Wegvisproef Japanse oesters in de Oosterschelde : eindrapportage

De Japanse oester, een exoot voor onze wateren, is in 1964 voor het eerst geïntroduceerd in de Oosterschelde ten behoeve van de oesterkwekers na de massale sterfte van platte oesters tijdens de strenge winter van 1962/1963. Sindsdien heeft deze soort zich ontwikkeld tot een dominante soort. In het voorjaar van 2006 is er een praktijkproef gestart om te onderzoeken of het noodzakelijk, zinvol en mogelijk is om de steeds verder oprukkende Japanse oesters (Crassostrea gigas) in de Oosterschelde te beheren. In het kader van deze proef is hiertoe 50 ha oesterbank (12,5 miljoen kg), verdeeld over vier locaties in de Oosterschelde weggevist door de Zeeuwse mosselvloot. De oesters zijn gestort op nabijgelegen stortlocaties alwaar de verwachting was dat de oesters zouden afsterven door verstikking. Het doel van deze proef is om na te gaan hoe effectief het bestand op geselecteerde proeflocaties kan worden verwijderd en eventueel hergebruikt d.m.v. toepassing van de mosselkor, tegen welke kosten, welke milieueffecten (morfologie, sedimentsamenstelling, bodemdiergemeenschap en vogels) dit met zich meebrengt en in welk tempo positieve (herstel sediment en oorspronkelijke bodemfauna) en negatieve effecten (herstel Japanse oester) zich voordoen. Dit eindrapport beschrijft de resultaten van de wegvisproef en de monitoring die in twee jaar erop volgend is uitgevoerd

Dynamics of nutrients, total organic carbon, prokaryotes and viruses in onboard incubations of cold-water corals

The potential influence of the cold-water corals (CWCs) Lophelia pertusa and Madrepora oculata on the dynamics of inorganic nutrient and total organic carbon (TOC) concentrations and the abundances of prokaryotes and viruses in bottom water was assessed in onboard incubation experiments. Ammonium, nitrite, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and TOC concentrations and N:P ratios were typically higher in incubation water with corals than in controls, whereas nitrate concentrations did not reveal a clear trend. Mucus release (normalized to coral surface) was estimated by the net increase rate of TOC concentrations and averaged 23 +/- 6 mg C m(-2) h(-1) for L. pertusa and 21 +/- 8 mg C m(-2) h(-1) for M. oculata. Prokaryotic and viral abundance and turnover rates were typically stimulated in incubation water with corals. This estimated prokaryotic stimulation averaged 6.0 +/- 3.0x10(9) cells m(-2) h(-1) for L. pertusa and 8.4 +/- 2.9x10(9) cells m(-2) h(-1) for M. oculata, whereas the estimated viral stimulation averaged 15.6 +/- 12.7x10(9) particles m(-2) h(-1) for L. pertusa and 4.3 +/- 0.4x10(9) particles m(-2) h(-1) M. oculata. Our data suggest that prokaryotes and viruses are released from corals and that nutrient and mucus release enhanced prokaryotic and viral production. The result of this stimulation could be a fuelling of bottom water in CWC reefs with nutrients and organic matter and consequently an enhancement of microbe-mediated processes

Monitoring vooroeververdediging Oosterschelde 2013

Dit rapport beschrijft de uitkomsten van de eco(toxico)logische monitoring van de vooroeververdediging in de Oosterschelde. Aanleiding hiervoor is dat Rijkswaterstaat sinds 2009 op locaties met voortschrijdende erosie in de Ooster- en Westerschelde bestortingen met staalslakken en breuksteen uitvoert op de vooroever van de dijken om de veiligheid tegen overstromingen te kunnen blijven garanderen. Het doel van deze monitoring is het bepalen van de samenstelling en biodiversiteit van de aanwezige levensgemeenschappen op harde en zachte substraten, en de bepaling van de gehalten aan zware metalen in mosselen en oesters op de nieuwe vooroever en referentie-locaties. Dit is in 2013 gedaan voor de locatie Zeelandbrug (oost/midden/west), waar voor het vierde opeenvolgende jaar is gemonitord na de bestorting in 2009. Daarnaast is de nulsituatie in kaart gebracht voor de locatie Zierikzee die in 2014 bestort zal worden. Ook zijn er verschillende referentie-locaties in de Oosterschelde meegenomen

Data rapport: effect van vooroeververdediging op bodemorganismen in Oosterschelde in 2015

Hoe verloopt de ontwikkeling van infauna gemeenschappen van jaar tot jaar in 2009-2015 in het afgezette sediment op de aangelegde vooroevers van staalslakken en breuksteen bij locatie Zeelandbrug (Zuidhoek-de Val) en Lokkersnol (Cauwersinlaag) in de Oosterschelde en twee referentielocaties in de Oosterschelde

Het 30e bestuur der B.I.L.

Maak kennis met het 30ste bestuur der B.I.L.! Zij zullen komend jaar jullie aanspreekpunt zijn in de kamers in Leiden en Den Haag. Om jullie alvast een beeld te geven, hebben we ze gevraagd zichzelf kort voor te stellen

The important role of sponges in carbon and nitrogen cycling in a deep-sea biological hotspot

Deep-sea sponge grounds are hotspots of biodiversity, harbouring thriving ecosystems in the otherwise barren deep sea. It remains unknown how these sponge grounds survive in this food-limited environment. Here, we unravel how sponges and their associated fauna sustain themselves by identifying their food sources and food-web interactions using bulk and compound-specific stable isotope analysis of amino and fatty acids. We found that sponges with a high microbial abundance had an isotopic composition resembling organisms at the base of the food web, suggesting that they are able to use dissolved resources that are generally inaccessible to animals. In contrast, low microbial abundance sponges had a bulk isotopic composition that resembles a predator at the top of a food web, which appears to be the result of very efficient recycling pathways that are so far unknown. The compound-specific-isotope analysis, however, positioned low-microbial abundance sponges with other filter-feeding fauna. Furthermore, fatty-acid analysis confirmed transfer of sponge-derived organic material to the otherwise food-limited associated fauna. Through this subsidy, sponges are key to the sustenance of thriving deep-sea ecosystems and might have, due to their ubiquitous abundance, a global impact on biogeochemical cycles.publishedVersio

The North Sea Benthos Project: planning, management and objectives

The ICES Benthos Ecology Working Group is integrating recent macrobenthic infaunal data (1999-2001) available from various sources, including national monitoring surveys, in North Sea soft bottom sediments. lt is expected to cover most of the North Sea. The main goal is an overall comparison with the North Sea Benthos Survey data of 1986, in order to determine whether there have been any significant changes and, if so, what may be the causal influences (e.g., climate change, fishing impacts). The work will contribute valuable information on several other topics such as habitat classification and the distribution of endangered species. Therefore, in addition to physico-chemical measurements of sediments samples alongside the benthic fauna, information on water depths, temperature, water quality and salinity will be incorporated in the analysis of species and community distributions. Also, we will use existing ecological and hydrographical models for currents, bottom shear stress and carbon input, along with information on the distribution of habitat types, to explain the observed distribution patterns. At the ASC, an overview of the data available will be presented as well as the anticipated outcomes, and the first steps taken to deal with taxonomic differences and other issues affecting the capability to integrate submitted information

Benthic habitat modelling and mapping as a conservation tool for marine protected areas: A seamount in the western Mediterranean

1. An ecologically representative, well‐connected, and effectively managed system of marine protected areas (MPAs) has positive ecological and environmental effects as well as social and economic benefits. Although progress in expanding the coverage of MPAs has been made, the application of management tools has not yet been implemented in most of these areas. 2. In this work, distribution models were applied to nine benthic habitats on a Mediterranean seamount within an MPA for conservation purposes. Benthic habitat occurrences were identified from 55 remotely operated vehicle (ROV) transects, at depths from 76 to 700 m, and data derived from multibeam bathymetry. Generalized additive models (GAMs) were applied to link the presence of each benthic habitat to local environmental proxies (depth, slope, backscatter, aspect, and bathymetric position index, BPI). 3. The main environmental drivers of habitat distribution were depth, slope, and BPI. Based on this result, five different geomorphological areas were distinguished. A full coverage map indicating the potential benthic habitat distribution on the seamount was obtained to inform spatial management. 4. The distribution of those habitats identified as vulnerable marine ecosystems (VMEs) was used to make recommendations on zonation for developing the management plan of the MPA. This process reveals itself as an appropriate methodological approach that can be developed in other areas of the Natura 2000 marine networkEn prensa1,92