitherto uninhabited by the diatom, depending on the mode of introduction of exotic trout in these rivers.     

New lichenicolous, muscicolous, corticolous and lignicolous taxa of Burgoa s. l. and Marchandiomyces s. l. (anamorphic Basidiomycota), a new genus for Omphalinafoliacea, and a catalogue and a key to the non-lichenized, bulbilliferous basidiomycetes

A catalogue and a key to the non-lichenized, bulbilliferous basidiomycetes are given. The new genus Burgella is described for the lichenicolous B. flavoparmeliae, phylogenetically close to Sistotrema oblongisporum and Multiclavula. The genera Pneumatospora and Tricellulortus are placed in synonymy of Minimedusa, the new combination M. obcoronata is proposed, and the new facultative lichenicolous M. pubescens is described. The new facultative lichenicolous Burgoa angulosa is phylogenetically close to the generic type B. verzuoliana, whilst the new B. moriformis and B. splendens are provisionally included in the genus Burgoa. A Burgoa-like species in the Ceratobasidiaceae is left unnamed. Two new species of Marchandiomyces, M. buckii and M. nothofagicola, are described. As Marchandiomyces aurantiacus is phylogenetically more close to Erythricium than to Marchandiomyces, it is proposed to exclude it from that genus and to use the holomorphic generic name Marchandiobasidium for both anamorph and teleomorph of this species. The new genus Marchandiomphalina is introduced for the lichenized Omphalina foliacea, a taxon phylogenetically close to Marchandiobasidium. Taxonomic novelties Burgella Diederich & Lawrey; B. flavoparmeliae Diederich & Lawrey; Burgoa angulosa Diederich, Lawrey & Etayo; B. moriformis Diederich, Ertz & Coppins; B. splendens Diederich & Coppins; Marchandiomphalina Diederich, Lawrey & Binder; Marchandiomphalina foliacea (P. M. J?rg.) Diederich, Lawrey & Binder; Marchandiomyces buckii Diederich & Lawrey; M. nothofagicola Diederich & Lawrey; Minimedusa pubescens Diederich, Lawrey & Heylen; M. obcoronata (B. Sutton, Kuthub. & Muid) Diederich & Lawrey     

中国膨果豆属(豆科)一新组合

原簇毛黄耆亚属的部分种类从黄耆属中分出,在此基础上恢复了膨果豆属,由此也产生了许多新组合。其中,新组合蒺藜叶膨果豆包含了原蒺藜叶黄耆和甘青黄耆。为验证该分类处理的合理性,该文统计分析了蒺藜叶黄耆和甘青黄耆在果实形态上的差异,同时比较了二者的地理分布式样。结果表明:甘青黄耆和蒺藜叶黄耆之间存在着明显区别,甘青黄耆种级的分类学地位应予以保留,新组合为甘青膨果豆[Phyllolobium tangutica(Batalin)Y.Kang M.L.Zhang]。     

Pollination of the southwestern Opuntias

This paper presents an overview of pollination systems inOpuntia sens. lat. in the southwestern United States. The floral syndrome of large, colorful, bowl-shaped, diurnal flowers is present in all of the prickly-pear species and most of the cholla (Cylindropuntia) species in this area. Pollination by medium-sized and large bees is established for some of the species with this floral syndrome and is predicted for the others. The same floral syndrome is widespread inOpuntia in other geographical areas.—Deviations from this floral syndrome occur in certain species of southwestern chollas, one of which has nocturnal disc-shaped flowers, and in several tropical American species groups or segregate genera with red hummingbird flowers. But such cases are relatively infrequent. Divergence between species with respect to floral syndrome and pollination system is not a common feature in the evolutionary pattern ofOpuntia. Pollination of North American Cacti, IV.—Previons parts of this series:Grant & Grant 1979a,Grant & al. 1979,Grant & Grant 1979b.