4 research outputs found

    From past to present: Biodiversity in a changing delta

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    A large-scale coastal engineering project (the \u91Delta works\u92) changed large-scale, dynamic estuarine nature in the southwest of the Netherlands into a diverse mosaic of ecosystems with different characteristics. This led to a suite of ecological problems, which is why plans are made to restore estuarine dynamics. Until today the effect of the Delta works on biodiversity in the subsystems is still poorly understood. We combined long-term datasets on macrobenthos, fish, birds and key species and present reliable and factual information on changes in biodiversity in the Southwest Delta in the past decennia in relation to the Delta works and other developments. Effects of the Delta works on biodiversity are highly diverse and depend on many different factors and histories specific for the different water bodies. If connections are restored, effects on species richness and biodiversity will depend on the specific characteristics of the separate basins. Because restoration of estuarine dynamics likely occurs on a reduced scale, effects on biodiversity may only be modest. However, effects on the occurrence of rare species of the brackish and intertidal transition zones may be more significant. It is recommended to study this further

    Inventarisatie van projecten relevant voor MEP Winning Suppletiezand 2014-2017

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    In de Noordzee wordt jaarlijks een grote hoeveelheid zand gewonnen om de Nederlandse kust door middel van suppleties te beschermen tegen overstroming. Voor het winnen van het zand is een vergunning nodig in het kader van de Ontgrondingenwet. MERs dienen ter onderbouwing van vergunningaanvragen. Ten behoeve van het MEP Winning Suppletiezand 2013 \u96 2017 hebben Rijkswaterstaat, Stichting LaMer en het Hoogheemraadschap Hollands Noorderkwartier aan IMARES gevraagd een inventarisatie te maken van lopende onderzoeks- en monitoringprojecten waarvan de uitkomsten relevant kunnen zijn voor de invulling van het MEP. Indien gesignaleerde kennisleemtes al in andere projecten worden ingevuld kan het MEP zandwinning zich beter richten op kennislacunes die nog niet geadresseerd worden in andere studies. Ook kan samenwerking gezocht worden met andere studies op basis van de inventarisatie

    Exploring the Trophic Spectrum: Placing Mixoplankton Into Marine Protist Communities of the Southern North Sea

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    While traditional microplankton community assessments focus primarily on phytoplankton and protozooplankton, the last decade has witnessed a growing recognition of photo-phago mixotrophy (performed by mixoplankton) as an important nutritional route among plankton. However, the trophic classification of plankton and subsequent analysis of the trophic composition of plankton communities is often subjected to the historical dichotomy. We circumvented this historical dichotomy by employing a 24 year-long time series on abiotic and protist data to explore the trophic composition of protist communities in the Southern North Sea. In total, we studied three different classifications. Classification A employed our current knowledge by labeling only taxa documented to be mixoplankton as such. In a first trophic proposal (classification B), documented mixoplankton and all phototrophic taxa (except for diatoms, cyanobacteria, and colonial Phaeocystis) were classified as mixoplankton. In a second trophic proposal (classification C), documented mixoplankton as well as motile, phototrophic taxa associated in a principle component analysis with documented mixoplankton were classified as mixoplankton. In all three classifications, mixoplankton occurred most in the inorganic nutrient-depleted, seasonally stratified environments. While classification A was still subjected to the traditional dichotomy and underestimated the amount of mixoplankton, our results indicate that classification B overestimated the amount of mixoplankton. Classification C combined knowledge gained from the other two classifications and resulted in a plausible trophic composition of the protist community. Using results of classification C, our study provides a list of potential unrecognized mixoplankton in the Southern North Sea. Furthermore, our study suggests that low turbidity and the maturity of an ecosystem, quantified using a newly proposed index of ecosystem maturity (ratio of organic to total nitrogen), provide an indication on the relevance of mixoplankton in marine protist communities.Environmental Fluid Mechanic
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