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See detailField Efficacy of Injectable Moxidectin in Cattle Naturally Infested with Chorioptes Bovis and Sarcoptes Scabiei
Losson, Bertrand ULg; Lonneux, J. F.

in Veterinary Parasitology (1993), 51(1-2), 113-21

Field efficacy of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Chorioptes bovis and Sarcoptes scabiei. Eight animals were allocated to two groups of four ... [more ▼]

Field efficacy of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Chorioptes bovis and Sarcoptes scabiei. Eight animals were allocated to two groups of four animals each, based on parasitological and clinical status. Animals of the treated group received one subcutaneous injection of injectable moxidectin at 0.2 mg kg-1 body weight on Day 0. Individuals of the control group received emergency treatment of a single injection of moxidectin at 0.2 mg kg-1 body weight on Day 28. Efficacy was assessed by (a) taking skin samples from each animal on Days 0, 7, 14, 21, 28, 42 and 56 and observing the numbers of viable mite stages and species and (b) clinical examination of animals on Days 7, 14, 21, 28, 42 and 56 with the percentage of affected body surface calculated for each animal on Days 0, 28 and 56. On the basis of the geometric means from treated and control animals, the percentage reductions in the total numbers of living C. bovis mites on Days 7, 14, 21 and 28 were 69, 87, more than 99 and 98, respectively. However, at the end of the trial, only two animals were negative for C. bovis. The percentage reductions in the total numbers of S. scabiei on Days 7, 14, 21 and 28 were 93, 100, 100 and 100, respectively. Clinical indices of the treated animals showed a sharp decrease in the affected body surface area from a mean of 43.6% on Day 0 to 0.9% and 0% on Days 28 and 56, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

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See detailField Efficacy of Moxidectin 0.5% Pour-on against Chorioptes Bovis, Damalinia Bovis, Linognathus Vituli and Psoroptes Ovis in Naturally Infected Cattle
Losson, Bertrand ULg; Lonneux, J. F.

in Veterinary Parasitology (1996), 63(1-2), 119-30

Field efficacy of a pour-on formulation of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Chorioptes bovis, Damalinia bovis, Linognathus vituli and ... [more ▼]

Field efficacy of a pour-on formulation of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Chorioptes bovis, Damalinia bovis, Linognathus vituli and Psoroptes ovis. In trial 1, two experimental groups of cattle naturally infested with P. ovis were formed. Group 1 animals remained as untreated controls whereas Group 2 animals were treated on day 0 with 0.5% moxidectin cattle pour-on at a dose of 0.5 mg kg-1 bw. Efficacy was assessed by (a) taking skin samples from each animal on days -4, 7, 14, 21, 28, 42 and 56 post treatment (PT) and observing the numbers of viable P. ovis mites and (b) clinical examination of animals on days 7, 14, 21, 28, 42 and 56 with the percentage of affected body surface calculated and live body weights recorded for each animal on days 4, 28 and 42. The pour-on formulation of moxidectin yielded excellent efficacy as no live mites were found in treated animals at 14, 21, 28, 42 and 56 days PT, except in one animal from which one adult mite was collected on day 42. Clinical indices showed a regular decrease in the affected body surface area. All untreated animals but one remained positive until day 28 and their clinical condition worsened rapidly. In trial 2, two experimental groups of cattle naturally infested with D. bovis and L. vituli were selected. Group 1 remained as untreated controls whereas Group 2 individuals were treated on day 0 with 0.5% moxidectin cattle pour-on at a dose of 0.5 mg kg-1 bw. Efficacy was assessed by identifying and counting lice on eight 15 cm hair partings at predefined anatomical sites on days 0, 14, 28 and 42. On the basis of animals cured and lice count reduction, efficacies were 100% on day 14 and from then onwards for both species. In trial 3, 24 animals naturally infested with C. bovis were divided into three experimental groups comprising eight (Group I), seven (Group 2) and nine animals (Group 3). Group 1 was the untreated control group whereas Groups 2 and 3 animals were treated on day 0 with 0.5% moxidectin cattle pour-on at a dose of 0.25 mg and 0.5 mg kg-1 bw, respectively. Efficacy was assessed as in trial 1. Skin scrapings were collected on days -3, 7, 14, 28, 42 and 56 PT. A clinical index was calculated for each animal on days 0, 28 and 56 whereas body weights were recorded on days 0 and 56. At 0.25 mg kg-1 bw, the efficacy of moxidectin cattle pour-on against C. bovis was incomplete. In contrast, at a dose of 0.5 mg kg-1 bw, moxidectin cattle pour-on was fully effective and by day 14 PT all animals were negative for C. bovis and remained so until the end of the trial. No side effects were observed during these three trials. These results indicate that at a dose of 0.5 mg kg-1 bw, the pour-on formulation of moxidectin is highly effective against C. bovis, D. bovis, L. vituli and P. ovis. [less ▲]

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See detailField evaluation of poor performance in Standardbred trotters
Van Erck, Emmanuelle; Jakesova, V.; Lekeux, Pierre ULg et al

in Pferdeheilkunde (2006), 22

Exercise tests allow evaluating athletic capacity and fitness, following training-induced adaptations and determining causes of poor performance. A retrospective study was conducted over the cases of 40 ... [more ▼]

Exercise tests allow evaluating athletic capacity and fitness, following training-induced adaptations and determining causes of poor performance. A retrospective study was conducted over the cases of 40 poor performing Standardbreds referred to an Equine Sports Medicine consultation at a Belgian racetrack. The study aimed at determining if the implementation of a standardised exercise test and determination of specific athletic parameters could discriminate between the poor performers and a group of eight healthy racehorses and help in establishing a diagnosis. After a through clinical examination, the horses were submitted to an exercise test that consisted of 3 bouts of 1500m at increasing speeds with a recovery phase of 500 m in between. Speed and heart rate were continuously monitored and blood lactate concentrations were evaluated after each step. Pre and post-effort blood work and respiratory endoscopy with sampling were done in each horse. Five main causes of poor performance were identified: locomotor, respiratory, cardiac, muscular problems and inadequate training. In the poor performers group, 24 horses suffered from upper and/or lower respiratory disease, 20 from lameness, 4 from cardiac disease, 4 from exercise-induced myopathy and 5 from maladjusted training. More than half of the horses had multiple problems (23 horses). The fitness parameters (V-LA4, V-200) obtained were useful for inter-individual comparisons and discriminated poor performers from healthy controls, whatever the cause of the intolerance. This study confirms the high prevalence of lameness and respiratory diseases as causes of poor performance in racehorses. The field exercise tests were readily performed with minimal equipment and enabled to identify conditions which were not clearly apparent as during the clinical examination at rest. The recovery of maximum information by a thorough questioning of the trainer and selected ancillary examinations was critical to reach a diagnosis. [less ▲]

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See detailField evaluation of pregnancy diagnosis using bovine pregnancy-associated glycoprotein (bPAG)
Skinner, J. G.; Gray, D.; Gebbie, F. E. et al

in Cattle Practice (1996), 4(3), 281-284

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See detailField evaluation of survival rates of Harmonia axyridis (Coleoptera: Coccinellidae) and other aphidophagous species
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

Poster (2011, May 24)

The multicoloured Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae), previously introduced as a biological control agent against aphids, is now frequently considered as an intraguild ... [more ▼]

The multicoloured Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae), previously introduced as a biological control agent against aphids, is now frequently considered as an intraguild predator, consuming other aphids natural enemies. Interactions between this exotic ladybird and the other aphidophagous species present in Belgian agro-ecosystems such as Coccinella septempunctata, Episyrphus balteatus, Chrysoperla carnea are asymmetric to the benefit of H. axyridis. Many studies have already shown its predatory behaviour. This study focuses on the survival rate of three aphidophagous species Harmonia axyridis (Ha), Coccinella septempunctata (C7) and Episyrphus balteatus (Eb) in biological fields of potato and sugar beet. During June and July, hermetic cages were disposed on the crops with 10 larvae (second stage) of each aphidophagous. There were 4 combinations of insects placed inside the cages (1) Ha+Eb+C7+ aphids, (2) Ha+Eb+C7, (3) Eb+C7+ aphids and (4) Eb+C7. Each combination was repeated three times. Aphids (Aphis fabae) were added in excess when needed. In sugar beet fields, E. balteatus was the species with the highest mortality rate. The two coccinellid species had a better survival rate than E. balteatus. All aphidophagous species had higher mortality rates in absence of aphids. In potato, the survival rate of all aphidophagous was lower than sugar beet when aphids were present in excess probably because A. fabae reproduced less in potato. Nevertheless, we have observed in potato no mortality of C. 7-punctata during all its development cycle. This suggests that C. 7-punctata could use more efficiently aphids as food sources than H. axyridis. In potato and sugar beet, H. axyridis had the longest development cycle, being still at the larval stage when C. 7-punctata and E. balteatus reached the pupae stage. We can suppose that pupae of E. balteatus and C. 7-punctata were an alternative food (intraguild prey) to H. axyridis when aphids were lacking. Pupae are immobile and therefore more sensitive to the attack of predators. [less ▲]

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See detailField halo stars: the globular cluster connection
Jehin, Emmanuel ULg; Magain, Pierre ULg; Neuforge, Corinne et al

in Astronomy and Astrophysics (1998), 330

High resolution and high signal-to-noise spectra of about 20 metal-poor stars have been analysed. The correlations between the relative abundances of 16 elements have been studied, with a special emphasis ... [more ▼]

High resolution and high signal-to-noise spectra of about 20 metal-poor stars have been analysed. The correlations between the relative abundances of 16 elements have been studied, with a special emphasis on the neutron-capture ones. This analysis reveals the existence of two subpopulations of field halo stars, namely Pop IIa and Pop IIb. They differ by the behaviour of the s-process elements versus the alpha and r-process elements. A scenario for the formation of these stars is presented, which closely relates the origin of field halo stars to the evolution of globular clusters. According to this scenario, the two sub-populations originate from two different stages in the globular cluster's chemical evolution. Based on observations carried out at the European Southern Observatory (La Silla, Chile) [less ▲]

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See detailThe field high-amplitude SX Phoenicis variable BL Camelopardalis: results from a multisite photometric campaign. I. Pulsation
Rodríguez, E.; Fauvaud, S.; Farrell, J. A. et al

in Astronomy and Astrophysics (2007), 471

Context: BL Cam is an extreme metal-deficient field high-amplitude SX Phe-type variable where a very complex frequency spectrum is detected, with a number of independent nonradial modes excited, unusual ... [more ▼]

Context: BL Cam is an extreme metal-deficient field high-amplitude SX Phe-type variable where a very complex frequency spectrum is detected, with a number of independent nonradial modes excited, unusual among the high-amplitude pulsators in the Lower Classical Instability Strip. Aims: An extensive and detailed study has been carried out to investigate the pulsational content and properties of this object. Methods: The analysis is based on 283 h of CCD observations obtained in the Johnson V filter, during a long multisite photometric campaign carried out along the Northern autumn-winter of 2005-2006. Additionally, multicolour BI photometry was also collected to study the phase shifts and amplitude ratios, between light curves obtained in different filters, for modal discrimination of the main excited modes. Results: The detailed frequency analysis revealed a very rich and dense pulsational content consisting of 25 significant peaks, 22 of them corresponding to independent modes: one is the already known main periodicity f[SUB]0[/SUB] = 25.5765 cd[SUP]-1[/SUP] (Delta V = 153 mmag) and the other 21 are excited modes showing very small amplitudes. Some additional periodicities are probably still remaining in the residuals. This represents the most complex spectrum ever detected in a high-amplitude pulsator of this type. The majority of the secondary modes suspected from earlier works are confirmed here and, additionally, a large number of new peaks are detected. The amplitude of the main periodicity f[SUB]0[/SUB] seems to be stable during decades, but the majority of the secondary modes show strong amplitude changes from one epoch to another. The suspected fundamental radial nature of the main periodicity of BL Cam is confirmed, while the secondary peak f[SUB]1[/SUB] = 25.2523 cd[SUP]-1[/SUP] is identified as a nonradial mixed mode g[SUB]4[/SUB] with l = 1. The radial double-mode nature, claimed by some authors for the main two frequencies of BL Cam, is not confirmed. Nevertheless, the frequency f[SUB]6[/SUB] = 32.6464 cd[SUP]-1[/SUP] could correspond to the first radial overtone. [less ▲]

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See detailField induced metastabilities in U(Ru0.96Rh0.04)(2)Si-2
Silhanek, Alejandro ULg; Jaime, M.; Harrison, N. et al

in Physica C: Superconductivity (2007), 460(Part 1), 682-683

U(Ru0.96Rh0.04)(2)Si-2 is an anisotropic itinerant 5f heavy electron system which exhibits a single field induced magnetic phase concealing a quantum critical point. We show that the boundary of this ... [more ▼]

U(Ru0.96Rh0.04)(2)Si-2 is an anisotropic itinerant 5f heavy electron system which exhibits a single field induced magnetic phase concealing a quantum critical point. We show that the boundary of this phase corresponds to a first order transition as revealed by (1) a large and symmetric specific heat anomaly, (2) an asymmetric magnetocaloric effect on entering and exiting this phase, and (3) a clear history and time-dependent specific heat. We explore the thermodynamic similarities with the mixed valence compound YbInCu4 and show that the out-of-equilibrium properties are analogous to those depicted by the critical state model for hard superconductors. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailField investigation of subacute rumen acidosis prevalence in walloon dairy herds
Lessire, Françoise ULg; Knapp, Emilie ULg; Theron, Léonard ULg et al

Poster (2013, June 24)

Subacute ruminal acidosis (SARA) has been considered as a major metabolic disease in high producing dairy herds for years. However, different feeding practices However, different feeding practices and ... [more ▼]

Subacute ruminal acidosis (SARA) has been considered as a major metabolic disease in high producing dairy herds for years. However, different feeding practices However, different feeding practices and herd’s production levels are found in Wallonia. SARA prevalence in local herds was thus required 174 cows (164 Holstein and 10 Brown Swiss) out of 24 walloon herds were sampled from 2011 to 2012 for evaluation of their ruminal function. Selection of minimum 5 cows per herd was made on basis of days in milk (<150 DIM), or low milk fat % (F <3.2%), or fat/protein % (F/P≤1), or at farmer’s request (animal debilitated or chronically ill). Ruminal fluid was sampled 4-8 h after feeding using a Geishauser oro-pharyngeal probe, preventing saliva contamination. pH was measured by a portable pHmeter and values were reduced by 0.35 as proposed by Duffield (2004) because of the higher pH values in reticulum sampling site compared with rumenocentesis. Redox potential was determined by Methylene Blue Reduction Time (MBRT) and protozoa assessed by microscopy. Production values were obtained by the National Dairy Herds Improvement. Health scores were determined as described by Zaaier et al. (2001). RESULTS Mean production values ± SD of these animals (DIM: 106 ± 84) were 33.2 ± 8.9 kg milk, F = 3.47 ± 0.72%, P = 3.25 ± 0.25%, F/P = 1.07 ± 0.23. Mean BCS was 2.6 ± 0.6. Mean pH value ± SD was 6.50 ± 0.42. 10 animals (5.7%) from 6 herds were below 5.8, of which 4 cows from H8 (23 sampled cows). No result was < 5.5. MBRT was 4.16 ± 3.13 min. In 5 cows, value < 1min indicated a more amylolytic bacterial flora. In 24 samples, no reduction of MB occurred, demonstrating bacterial inactivity. Disappearance of large protozoa was observed in 6 samples, of which 5 abnormal specimens came from H8. No correlation between low pH values and F/P or %F could be found. CONCLUSION In no herd, prevalence was >25%, required for SARA diagnosis. Regarding these results, prevalence of SARA appears very low in Wallonia while on the opposite, ruminal flora inactivity seems far more common. [less ▲]

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See detailField Investigation of subacute ruminal acidosis in Walloon dairy herds
Lessire, Françoise ULg; Knapp, Emilie ULg; Theron, Léonard ULg et al

in Universität Bern (Ed.) Proceedings of 8th ECBHM (2013, August 28)

Subacute ruminal acidosis (SARA) has been considered as a major metabolic disease in high producing dairy herds for years. For instance, out of 737 cows from Wisconsin farms, 20% exhibited ruminal pH ... [more ▼]

Subacute ruminal acidosis (SARA) has been considered as a major metabolic disease in high producing dairy herds for years. For instance, out of 737 cows from Wisconsin farms, 20% exhibited ruminal pH values lower than 5.5, allowing diagnosis of SARA, while 23% of animals were considered at risk with ruminal pH values between 5.5 and 5.8. These findings were corroborated by further studies in Europe. However, different feeding practices and herd’s production levels are found in Wallonia, requiring evaluation of SARA prevalence in local herds. [less ▲]

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See detailThe field laboratory in the sugar industry
Melard, François ULg

Conference (1999, October 29)

Abstract for the thematic stream « Disciplines & Instruments » The aim of my intervention concern the implication of a scientific instrument inside an industrial context of usage. The latter takes the ... [more ▼]

Abstract for the thematic stream « Disciplines & Instruments » The aim of my intervention concern the implication of a scientific instrument inside an industrial context of usage. The latter takes the form of various little laboratories situated in the countryside. More precisely, those laboratories are generally situated in the area surronding fields and have the objective to evaluate the weight and the content of saccharose of the sugar beets deliveries ; and this for contractual purposes. The beet testing laboratories constitute a social and technical mediator by which a mode of coordination is temporarly crafted between two groups of actors : the growers and the sugar manufactuers. The instruments of measurment, and more specifically the polariscope, which compose this technological system have the interesting particularities to be submited to the contradictory supervision of both parties. Instead of just being a private place for secret industrial practices, the beet testing laboratory is widely open to public scrutiny. The perpetual negociations that take place inside the laboratories are done according to the « correct » application of a chemical protocol. In that respect, modes of visualisation are produced in order to give form to general values like efficacity, soundness or equity inside concrete procedures. The contradictory control that make the testing of sugar beets operational is conceived here as a dynamic pattern through which the reality of both a natural resource and the commited economical actors, is produced. Measurement as form of coordination is one of the central subjects in the field of the sociology of metrological practices. I will treat some aspects of industrial practices inside those beet testing laboratories in the light of the many ethnographical works done about scientific laboratories. [less ▲]

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See detailField measurements of inorganic nitrogen uptake by epiflora components of the seagrass Posidonia oceanica (Monocotyledons, Posidoniaceae)
Lepoint, Gilles ULg; Jacquemart, Julien; Bouquegneau, Jean-Marie ULg et al

in Journal of Phycology (2007), 43(2), 208-218

Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass ... [more ▼]

Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass, and specific composition of this epiphyte-seagrass association are impacted by anthropogenic increase of nutrient load in this oligotrophic area. In this context, nitrogen uptake by P. oceanica and its epiflora was measured using the isotope N-15 at a 10 m depth in the Revellata Bay (Corsica, Mediterranean Sea). Epiflora components showed various seasonal patterns of biomass and abundance. The epiphytic brown algae appeared at the end of spring, later than the crustose corallines, and after the nitrate peak in the bay. Because of their later development in the season, epiphytic brown algae mostly rely on ammonium for their N needs. We hypothesize that the temporal succession of epiphytic organisms plays a crucial role in the N dynamics of this community under natural conditions. The epiphytic brown algae, which have a growth rate one order of magnitude greater than that of crustose corallines, showed lower N-uptake rates. The greater N-uptake rates of crustose corallines probably reflect the greater N requirements (i.e., lower C/N ratios) of red algae. We determined that the epiflora incorporated ammonium and nitrate more rapidly than their host. Nevertheless, when biomass was taken into account, P. oceanica was the most important contributor to N uptake from the water column by benthic macrophytes in this seagrass bed. [less ▲]

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See detailField melanin mapping of the hairless scalp.
PIERARD, Gérald ULg; FRANCHIMONT, Claudine ULg; Quatresooz, Pascale ULg

in Skin Research & Technology (2011), 18(4), 431-5

BACKGROUND: Mottled subclinical melanoderma (MSM) is frequently seen on facial skin using the ultraviolet light enhanced visualization (ULEV) method. The corresponding aspect on the hairless scalp remains ... [more ▼]

BACKGROUND: Mottled subclinical melanoderma (MSM) is frequently seen on facial skin using the ultraviolet light enhanced visualization (ULEV) method. The corresponding aspect on the hairless scalp remains unknown. OBJECTIVE: To explore the field distribution of melanin on the scalp of fair-skinned Caucasian subjects. METHOD: The scalp was examined in 43 men with androgenic alopecia. The Visioscan((R)) camera provided the ULEV pictures. Another optical (Visioface((R)) Quick) device was used under white light illumination followed by colour contrast enhancement. This was reached after specific computer filtration of the cyan hue wavelengths. RESULTS: Under white light illumination, the scalp looked normal. MSM patterns were disclosed by both optical procedures as evenly scattered discrete patchy fields of hypermelanosis. The smaller rounded spots were restricted to the lips of the hair infundibula. Larger irregularly shaped spots predominated in the interfollicular areas. A few hypomelanotic spots were scattered over the scalp. CONCLUSION: The present observations based on dual optical methods possibly provide information about a patterned pathobiology of melanocytes on the scalp. The spotty MSM pattern looked similar to the reported aspects on the face. It somewhat resembled the widespread PUVA-induced lentiginosis. [less ▲]

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See detailA field observation on the influence of aggressive behaviour on mating success in the European grayling
Poncin, Pascal ULg

in Journal of Fish Biology (1996), 48(4), 802-804

The biggest male grayling present on a spawning area was strongly territorial and developed more aggressive behaviours than smaller males. However, its spawning frequency was similar to that of smaller ... [more ▼]

The biggest male grayling present on a spawning area was strongly territorial and developed more aggressive behaviours than smaller males. However, its spawning frequency was similar to that of smaller males. (C) 1996 The Fisheries Society of the British Isles [less ▲]

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See detailField observations of the spawning behaviour of European grayling
Darchambeau, François ULg; Poncin, Pascal ULg

in Journal of Fish Biology (1997), 51(5), 1066-1068

During observations of the River Ourthe, Belgium, 70 spawning attempts were recorded during the reproductive period of the European grayling. Thirty-six per sent of the spawning attempts proceeded to ... [more ▼]

During observations of the River Ourthe, Belgium, 70 spawning attempts were recorded during the reproductive period of the European grayling. Thirty-six per sent of the spawning attempts proceeded to completion, while interference by another male may explain some of the incomplete acts. Sneaking behaviour was observed and one spawning act included two males and one female. (C) 1997 The Fisheries Society of the British Isles. [less ▲]

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See detailFIELD OBSERVATIONS ON A MATING ATTEMPT OF A SPAWNING GRAYLING, THYMALLUS-THYMALLUS WITH A FEEDING BARBEL, BARBUS-BARBUS
Poncin, Pascal ULg

in Journal of Fish Biology (1994), 45(5), 904-906

During the spawning period of the grayling, one male was sexually stimulated by a feeding barbel and consequently exhibited the behavioural pattern of 'approach', 'quivering' and 'dorsal fin clasping'.

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See detailField observations on the variability of crude oil impact on indigenous hydrocarbon-degrading bacteria from sub-Antarctic intertidal sediments
Delille, Daniel; Delille, Bruno ULg

in Marine Environmental Research (2000), 49(5), 403-417

Oil pollution of the oceans has been a problem ever since man began to use fossil fuels. Biodegradation by naturally occurring populations of micro-organisms is a major mechanism for the removal of ... [more ▼]

Oil pollution of the oceans has been a problem ever since man began to use fossil fuels. Biodegradation by naturally occurring populations of micro-organisms is a major mechanism for the removal of petroleum from the environment. To examine the effects of crude oil pollution on intertidal bacteria, we repeated the same contamination experiments on nine different sub-Antarctic intertidal beaches using specifically built enclosures (PVC pipe, 15 cm in inner diameter and 30 cm in height). Despite the pristine environmental conditions, significant numbers of indigenous hydrocarbon-degrading bacteria were observed in all the studied beaches. Introduction of oil into these previously oil-free environments resulted in several orders of magnitude of increase in hydrocarbon-degrading micro-organisms within a few days in some of the studied sites but has no obvious effects on two others. The physical environment of the bacterial assemblage seems to play a major role in the biodegradation capacities. After 3 months of contamination, both remaining oil concentrations and biodegradation indexes differ strongly between the different stations. Thus, chemical and biological parameters reveal a strong heterogeneity of biodegradation capacities between the different sites. (C) 2000 Elsevier Science Ltd. All rights reserved. [less ▲]

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