809 resultados para fish-ponds
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Water fact sheet for Iowa Department of Natural Resources and the Geological Bureau.
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Iowa has nearly 72,000 miles of streams. With one week of camping, miles of paddling, on-going educational opportunities, and hundreds of dedicated and hard-working Iowans, Project AWARE can make a difference – one stretch of river, one week a year, one piece of trash at a time. If it seems like a vacation to the participants…it is. They just learn and improve the river as they go.
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Transposable elements, as major components of most eukaryotic organisms' genomes, define their structural organization and plasticity. They supply host genomes with functional elements, for example, binding sites of the pleiotropic master transcription factor p53 were identified in LINE1, Alu and LTR repeats in the human genome. Similarly, in this report we reveal the role of zebrafish (Danio rerio) EnSpmN6_DR non-autonomous DNA transposon in shaping the repertoire of the p53 target genes. The multiple copies of EnSpmN6_DR and their embedded p53 responsive elements drive in several instances p53-dependent transcriptional modulation of the adjacent gene, whose human orthologs were frequently previously annotated as p53 targets. These transposons define predominantly a set of target genes whose human orthologs contribute to neuronal morphogenesis, axonogenesis, synaptic transmission and the regulation of programmed cell death. Consistent with these biological functions the orthologs of the EnSpmN6_DR-colonized loci are enriched for genes expressed in the amygdala, the hippocampus and the brain cortex. Our data pinpoint a remarkable example of convergent evolution: the exaptation of lineage-specific transposons to shape p53-regulated neuronal morphogenesis-related pathways in both a hominid and a teleost fish.
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This monthly report from the Iowa Department of Natural Resources is about the water quality management of Iowa's rivers, streams and lakes.
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This monthly report from the Iowa Department of Natural Resources is about the water quality management of Iowa's rivers, streams and lakes.
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We examined Hg biogeochemistry in Baihua Reservoir, a system affected by industrial wastewater containing mercury (Hg). As expected, we found high levels of total Hg (THg, 664-7421 ng g(-1)) and monomethylmercury (MMHg, 3-21 ng g(-1)) in the surface sediments (0-10 cm). In the water column, both THg and MMHg showed strong vertical variations with higher concentrations in the anoxic layer (>4m) than in the oxic layer (0-4 m), which was most pronounced for the dissolved MMHg (p < 0.001). However, mercury levels in biota samples (mostly cyprinid fish) were one order of magnitude lower than common regulatory values (i.e. 0.3-0.5 mg kg(-1)) for human consumption. We identified three main reasons to explain the low fish Hg bioaccumulation: disconnection of the aquatic food web from the high MMHg zone, simple food web structures, and biodilution effect at the base of the food chain in this eutrophic reservoir.
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Estudio de observación de los peses voladores durante la travesia del CSS BAFFIN entre Panamá y el norte del Perú
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Estudio de muestras recolectadas con el BIONESS a varias profundidades en trece estaciones.
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In order to evaluate the success of the reintroduction of the Eurasian otter (Lutra lutra) in the Empordh wetlands (Parc Natural dels Aiguamolls de I'Empordhà), and the Muga and Fluvih basins, density of fish, biomass and production in the Muga and Fluvia Rivers have been estimated, since fishes represent the principal prey in the otter diet. 12 study sites were selected in order to survey the main flows in both basins. Electrofishing surveys were conducted by blocking off the station with barrier nets, which was performed upon 3 successive catches. The density estimated presents a range of 1,136-1 25 ind .ha' in the Muga basin, 4,49-163 ind.ha' in the Fluvih basin and 3,76-52,2 ind.ha' in the Empordh wetlands. Estimated biomass ranges are 0,616-277,6 g.m2, 8,79-351,2 g.m2, and 5,7-108 g.m-2 respectively. These density anfi biomass ranges are similar to other results obtained from rivers inhabited by the Eurasian otter in NE Spain
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Lake Banyoles is the second largest lake in the Iberian Peninsula and due to this relative uniqueness, its peculiar geological origin, and its considerable age attracted the early attention of the late Professor Ramon Margalef. One of the first papers by Margalef was on the biota of Lake Banyoles and two of the first four Ph.D. theses that he supervised were about the limnology of this lake. Unfortunately, the uniqueness of this lake also implied that it was the first place of introduction into the Iberian Peninsula of several exotic fish species, early in the XXth Century and nowadays the lake fish assemblage is dominated by invasive species, and some native ones have been extirpated. Although the limnological studies in Lake Banyoles were pioneering within the Iberian Peninsula, studies on fish ecology of the lake did not start until 1989. Thereafter, four Ph.D. theses have been completed on different aspects of the fish assemblages of Lake Banyoles. The aim of this paper is to provide a short overview of this research, largely brought about by the considerable limnological information previously available for this lake, thanks to the insightful, pioneering work of Professor Margalef
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Among the most common pollutants that enter the environment after passing municipal wastewater treatment are estrogens, especially the synthetic 17α-ethinylestradiol that is used in oral contraceptives. Estrogens are potent endocrine disruptors at concentrations frequently observed in surface waters. However, new genetic analyses suggest that some fish populations can be self-sustaining even in heavily polluted waters. We now need to understand the basis of this tolerance.
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El IMARPE cuenta con un nuevo muestreador de huevos de peces pelágicos, con características diferentes aquéllas de las redes convencionales.
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A tree frog (Hyla arborea L., 1758) metapopulation in western Switzerland was studied during spring 2001. All potential calling ponds in an area of 350 km(2) were searched for tree frog calling males. Twenty-nine out of 111 ponds sheltered between 1 and 250 callers. Most ponds were occupied by less than 12 males. Pond parameters were measured at three different levels using field analysis and a Geographical Information System (GIS). The first level was water chemistry and pond-associated measures. The second level was the surrounding land use in a 30 m buffer around the pond. The third level consisted of landscape indices on a broader scale (up to 2 km). Logistic regression was applied to identify parameters that can predict the presence of calling males in a pond. Response variable was the presence or absence of callers. Four significant parameters allowed us to explain about 40% of the total deviance of the observed occupational pattern. Urbanization around the pond had a highly negative impact on the probability of presence of calling males. Hours of direct sunlight on the pond was positively correlated with callers. Higher water conductivity was associated with a lesser probability of species presence. Finally, the further the closest two-lane road, the higher the probability of callers presence. Our results show that presence or absence of callers is influenced by factors acting at various geographical scales.
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Friedman et al. report that hemodialysis patients with the highest levels of n-3 fatty acids had impressively low odds of sudden cardiac death. The study is limited by a small sample size, and the analysis relies on only a single baseline measurement of blood levels. Recent randomized evidence indeed fails to support that n-3 fatty acids may prevent sudden death in nonrenal patients. More evidence is needed to advocate fish oil in this setting.