ENVIRONMENTAL PROTECTION AND ECONOMIC GROWTH

This paper explores the link between an environmental policy and economic growth employing an extension of the Neoclassical Growth Model. We include a state equation to renewable natural resources, and consider natural resources as a component of the aggregate productivity. It is assumed that the change of the environmental regulations induces costs and that economic agents also derive some utility from stock capital accumulation vis-`a-vis environment. Using the Hopf bifurcation theorem, it can be shown that cyclical environmental policy strategies are optimal, providing a theoretical support to the Environmental Kuznets Curve.

Fine‐scale measurement of diffusivity in a microbial mat with nuclear magnetic resonance imaging

Noninvasive 1H‐nuclear magnetic resonance (NMR) imaging was used to investigate the diffusive properties of microbial mats in two dimensions. Pulsed field gradient NMR was used to acquire images of the H2O diffusion coefficient, Ds, and multiecho imaging NMR was used to obtain images of the water density in two structurally different microbial mats sampled from Solar Lake (Egypt). We found a pronounced lateral and vertical variability of both water density and water diffusion coefficient, correlated with the laminated and heterogeneous distribution of microbial cells and exopolymers within the mats. The average water density varied from 0.5 to 0.9, whereas the average water diffusion coefficient ranged from 0.4 to 0.9 relative to the values obtained in the stagnant water above the mat samples. The apparent water diffusivities estimated from NMR imaging compared well to apparent O2 diffusivities measured with a diffusivity microsensor. Analysis of measured O2 concentration profiles with a diffusion‐reaction model showed that both the magnitude of calculated rates and the depth distribution of calculated O2 consumption/production zones changed when the observed variations of diffusivity were taken into account. With NMR imaging, diffusivity can be determined at high spatial resolution, which can resolve inherent lateral and vertical heterogeneities found in most natural benthic systems

Deriving observation distances for camera trap distance sampling

Camera trap distance sampling (CTDS)o is a recently developed survey method to estimate animal abundance from camera trap data for unmarked populations. It re-quires the estimation of camera-animal observation distances, which previously was done by comparing animal positions to reference labels at predefined intervals. Here, we test a photogrammetry approach to derive camera-animal observation distances. We applied both, the reference label and photogrammetry approaches to five un-gulate species varying widely in body size (Giraffa camelopardalis, Equus grevyi, Oryx dammah, Kobus megaceros and Eudorcas thomsonii) and one ground-dwelling bird spe-cies (Numida meleagris) inhabiting a large enclosure and estimated their density with CTDS. Both procedures provided highly correlated observation distances (ρ= 0.99, pCTDS en anglais) est une technique de recensement développée récemment qui permet d’estimer l’effectif de populations animales non marquées avec des pièges photographiques. Cette technique requiert l’estimation de la distance entre le piège photographique et l’animal observé, ce qui était précédemment obtenu en comparant la position de l’animal à des points de référence placés à des intervalles prédéfinis. Ici nous testons une approche de photogrammétrie pour estimer les distances entre les pièges photographiques et les animaux observés. Nous avons appliqué les deux approches, points de référence et photogrammétries, à cinq espèces d’ongulés de tailles différentes (Giraffa camelopardalis, Equus grevyi, Oryx dammah, Kobus megaceros et Eudorcas thomsonii) ainsi qu’une espèce d’oiseau (Numida meleagris) vivant dans un espace clôturé et avons estimé leur densités de populations avec le CTDS. Les deux méthodes ont fourni des distances d’observations fortement corrélées (ρ = 0.99, p significative pour la technique de photogrammétrie (MD = 0.28 m, p est néanmoins négligeable dans la mesure où, pour les analyses, les distances étaient groupées dans des intervalles allant de 2 à 5 mètres. En règle générale, les estimations d’abondances étaient proche du nombre réel d’individus dans l’enclos, et ce pour les deux techniques, avec l’exception des zèbres pour lesquels les densités étaient sous- estimées. La technique de photogrammétrie offre une alternative pour dériver les distances entre les pièges photographiques et les animaux observés et pourrait être particulièrement utile dans des habitats ouverts où les animaux sont peu cachés

A Novel Non-invasive Method to Detect RELM Beta Transcript in Gut Barrier Related Changes During a Gastrointestinal Nematode Infection

Currently, methods for monitoring changes of gut barrier integrity and the associated immune response via non-invasive means are limited. Therefore, we aimed to develop a novel non-invasive technique to investigate immunological host responses representing gut barrier changes in response to infection. We identified the mucous layer on feces from mice to be mainly composed of exfoliated intestinal epithelial cells. Expression of RELM-β, a gene prominently expressed in intestinal nematode infections, was used as an indicator of intestinal cellular barrier changes to infection. RELM-β was detected as early as 6 days post-infection (dpi) in exfoliated epithelial cells. Interestingly, RELM-β expression also mirrored the quality of the immune response, with higher amounts being detectable in a secondary infection and in high dose nematode infection in laboratory mice. This technique was also applicable to captured worm-infected wild house mice. We have therefore developed a novel non-invasive method reflecting gut barrier changes associated with alterations in cellular responses to a gastrointestinal nematode infection

Photosynthetic acclimation of <i>Symbiodinium</i> <i>in hospite</i> depends on vertical position in the tissue of the scleractinian coral <i>Montastrea curta</i>

Coral photophysiology has been studied intensively from the colony scale down to the scale of single fluorescent pigment granules as light is one of the key determinants for coral health. We studied the photophysiology of the oral and aboral symbiont band of scleractinian coral Montastrea curta to investigate if different acclimation to light exist in hospite on a polyp scale. By combined use of electrochemical and fiber-optic microsensors for O(2), scalar irradiance and variable chlorophyll fluorescence, we could characterize the physical and chemical microenvironment experienced by the symbionts and, for the first time, estimate effective quantum yields of PSII photochemistry and rates of electron transport at the position of the zooxanthellae corrected for the in-tissue gradient of scalar irradiance. The oral- and aboral Symbiodinium layers received ∼71% and ∼33% of surface scalar irradiance, respectively, and the two symbiont layers experience considerable differences in light exposure. Rates of gross photosynthesis did not differ markedly between the oral- and aboral layer and curves of PSII electron transport rates corrected for scalar irradiance in hospite, showed that the light use efficiency under sub-saturating light conditions were similar between the two layers. However, the aboral Symbiodinium band did not experience photosynthetic saturation, even at the highest investigated irradiance where the oral layer was clearly saturated. We thus found a different light acclimation response for the oral and aboral symbiont bands in hospite, and discuss whether such response could be shaped by spectral shifts caused by tissue gradients of scalar irradiance. Based on our experimental finding, combined with previous knowledge, we present a conceptual model on the photophysiology of Symbiodinium residing inside living coral tissue under natural gradients of light and chemical parameters