Trans*Kinder und *Jugendliche in Deutschland : Problemlagen von Trans*Kindern und *Jugendlichen im schulischen Kontext und mögliche Beiträge der Angewandten Kindheitswissenschaften zur Veränderung

[s.c.]

La perception du temps et sa modulation par la température chez les guêpes parasitoïdes

Les modèles d'optimalité postulent que les animaux en quête de ressources utilisent le taux de gain de valeur adaptative pour optimiser plusieurs comportements tels que la répartition du temps lors de l’exploitation d‘un agrégat et l'investissement en progénitures. Bien que la durée de plusieurs comportements doit être régulée, peu d’évidences de la perception du temps sont actuellement disponibles pour les insectes et aucune pour les guêpes parasitoïdes, et ce malgré leur importance en tant que modèles écologiques. De plus, puisque les guêpes parasitoïdes sont poïkilothermes, cette capacité pourrait être affectée par la température. Nous avons supposé que les guêpes parasitoïdes auraient la capacité de percevoir le temps, à la fois de façon prospective (mesure du temps écoulé) et rétrospective (durée d'un événement passé), afin d'optimiser les décisions liées à l'exploitation d’agrégats d’hôtes et à la reproduction. Nous avons également émis l'hypothèse que la température aurait une incidence sur la perception du temps des guêpes parasitoïdes. Pour la mesure prospective du temps, nous avons utilisé la capacité d’apprentissage associatif de Microplitis croceipes (Hymenoptera: Braconidae). Les guêpes ont été entraînées à associer une odeur à la durée d'un intervalle entre des hôtes. Après leur entraînement, elles ont été testées dans un tunnel de vol avec un choix d’odeurs. Les guêpes ont choisi majoritairement l'odeur associée à l'intervalle de temps auquel elles étaient testées. Nous avons également investigué le rôle de la dépense énergétique sur la mesure du temps. Suite à une restriction de mouvement des guêpes pendant l'intervalle de temps entre les hôtes, elles choisissaient aléatoirement dans le tunnel de vol. L'absence de dépense énergétique les aurait rendues incapables de mesurer le temps. La dépense d'énergie est donc un substitut essentiel pour mesurer le temps. Pour la mesure rétrospective du temps, nous avons utilisé le processus d'évaluation de l'hôte de Trichogramma euproctidis (Hymenoptera: Trichogrammatidae). Certains trichogrammes utilisent la durée du transit initial sur l'œuf hôte afin d’en évaluer la taille et d’ajuster le nombre d’œufs à y pondre. Nous avons augmenté artificiellement la durée de transit initiale de T. euproctidis en suspendant l'œuf hôte pour le faire paraître plus gros qu'un œuf de taille similaire. Une augmentation de la durée de transit initiale a augmenté la taille de la ponte. Ceci démontre la capacité de T. euproctidis de mesurer la durée du transit initial, et donc d’une mesure du temps rétrospective. Pour déterminer si la température modifie la mesure du temps dans les espèces poïkilothermes, nous avons utilisé le comportement d’exploitation d’agrégats d’hôtes de T. euproctidis. Les modèles d’optimalités prédisent que les guêpes devraient rester plus longtemps et quitter à un faible taux de gain de valeur adaptative suite à un déplacement de longue durée plutôt que pour un déplacement de courte durée. Nous avons testé l'impact d'un déplacement de 24 h à différentes températures sur l'exploitation d’agrégats d’hôtes. Un déplacement à température chaude augmente le temps de résidence dans l’agrégat et diminue le taux de gain de valeur adaptative au moment de quitter ; ces comportements sont associés à un trajet de longue durée. L'inverse a été observé lors d’un déplacement à une température froide. Les températures chaude et froide ont modulé la mesure du temps en accélérant ou ralentissant l'horloge biologique, faisant paraître le déplacement respectivement plus long ou plus court qu’il ne l’était réellement. Ces résultats démontrent clairement que les guêpes parasitoïdes ont la capacité de mesurer le temps, autant rétrospectivement que prospectivement. Des preuves directes de leur capacité sont maintenant disponibles pour au moins deux espèces de guêpes parasitoïdes, une composante essentielle des modèles d'optimalité. Le rôle de la dépense énergétique dans la mesure du temps a aussi été démontré. Nos résultats fournissent également la preuve de l'impact de la température sur la perception du temps chez les insectes. L'utilisation de la dépense énergétique en tant que proxy pour mesurer le temps pourrait expliquer une partie de sa thermosensibilité, puisque les guêpes parasitoïdes sont poïkilothermes. Cette mesure du temps sensible à la température pourrait affecter des stratégies de lutte biologique. Sur le terrain, au début de la journée, la température de l'air sera similaire à la température de l'air autour des plantes infestées par des parasites, alors qu'elle sera plus chaude pendant la journée. En lutte biologique augmentative, les guêpes parasitoïdes libérées resteraient plus longtemps dans les agrégats d’hôtes que celles relâchées en début de journée.

Mapping of Submerged Aquatic Vegetation in Rivers From Very High Resolution Image Data, Using Object Based Image Analysis Combined with Expert Knowledge

The use of remote sensing for monitoring of submerged aquatic vegetation (SAV) in fluvial environments has been limited by the spatial and spectral resolution of available image data. The absorption of light in water also complicates the use of common image analysis methods. This paper presents the results of a study that uses very high resolution (VHR) image data, collected with a Near Infrared sensitive DSLR camera, to map the distribution of SAV species for three sites along the Desselse Nete, a lowland river in Flanders, Belgium. Plant species, including Ranunculus aquatilis L., Callitriche obtusangula Le Gall, Potamogeton natans L., Sparganium emersum L. and Potamogeton crispus L., were classified from the data using Object-Based Image Analysis (OBIA) and expert knowledge. A classification rule set based on a combination of both spectral and structural image variation (e.g. texture and shape) was developed for images from two sites. A comparison of the classifications with manually delineated ground truth maps resulted for both sites in 61% overall accuracy. Application of the rule set to a third validation image, resulted in 53% overall accuracy. These consistent results show promise for species level mapping in such biodiverse environments, but also prompt a discussion on assessment of classification accuracy.

The evolution of imperfect mimicry in hoverflies

Ideas about the evolution of imperfect mimicry are reviewed. Their relevance to the colours patterns of hoverflies (Diptera, Syrphidae) are discussed in detail. Most if not all of the hoverflies labelled as mimetic actually are mimics. The apparently poor nature of their resemblance does not prevent them from obtaining at least some protection from suitably experienced birds. Mimicry is a dominant theme of this very large family of Diptera, with at least a quarter of all species in Europe being mimetic. Hoverfly mimics fall into three major groups according to their models, involving bumblebees, honeybees and social wasps. There are striking differences in the general levels of mimetic fidelity and relative abundances of the three groups, with accurate mimicry, low abundance and polymorphism characterizing the bumblebee mimics: more than half of all the species of bumblebee mimics are polymorphic. Mimics of social wasps tend to be poor mimics, have high relative abundance, and polymorphism is completely absent. Bumblebee models fall into a small number of Muellerian mimicry rings which are very different between the Palaearctic and Nearctic regions. Social wasps and associated models form one large Muellerian complex. Together with honeybees, these complexes probably form real clusters of forms as perceived by many birds. All three groups of syrphid mimics contain both good and poor mimics; some mimics are remarkably accurate, and have close morphological and behavioural resemblance. At least some apparently 'poor' mimetic resemblances may be much closer in birds' perception than we imagine, and more work needs to be done on this. Bumblebees are the least noxious and wasps the most noxious of the three main model groups. The basis of noxiousness is different, with bumblebees being classified as non-food, whereas honeybees and wasps are nasty-tasting and (rarely) stinging. The distribution of mimicry is exactly what would be expected from this ordering, with polymorphic and accurate forms being a key feature of mimics of the least noxious models, while highly noxious models have poor-quality mimicry. Even if the high abundance of many syrphid mimics relative to their models is a recent artefact of man-made environmental change, this does not preclude these species from being mimics. It seems unlikely that bird predation actually controls the populations of adult syrphids. Being rare relative to a model may have promoted or accelerated the evolution of perfect mimicry: theoretically this might account for the pattern of rare good mimics and abundant poor ones, but the idea is intrinsically unlikely. Many mimics seem to have hour-to-hour abundances related to those of their models, presumably as a result of behavioural convergence. We need to know much more about the psychology of birds as predators. There are at least four processes that need elucidating: (a) learning about the noxiousness of models; (b) the erasing of that learning through contact with mimics (extinction, or learned forgetting); (c) forgetting; (d) deliberate risk-taking and the physiological states that promote it. Johnston's (2002) model of the stabilization of imperfect mimicry by kin selection is unlikely to account for the colour patterns of hoverflies. Sherratt's (2002) model of the influence of multiple models potentially accounts for all the patterns of hoverfly mimicry, and is the most promising avenue for testing.

Does the abundance of hoverfly mimics (Syrphidae) depend on the numbers of their hymenopteran models ?

We tested the prediction that, if hoverflies are Batesian mimics, this may extend to behavioral mimicry such that their numerical abundance at each hour of the day (the daily activity pattern) is related to the numbers of their hymenopteran models. After accounting for site, season, microclimatic responses and for general hoverfly abundance at three sites in north-west England, the residual numbers of mimics were significantly correlated positively with their models 9 times out of 17, while 16 out of 17 relationships were positive, itself a highly significant non-random pattern. Several eristaline flies showed significant relationships with honeybees even though some of them mimic wasps or bumblebees, perhaps reflecting an ancestral resemblance to honeybees. There was no evidence that good and poor mimics differed in their daily activity pattern relationships with models. However, the common mimics showed significant activity pattern relationships with their models, but the rarer mimics did not. We conclude that many hoverflies show behavioral mimicry of their hymenopteran models.

Monetarismo y capitalismo periférico en América Latina

Originalmente presentada como tesis del autor (Dr. en Ciencias Económicas -- Universidad de San Gall. Facultad de Ciencias Ecómicas y Sociales, 1982).

Report tecnico – BioQuestionario e BioScoperta Applicazioni mobili per imparare giocando

L’informazione in campo ambientale assume un’importanza fondamentale in relazione all’obiettivo di accrescere il livello di consapevolezza e di sensibilità in relazione al concetto di ambiente, sia al fine di promuovere comportamenti coerenti con il principio di sviluppo sostenibile, sia per contribuire allo sviluppo di una responsabilità individuale e collettiva. Le tecnologie mobili nascono e si evolvono a partire dalla necessità dell’uomo di espandere i propri limiti e dall’esigenza di avere la possibilità di comunicare e accedere alle informazioni in maniera diretta e immediata. L'utilizzo di dispositivi mobili, quali smartphone e tablet, è in netta crescita in tutte le categorie di utenza e nei differenti contesti sociali. Possedere un dispositivo mobile dotato di accesso alla rete internet permette di avere il sapere a portata di mano e di comunicare con utenti in tutto il modo senza barriere fisiche e temporali. Inoltre, possono essere strumenti di grande aiuto, sia nel campo lavorativo che nel tempo libero, grazie all’utilizzo di innumerevoli applicazioni create ad hoc per l'acquisizione di informazioni e la loro fruizione. L’aspirazione del progetto, inserito nel Sistema di Comunicazione, Informazione e Diffusione dell’Osservatorio della Biodiversità della Sicilia, è la realizzazione di una applicazione che permetta ai visitatori di approfondire e consolidare i luoghi e forme della conoscenza offerti, durante la visita dell’Osservatorio della Biodiversità Regione Sicilia, dal personale qualificato rivestito dalle figure di ricercatori e tecnologi dell’IAMC CNR della sede di Capo Granitola. Gli scopi principali sono la comunicazione, l’informazione e l’educazione per lo sviluppo di conoscenze e sensibilità sul tema della Biodiversità per spronare gli utenti alla salvaguardia del territorio, rendendo facilmente accessibile l’approfondimento dei concetti riguardanti numerose specie e habitat del nostro territorio, attraverso una dimensione scientifica di stampo ludico.

Nuove specie per l'acquacoltura: tecniche di produzione di novellame di Sardina pilchardus

Il progetto all’interno del quale si è inserita l' attività "Sperimentare in acquacoltura il novellame di Sardina pilchardus" è il Progetto Ritmare (La Ricerca Italiana per il Mare). Il progetto Ritmare è un progetto strategico per la ricerca sul mare in Italia, che vuole coniugare le risorse ambientali del mare con l’uso connesso alle attività produttive e allo sfruttamento energetico delle sue risorse, sviluppando tecnologie ed innovazione e, al tempo stesso, promuovendone la sua conoscenza e il rispetto. In tale contesto il progetto mira a sperimentare in acquacoltura il novellame di sardina, prodotto agroalimentare tradizionalmente consumato e molto richiesto nei paesi rivieraschi del Mediterraneo. ll novellame per anni è stato pescato in modo puntuale ma per la bassissima sostenibilità e per l’impatto sugli stock adulti, la comunità europea ne ha deciso la sospensione. Il progetto vuole tentare di reintegrare il prodotto sul mercato attraverso una produzione sostenibile, evitando la perdita culturale. Saranno indagate le caratteristiche organolettiche del prodotto per promuoverne il consumo e verificate le ricadute industriali attraverso la realizzazione di un Business plan.

Close encounters: international exhibitions and the material culture of the British Empire, c.1880-1940

Apparitions of empire and imperial ideologies were deeply embedded in the International Exhibition, a distinct exhibitionary paradigm that came to prominence in the mid-nineteenth century. Exhibitions were platforms for the display of objects, the movement of people, and the dissemination of ideas across and between regions of the British Empire, thereby facilitating contact between its different cultures and societies. This thesis aims to disrupt a dominant understanding of International Exhibitions, which forwards the notion that all exhibitions, irrespective of when or where they were staged, upheld a singular imperial discourse (i.e. Greenhalgh 1988, Rydell 1984). Rather, this thesis suggests International Exhibitions responded to and reflected the unique social, political and economic circumstances in which they took place, functioning as cultural environments in which pressing concerns of the day were worked through. Understood thus, the International Exhibition becomes a space for self-presentation, serving as a stage from which a multitude of interests and identities were constructed, performed and projected. This thesis looks to the visual and material culture of the International Exhibition in order to uncover this more nuanced history, and foregrounds an analysis of the intersections between practices of exhibition-making and identity-making. The primary focus is a set of exhibitions held in Glasgow in the late-1880s and early-1900s, which extends the geographic and temporal boundaries of the existing scholarship. What is more, it looks at representations of Canada at these events, another party whose involvement in the International Exhibition tradition has gone largely unnoticed. Consequently, this thesis is a thematic investigation of the links between a municipality routinely deemed the ‘Second City of the Empire’ and a Dominion settler colony, two types of geographic setting rarely brought into dialogue. It analyses three key elements of the exhibition-making process, exploring how iconographies of ‘quasi-nationhood’ were expressed through an exhibition’s planning and negotiation, its architecture and its displays. This original research framework deliberately cuts across strata that continue to define conceptions of the British Empire, and pushes beyond a conceptual model defined by metropole and colony. Through examining International Exhibitions held in Glasgow in the late-Victorian and Edwardian periods, and visions of Canada in evidence at these events, the goal is to offer a novel intervention into the existing literature concerning the cultural history of empire, one that emphasises fluidity rather than fixity and which muddles the boundaries between centre and periphery.

Performance of Sirex noctilio’s biocontrol agent Deladenus siricidicola, in known and predicted hosts

Survival of the free-living mycetophagous form of Deladenus siricidicola, the major biological control agent of Sirex woodwasp, Sirex noctilio, was tested in known (Pinus taeda) and predicted novel (P. elliottii subsp. elliottii × P. caribaea var. hondurensis) hybrid host taxa. Trials were established in the field to simulate nematode dispersal both naturally by infected wasps and following commercial inoculation, as well as in the laboratory under controlled conditions. Nematodes showed reduced survival in hybrid pine compared with P. taeda for all tree-associated treatments, but performed equivalently in petri-dish bioassays containing substrate of each taxon. Growth of Amylostereum areolatum, the food source of D. siricidicola was lower on plates containing ground hybrid substrate than on plates containing ground P. taeda. Some physical differences were found between taxa, including differences in bordered pit diameters, tracheid widths, and basic density, but these did not consistently explain reduced performance. More plant secondary compounds (predominantly oleoresins) were present in hybrid taxa than in P. taeda, and in standing trees compared with felled trees. Our results suggested that D. siricidicola may not be as effective in hybrid pine taxa for the biological control of S. noctilio as it is in its current known host taxa, possibly because of reduced growth of its food source, A. areolatum in hybrid pine.

Acute Acalculous Cholecystitis as a Presenting Manifestation in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is known to involve the gastrointestinal tract, but gallbladder involvement is rare. The authors report the case of a 26-year-old postpartum female who presented with acute right upper quadrant abdominal pain and was diagnosed with acute acalculous cholecystitis (AAC). In the presence of concomitant features of nephritis, pericardial effusion, anaemia and positive ANA titre, the diagnosis of SLE was confirmed during hospitalisation. Histopathological analysis of the gall bladder revealed evidence of vasculitis. Although rare, AAC can be the first presentation of patients diagnosed with SLE. Prompt diagnosis and management results in a better patient outcome.

A surface plasmon resonance system for the underwater detection of domoic acid

Over the past decade Surface Plasmon Resonance (SPR) techniques have been applied to the measurement of numerous analytes. In this article, an SPR biosensor system deployed from an oceanographic vessel was used to measure dissolved domoic acid (DA), a common and harmful phycotoxin produced by certain microalgae species belonging to the genus Pseudo-nitzschia. During the biosensor deployment, concentrations of Pseudo-nitzschia cells were very low over the study area and measured DA concentrations were below detection. However, the in situ operational detection limit of the system was established using calibrated seawater solutions spiked with DA. The system could detect the toxin at concentrations as low as 0.1 ng mL−1 and presented a linear dynamic range from 0.1 ng mL−1 to 2.0 ng mL−1. This sensor showed promise for in situ detection of DA.

Bilan 2015 du dispositif national de surveillance de la santé des mollusques marins

Depuis 1992, la surveillance de la santé des mollusques marins du littoral français est assurée par le réseau de Pathologie des Mollusques (Repamo). Ses activités s’inscrivent dans le cadre de la Directive Européenne 2006/88/CE. Depuis son évaluation par la plateforme nationale d’épidémiosurveillance en santé animale en 2012, l’objectif de surveillance est la détection précoce des infections dues à des organismes pathogènes exotiques et émergents affectant les mollusques marins sauvages et d’élevage. L’année 2015 est la première année de transition pour laquelle un début d’évolution des modalités de surveillance de la santé des mollusques marins animées par l’Ifremer a été amorcé. Un dispositif hybride de surveillance a été mis en place, s’appuyant sur l’existant et intégrant des débuts d’évolution. La surveillance événementielle a constitué l’activité principale du dispositif en 2015 et s’est appuyée sur des réseaux existants : (1) la surveillance des mortalités observées sur des animaux sentinelles déployés sur les sites ateliers des réseaux Ifremer RESCO 2 (12 sites) pour l’huître creuse Crassostrea gigas et MYTILOBS 2 (8 sites) pour la moule bleue Mytilus edulis. Pour l’huître creuse Crassostrea gigas, la mortalité cumulée moyenne était de 50,3% (écart-type 10,9%) pour le naissain standardisé Ifremer (NSI), de 11,0% (écart-type 9,1%) pour les huîtres de 18 mois et de 7,3% (écart-type 5,6%) pour les huîtres de 30 mois. Les mortalités ont été observées principalement entre le début du mois de mai et la mi-juillet. Lors de ces épisodes de mortalité, des prélèvements d’animaux ont été réalisés en vue d’analyses diagnostiques : 7 prélèvements pour le NSI, 2 pour les huîtres de 18 mois et 1 pour les huîtres de 30 mois. Aucun agent réglementé n’a été détecté dans les échantillons d’huîtres creuses prélevés et analysés. Le virus OsHV-1 a été détecté dans les 7 échantillons analysés de NSI, dans 2 échantillons analysés d’huîtres de 18 mois et dans 1 échantillon analysé d’huîtres de 30 mois. La bactérie Vibrio aestuarianus a été détectée dans 5 échantillons analysés de NSI, dans 1 échantillon d’huîtres de 18 mois et dans 1’échantillon d’huîtres de 30 mois. Pour la moule bleue Mytilus edulis, des mortalités cumulées variant de 9% sur le site du Vivier à 51% sur le site des filières du Pertuis Breton ont été estimées. Les mortalités ont été observées au printemps sur des moules âgées d’une année et en automne sur des moules plus jeunes. Lors de ces épisodes de mortalités, des prélèvements d’animaux ont été réalisés en vue d’analyses diagnostiques : 2 prélèvements pour les moules d’une année et 1 pour les jeunes moules. Ces prélèvements ont eu lieu dans le Pertuis Breton. Aucun agent réglementé n’a été détecté dans les échantillons de moules prélevés et analysés. Des bactéries du groupe Splendidus ont été détectées dans les 3 échantillons de moules analysés. (2) la surveillance s’appuyant sur les déclarations de mortalités de mollusques par les conchyliculteurs et pêcheurs à pied professionnels auprès des Directions départementales des territoires et de la mer (DDTM). Cette modalité s’applique aux huîtres creuses et aux moules bleues lorsqu’il n’existe pas de site atelier RESCO 2 ou MYTILOBS 2 dans la zone où des mortalités sont déclarées par les conchyliculteurs ou pêcheurs à pied. Le réseau REPAMO 2 a réalisé 22 interventions, dont 15 pour les moules Mytilus edulis, 4 pour les coques Cerastoderma edule, 2 pour les palourdes Ruditapes sp. et 1pour les coquilles saint Jacques Pecten maximus. La recherche d’agents infectieux dans ces espèces de mollusques prélevés lors de hausse de mortalité a permis de mettre en évidence les parasites réglementés Perkinsus olseni dans 1 lot de palourdes, et Marteilia refringens dans 4 lots de moules, ainsi que le virus OsHV-1 dans 1 lot de palourdes et 1 lot de coques, la bactérie Vibrio aestuarianus dans 3 lots de coques, et des bactéries du groupe Splendidus dans 3 lots de coques et dans 13 lots de moules. L’année 2015 a également permis la démonstration sur un site atelier d’un exercice de surveillance programmée, ciblée et fondée sur les risques d’introduction et d’installation d’un organisme pathogène exotique. Elle a concerné le parasite Mikrocytos mackini de l’huître creuse Crassostrea gigas, sur un site atelier de la Charente-Maritime, suivi par le réseau RESCO 2. Le parasite Mikrocytos mackini n’a pas été détecté. En revanche, le parasite Marteilia refringens a été détecté dans ¾ des prélèvements d’huîtres réalisés. Dans le cadre du soutien scientifique et technique de l’évolution de la surveillance événementielle, l’année 2015 a également permis de poursuivre la démarche relative aux développements méthodologiques en lien avec la surveillance événementielle des mortalités de mollusques marins. Une étude de faisabilité de la recherche prospective de regroupements spatio-temporels d’événements de mortalités d’huîtres creuses a été préparée en collaboration avec tous les acteurs de la santé des mollusques marins en Normandie. Un outil de collecte et d’analyse des données de signalements des mortalités, automatisé, simple d’utilisation et flexible, a été élaboré.

Ingestion of a bacterivorous ciliate by the oyster Crassostrea gigas: Protozoa as a trophic link between picoplankton and benthic suspension-feeders

The linked concepts of 'microbial loop' and 'protozoan trophic link' have been very well documented in filter-feeding microzooplankton such as copepods, but have not been applied to energy transfer to benthic suspension-feeding macrofauna, with the exception of the recent demonstration of heterotrophic flagellate assimilation by mussels. The oyster Crassostrea gigas obtains energy resources by filtering microalgae (similar to 5 to 100 mu m). However, in turbid estuaries, light-limited phytoplanktonic production cannot entirely account for oyster energy requirements. Conversely, picoplankters (<2 mu m), which are main effecters of coastal energy flow and matter cycling, are not efficiently retained by oyster filtration. Ciliate protozoal as both micro-sized cells (similar to 5 to 100 run) and bacteria grazers, may represent a major intermediary in trophic transfer between picoplankton and metazoa. The ciliate Uronema was intensely cultured and labelled, using the cyanobacteria Synechococcus as an auto-fluorescent biomarker. The labelled ciliates were offered as potential prey to oysters. We report here the first experimental evidence of a significant retention and ingestion of ciliates by oysters, supporting the role of protozoa as a realistic trophic link between picoplankters and filter-feeding bivalves and thus enhancing their potential importance in estuarine microbial food webs.

Kinetics of tidal resuspension of microbiota: Testing the effects of sediment cohesiveness and bioturbation using flume experiments

Resuspension of the top few sediment layers of tidal mud flats is known to enhance planktonic biomass of microbiota (benthic diatoms and bacteria). This process is mainly controlled by tidal shear stress and cohesiveness of mud, and is also influenced by bioturbation activities. Laboratory experiments in a race track flume were performed to test the interactive effects of these factors on both the critical entrainment and resuspension kinetics of microbiota from silt-clay sediments from the Marennes-Oleron Bay, France. The marine snail Hydrobia ulvae was used to mimic surface bioturbation activities. As expected, the kinetics of microbial resuspension versus shear stress were largely controlled by the cohesiveness of silt-clay sediments. However, our results indicate that the effect of surface tracking by H. ulvae on microbial resuspension was clearly dependent on the interaction between sediment cohesiveness and shear velocity. Evidence was also found that microphytobenthos and bacteria are not simultaneously resuspended from silt-clay bioturbated sediments. This supports the theory that diatoms within the easily eroded mucus matrix behave actively and bacteria adhering to fine silt particles eroded at higher critical shear velocities behave passively.