The role of ecosystem engineers in the ecomorphological development of intertidal habitats

In het afgelopen decennium is er een verschuiving gaande naar een meer ecosysteem gebaseerde kustverdediging met integratie van natuurlijke verdedigingsstructuren zoals duinen, mangroves, schorren, zeegras bedden, schelpdier- en koraalriffen. Deze soorten staan bekend als biobouwers. Het toepassen van natuurlijke verdedigingsstructuren vereist kennis over: waar deze habitats erosie verminderen en bescherming bieden; evenals ecologische gegevens, zoals soortafhankelijke habitatseisen, levenscyclus, populatiedynamiek en lange-termijn persistentie. Dit laatste kan gebruikt worden om plaatsen te identificeren waar habitats succesvol geïmplementeerd kunnen worden. Intergetijdengebieden en oesterriffen zijn bestudeerd in de Oosterschelde, welke dient als modelsysteem. In dit systeem eroderen getijdengebieden in een rap tempo als gevolg van significante wijzigingen aan het Oosterschelde bekken door de Deltawerke

Oesterbank is wapen tegen zandhonger

De aanleg van kunstmatige oesterbanken helpt wellicht de natuur te ontzien en geld te besparen bij kustbescherming. Oesterbanken voorkomen dat achterliggende zandplaten afkalven door de golven. Ze beschermen niet alleen de plek die ze zelf bedekken, maar ook nog eens een achterliggend gebied. Dat stelt Brenda Walles, promovendus bij de leerstoelgroep Duurzame schelpdiercultuur, in het proefschrift dat ze op 1 juni verdedigde

Guidelines for evaluating performance of oyster habitat restoration should include tidal emersion: reply to Baggett et al.

Baggett et al. (2015) identified a set of three universal environmental variables to be monitored for evaluating all oyster habitat restoration projects: salinity, temperature, and dissolved oxygen. Perhaps evidencing a bias toward subtidal reefs, this set of parameters omits another first-order environmental factor, tidal emersion. Intertidal oyster reefs can be the dominant reef habitat in estuaries, with clear zonation in oyster performance across the intertidal exposure gradient. Therefore, we propose to include tidal emersion as a fourth universal environmental parameter when designing and evaluating oyster restoration projects to better encompass the whole environmental spectrum along which reefs occur

Persisting Cough as the Single Presenting Symptom of an Intrathoracic Tumor in a Nine-Month-Old Child with Adenovirus Airway Infection

We report on a nine-month-old girl who presented with persisting cough, and diminished ventilation of the left hemithorax. Viral pneumonia was suspected after Adenovirus detection by PCR, but chest X-rays showed a persistent shadowing of the left hemithorax and persistent coughing despite clinical improvement. Because of the discrepancy between clinical and radiological signs further investigations by ultrasound and CT scan were performed, which visualized an intrathroracic tumor. Histopathology confirmed diagnosis of a teratoma. This case highlights the need for careful evaluation by the treating physicians. If the chest X-ray provides a discrepancy to the clinical findings or persistent pathologies exist, differential diagnosis should be discussed and further diagnostics be performed

Guidelines for evaluating performance of oyster habitat restoration should include tidal emersion: Reply to Baggett et al.

Baggett et al. (2015) identified a set of three universal environmental variables to be monitored for evaluating all oyster habitat restoration projects: salinity, temperature, and dissolved oxygen. Perhaps evidencing a bias toward subtidal reefs, this set of parameters omits another first-order environmental factor, tidal emersion. Intertidal oyster reefs can be the dominant reef habitat in estuaries, with clear zonation in oyster performance across the intertidal exposure gradient. Therefore, we propose to include tidal emersion as a fourth universal environmental parameter when designing and evaluating oyster restoration projects to better encompass the whole environmental spectrum along which reefs occur

Promoting self-facilitating feedback processes in coastal ecosystem engineers to increase restoration success:Testing engineering measures

Coastal ecosystem engineers often depend on self‐facilitating feedbacks to ameliorate environmental stress. This makes the restoration of such coastal ecosystem engineers difficult. We question if we can increase transplantation success in highly dynamic coastal areas by engineering measures that promote the development of self‐facilitating feedback processes.Intertidal blue mussels Mytilus edulis are a typical example of ecosystem engineers that are difficult to restore. A lack of self‐facilitating feedbacks at low densities limits establishment success when young mussels are transplanted on dynamic mudflats.In a large field experiment, we investigated the possibility of increasing transplantation success by stimulating the formation of an aggregated spatial configuration in mussels, thereby reducing hydrologically induced dislodgment and the risks of predation. For this, we applied engineering measures in the form of fences that trapped wave dislodged mussels.Mussel loss rates were significantly lower when mussels were placed between both artificial fences, and in high densities (4.2 kg/m2) compared with mussels placed in areas without fences and in low densities (2.1 kg/m2). The fences induced the formation of a banded pattern with high local mussel densities, which locally reduced predation.Synthesis and applications. Our results underline the importance of actively promoting the development of self‐facilitating processes, such as aggregation into patterns, in restoration projects of ecosystem engineers. In particular, the current study shows that engineering measures can help to initiate these kinds of self‐facilitating interactions, especially in highly dynamic areas

Electrospun poly(d/l-lactide-co-l-lactide) hybrid matrix: a novel scaffold material for soft tissue engineering

Electrospinning is a long-known polymer processing technique that has received more interest and attention in recent years due to its versatility and potential use in the field of biomedical research. The fabrication of three-dimensional (3D) electrospun matrices for drug delivery and tissue engineering is of particular interest. In the present study, we identified optimal conditions to generate novel electrospun polymeric scaffolds composed of poly-d/l-lactide and poly-l-lactide in the ratio 50:50. Scanning electron microscopic analyses revealed that the generated poly(d/l-lactide-co-l-lactide) electrospun hybrid microfibers possessed a unique porous high surface area mimicking native extracellular matrix (ECM). To assess cytocompatibility, we isolated dermal fibroblasts from human skin biopsies. After 5 days of in vitro culture, the fibroblasts adhered, migrated and proliferated on the newly created 3D scaffolds. Our data demonstrate the applicability of electrospun poly(d/l-lactide-co-l-lactide) scaffolds to serve as substrates for regenerative medicine applications with special focus on skin tissue engineering

In situ guided tissue regeneration in musculoskeletal diseases and aging: Implementing pathology into tailored tissue engineering strategies

In situ guided tissue regeneration, also addressed as in situ tissue engineering or endogenous regeneration, has a great potential for population-wide “minimal invasive” applications. During the last two decades, tissue engineering has been developed with remarkable in vitro and preclinical success but still the number of applications in clinical routine is extremely small. Moreover, the vision of population-wide applications of ex vivo tissue engineered constructs based on cells, growth and differentiation factors and scaffolds, must probably be deemed unrealistic for economic and regulation-related issues. Hence, the progress made in this respect will be mostly applicable to a fraction of post-traumatic or post-surgery situations such as big tissue defects due to tumor manifestation. Minimally invasive procedures would probably qualify for a broader application and ideally would only require off the shelf standardized products without cells. Such products should mimic the microenvironment of regenerating tissues and make use of the endogenous tissue regeneration capacities. Functionally, the chemotaxis of regenerative cells, their amplification as a transient amplifying pool and their concerted differentiation and remodeling should be addressed. This is especially important because the main target populations for such applications are the elderly and diseased. The quality of regenerative cells is impaired in such organisms and high levels of inhibitors also interfere with regeneration and healing. In metabolic bone diseases like osteoporosis, it is already known that antagonists for inhibitors such as activin and sclerostin enhance bone formation. Implementing such strategies into applications for in situ guided tissue regeneration should greatly enhance the efficacy of tailored procedures in the future