Diatomeeën als indicator voor waterkwaliteit nabij rwzi’s ?

Waterschap Aa en Maas volgt de fysisch-chemische kwaliteit van het oppervlaktewater nabij rwzi's om de invloed van het rwzi-effluent op die kwaliteit in beeld te krijgen. Het waterschap wil ook de invloed van de rwzi’s op de biologische waterkwaliteit weten. Diatomeeën lijken daarvoor geschikte indicatoren te zijn. Een monitoringspilot toont dat de biologische waterkwaliteit op basis van de KRW-maatlat van diatomeeën benedenstrooms van rwzi’s een lagere score geeft dan bovenstrooms. Ook worden benedenstrooms significant meer soorten aangetroffen die hogere organische en stikstofbelastingen en een lager zuurstofniveau indiceren. Een uitgebreidere monitoring is nodig om deze bevindingen steviger te onderbouwen

Invasive crayfish threaten the development of submerged macrophytes in lake restoration

Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.

Immuno-radiotherapy with cetuximab and avelumab for advanced stage head and neck squamous cell carcinoma: Results from a phase-I trial

Item does not contain fulltextBACKGROUND AND PURPOSE: Radiotherapy (RT) with cetuximab is an alternative for advanced-stage head and neck squamous cell carcinoma (HNSCC) patients who are unfit for cisplatin treatment. As 5-year overall survival is below 50%, it is of interest to test PD-L1 immune checkpoint blockade (avelumab) with cetuximab-RT in the curative setting. MATERIALS AND METHODS: Phase-I feasibility trial (planned n=10, NCT02938273) of conventional cetuximab-RT with avelumab (concurrent 10mg/kg Q2W+4months maintenance) for advanced-stage HNSCC patients unfit for cisplatin treatment. RESULTS: One of ten included patients experienced grade 2 cetuximab-related infusion reaction and withdrew from the study before avelumab was administered. One patient discontinued treatment after 2 courses of avelumab and 12x2Gy RT for personal reasons. In 2/8 remaining patients, avelumab was stopped after 4 and 8 courses because of toxicity and tumor progression, respectively. There was no grade 4-5 toxicity. Grade 3 immune-related toxicity was manageable and occurred in 4 patients. One patient was treated with topical steroids for grade 3 maculopapular rash and 3 patients received high-dose prednisone for grade 3 elevated liver enzymes (n=1) and pneumonitis (n=2). Seven patients experienced grade 3 RT-related toxicity with no severe specific cetuximab-related toxicity. Tumor recurrence occurred in 4/8 patients (50%) after a median of 12 (8-26) months follow-up. CONCLUSION: Cetuximab-RT plus avelumab is feasible in patients with advanced-stage HNSCC who are unfit for cisplatin treatment. Immune-related toxicity was transient and manageable and radiotherapy-related toxicity was in accordance with standard of care. This pilot study provides grounds for larger efficacy trials