The effect of nutrient supplementation on the biofiltration removal of butanal in contaminated air

Butanal is one of the odorous compounds produced in the animal-rendering and food-processing industries and also in sewage-treatment plants. It shows the necessity for complementing such plants with systems for off-gas treatment. Biofiltration using simple packing material was tested for the removal of butanal. Excellent results were obtained when the filters operated at optimal humidity and were supplemented with inorganic nutrients. Without nutrients, butyric acid was detected in the effluent gas, which may explain the lower efficiency of filters without nutrients. Under optimal conditions an elimination of around 90 g·m^–3·h^–1 was reached.     

Bio-availability of phosphorus in sediments of the western Dutch Wadden Sea

The purpose of this study was to make a prognosis of the effects of extended purification of terrestrial waste water, reaching the Wadden Sea by the River Rhine and Lake IJssel, on the phosphate concentration in the western Wadden Sea.The quantities of different phosphorus fractions in intertidal and subtidal sediments of the Marsdiep tidal basin (western Dutch Wadden Sea) were measured. Different methods are applied to determine the amount of phosphorus that can be released from these sediments. The direct bioavailability is determined by inoculating sediment suspensions with a natural mixture of precultured micro-organisms from the sampling area. A second approach is the measurement of the phosphate release under different redox conditions. Sequential extraction of sediment samples with different solvents is also applied. Under the present conditions and compared to the nutrient loads from fresh water (Lake IJssel) and from the North Sea, the phosphorus stored in the sediments of the western Dutch Wadden Sea plays a minor role in the total supply to micro-algae and bacteria. The bulk of the biologically available phosphorus in the sediments originates from the metal-associated fraction. Releasable phosphate may contribute to the local annual primary production to an extent of ca 45 to ca 150 g C m^–2 a^–1. The total amount of phosphorus in the sediment (mainly calcite associated) is twice to 6 times the biologically available amount.     

Seagrass ecosystem multifunctionality under the rise of a flagship marine megaherbivore

Large grazers (megaherbivores) have a profound impact on ecosystem functioning. However, how ecosystem multifunctionality is affected by changes in megaherbivore populations remains poorly understood. Understanding the total impact on ecosystem multifunctionality requires an integrative ecosystem approach, which is especially challenging to obtain in marine systems. We assessed the effects of experimentally simulated grazing intensity scenarios on ecosystem functions and multifunctionality in a tropical Caribbean seagrass ecosystem. As a model, we selected a key marine megaherbivore, the green turtle, whose ecological role is rapidly unfolding in numerous foraging areas where populations are recovering through conservation after centuries of decline, with an increase in recorded overgrazing episodes. To quantify the effects, we employed a novel integrated index of seagrass ecosystem multifunctionality based upon multiple, well-recognized measures of seagrass ecosystem functions that reflect ecosystem services. Experiments revealed that intermediate turtle grazing resulted in the highest rates of nutrient cycling and carbon storage, while sediment stabilization, decomposition rates, epifauna richness, and fish biomass are highest in the absence of turtle grazing. In contrast, intense grazing resulted in disproportionally large effects on ecosystem functions and a collapse of multifunctionality. These results imply that (i) the return of a megaherbivore can exert strong effects on coastal ecosystem functions and multifunctionality, (ii) conservation efforts that are skewed toward megaherbivores, but ignore their key drivers like predators or habitat, will likely result in overgrazing-induced loss of multifunctionality, and (iii) the multifunctionality index shows great potential as a quantitative tool to assess ecosystem performance. Considerable and rapid alterations in megaherbivore abundance (both through extinction and conservation) cause an imbalance in ecosystem functioning and substantially alter or even compromise ecosystem services that help to negate global change effects. An integrative ecosystem approach in environmental management is urgently required to protect and enhance ecosystem multifunctionality.     

NAD+ binding to the Escherichia coli K+-uptake protein TrkA and sequence similarity between TrkA and domains of a family of dehydrogenases suggest a role for NAD+ in bacterial transport

The nucleotide sequence of trkA, a gene encoding a surface component of the constitutive K⁺-uptake systems TrkG and TrkH from Escherichia coli, was determined. The structure of the TrkA protein deduced from the nucleotide sequence accords with the view that TrkA is peripherally bound to the inner side of the cytoplasmic membrane. Analysis by a dot matrix revealed that TrkA is composed of similar halves. The M-terminal part of each TrkA half (residues 1–130 and 234–355, respectively) is similar to the complete NAD⁺-binding domain of NAD⁺-dependent dehydrogenases. The C-terminal part of each TrkA half (residues 131–233 and 357–458, respectively) aligns with the first 100 residues of the catalytic domain of glyceraldehyde-3-phosphate dehydrogenase. Strong u.v. illumination at 252 nm led to cross-linking of NAD⁺ or NADH, but not of ATP to the isolated TrkA protein.     

Reproductive Competition in Colonies of the Ant Leptothorax gredleri

Colonies of the ant, Leptothorax (s. str.) gredleri may contain several inseminated female reproductives of which typically only one is laying eggs. Observations suggest that “functional monogyny” is caused by aggressive interactions among nestmate queens. Only the most dominant queen reproduces. Subordinate queens either leave the colony to found their own nests solitarily or by budding, or stay in the nest without reproducing, but may eventually replace the dominant queen. The interrelations of life history of L. gredleri, population structure and habitat characteristics are examined.     

Effects of elevated atmospheric CO2 on net ecosystem CO2 exchange of a scrub–oak ecosystem

We report the results of a 2‐year study of effects of the elevated (current ambient plus 350 μmol CO₂ mol^?1) atmospheric CO₂ concentration (C_a) on net ecosystem CO₂ exchange (NEE) of a scrub–oak ecosystem. The measurements were made in open‐top chambers (OTCs) modified to function as open gas‐exchange systems. The OTCs enclosed samples of the ecosystem (ca. 10 m² surface area) that had regenerated after a fire, 5 years before, in either current ambient or elevated C_a. Throughout the study, elevated C_a increased maximum NEE (NEE_max) and the apparent quantum yield of the NEE (φ_NEE) during the photoperiod. The magnitude of the stimulation of NEE_max, expressed per unit ground area, was seasonal, rising from 50% in the winter to 180% in the summer. The key to this stimulation was effects of elevated C_a, and their interaction with the seasonal changes in the environment, on ecosystem leaf area index, photosynthesis and respiration. The separation of these factors was difficult. When expressed per unit leaf area the stimulation of the NEE_max ranged from 7% to 60%, with the increase being dependent on increasing soil water content (W_soil). At night, the CO₂ effluxes from the ecosystem (NEE_night) were on an average 39% higher in elevated C_a. However, the increase varied between 6% and 64%, and had no clear seasonality. The partitioning of NEE_night into its belowground (R_below) and aboveground (R_above) components was carried out in the winter only. A 35% and 27% stimulation of NEE_night in December 1999 and 2000, respectively, was largely due to a 26% and 28% stimulation of R_below in the respective periods, because R_below constituted ca. 87% of NEE_night. The 37% and 42% stimulation of R_above in December 1999 and 2000, respectively, was less than the 65% and 80% stimulation of the aboveground biomass by elevated C_a at these times. An increase in the relative amount of the aboveground biomass in woody tissue, combined with a decrease in the specific rate of stem respiration of the dominant species Quercus myrtifolia in elevated C_a, was responsible for this effect. Throughout this study, elevated C_a had a greater effect on carbon uptake than on carbon loss, in terms of both the absolute flux and relative stimulation. Consequently, for this scrub–oak ecosystem carbon sequestration was greater in the elevated C_a during this 2‐year study period.     

Biodiversity of soil biota and plants in abandoned arable fields and grasslands under restoration management

The currently widespread abandoning of agricultural land use in Western Europe offers new opportunities for ecological restoration and nature conservation. This is illustrated for abandoned arable fields and for permanent grasslands cut for hay after the cessation of fertilizer application. Although initiated by a sudden reduction of nutrient input to the system, the changing nutrient supply from the soil is considered to be the main driving force of succession. The soil nutrient supply is affected by soil organisms, both directly (root symbionts and herbivores) and indirectly (nutrient mineralization from dead organic matter). It is argued that because of the close association of changes in species diversity with changes in the functioning of ecosystems, biodiversity has to be studied in an ecosystem ecology context.     

Persistence of the Nocturnal Thyrotropin Surge and Preservation of the Sleep-Related Variations of TSH in African Trypanosomiasis

The aim of this work was to study the nycthemeral and sleep-related variations of thyrotropin (TSH) in sleeping sickness (Human African trypanosomiasis). Six untreated patients were studied during 24 hours using 10 min blood sampling and polygraphic sleep recordings. These patients were compared to 5 healthy African subjects. The patients were selected during a medical investigation in Congo. Sleeping sickness was diagnosed clinically and confirmed by the detection of Trypanosoma brucei gambiense in the blood, the cerebrospinal fluid, or in a lymph node puncture, and by a serologic immunofluorescence test. Blood was withdrawn continuously via a catheter and sampled into 10 min aliquots in an adjoining room. TSH was measured by a commercial IRMA kit. Sleep was recorded by continuous polysomnography and scored visually. The integrity of the sleep-wake cycle varied greatly among patients, ranging from major disruption with insomnia to almost undisturbed nocturnal sleep. Mean TSH levels were slightly higher in the patients than in the controls, although the difference was not significant. The nocturnal surge was preserved in all but one patient and its amplitude was not different between patients and controls. There were more TSH pulses in the patients, maybe due to fragmented sleep with many awakenings. The relationships between sleep structure and TSH variations were preserved, with decreasing TSH levels during slow-wave sleep and increasing levels after awakenings. We conclude that contrarily to other biological rhythms, the nycthemeral pattern of TSH is preserved in the sleeping sickness patients. The TSH nocturnal surge persisted, unlike in other nonthyroidal illnesses. The relationhsips between TSH variations and sleep structure are also preserved, demonstrating the robustness of this association.