SUBSTRATE HETEROGENEITY AND REGENERATION OF A SWAMP TREE,NYSSA AQUATICA

We investigated physical characteristics of several substrate types in a South Carolina riverine swamp forest, and the effect of those characteristics upon germination and seedling growth of the dominant swamp tree, Nyssa aquatica (water tupelo). Substrates were categorized as emergent (surfaces of trees, living cypress knees, stumps, or logs), protected (submerged sediment adjacent to an emergent object), or open (sediment > 50 cm from any emergent object and fully submerged during the growing season). Water tupelo seeds germinated best (>25% in 16 days) on emergent substrates, but seed predation was extremely high on these same substrates. Substrate types differed significantly in permanence and in rates of sediment loss or deposition. Growth rates of transplanted seedlings did not differ among substrate types. The results suggest that mortality due to erosional scour or impermanent rooting zones, superimposed on germination patterns, is responsible for the observed nonrandom distribution of woody plant seedlings among substrate types in the swamp forest.     

硅酸盐矿物麦饭石对沉水植物生理生态的影响

沉水植物的稳定生长是重建健康湖泊生态系统重要环节, 底质条件是沉水植物生长的关键因素。研究通过观测沉水植物生理生态的变化来探讨麦饭石对其影响及作用机理。研究结果表明, 与湖泥组相比, 麦饭石可明显促进沉水植物苦草生长, 覆盖1 cm厚度麦饭石的苦草植株高度、单株生物量优于湖泥组(P<0.05); 改性麦饭石组的苦草株高、单株生物量高于麦饭石原石组(P<0.05)。麦饭石组中两种植物苦草和轮叶黑藻的光合色素、根系活力、丙二醛、过氧化物酶活等指标在一定程度上均优于湖泥组。检测发现麦饭石中含有丰富的植物生长所需的常量和微量元素, 可以明显促进沉水植物生长。可见麦饭石有益于沉水植物生长, 可进一步作为底质改良材料应用于湖泊生态修复工程。     

A new sampler for collecting invertebrates in submerged vegetation

A new sampler is described that can rapidly enclose a specific volume of water at a given depth, including submerged macrophytes and associated invertebrates. The sampler is a tong-shaped instrument consisting of two metal rods connected by a flexible joint. At the end of each arm is a metal cylinder (diameter 10 cm); one end of the cylinder has a sharpened edge and the other is equipped with a net. Powerful metal springs force the cylinders together at high speed, and macrophytes are enclosed in the nets. The sampler is suitable for studying vertical and horizontal distribution of invertebrates, even fast-moving taxa, within submerged vegetation. The device causes little disturbance of the vegetation, hence it is also suitable for repeated sampling within mesocosms.     

The Bottom Sampler – a new technique for sampling bed sediments in streams and lakes

New, easy to use, liquid nitrogen-cooled equipment is described for sampling the upper layer (80–160 mm) of water sediment and associated benthic organisms in streams and lakes up to 1.2 m deep. The sediment sample has an area of 0.0531 m² and retains its natural composition and spatial structure. The two sampler components weigh 15 kg in total, which enables sampler use by hand, even in rural areas that are not readily accessible. A successful 2-year testing period in several first and second order streams demonstrated the suitability of the apparatus for sampling sediment textures ranging from fine clay to cobbles and current velocities up to 1 m s^?1.     

不同基质中水鳖对共存的穗花狐尾藻和金鱼藻的影响

研究设置了营养水平不同的3种基质,在有或无浮水植物水鳖共存的情况下,混合种植营养吸收方式不同的两种沉水植物（仅从水中吸收营养的金鱼藻和从水和基质都能吸收营养的穗花狐尾藻）,探讨在不同的基质中浮水植物对沉水植物的影响。结果显示:实验中水鳖的存在均未对共存的两种沉水植物的生长产生抑制作用。当水鳖覆盖水面时,与无根的金鱼藻竞争光照和水体营养,促使其增加分枝数和茎长,并增加叶生物量的分配,最终导致水鳖的共存促进了金鱼藻的生物量积累。但与金鱼藻不同,有根的穗花狐尾藻可通过基质吸收营养,与共存的水鳖之间只存在光照竞争,使穗花狐尾藻仅以改变植株形态来适应浮水植物的表层覆盖,生物量积累并未发生显著变化。与沙处理相比,水鳖在营养水平较高的泥处理和泥沙混合处理中生长更旺盛,基质没有显著影响沉水植物的生物量和分株数。因此,在退化湿地生态系统中恢复水生植物时,为了提高群落的物种多样性,可以将沉水植物与少量的浮水植物组合配置,少量的浮水植物不会对沉水植物的生长带来负面影响。     

Impacts of sediment type on the performance and composition of submerged macrophyte communities

To restore deteriorated lake ecosystems, it is important to identify environmental factors that influence submerged macrophyte communities. While sediment is a critical environmental factor for submerged macrophytes and many studies have examined effects of sediment type on the growth of individual submerged macrophytes, very few have tested how sediment type affects the growth and species composition of submerged macrophyte communities. We constructed submerged macrophyte communities containing four co-occurring submerged macrophytes (Hydrilla verticillata, Myriophyllum spicatum, Ceratophyllum demersum and Chara fragilis) and subjected them to three sediment treatments, i.e., clay, a mixture of clay and quartz sand at a volume ratio of 1:1 and a mixture at a volume ratio of 1:4. Compared to the clay, the 1:1 mixture treatment greatly increased overall biomass, number of shoot nodes and shoot length of the community, but decreased its diversity. This was because it substantially promoted the growth of H. verticillata within the community, making it the most abundant species in the mixture sediment, but decreased that of M. spicatum and C. demersum. The sediment type had no significant effects on the growth of C. fragilis. As a primary nutrient source for plant growth, sediment type can have differential effects on various submerged macrophyte species and 1:1 mixture treatment could enhance the performance of the communities, increasing the overall biomass, number of shoot nodes and shoot length by 39.03%, 150.13% and 9.94%, respectively, compared to the clay treatment. Thus, measures should be taken to mediate the sediment condition to restore submerged macrophyte communities with different dominant species.     

The propagation and dispersal of misinformation in ecology: Is there a relationship between citation accuracy and journal impact factor?

The biological and physico-chemical structure of near bottom habitats located under densely growing submerged vegetation, and their significance in the functioning of whole aquatic ecosystems, are very little known due to difficulties in sampling. Corer-type samplers, believed to be the best in littoral studies, do not work properly in such places, because their tube opening is easily clogged by plant shoots, acting as a stopper. In order to overcome this problem, an alteration to the shape of the tube ending is proposed. This can be done by its trimming at an accurate angle, or by fitting (permanently or interchangeably) a metal collar made of stainless steel to its end, so that the ending would resemble the shape of a needle. The modification can be applied to virtually all corer samplers. It was found to be efficient while sampling sediment cores for the purposes of both hydrobiological and paleolimnological studies on heavily overgrown macrophyte-dominated water ecosystems.     

Measurement of organic loading under an open-ocean aquaculture cage, using sediment traps on the bottom

Organic loading under a submerged fish cage in commercial operation has been quantified for the first time in the open ocean. Sediment traps out to 100 m sampled the loading continuously over the 15 months of a complete grow‐out cycle for cobia (Rachycentron canadum). Typically 4% or 5% of the feed arrived directly to the sediment, although this benthic percentage became much higher in the last two months of this study. Almost all the loading (90%) lands within 30 m of the cage mooring block. The loading consists of fragments of feed pellets that wash out from the mouths and gills of the fish. The fragments sink rapidly and almost vertically; they are not carried horizontally into large dilution volumes. Dispersal on the sediment surface is much more extensive than dispersal in the water. This study developed expeditious and cost‐effective techniques for sampling and analyzing organic loading, using a minimum of technological resources.     

A simple syringe sampler for sampling bottom waters

SUMMARY. A cheap messenger-operated device for sampling water immediately above sediment is described.     

The structure of the littoral: effects of waterlily density and perch predation on sediment and plant‐associated macroinvertebrate communities

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可调式沉水植被网床对泥沙型富营养化河道生态修复工程研究

分别采用水花生(Alternanthera philoxeroides (Mart.) Griseb)和狐尾藻(Myriophyllum verticillatum)2种可调式沉水植被网床对临港新城环湖流动泥沙型河道进行修复, 通过4个月连续跟踪测定修复河道总氮(TN)、硝态氮(NO₃-N)、亚硝态氮(NO₂-N)、总磷(TP)、活性磷酸盐(PO₄-P)的含量变化以及水体透明度(SD)变化以评价可调式沉水植物网床生态修复效果。结果显示, 沉水植物网床对流动泥沙型河道透明度具有明显改善作用。其中, 水花生网床和狐尾藻网床对TN、NO₃-N、NO₂-N、TP、PO₄-P的削减率分别为69.58%、67.91%、84.48%、62.26%、82.61%和45.48%、58.32%、76.56%、43.12%、73.68%, 且分别对泥沙型河道透明度提高了18%和26%。可见, 水花生网床对营养盐的削减效果优于狐尾藻网床, 而狐尾藻网床对透明度改善效果优于水花生网床。因此把这2种可调式沉水植物网床结合起来, 对流动泥沙型富营养化河道具有更好去除富营养物及泥沙的生态修复效果。     

High levels of sediment contamination have little influence on estuarine beach fish communities

While contaminants are predicted to have measurable impacts on fish assemblages, studies have rarely assessed this potential in the context of natural variability in physico-chemical conditions within and between estuaries. We investigated links between the distribution of sediment contamination (metals and PAHs), physico-chemical variables (pH, salinity, temperature, turbidity) and beach fish assemblages in estuarine environments. Fish communities were sampled using a beach seine within the inner and outer zones of six estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. All sampling was replicated over two years with two periods sampled each year. Shannon diversity, biomass and abundance were all significantly higher in the inner zone of estuaries while fish were larger on average in the outer zone. Strong differences in community composition were also detected between the inner and outer zones. Few differences were detected between fish assemblages in heavily modified versus relatively unmodified estuaries despite high concentrations of sediment contaminants in the inner zones of modified estuaries that exceeded recognized sediment quality guidelines. Trends in species distributions, community composition, abundance, Shannon diversity, and average fish weight were strongly correlated to physico-chemical variables and showed a weaker relationship to sediment metal contamination. Sediment PAH concentrations were not significantly related to the fish assemblage. These findings suggest that variation in some physico-chemical factors (salinity, temperature, pH) or variables that co-vary with these factors (e.g., wave activity or grain size) have a much greater influence on this fish assemblage than anthropogenic stressors such as contamination.     

珠江河网典型水草床与贝类群落生物量特征

于2015年和2018年12月初调查珠江河网4个江段(左滩、小塘、外海和榄核)的典型水草床群落生物量时空变化特征,同时调查了相应江段的水草床、邻近非水草床区域的主要贝类生物量时空变化,并利用CCA分析其与主要水文、水质及沉积环境因子的相关性。结果表明:珠江河网典型水草床群落主要以刺苦草为优势种,偶伴生金鱼藻、穗状狐尾藻和轮叶黑藻等种类;对比两次调查结果发现,除小塘江段水草床生物量(以鲜重计)维持较稳定,高达9 kg·m^-2以外,其余3个江段的水草床均有种类减少、生物量下降的消落趋势。小塘江段贝类生物量最高,均值达968.8 g·m^-2,显著高于其他江段;所调查江段水草床区域中的贝类均高于非水草床区域;在由浅至深的水草床区域,虽然水草生物量逐增,但其贝类生物量却逐减;相同江段非水草床区域的贝类生物量显著低于水草床区域,表明珠江河网水草床为贝类提供良好的栖息、生长和繁育生境。径流量和水位变化可能是驱动珠江河网典型水草床群落年际演替的主要因素,而水草优势种类的保持可能受沉积物粒径组分和水体流速等因子的调控。     

Modeling industrial centrifugation of mammalian cell culture using a capillary based scale-down system

Continuous-flow centrifugation is widely utilized as the primary clarification step in the recovery of biopharmaceuticals from cell culture. However, it is a challenging operation to develop and characterize due to the lack of easy to use, small-scale, systems that can be used to model industrial processes. As a result, pilot-scale continuous centrifugation is typically employed to model large-scale systems requiring a significant amount of resources. In an effort to reduce resource requirements and create a system which is easy to construct and utilize, a capillary shear device, capable of producing energy dissipation rates equivalent to those present in the feed zones of industrial disk stack centrifuges, was developed and evaluated. When coupled to a bench-top, batch centrifuge, the capillary device reduced centrate turbidity prediction error from 37% to 4% compared to using a bench-top centrifuge alone. Laboratory-scale parameters that are analogous to those routinely varied during industrial-scale continuous centrifugation were identified and evaluated for their utility in emulating disk stack centrifuge performance. The resulting relationships enable bench-scale process modeling of continuous disk stack centrifuges using an easily constructed, scalable, capillary shear device coupled to a typical bench-top centrifuge.     

A Portable Coring Device for Rapid Site-Sampling

Abstract

A portable hydraulic coring device facilitates rapid sampling of archaeological sites and collection of undisturbed sediment monoliths for reference in research and teaching. The modestly priced device may be used in dense forests or on terrain unsuited to more expensive, truck-mounted rigs.     

Assessing the potential for recovery of lakeshore vegetation: species richness of sediment propagule banks

To assess the potential and develop appropriate techniques for the recolonization of lakeshore vegetation at sites where it had been completely lost, a pilot project was launched at Lake Kasumigaura, Japan. We investigated the species composition and density of the soil seed banks (propagule banks) of lake sediments at nine sites (total area, 65,200 m²) where lake sediments were spread thinly (∼10 cm) on the surfaces of artificial littoral zones. These zones were constructed in front of concrete levees and had microtopographic variations. In total, 180 species, including six endangered or vulnerable species and 12 native submerged plants that had disappeared from the aboveground vegetation of the lake, were recorded during the first year of restoration. The distribution of each restored species at the sites suggested the importance of microtopographic variation for recolonizing species-rich lakeshore vegetation. Furthermore, the origin of the source sediment affected the species composition of the established vegetation.     

A new device for sampling water from the benthic boundary layer

An instrument is described, which collects water from the benthic boundary layer in shallow waters with a maximum depth of 50 m. Four water samples of 71 each can be collected between 5 cm and 40 cm above the sediment. Handling is easy, and the sampling operation is short enough to allow repeated employment even on time-limited, routine investigations. First results show gradients in the organic matter and seston content of samples from the 5 to 35 cm above the sediment. The oxygen concentrations near the sea bottom decreased faster than those 3 m above, just below the summer pycnocline.     

Implications of the spatial variability of macroinvertebrate communities for monitoring of ephemeral lakes. An example from turloughs

Turloughs, ephemeral water bodies associated with karstified limestone, are an important habitat found in the West of Ireland. They are a priority habitat under the European Habitats Directive (92/43/EEC) and are groundwater-dependent habitats under the European Water Framework Directive (2000/60/EC; WFD). Sampling to meet the objectives of either Directive requires discrimination of inherent natural variation from anthropogenically induced disturbances and accounting for both spatial and seasonal patterns of biotic distribution. This study reports within- (submerged grassland) and between-habitat (submerged and emergent grassland) variability of macroinvertebrate communities in six turloughs. Two different habitat types were sampled from two turloughs in April 2007, and further assessment of spatial pattern in commonly found submerged grassland habitat was determined from four additional turloughs in spring 2008. While cluster analysis and non-metric multidimensional scaling identified differences in macroinvertebrate community structures between habitats in one out of two turloughs, congruence of invertebrate communities was, nevertheless, greater within than among turloughs. Within-habitat variability of macroinvertebrate communities across sampling locations of submerged grassland habitat was sufficiently low so that samples collected at any location of a turlough can provide a reliable metric of the macroinvertebrate community of a turlough as a whole. A standardized submerged grassland sampling approach for routine turlough sampling is recommended as a pressure response method to fulfil the requirements of the WFD. For a comprehensive conservation assessment, however, as demanded under the EC Habitats Directive, we suggest a multi-habitat sampling approach to obtain a thorough assessment of turlough macroinvertebrate biodiversity.     

Prehistoric land use as recorded in a lake-shore core at Lake Constance

The second part of a pollen profile from Hornstaad/Lake Constance (Germany), containing the Atlantic and Subboreal (6400 cal B.C. to 700 cal B.C.) is presented. The diagram has a sampling interval of 1 cm and an average time resolution of 10 years. The cereal curve provided the basis for cereal zones, which are used to classify the human impact. Twenty-six cereal zones can be distinguished, most of them divided into subzones, from 5500 cal B.C. to 700 cal B.C. They correspond to both known and, mostly, unknown settlements in the surrounding landscape from the Early Neolithic to the Late Bronze Age. Charcoal and chemical analyses as well as sediment accumulation, confirmed by accelerator dates, provide evidence for human impact on the environment.A contribution to the 8th IPC, Aix-en-Provence, Sept. 1992