170 resultados para burrowing


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The Rocky Mountain Arsenal National Wildlife Refuge is being re-seeded to native shortgrass prairie, but the effects of prairie dog colonization on some sites may be limiting successful native plant establishment. This Capstone Project compares vegetation monitoring data and prairie dog distributions in four refuge sites to evaluate the effects of prairie dog colonization on restoration. In general, native plant abundance has increased on study plots since initiation of restoration. Localized changes in plant abundance have occurred among transects, but prairie dog densities could not be correlated with the changes. Future prairie dog expansion is cause for concern due to intensified burrowing and grazing effects. Seven recommendations are presented to aid future restoration efforts.

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The study of textural, structural, chemical, and physical properties of fine-grained recent marine sediments leads to the conclusion that only a few compositional factors are responsible for significant changes in mass physical characteristics in the upper meters below sea bottom. Fossil-induced porosity increases water content and liquid limit. It also seems to have partially influenced the plastic limit and plasticity index of calcareous sandy silts from the Red Sea and the western Gulf of Aden so that they become similar to the montmorillonite rich prodelta clays from the Nile Delta. Diagrams based on liquid limit and plasticity loose their original meaning in these cases. Activity of sediments rich in microorganisms can be higher than that of montmorillonitic clay. The shear strength-depth relationship of normally consolidated sediments is surprisingly little influenced by changes in sand or clay content and clay mineralogy. Only high lime content, submarine erosion and beginning cementation increase the strength considerably. Erosional disconformities near the present surface can be deduced from the strength-depth curve when as little as 1 or 2 m sediment have been removed. Flat or irregular strength-depth curves indicate beginning cementation and probably discontinuous sedimentation, provided the composition of the material remains in some degree constant. In our samples diagenetic pyrite, but no recristallisation of carbonates could be detected under the microscope. Underconsolidation and excess pore-water pressure, factors which tend to foster submarine slides, mud lumps, and diapiric folding, seem to be restricted Varito areas with mainly rapidly deposited, homogeneous or layered sediments. But where an abundance of burrowing organisms increases the vertical permeability of the sediment, normal consolidation and stable deposits are to be expected, at least in the upper meters below the present surface. According to 14C-determinations on calcareous microorganisms the rate of deposition of the investigated sediments seems to range from 26 to 167 cm per 1000 years.

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During the austral summer of 2005, the Weddell deep sea and adjacent basins were sampled in the course of the ANDEEP III project. In this study, 19 epibenthic-sledge stations are analyzed, with a focus on species diversity and distribution patterns of polychaetes. The polychaete fauna of the deep Southern Ocean has been found to be similarly speciose and diverse compared with deep-sea basins worldwide. Also, in depths below 2,000 m many polychaete species do not seem to be endemic for certain areas but are rather far spread within the Southern Ocean and beyond. Therefore, ongoing faunal exchanges between adjacent basins, even beyond the Antarctic convergence, are strongly suggested, ruling out a general isolation of the Southern Ocean deep-sea benthos. Driving forces behind species distribution patterns were investigated. The findings indicate that polychaete species' distribution in the Southern Ocean deep sea is rather dependent on local environment than depths.

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Thesis (Master's)--University of Washington, 2016-06

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Amphisbaenians are legless reptiles that differ significantly from other vertebrate lineages. Most species dig underground galleries of similar diameter to that of the animal. We studied the muscle physiology and morphological attributes of digging effort in the Brazilian amphisbaenid Leposternon microcephalum (Squamata; Amphisbaenia), which burrows by compressing soil against the upper wall of the tunnel by means of upward strokes of the head. The individuals tested (

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The thelastomatoid fauna of two species of wood-burrowing cockroach (Blattodea, Blaberidae), Panesthia cribrata and Panesthia tryoni tryoni, from Lamington National Park, Australia, is described. The following eight new species and three new genera of thelastomatid are proposed: Bilobostoma exerovulva n. g., n. sp.; Cordonicola gibsoni n. sp.; Coronostoma australiae n. sp.; Desmicola ornata n. sp.; Hammerschmidtiella hochi n. sp.; Malaspinanema goateri n. g., n. sp.; Travassosinema jaidenae n. sp.; and Tsuganema cribratum n. g., n. sp. Additional data are given for Blattophila sphaerolaima and Leidynemella fusiformis. Of the 11 species reported, nine were found in P. cribrata and ten in P. tryoni tryoni. Such levels of thelastomatoid species richnessness in single host species are exceptional. Only the mole cricket, Gryllotalpa africana (23), and the domestic cockroach, Periplaneta americana (20), have higher reported richness. Three species, T jaidenae, C. australiae and D. ornata, were found either exclusively or significantly more prevalently in P tryoni tryoni than in R cribrata. Species of Travassosinema, Coronostoma and Desmicola have been found previously only in millipedes (Diplopoda), a fact that suggests that there is a greater degree of niche overlap between R tryoni tryoni and millipedes than for R cribrata.

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Long (6- to 9-mo) bouts of estivation in green-striped burrowing frogs lead to 28% atrophy of cruralis oxidative fibers (P < 0.05) and some impairment of in vitro gastrocnemius endurance (P < 0.05) but no significant deficit in maximal twitch force production. These data suggest the preferential atrophy of oxidative fibers at a rate slower than, but comparable to, laboratory disuse models. We tested the hypothesis that the frog limits atrophy by modulating oxidative stress. We assayed various proteins at the transcript level and verified these results for antioxidant enzymes at the biochemical level. Transcript data for NADH ubiquinone oxidoreductase subunit 1 (71% downregulated, P < 0.05) and ATP synthase (67% downregulated, P < 0.05) are consistent with mitochondrial quiescence and reduced oxidant production. Meanwhile, uncoupling protein type 2 transcription (P < 0.31), which is thought to reduce mitochondrial leakage of reactive oxygen species, was maintained. Total antioxidant defense of water-soluble (22.3 +/- 1.7 and 23.8 +/- 1.5 mu M/mu g total protein in control and estivator, respectively, P = 0.53) and membrane-bound proteins (31.5 +/- 1.9 and 42.1 +/- 7.3 mu M/mu g total protein in control and estivator, respectively, P = 0.18) was maintained, equivalent to a bolstering of defense relative to oxygen insult. This probably decelerates muscle atrophy by preventing accumulation of oxidative damage in static protein reserves. Transcripts of the mitochondrially encoded antioxidant superoxide dismutase type 2 ( 67% downregulated, P < 0.05) paralleled mitochondrial activity, whereas nuclear-encoded catalase and glutathione peroxidase were maintained at control values (P = 0.42 and P = 0.231), suggesting a dissonance between mitochondrial and nuclear antioxidant expression. Pyruvate dehydrogenase kinase 4 transcription was fourfold lower in estivators (P = 0.11), implying that, in contrast to mammalian hibernators, this enzyme does not drive the combustion of lipids that helps spare hypometabolic muscle.

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Short-beaked echidnas have an impressive ability to submerge completely into soil or sand and remain there, cryptic, for long periods. This poses questions about how they manage their respiration, cut off from a free flow of gases. We measured the gradient in oxygen partial pressure (P-O2) away from the snouts of buried echidnas and oxygen consumption (V-O2) in five individuals under similar conditions, in two substrates with different air-filled porosities (f(a)). A theoretical diffusion model indicated that diffusion alone was insufficient to account for the flux of oxygen required to meet measured rates of V-O2. However, it was noticed that echidnas often showed periodic movements of the anterior part of the body, as if such movements were a deliberate effort to flush the tidal air space surrounding their nostrils. These 'flushing movements' were subsequently found to temporarily increase the levels of interstitial oxygen in the soil around the head region. Flushing movements were more frequent while V-O2 was higher during the burrowing process, and also in substrate with lower fa. We conclude that oxygen supply to buried echidnas is maintained by diffusion through the soil augmented by periodic flushing movements, which ventilate the tidal airspace that surrounds the nostrils.

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Bioturbation in marine sediments has basically two aspects of interest for palaeo-environmental studies. First, the traces left by the burrowing organisms reflect the prevailing environmental conditions at the seafloor and thus can be used to reconstruct the ecologic and palaeoceanographic situation. Traces have the advantage over other proxies of practically always being preserved in situ. Secondly, for high- resolution stratigraphy, bioturbation is a nuisance due to the stirring and mixing processes that destroy the stratigraphic record. In order to evaluate the applicability of biogenic traces as palaeoenvironmental indicators, a number of gravity cores from the Portuguese continental slope, covering the period from the last glacial to the present were investigated through X-ray radiographs. In addition, physical and chemical parameters were determined to define the environmental niche in each core interval. A number of traces could be recognized, the most important being: Thalassinoides, Planolites, Zoophycos, Chondrites, Scolicia, Palaeophycus, Phycosiphon and the generally pyritized traces Trichichnus and Mycellia. The shifts between the different ichnofabrics agree strikingly well with the variations in ocean circulation caused by the changing climate. On the upper and middle slope, variations in current intensity and oxygenation of the Mediterranean Outflow Water were responsible for shifts in the ichnofabric. Larger traces such as Planolites and Thalassinoides dominated in coarse, well oxygenated intervals, while small traces such as Chondrites and Trichichnus dominated in fine grained, poorly oxygenated intervals. In contrast, on the lower slope where calm steady sedimentation conditions prevail, changes in sedimentation rate and nutrient flux have controlled variations in the distribution of larger traces such as Planolites, Thalassinoides, and Palaeophycus. Additionally, distinct layers of abundant Chondrites correspond to Heinrich events 1, 2, and 4, and are interpreted as a response to incursions of nutrient rich, oxygen depleted Antarctic waters during phases of reduced thermohaline circulation. The results clearly show that not one single factor but a combination of several factors is necessary to explain the changes in ichnofabric. Furthermore, large variations in the extent and type of bioturbation and tiering between different settings clearly show that a more detailed knowledge of the factors governing bioturbation is necessary if we shall fully comprehend how proxy records are disturbed. A first attempt to automatize a part of the recognition and quantification of the ichnofabric was performed using the DIAna image analysis program on digitized X-ray radiographs. The results show that enhanced abundance of pyritized microburrows appears to be coupled to organic rich sediments deposited under dysoxic conditions. Coarse grained sediments inhibit the formation of pyritized burrows. However, the smallest changes in program settings controlling the grey scale threshold and the sensitivity resulted in large shifts in the number of detected burrows. Therefore, this method can only be considered to be semi-quantitative. Through AMS-^C dating of sample pairs from the Zoophycos spreiten and the surrounding host sediment, age reversals of up to 3,320 years could be demonstrated for the first time. The spreiten material is always several thousands of years younger than the surrounding host sediment. Together with detailed X-ray radiograph studies this shows that the trace maker collects the material on the seafloor, and then transports it downwards up to more than one meter in to the underlying sediment where it is deposited in distinct structures termed spreiten. This clearly shows that age reversals of several thousands of years can be expected whenever Zoophycos is unknowingly sampled. These results also render the hitherto proposed ethological models proposed for Zoophycos as largely implausible. Therefore, a combination of detritus feeding, short time caching, and hibernation possibly combined also with gardening, is suggested here as an explanation for this complicated burrow.

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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

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This Ph.D. thesis addresses current issues with ichnotaxonomic practice, and characterizes an exceptionally well preserved ichnological assemblage from the Carboniferous Stainmore Formation, Northumberland, United Kingdom. Samples were collected from closely localized float representative of various units throughout the succession, which was deposited in a storm-dominated marine shoreface. Three dominant ichnotaxa were selected for three-dimensional morphological analysis due to their complicated morphology and/or unclear taxonomic status: 1) Dactyloidites jordii isp. nov.; 2) Beaconites capronus, and; 3) Neoeione moniliformis comb. nov. Using serial grinding and photography, these ichnotaxa were ground and modelled in true colour. High-resolution models of three taxa produced in this study are the basis of the first complete three-dimensional consideration of the traces, and forms the basis for refined palaeobiological and ethological analysis of these taxa. Dactyloidites jordii isp. nov. is a stellate to palmate burrow composed of numerous long, narrow rays that exhibit three orders of branching arranged into tiered galleries radiating from a central shaft. It is considered to be the feeding structure produced by a vermiform organism. Beaconites capronus is a winding trace with distinctly chevron-shaped, meniscate backfill demonstrated herein to backfill the vertical shafts associated with its burrows in a comparable fashion to the horizontal portion of the burrow. This lack of a surface connection would result in the trace making organism being exposed to low-oxygen porewater. Coping with this porewater dysoxia could be approached by burrowing organisms in a number of ways: 1) revisiting the sediment-water interface; 2) creating periodic shafts; or 3) employing anaerobic metabolism. Neoeione moniliformis was originally introduced as Eione moniliformis, however, the genus Eione Tate, 1859 is a junior homonym of Eione Rafinesque, 1814. This led to the transfer of Eione moniliformis to Parataenidium. Through careful examination and three-dimensional characterization of topotypes, the transfer to Parataenidium moniliformis is demonstrated herein to be problematic, as Parataenidium refers to primarily horizontal burrows with two distinct layers and Eione moniliformis is composed of one distinct level. As such, the new ichnogenus Neoeione is created to accommodate Neoeione moniliformis.

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The lamination and burrowing patterns in 17 box cores were analyzed with the aid of X-ray photographs and thin sections. A standardized method of log plotting made statistical analysis of the data possible. Several 'structure types' were established, although it was realized that the boundaries are purely arbitrary divisions in what can sometimes be a continuous sequence. In the transition zone between marginal sand facies and fine-grained basin facies, muddy sediment is found which contains particularly well differentiated, alternating laminae. This zone is also characterized by layers rich in plant remains. The alternation of laminae shows a high degree of statistical scattering. Even though a small degree of cyclic periodicity could be defined, it was impossible to correlate individual layers from core to core across the bay. However, through a statistical handling of the plots, zones could be separated on the basis of the number of sand layers they contained. These more or minder sandy zones clarified the bottom reflections seen in the records of the echograph from the area. The manner of facies change across the bay, suggests that no strong bottom currents are effective in the Eckernförde Bay. The marked asymmetry between the north and south flanks of the profile can be attributed to the stronger action of waves on the more exposed areas. Grain size analyses were made from the more homogeneous units found in a core from the transition-facies zone. The results indicate that the most pronounced differences between layers appear in the silt range, and although the differences are slight, they are statistically significant. Layers rich in plant remains were wet-sieved in order to separate the plant detritus. This was than analyzed in a sediment settling balance and found to be hydrodynamically equivalent to a well-sorted, finegrained sand. A special, rhythmic cross-bedding type with dimensions in the millimeter range, has been named 'Crypto-cross-lamination' and is thought to represent rapid sedimentation in an area where only very weak bottom currents are present. It is found only in the deepest part of the basin. Relatively large sand grains, scattered within layers of clayey-silty matrix, seem to be transported by flotation. Thin section examination showed that the inner part of Eckernförder Bay carbonate grains (e. g. Foraminifera shells) were preserved throughout the cores, while in the outer part of the bay they were not present. Well defined tracks and burrows are relatively rare in all of the facies in comparision to the generally strongly developed deformation burrowing. The application of special measures for the deformation burrowing allowed to plot their intensity in profile for each core. A degree of regularity could be found in these burrowing intensity plots, with higher values appearing in the sandy facies, but with no clear differences between sand and silt layers in the transition facies. Small sections in the profiles of the deepest part of the bay show no bioturbation at all.

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Trois études de zones ont été conduites en 1997/1998 dans le bassin de Marennes-Oléron (Charente-Maritime). Deux concernaient la contamination des coquillages fouisseurs de la Seudre et du banc de Ronce-Perquis. La troisième concernait la contamination des coquillages filtreurs des bouchots à moules des Saumonards (Ile d'Oléron). Ces études avaient pour objet d'évaluer les niveaux de contamination microbiologique et chimique de ces zones de production de coquillages afin que l'Administration puisse en effectuer le classement sanitaire conformément à l'arrêté du 21 juillet 1995. La Seudre, à l'aval de la rivière, a montré, pour les fouisseurs, une qualité microbiologique de catégorie B et une qualité microbiologique de catégorie C pour la partie amont. De son côté, le Banc de Ronce-Perquis a présenté, pour les fouisseurs, une qualité microbiologique de catégorie B. Enfin, la catégorie microbiologique des moules des bouchots des Saumonards est de type A. Le suivi du mercure total, du cadmium et du plomb dans la chair des coquillages a mis en évidence des teneurs inférieures aux valeurs seuil.

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The life history of a population of Lutraria lutraria in a depth of 7m at Hunterston, Ayrshire is discussed. Much of the present population Is thought to have settled in 1967. The functional morphology of Lutraria is described and related to its life as a large, deep-burrowing bivalve. Lutraria spawned in late spring and continued to do so through the summer in 1979 and 1980. Animals became spent in August and September. Unsuccessful attempts were made to induce spawning in the laboratory. Artificial fertilization was successful but development did not proceed beyond the ciliated gastrula stage. Larvae of Lutraria were not identified in plankton samples and young stages were not encountered in sieved sediment samples. The biochemical cycle of the total animal and five component parts (gonad and visceral mass, digestive gland, adductor muscle, siphon and 'other' tissue) is investigated. A marked increase in weight, reflected in an increase in weight of the component parts, was recorded in Autumn 1979. This is thought to be related to an exceptional increase in the phytoplankton at this time. Although a relationship between the biochemical cycle and reproductive cycle remains uncertain, definite seasonal changes were recorded in the respiration rate of Lutraria. At 10°C, the maximum rate of a standard 20g animal was 0.1283m1s 02/g. dry wt./hr. in May 1980 and the minimum rate was 0.O59mls 02/g. dry wt./hr. in October 1980. The effect of temperature on respiration rate was also investigated. Significant differences were recorded for five experimental temperatures (10°C, 15°C, 20°C, 25°C and 30 °C) in August and October but only between two temperatures (10 C and 30 C) in April. There was a decrease in respiration rate at 30 C in August and October, but an increase in April. Respiration rate is affected by a reduction in oxygen tension. A variety of responses were recorded with a small degree of regulation shown. Individuals of Lutraria were able to survive 48 hours under anaerobic conditions. In fully oxygenated conditions heart rate ranged from 4-15 beats per minute with an average of 8 beats per minute. Heart beat was markedly affected by changes in temperature and oxygen tension, increasing to a maximum 22 beats per minute at 25 C, and decreasing to a minimum 2 beats per minute in anaerobic conditions. Heart rate is reduced (12 beats per minute to 5 beats per minute) on exposure to air. Lutraria exhibits an intermittent pattern of pumping activity. Under normal conditions 35% of the time is spent pumping and this Increases as oxygen is reduced (3.00mls 02/litre) to 65% of the time spent pumping. 15. Under normal conditions the respiratory flow varies between 0.382 litres per hour and 1.023 litres per hxir. Adult Lutraria maintain their ability to burrow, albeit slowly.