SEDIMENT AND NITROGEN TRANSPORT IN GRASS FILTER STRIPS1

ABSTRACT: An 18-month field experiment was conducted to evaluate the effectiveness of grass filter strips in removing sediment and various nitrogen species from runoff. Runoff was collected from six 3.7 m wide experimental plots with 24.7 m long runoff source areas. Two plots had 8.5 m filters, two plots had 4.3 m filters, and two plots had no filters. Runoff was analyzed for total suspended solids (TSS), total Kjeldahl nitrogen (TKN),. filtered TKN (FTKN), NH₄⁺-N, and NO₃-N. The Mann-Kendall nonparametric test for trend (changes in filter effectiveness over time) indicated that there were no trends in the yields and concentrations of TSS, NO₃^--N, NH₄-N, TKN, and FTKN for the 8.5 m filter over time. For the shorter 4.3 m filters, there were significant upward trends in TKN yield and downward trends in TSS, NH4-N, and FTKN concentrations, indicating that trapping efficiency may have started changing with time. The Kruskal-Wallis test indicated that the 8.5 m filters reduced median yields and concentrations of TSS and all N species, but the 4.3 m filters only reduced the median yields and concentrations of TSS, NH₄⁺-N, TKN, and the median concentration of FTKN. The 8.5 and 4.3 m filters reduced contaminate yields and concentrations from 42 to 90 percent and from 20 to 83 percent, respectively.     

Schwermetalle in Regenwürmern Baden-Württembergs

Goal and Scope

The heavy metal burden of the soil and of earthworms from representative long-term forest observation plots has been measured since 1984 as one component of the media-embracing environmental monitoring network of the State of Baden-Wuerttemberg. These investigations are aimed at elucidating and assessing adverse effects of pollutants on the soil biocenosis

Methods

So-called characteristic curves for the metals Cd, Cu, Ni, Pb, and Zn were developed for the assessment. Earthworm toxicity data and background values in soil served as criteria. This procedure facilitates a comparative assessment of different pollutants. The mobility of the metals, which greatly influences their bioavailability and toxicity, was taken into account for the effects assessment.

Results and Conclusion

Besides inventorying the heavy metals (Part 1), the question of threshold values for toxic reactions as well as for accumulation was raised. The metal concentrations were assessed in the soil with regard to its habitat function. The ecotoxicological assessment revealed that the heavy metal burden of the investigated plots lies within the background- or precautionary range, well below the screening value established here to indicate the effect threshold in earthworms. This result means that a pollution of the forest observation plots with the metals cadmium, copper, lead, nickel, and zinc is low or absent. Only the distribution of the lead content is centered slightly above background (but clearly below the toxicity threshold). This slight lead burden of the soil of the observation plots can be explained by emissions from motor vehicles. Investigations at sites that are contaminated with either chromium or copper or cadmium showed that an accumulation of these metals in the body of the worms can be observed only above a threshold concentration of several hundred micrograms of mobile metal per kilogram in the upper layer of the soil.

Recommendations and Perspectives

The hitherto unknown threshold values for the accumulation in the body of the earthworm should be statistically validated and extended to other elements. Further research is needed in order to build a well founded basis for the ecotoxicological assessment of soil pollution. Acute and chronic earthworm effect thresholds are neither available yet for arsenic, cobalt, and mercury nor for some other elements occurring less frequently as soil pollutants. Background values depending on the kind of rock have been measured so far for total chromium only. They are lacking for the more toxic chromium (VI) which is a frequent soil pollutant but naturally occurs in traces only.     

Distribution and dynamics of larval populations of Anopheles messeae and A. atroparvus in the delta of the rivers Rhine and Meuse,The Netherlands

The distribution and ecology of mosquitoes of the Anopheles maculipennis complex were studied in the delta of the rivers Rhine and Meuse in the southwest of The Netherlands. The study area was previously malarious, with A. atroparvus being the only vector. 125 potential aquatic habitats of A. maculipennis were sampled, of which 47 (37.6%) contained larvae of this species complex. Larval densities varied from 7.4-325.93 larvae m-2. There was no correlation between chlorinity (@1000) of the water and presence and/or density of larvae. The presence of A. maculipennis was not associated with one particular aquatic floristic habitat, although larvae were often found together with floating algae (Enteromorpha spp.). Larvae were not found in areas experiencing tidal flooding. A newly developed PCR method was used for identification of the mosquito sibling species. Of 150 larvae examined, only 4 were identified as A. atroparvus. All other larvae examined were A. messeae. Adult mosquitoes were identified as A. messeae and 30 wild-caught mosquitoes had fed on domestic animals. Because most anophelines found in 1999 were A. messeae, it is concluded that the study area has undergone a dramatic ecological change since the previous anopheline investigations in 1935, causing the near extinction of A. atroparvus. This species was the only malaria vector in The Netherlands and therefore it is not expected that malaria can return to its former endemic status in the coastal areas of The Netherlands.     

Matter, spacetime and the vacuum

We distinguish three historical and scientific views of matter, spacetime, and the relationship between them: the absolute approach of Newton, the relational approach most often associated with Mach, and a third, geometrical approach which inspired Einstein and continues to drive efforts toward a unified theory of fundamental interactions today. Which is correct? We suggest that this is, to a large extent, an "ill-posed question," reminiscent of the wave/particle debate in earlier times. The boundary between matter and spacetime is no longer easy to draw, and it is likely that they are complementary aspects of the same reality. There is no clearer illustration of this than the modern view of the vacuum. We review the importance of this concept in cosmology, and explore the extent to which the old idea of an "empty" vacuum might still be maintained. If the real cosmological vacuum is far from empty, as observations now suggest, then it may be possible to achieve an even simpler goal: a Universe with a net energy of zero.     

Courting virtual rivals increase ejaculate size in sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>)

Sperm competition occurs when sperm of two or more males compete to fertilize a given set of eggs. Game-theory models of sperm competition predict that males, which face an increased risk of sperm competition, will invest more sperm in a mating. In the pair-spawning three-spined stickleback ( Gasterosteus aculeatus), males attempt to steal fertilizations (i.e. to sneak) when they are in the courting phase, but not when they are parental. The behaviour of neighbouring males may therefore indicate the risk of sperm competition. We visually confronted males before spawning with computer animations of the same virtual stickleback showing two different behaviours: either courting (high risk of sperm competition) or brood-caring (low risk of sperm competition). We show that males invest significantly more sperm (absolutely and relatively with respect to available sperm in the testes) after the courting stimulus. The relative investment ratio between the courting and the brood-caring treatment was on average 1.75. Three-spined sticklebacks thus seem to assess the risk of sperm competition by the behaviour of neighbours and to adjust their ejaculate accordingly. This result suggests that the evolutionary force of sperm competition has led to precise mechanisms of future risk assessment.     

Schwermetalle in Regenwürmern Baden-Württembergs Teil 2: ?kotoxikologische Bewertung des Bodens

Methoden  

Zur Bewertung der gemessenen Schwermetallbelastungen des Bodens wurden sog. Risiko-Kennlinien für die Metalle Blei, Cadmium, Kupfer, Nickel und Zink entwickelt, die eine einheitliche Charakterisierung von Bodengehalten im Hinblick auf ihre Wirkung auf den Regenwurm sowie auf naturr?umliche Gegebenheiten erm?glichen. Die Mobilit?t der Metalle, die für die biologische Wirkung entscheidender ist als der Gesamtgehalt im Boden, wurde bei der Bewertung berücksichtigt.     

Males do not see only red: UV wavelengths and male territorial aggression in the three-spined stickleback (Gasterosteus aculeatus)

Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks (Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback.     

Wolfgang Priester: from the big bounce to the $\Lambda$-dominated universe

Wolfgang Priester (1924–2005) was one of Germany’s most versatile and quixotic astrophysicists, reinventing himself successively as a radio astronomer, space physicist and cosmologist, and making a lasting impact on each field. We focus in this personal account on his contributions to cosmology, where he will be most remembered for his association with quasars, his promotion of the idea of a nonsingular “big bounce” at the beginning of the current expansionary phase, and his recognition of the importance of dark energy (Einstein’s cosmological constant Λ) well before this became the standard paradigm in cosmology. In memoriam Wolfgang Priester, 22 April 1924 – 9 July 2005     

Improving species status assessments under the U.S. Endangered Species Act and implications for multispecies conservation challenges worldwide

Despite its successes, the U.S. Endangered Species Act (ESA) has proven challenging to implement due to funding limitations, workload backlog, and other problems. As threats to species survival intensify and as more species come under threat, the need for the ESA and similar conservation laws and policies in other countries to function efficiently has grown. Attempts by the U.S. Fish and Wildlife Service (USFWS) to streamline ESA decisions include multispecies recovery plans and habitat conservation plans. We address species status assessment (SSA), a USFWS process to inform ESA decisions from listing to recovery, within the context of multispecies and ecosystem planning. Although existing SSAs have a single-species focus, ecosystem-based research can efficiently inform multiple SSAs within a region and provide a foundation for transition to multispecies SSAs in the future. We considered at-risk grassland species and ecosystems within the southeastern United States, where a disproportionate number of rare and endemic species are associated with grasslands. To initiate our ecosystem-based approach, we used a combined literature-based and structured World Café workshop format to identify science needs for SSAs. Discussions concentrated on 5 categories of threats to grassland species and ecosystems, consistent with recommendations to make shared threats a focus of planning under the ESA: (1) habitat loss, fragmentation, and disruption of functional connectivity; (2) climate change; (3) altered disturbance regimes; (4) invasive species; and (5) localized impacts. For each threat, workshop participants identified science and information needs, including database availability, research priorities, and modeling and mapping needs. Grouping species by habitat and shared threats can make the SSA process and other planning processes for conservation of at-risk species worldwide more efficient and useful. We found a combination of literature review and structured discussion effective for identifying the scientific information and analysis needed to support the development of multiple SSAs. Article impact statement: Species status assessments can be improved by an ecosystem-based approach that groups imperiled species by shared habitats and threats.     

Floral colour change in <Emphasis Type="Italic">Byrsonima variabilis</Emphasis> (Malpighiaceae) as a visual cue for pollen but not oil foraging by oil-collecting bees

Pollinators search for multiple flora resources throughout their life cycle. Most studies, however, only assess how bees discriminate floral cues in the context of nectar foraging. In the present study, we sought to elucidate whether oil-collecting bees discriminate flowers of Byrsonima variabilis (Malpighiaceae) with petals of different colours when foraging for pollen or oil. As the colour of the standard petal changes during anthesis, we characterised the spectral reflectance patterns of flowers throughout anthesis and modelled chromatic perceptual space to determine how these colour patterns are perceived by bees. Through the quantification of flower pollen in the different phases, we found that the colour of the standard petal is an honest cue of the presence of pollen. Centridine bees preferentially visited flowers with a yellow (bee’s green) colour when searching for pollen, but indiscriminately visited flowers with different petal colours when searching for floral oil. We suggest that standard petals, in the species studied and others of the genus, like nectar guides, act as pollen guides, which oil-collecting females use to detect pollen-rich flowers. Moreover, they use different floral clues during foraging for different resources in the same host plant.