Search results for "conservation."
showing 10 items of 1994 documents
Relationship between the endangered freshwater pearl mussel Margaritifera margaritifera, its salmonid host and co-infectants
2018
The relationship between the freshwater pearl mussel (hereafter FPM), Margaritifera margaritifera, and its salmonid host — pivotal for the conservation of this endangered bivalve — is characterized by a long parasitic stage (up to 11 months) and excessive host specificity. This thesis focuses on this relationship by experimentally studying the effect of FPM infection on the growth and resistance of salmonid fish and how the infection influences vulnerability of the host to other parasites and diseases, as well as how exposure of the host to other parasites affects vulnerability to FPM. Infection with FPM results in (i) reduced growth of the host, brown trout, during the parasitic period. Gl…
Effect of glochidia infection on growth of fish : freshwater pearl mussel Margaritifera margaritifera and brown trout Salmo trutta
2019
AbstractEffect of freshwater mussels’ (Unionoida) glochidia on the growth of fish host has remained poorly studied. We compared the specific growth rate of the juvenile, PIT-marked brown trout (Salmo trutta) between uninfected controls to those experimentally infected (average initial intensity of infection 8000 fish−1) with Margaritifera margaritifera glochidia, kept in high and low feeding. Growth and mortality of fish were monitored for 10 months. Our hypothesis was that glochidiosis would impair the growth of fish. According to our hypothesis, infected fish gained statistically significantly less weight than the control fish throughout the experiment. A proportional increase in weight o…
Soil erosion assessment and control in Northeast Wollega, Ethiopia
2018
Soil erosion is the main driver of land degradation in Ethiopia, and in the whole region of East Africa. This study was conducted at the Northeast Wollega in West Ethiopia to estimate the soil losses by means of the Revised Universal Soil Loss Equation (RUSLE). The purpose of this paper is to identify erosion spot areas and target locations for appropriate development of soil and water conservation measures. Fieldwork and household survey were conducted to identify major determinants of soil erosion control. Six principal factors were used to calculate soil loss per year, such as rainfallerosivity, soil erodiblity, slope length, slope steepness, crop management and erosion-control practices…
Visual Representation of Urban Environment: Microraioni of Riga in Soviet Cinematography
2017
Abstract The aim of this article is to interpret the discourse of residential areas of Riga through the films of the Soviet period and to examine essential changes in residential structure. Specific image of cinematic formal techniques is used in relation to the urban. The results of movie review are compared with changes in the residential development between 1945–1990. 124 movies display that residential areas are frequently portrayed in the Soviet cinema and they form an integral part of the Soviet urban perception.
A Double-Hurdle model of urban green areas valuation: Dealing with zero responses
2008
Due to the widespread support for public parks and open spaces in urban areas, there is an increasing need to analyse the social benefits that are generated by such amenities. The city of Valencia (Spain) has a large park that can be considered its green backbone due to its transversal layout running along 9 of the 19 districts into which the city is divided. A contingent valuation survey was therefore conducted in order to obtain the non-market benefits derived from the use of this park by the inhabitants of Valencia. In addition, to deal with the large number of zero responses obtained, a Double-Hurdle model was applied. The results show that this model is more appropriate than other, sim…
Economic theory and space : a reconciliation
1997
Malgré des apports importants au XIXe siècle et dans la première moitié du XXe et en dépit des efforts de l'après guerre, l’économie spatiale est longtemps restée un domaine marginal par rapport au corpus principal de la théorie économique. L’attachement aux hypothèses de concurrence pure et de rendements non croissants explique en grande partie cette séparation. Depuis quelques années, on assiste, dans le cadre de l'Economie géographique, à un mouvement d’intégration dont le moteur principal est la reconnaissance et l’exploitation des rendements croissants comme explication de la formation de l’espace économique. Ce papier présente un panorama de 25 années d’économie spatiale en soulignant…
Food predictability determines space use of endangered vultures: implications for management of supplementary feeding.
2013
Understanding space use of free-living endangered animals is key to inform management decisions for conservation planning. Like most scavengers, vultures have evolved under a context of unpredictability of food resources (i.e. exploiting scattered carcasses that are intermittently available). However, the role of predictable sources of food in shaping spatial ecology of vultures has seldom been studied in detail. Here, we quantify the home range of the Egyptian vulture (Neophron percnopterus), a long-lived raptor which has experienced severe population decline throughout its range and is qualified as endangered worldwide. To this end six adults were tracked by satellite telemetry in Spain d…
Allee effects and the Allee-effect zone in northwest Atlantic cod
2022
According to the theory of compensatory dynamics, depleted populations should recover when the threat responsible for their decline is removed because per capita population growth is assumed to be highest when populations are at their smallest viable sizes. Yet, many seriously depleted fish populations have failed to recover despite threat mitigation. Atlantic cod (Gadus morhua) stocks off Newfoundland, despite 30 years of dramatically reduced fishing mortality and numerous fishery closures, have not recovered, suggesting that drivers other than fishing can regulate the growth of collapsed fish populations, inhibiting or preventing their recovery. Here, using Bayesian inference, we show str…
Propuesta de microrreservas vegetales. Una alternativa para la conservación de líquenes en la comunidad Valenciana.
2001
ATIENZA, V., SEGARRA, J. G & LAGUNA, E. 2001. Plant micro-reserves proposal, as an alternative for lichen conservation in the Valencian Community. Bot. Complutensis 25: 115-128. In the scope of the Valencian Community 6 areas are proposed as lichenological flora micro-reserves, two of them are located in the Alicante province: 1.Villena, Cabezo del Chocolaino and 2. Xàbia, Cabo de San Antonio, Morro dels Cocons, two in the Castellón province: 3. Pina de Montalgrao. Santa Bárbara de Pina and 4. Illes Columbretes. Illa Grossa and two in the Valencia province: 5. Puebla de San Miguel. Cerro Calderón and 6. El Saler. Pujol Nou. Location, description and a list of the most interesting lichen…
Anotaciones sobre Lasiopogon muscoides (Desf.) DC. (Compositae) en la Comunidad Valenciana
2014
Se dan a conocer nuevos datos sobre Lasiopogon muscoides, planta autóctona de la flora de la Comunidad Valenciana (E de España), en cuyas comarcas centrales alcanza su límite septentrional de distribución. Se aporta por primera vez información concreta sobre su ubicación y su comportamiento ecológico y fitosociológico. Además, dada su rareza y originalidad en el conjunto de la flora de este territorio, se propone su inclusión en el Catálogo Valenciano de Especies de Flora Amenazadas con la categoría “en peligro de extinción”. New data are reported on Lasiopogon muscoides in the Valencian Community (E of Spain), a territory in which its northernmost distribution is found. Data are shown for …