Age and growth in wild Kemp''s ridley seaturtles Lepidochelys kempii from skeletochronological data

Skeletochronological analysis provides age estimates, not actual ages, for seaturtles. Unlike age and growth data from captive and headstart turtles, these estimates predict the actual patterns of age and growth in free-living turtles. A moderate-sized sample of 69 Lepidochelys kempii, salvaged from the Atlantic and Gulf coasts of the USA, had straight-line carapace lengths (SCL) of 188–720 mm and age-estimates of 2–15 years. The von Bertalanffy growth model provides the best fit for the age-estimate and size data and predicts maturity between 11 and 16 years, depending upon the body size selected to represent sexual maturity. The logistic growth model suggests later maturity of 13–19 years. Comparison of the Atlantic and Gulf components of the sample suggests a faster growth rate for ridleys in the Gulf of Mexico, although the sizes of the subsamples are too small for this interpretation to be reliable without additional data. Our age and growth estimates indicate that some members of the early cohorts of headstart ridleys are mature and may have nested already.     

Phosphorus management in balanced agricultural systems

Abstract. The practice of large phosphorus (P) additions to agricultural land has resulted in an increased depletion of limited mineable rock phosphate resources, P accumulation in soils with an increased risk for P losses, and intensified eutrophication and deterioration of water quality in recipient water bodies. A number of measures have been used to reach balance between P inputs and outputs in agricultural systems, with the goal of achieving improved P use efficiency, sustained high crop yields and reduced P losses. This paper discusses how this goal may be achieved. Results from a Swedish long-term fertility experiment combined with results of a P leaching study using a selection of soils from the fertility experiment are used to evaluate the effects of a balanced P system on yields, soil P levels and P leaching. Three P fertilizer application strategies are compared (zero P, replacement P, and a treatment where surplus P fertilization was used to achieve a rapid increase in the soil P status). The replacement P strategy appeared to be the most sustainable system but P fixation in this system must be accounted for. When surplus P rates were applied, increased crop yields were counterbalanced by poorer use efficiency and P accumulation in soil. Topsoil P content was a poor predictor of P leaching. Instead, balancing P inputs and outputs represents a first step in the management of P losses, but additional, site-specific measures are required to counteract site-specific factors responsible for P losses.     

Analysis of sulfur-containing components of a soil treated with simulated acid rain

Samples of the LFH and Bfh horizons of an Orthic Humo-Ferric Podzol were analyzed for S components after irrigation with simulated acid rain solutions of pH 5.7, 3.5, and 2.0 for 720 days. Organic S was preponderant. In the LFH horizon, the mass ratio of ester sulfate: carbon-bonded S was approximately I : 1 for samples treated with solutions of pH 5.7 and 3.5; for the sample treated with the pH-2.0 solution, the ratio was about 2 : 1 and the concentrations of both inorganic sulfate and ester sulfate were markedly higher. In the Bth horizon, carbon-bonded S was the major form of organic S, except in the sample subjected to the high-acid (pH 2.0) simulated rain. The organic S components were further separated into chloroform-soluble, aqueous trifluoracetic acid-soluble, and residual fractions. Significant increases in inorganic sulfate, both water soluble and adsorbed were found after the pH-2.0 treatment.     

The mutual interference of spruce canopy structural elements

The drag force on fourteen three-prong spruce shoots (Picea rubens) has been measured in a wind tunnel in velocities ranging from 0.4 to 4.5 m s^?1. The influence of wind velocity and shoot needle density on momentum transfer and the mutual interference to momentum transfer are evaluated.The influence of the shoot needle density (ranging from 0.6 to 1.7) on momentum transfer is velocity dependent. The shoot needle density does not influence the momentum transfer to the shoot when the wind velocity is less than about 1.5 m s^?1. However, a slight trend of increased momentum transfer to the shoot with decreased shoot needle density was found for wind velocities between 1.5 and 4.5 m s^?1. This trend is not statistically significant.The shelter factor, a measure of the mutual interference to momentum transfer to the shoot structure, is shown to be dependent on the model used to describe the flow around and through the shoot. This suggests that any apparent velocity dependence of the shelter factor may actually be due to a change in flow conditions. It is concluded that: (1) the needles are the vegetative component involved in mutual interference within the shoot for wind speeds between 0.4 and 1.5 ms^?1, and (2) the shoots themselves are the vegetative component involved in mutual interference within a shoot array for wind speeds between 1.5 and 4.5 ms^?1. The shelter factor at the low wind speeds is estimated to be 2.1 The shelter factor at the higher wind speeds should be based on interference between shoots and not between needles within a single shoot.     

Recreation and large mammal activity in an urban nature reserve

Human recreation has immediate and long-term impacts on wildlife, and exposure to recreational activities might be particularly high in urban systems. We investigated the relationship between human recreation and the spatial and temporal activity patterns of large mammals in an urban nature reserve. Data from remotely triggered infra-red cameras (1999-2001) were used to assess activity for bobcat, coyote, mule deer, humans, and domestic dogs along paths in the Nature Reserve of Orange County (NROC), California. Forty-nine camera sites established across the NROC yielded 16,722 images of humans, dogs, and our three target large mammal species during 4232 observation nights. Results suggest that bobcats, and to a lesser degree coyotes, exhibited both spatial and temporal displacement in response to human recreation. Bobcats were not only detected less frequently along trails with higher human activity, but also appeared to shift their daily activity patterns to become more nocturnal in high human use areas; negative associations between bobcat and human activity were particularly evident for bikers, hikers, and domestic dogs. In general, both bobcats and coyotes displayed a relatively wide range of activity levels at sites with low human use, but a lower and markedly restricted range of activity at those sites with the highest levels of recreation. Although we did not find a clear and consistent pattern of avoidance of human recreation by deer, the probability of detecting deer during the day was lower with increasing levels of human recreation. Future studies that experimentally investigate the impacts of recreationists on wildlife, as well as relate behavioral responses to survival and reproduction, will allow further insight of the effects of urban recreation on large mammal populations.     

Evaluation of estrogenic/antiestrogenic activity of ellagic acid via the estrogen receptor subtypes ERalpha and ERbeta

Ellagic acid is a plant-derived polyphenol, possessing antioxidant, antiproliferative, and antiatherogenic properties. Whether this compound has estrogenic/antiestrogenic activity, however, remains largely unknown. To answer this question, we first investigated the ability of ellagic acid to influence the activity of the estrogen receptor subtypes ERalpha and ERbeta in HeLa cells. Cells co-transfected with an estrogen response element (ERE)-driven luciferase (Luc) reporter gene and an ERalpha- or ERbeta-expression vector were exposed to graded concentrations of ellagic acid. At low concentrations (10(-7) to 10(-9) M), this compound displayed a small but significant estrogenic activity via ERalpha, whereas it was a complete estrogen antagonist via ERbeta. Further evaluation revealed that ellagic acid was a potent antiestrogen in MCF-7 breast cancer-derived cells, increasing, like the pure estrogen antagonist ICI182780, IGFBP-3 levels. Moreover, ellagic acid induced nodule mineralization in an osteoblastic cell line (KS483), an effect that was abolished by the estrogen antagonist. Endometrium-derived epithelial cells (Ishikawa) showed no response to the natural compound by using a cell viability assay (MTT). These findings suggest that ellagic acid may be a natural selective estrogen receptor modulator (SERM).     

Critical aspects of potassium management in agricultural systems

Abstract. Fertilizer and manure application rate and timing are often based on the optimal nitrogen rate and not on potassium (K) requirements. This can lead to excess or shortage of K depending on the crop and rotation. In grass‐dominated agricultural production, including many organic farming systems, K has become a critical element, especially in areas dominated by coarse‐textured or organic soils. In this paper we review K management in relation to long‐term sustainability of both the soil resource and the production of crops of high yield and quality. One question for the future is whether we can adopt management options that favour efficient use of K and secure a sustainable future for global K reserves. For example, is it possible to enhance the release rate of K from soil mineral sources so that we require less fertilizer K from K‐bearing salt deposits? A reduction in external K inputs requires improved on‐farm recycling of K in order to reduce losses. We also need a better understanding of soil processes and soil–plant interactions and decision‐support tools to predict the potential K release from mineral weathering. Certain areas dominated by young, clay‐rich soils can potentially supply enough K, whereas other areas with coarse sandy or organic soils have a very low weathering potential and would thus need external inputs of K.     

Directed search for plant constituents: a case study concerning flavonoids in Norway spruce

The reported content of flavonoids in the needles of Norway spruce, Picea abies, has been used as a basis for a directed search for compounds previously undetected in this species. Combined with advanced chromatographic methods and sensitive detection techniques, the directed search approach assisted in the identification of the novel flavonols, myricetin 3- O- (6-acetylglucoside) and syringetin 7- O-glucoside, and several other flavonoids isolated for the first time from this species.