181,639 research outputs found
Biological traits of European pond macroinvertebrates
No full textWhilst biological traits of river macroinvertebrates show unimodal responses to geographic changes in habitat conditions in Europe, we still do not know whether spatial turnover of species result in distinct combinations of biological traits for pond macroinvertebrates. Here, we used data on the occurrence of 204 macroinvertebrate taxa in 120 ponds from four biogeographic regions of Europe, to compare their biological traits. The Mediterranean, Atlantic, Alpine, and Continental regions have specific climate, vegetation and geology. Only two taxa were exclusively found in the Alpine and Continental regions, while 28 and 34 taxa were exclusively recorded in the Atlantic and Mediterranean regions, respectively. Invertebrates in the Mediterranean region allocated much energy to reproduction and resistance forms. Most Mediterranean invertebrate species had narrow thermal ranges. In Continental areas, invertebrates allocated lesser energy to reproduction and dispersal, and organisms were short lived with high diversity of feeding groups. These characteristics suggest higher resilience. The main difference between ponds in the Alpine and Atlantic regions was their elevation. Alpine conditions necessitate specific adaptations related to rapid temperature fluctuations, and low nutrient concentrations. Even if our samples did not cover the full range of pond conditions across Europe, our analyses suggest that changes in community composition have important impacts on pond ecosystem functions. Consistent information on a larger set of ponds across Europe would be much needed, but their low accessibility (unpublished data and/or not disclosed by authors) remains problematic. There is still, therefore, a pressing need for the incorporation of high quality data sets into a standardized database so that they can be further analyzed in an integrated European-wide manner
Vegetation and discharge effects on the hydraulic residence time distribution within a natural pond
No full textResults are presented from sets of field and laboratory experiments conducted to
measure and quantify the Hydraulic Residence Time Distribution in treatment
ponds containing vegetation. The field measurements were taken in the Lyby field
pond (Sweden) with complementary experiments on a distorted, laboratory scale
model pond designed and built in the University of Warwick’s engineering
laboratory. Rhodamine WT Dye tracer experiments were used in both the Lyby
field pond and the distorted physical scale model to investigate vegetation and
discharge affects on HRTD characteristics and the technique of PIV (Particle
Image Velocimetry) was used in the distorted physical scale model to investigate
how surface flow profiles were affected by different vegetation and discharge
configurations.
The results show that the distorted physical scale pond did not reflect the HRTD
characteristics of the field site, with the actual residence time, (tm), for the distorted
physical scale pond ranging from 85 % to 125% of its nominal residence time. For
the distorted scale model, pond vegetation and discharge did not affect the relative
HRTD centroid, em, or the actual residence time, tm. This finding is attributed to
the unique pond geography and associated aspect ratios However, flow rates did
have a significant effect on the HRTD e0 (time of first dye arrival at the outlet) and
ep (time of peak dye concentration). Changes in vegetation were found to have
little effect on e0 and ep. For the laboratory pond, vegetation had a significant
control on the surface flow field whereas, flow rates did not – the latter suggests
that surface flow fields are not representative of the internal flow field in different
layers of the pond.
The experiments demonstrate that the specific shape of the distorted physical
scale pond in this study enables optimal actual resident times to be achieved over
a wide range of vegetation and flow rate configurations. If full scale field ponds
based upon this design give the same stable centroid results, then this would be a
substantial breakthrough in pond design, which would aid the design and
management of pond treatment and allow more robust optimisation of treatment
efficiency
Estimating selection pressures on HIV-1 using phylogenetic likelihood models
No full textHuman immunodeficiency virus (HIV-1) can rapidly evolve due to selection pressures exerted by HIV-specific immune responses, antiviral agents, and to allow the virus to establish infection in different compartments in the body. Statistical models applied to HIV-1 sequence data can help to elucidate the nature of these selection pressures through comparisons of non-synonymous (or amino acid changing) and synonymous (or amino acid preserving) substitution rates. These models also need to take into account the non-independence of sequences due to their shared evolutionary history. We review how we have developed these methods and have applied them to characterize the evolution of HIV-1 in vivo. To illustrate our methods, we present an analysis of compartment-specific evolution of HIV-1 em) in blood and cerebrospinal fluid and of site-to-site variation in the gag gene of subtype C HIV-1. Copyright (C) 2008 John Wiley & Sons, Ltd
Pond research and management in Europe: "Small is Beautiful"
No full textThe phrase "Small is Beautiful" was first used by the talented scholar Leopold Kohr (1909 131994), but it becames more popular thanks to the essays of one of his students, the British economist E. F. Schumacher, and it was coined as a response to the socially established idea that "Big is Powerful". It could be argued that this desire for "bigness" explains why current legal frameworks and the conservation planning and management related to standing waters often overlook ponds, despite their well-known value in terms of biodiversity and socio-economic benefits (Oertli et al., 2004; Cereghino et al., 2008). Of course, this is only one of several possible explanations, but it is important to understand that such long-established ideas can have a lasting effect upon the efficiency of our conservation actions. Beyond this social perspective, the history of science can also provide some explanation as to why ponds have been undervalued for so long
Boat electrofishing survey of the Waimapu and Kopurererua streams, Bay of Plenty, Waitara River, and a pond at Mokoia, Taranaki
No full textWe conducted boat electrofishing surveys at four sites to establish the presence of, and to remove, koi carp (Cyprinus carpio). We fished the lower Waimapu Stream, Bay of Plenty, on 15 April and 14 June 2005, and the adjacent Kopurererua Stream on 15 June 2005. We caught and removed two large koi carp ( a 7.9 kg male and a 6.9 kg female) from the Waimapu Stream in 15 April, but saw no other koi carp in 3.2-km reaches of both streams on 14-15 June. We did, however, catch a wide diversity of native fish species, including common smelt, shortfin and longfin eels, yelloweye mullet, brown and rainbow trout, giant bullies, and black flounder. We also caught a lamprey macrophthalmia in the Waimapu Stream.
No koi carp were found in a 2.4-km tidal reach of the Waitara River, northern Taranaki, on 8 June 2005, but we did catch a sparse native fish assemblage of adult inanga, shortfin eels, a few common smelt, black flounder, yelloweye mullet, and a 200-mm giant bully.
We caught and killed 16 large koi carp (total weight 58.5 kg) from a pond on private farmland near Mokoia, southern Taranaki, on 9 June 2005. This pond had a perimeter of 215 m, a surface area of 951 m², and maximum depth of 2.0 m. These fish were removed by depletion fishing in 7 circuits of the pond. We caught 9, 3, 1, 1, 1, 1, and 0 carp in successive circuits. The Zippin method of population estimation (±95% confidence interval) suggests that there were 16±1 koi carp in the pond, so it is possible that we eradicated all of the koi. All the carp were the same age and no juveniles were found, so it appears that the carp had not breed successfully in this pond
Changes in Emiliania huxleyi fatty acid profiles during infection with E. huxleyi virus 86: physiological and ecological implications
No full textFatty acids profiles of Emiliania huxleyi strain CCMP1516 were determined in a virus-induced culture crash with E. huxleyi virus 86 (EhV-86). As cell numbers declined in the infected cultures due to virus lysis, a concomitant decrease in fatty acids was observed in the particulate fraction. The composition of fatty acids within infected E. huxleyi cells was restructured, with a shift from polyunsaturated to monounsaturated and saturated fatty acids (respective distributions changing from 70:10:20% at the start of the experiment to 44:24:32% at the final time point). In particular, decreases were seen in the major fatty acid 22:6(n-3) and in 18:5(n-3), whereas greatest increases were seen in 18:1(n-9) and 22:0. The increase in the amount and restructuring of the fatty acid pool in E. huxleyi was indicative of a combination of specific and non-specific effects of virus infection. Specific effects primarily included induction of metabolic pathways such as the synthesis of components involved in virus replication, the production of virions and signal transduction via sphingolipid biosynthesis. Non-specific effects due to stress were likely mediated by reactive oxygen species. Changes in the composition of virus-infected E. huxleyi are of significance to the food web since grazing on virus-infected blooms will decrease the amount of essential polyunsaturated fatty acids passed on to higher trophic levels. Consequently, this could decrease the overall productivity of marine ecosystems
Say how may earth and heav'n unite? [first line]
No full textstrophicpiano and voicecover same as Box 121 Item 51-ACover is duplicated in 121.051a.Johns Hopkins University, Levy Sheet Music Collection, Box
121, Item 051bArranged for the Piano Forte by John C. Andrews. From an Air by S.B. Pond
Stoichiometric theory extended to micronutrients: comparison of the roles of essential fatty acids, carbon, and nitrogen in the nutrition of marine copepods
No full textConventional stoichiometric theory, which is used to study the limitation of zooplankton production by C, N, and other elements, is extended to include the essential polyunsaturated fatty acids (PUFAs) 20:5(n-3) and 22:6(n-3). Using typical biochemical compositions of consumer (Calanus helgolandicus) and algal food (hypothetical diatom-dinoflagellate mixtures), the analysis shows that PUFAs or macronutrients can be important in limiting zooplankton production, depending on the biochemical compositions of consumer and food and the efficiencies with which dietary components are used. Predicted limitation by fatty acids is strongest when zooplankton use a monospecific diet, indicating that such limitation may be of particular significance in laboratory zooplankton, which are often fed phytoplankton monocultures. The analysis illustrates several factors that operate to minimize the limiting potential of fatty acids to the extent that limitation by C or N could occur: selective grazing to obtain a nutritionally balanced diet, plasticity in consumer biochemical composition, and high C requirements for respiration. The possibility of macronutrient limitation is increased further if zooplankton are able to actively synthesize essential PUFAs, although this is not thought to be the case in most aquatic systems. The work highlights the need for complete data sets incorporating fatty acids and bulk elemental properties of consumers and prey, as well as an improved understanding of the roles and cycling of essential fatty acids, if we are to be able to provide a unified view of zooplankton nutrition
Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
No full textA compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and acoustic data from the Scotia Sea show that in summer 2-20% of the population reside at depths between 200 and 2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage, might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding, and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental repositories
Sustainable mortar with waste glass fine aggregates and pond ash as an alkali-silica reaction suppressor
No full textThe construction industry seeks sustainable alternatives to conventional materials, with numerous waste types currently destined for landfills offering potential for repurposing. This study examines the replacement of natural sand with crushed waste glass and using pond ash as a supplementary cementitious material in mortar, with a particular focus on mitigating alkali-silica reaction (ASR) and assessing compressive strength. Fly ash, widely recognised for its ASR suppression capabilities, is becoming less available due to the decline in coal-fired power generation, necessitating the exploration of pond ash as a viable alternative. However, given the prolonged storage of pond ash in repositories, its direct substitution for fly ash necessitates thorough
investigation. Hence, microstructural and chemical analyses are conducted to investigate the underlying reaction mechanisms. The strength results show that glass can replace natural sand with minimal impact on compressive strength up to 60 %, beyond which strength decreases by 11 % at 100 % glass. However, the ASR expansion results indicate that using more than 20 % glass could lead to long-term detrimental effects. Nevertheless, pond ash effectively mitigates ASR,
keeping expansions below 0.1 % at a 10 % OPC replacement, although it performs slightly less efficiently than fly ash. At 20 % replacement, pond ash performs similarly to fly ash. Pond ash outperforms fly ash in 28-day strength up to a 20 % OPC replacement and shows better strength development. The optimal balance between ASR mitigation and compressive strength is achieved with 20 % pond ash, allowing for higher glass utilisation without increasing the risk of AS
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