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Applying underwater released exhaust gas as ‘air lubrication’ along the ship’s hull to reduce the energy consumption is under development. However, this direct emission to the water could pose a risk to the local marine environment, especially in shipping-dense areas. Specifically, CO2, a dominant component in the exhaust gas, has the potency to enhance algal blooms and cause acidification. This study provides the first relative risk assessment of ships with underwater release exhaust gas systems on a global scale, taking into account local water conditions and shipping intensity. Risk was characterized for 262 marine ecoregions by plotting the expected CO2 emission from ships to water against the estimated vulnerability to acidification and algal blooms. The vulnerability of each ecoregion was assessed based on background dissolved inorganic carbon (DIC) level, chlorophyll-a concentrations and total alkalinity. The results reveal that areas with relatively high vulnerability are mainly located above 30° N latitude. The Yellow Sea, Southern China Sea, and North Sea come out as relatively high risk areas. Looking in more detail to European high-risk ecoregions, the highest risk levels are found in areas with dense shipping lanes and maritime chokepoints, e.g. the Strait of Dover and the Strait of Gibraltar. This was the first attempt to make such a risk assessment and the outcome is only indicative. In a next phase additional parameters, such as water currents and biological composition of the ecosystem should be included.

It has been hypothesized that ingestion of microplastic increases exposure of aquatic organisms to hydrophobic contaminants. To date, most laboratory studies investigated chemical transfer from ingested microplastic without taking other exposure pathways into account. Therefore we studied the effect of polyethylene (PE) microplastic in sediment on PCB uptake by Arenicola marina as a model species, quantifying uptake fluxes from all natural exposure pathways. PCB concentrations in sediment, biota lipids (Clip) and porewater measured with passive samplers were used to derive lipid-normalized bioaccumulation metrics Clip, Biota sediment accumulation factor (BSAF), Bioaccumulation factor (BAF) and the Biota plastic accumulation factor (BPAF). Small effects of PE addition were detected suggesting slightly increased or decreased bioaccumulation. However, the differences decreased in magnitude dependent on the metric used to assess bioaccumulation, in the order: Clip>BSAF>BPAF>BAF, and were non-significant for BAF. The fact that BAF, i.e. normalization of Clip on porewater concentration, largely removed all effects of PE, shows that PE did not act as a measurable vector of PCBs. Biodynamic model analysis confirmed that PE ingestion contributed marginally to bioaccumulation. This work confirmed model-based predictions on the limited relevance of microplastic for bioaccumulation under environmentally realistic conditions, and illustrated the importance of assessing exposure through all media in microplastic bioaccumulation studies.

Recently, the Dutch state of play regarding blue carbon in the Netherlands was reviewed (Tamis & Foekema 2015)1. Since the review was focussed on the North East Atlantic, the Dutch Caribbean was not included. Therefore an additional review was conducted providing information on blue carbon in the Dutch Caribbean, including a discussion on the relevance of ecosystems other than the internationally accepted blue carbon ecosystems (i.e. mangroves, salt marshes and seagrass beds) and the potential of blue carbon as an ecosystem service. Marine molluscs and coral reefs cannot be regarded as blue carbon ecosystems. Other potential blue carbon ecosystems (i.e. open oceans, fish, kelp and algal mats) are unsure or unknown. Thus no other ecosystems were included. All three blue carbon ecosystems are found in the Dutch Caribbean, with mangroves containing the highest blue carbon stock. An estimated amount of nearly 564 thousand tonnes carbon is stored in these ecosystems, which is less than the estimated amount in the Netherlands. Mangroves are found on Aruba, Bonaire and Curacao but not on Saba and St Eustatius. On St. Maarten some mangrove vegetation is present, but most has been removed. Carbon sequestration is acknowledged as ecosystem service and the economic value of blue carbon ecosystems has been quantified in different case studies.

Het onderzoek had de volgende doelen: 1. Opstellen van protocollen voor bemonstering, verwerking en analyse van vismonsters ten bate van chemische biotamonitoring, met onderbouwing van de keuzes die in deze protocollen zijn vastgelegd. 2. In praktijk toetsen en waar nodig aanpassen van de protocollen. 3. Bepalen van de gehalten van geselecteerde microverontreinigingen in het IJsselmeer, de Getijdenmaas, het Hollands Diep en het Ketelmeer van vier vissoorten die voldoende aanwezig zijn en representatief voor het milieu, en het toetsen van deze gehalten aan de biotanormen. De resultaten zijn vast gelegd in voorliggend rapport.

Het doel van dit project was vast te stellen in welke mate zware metalen uit in zee gebrachte staalslakken bij een voor de Oosterschelde realistische en een worst-case waterverversingssnelheid: - uitlogen naar de waterkolom; - opgenomen worden door schelpdieren (mossel), wieren (Zee-eik), zakpijpen en sponzen; - negatieve effecten veroorzaken bij bovengenoemde organismen en op het mesocosm ecosysteem. De resultaten van de staalslakken zijn vergeleken met breuksteen, het materiaal dat traditioneel voor dijkverzwaring gebruikt wordt en maasgrind als referentiemateriaal met naar verwachting weinig of geen uitloging.

Reported concentrations of dioxin-like compounds accumulated in the European eel (Anguilla anguilla) were used to perform a risk assessment for eel larval survival, taking into account a modelled amplification of tissue concentrations with a factor of 1.33 during spawning migration. The calculated concentrations of dioxin-like compounds finally deposited in the eggs were compared to the internal effect concentrations for survival of early life stages of the European eel; these concentrations, by lack of experimental data, were estimated from a sensitivity distribution based on literature data by assuming that eel larvae are among the 10% most sensitive teleost fish species. Given concentrations of dioxin-like contaminants, and assuming a relatively high sensitivity it can be expected that larvae from eggs produced by eel from highly contaminated locations in Europe will experience increased mortality due to maternally transferred dioxin-like contaminants. As historical POP concentrations in eel tissue were higher this impact must have been stronger in the past. Potential effects of other compounds or effects on the migration, condition and fertility of the parental animals were not taken into account. It is important to further study the overall impact of contaminants on the reproduction success of the European eel, as this may have been underestimated until now.

Invasive species can have strong impact on the local ecosystem, not only substantial impact on the local ecosystem, but also on economy and human health. This review on marine alien species outlines aspects of prevention, eradication and control strategies. When managing invasive species, prevention is preferable and less costly than controlling species. Especially for marine environments, invasive species can disperse rapidly and can be particularly hard to detect.

Blue carbon (the carbon stored in marine and coastal ecosystems – in biomass, buried in sediments and sequestered from the atmosphere and ocean) is considered as an issue of interest regarding its potential as a climate change mitigation measure in the OSPAR maritime area (OSPAR, 2015). Because blue carbon has not yet been properly explored in the North East Atlantic, OSPAR requested the Dutch government to provide information about blue carbon in the Netherlands and opportunities to enhance blue carbon in the Netherlands.

Meer dan 15 jaar praktijkervaring met de Waterharmonica kwam aan bod tijdens een goed bezochte bijeenkomst in de Efteling. De Waterharmonica is een speciaal ingerichte verbindingszone tussen een rwzi en het oppervlaktewater, waarin het effluent een meer natuurlijk karakter krijgt. Belangrijk voor waterbeheerders, omdat de Kaderrichtlijn Water expliciet om een goede ecologische kwaliteit van het oppervlaktewater vraagt. Waterharmonicasystemen zijn de afgelopen jaren op verschillende locaties in Nederland aangelegd. Op basis van de (positieve) ervaringen zijn er momenteel meerdere in ontwikkeling. De werking van de systemen is in die jaren onderzocht met aandacht voor onder andere nutriëntenverwijdering, desinfectie, zwevend materiaal, buffercapaciteit, ecotoxicologie, beheer en onderhoud, kosten en vergunningen. Tijdens het symposium werden de laatste ontwikkelingen op dit gebied gepresenteerd en werd een veldbezoek gebracht aan het Waterharmonicasysteem van de Efteling.

Op dit moment is er onvoldoende kennis over het gedrag van glasalen rond migratieknelpunten zoals schut- en spuisluizen. Vanwege hun geringe formaat zijn glasalen met akoestische camera’s niet goed te onderscheiden van andere kleine vissen. IMARES heeft onderzocht of videotechnieken bruikbaar zijn om het gedrag van glasalen in een veldsituatie te onderzoeken. Voor dit project is een onderwater inzetbare combinatie gebouwd van een infrarood-camera en LED-infrarood belichting. Infrarood licht wordt door vissen als niet/minder storend ervaren en zal gedrag dus weinig of in het geheel niet beïnvloeden, terwijl dit met normaal licht wel het geval zal zijn. Tijdens de veldtesten bleek dat de zichtdiepte van het systeem beperkt was, zeker wanneer het water veel zwevend materiaal bevatte. Desondanks werden naast garnalen en andere kleine vissen toch duidelijk herkenbare glasalen waargenomen. Vanwege de geringe zichtdiepte zal het in de meeste gevallen niet mogelijk zijn om een individuele glasaal gedurende langere tijd te volgen om zo inzicht te krijgen in zoekgedrag rond migratieknelpunten. Het videosysteem kan wel ingezet worden om de aanwezigheid van glasaal op een specifieke plek van geringe omvang zichtbaar te maken en in de tijd te monitoren.

Schelpdiertransport vormt een van de potentiele routes waarlangs mariene invasieve soorten de Oosterschelde en de Waddenzee kunnen bereiken. In opdracht van de afdeling Team Invasieve Exoten van Bureau onderzoeksprogrammering en risicobeoordeling (BuRo) heeft IMARES een inventarisatie uitgevoerd van mariene soorten bij schelpdier gerelateerde bedrijven in Yerseke, met als doel inzicht te krijgen in het voorkomen van exoten. De soorteninventarisatie is uitgevoerd in de maanden september en oktober 2013, in de binnendijkse oesterputten en rond de buitendijkse uitlaten van de oesterputten en de schelpdier verwerkingsbedrijven aan de Korringaweg. Binnen- en buitendijks werden 20 macrofauna soorten aangetroffen die als exoot worden beschouwd.

The invention relates to environmentally friendly methods of reducing and/or preventing fouling on a surface of a component that is in contact with water. The invention further relates to a cooling system that is suited for employing the methods of the invention, and to a power plant, comprising such cooling system.

Waterschap Rivierenland (WSRL) heeft samen met Wageningen UR een verkennend onderzoek gedaan naar de aanwezigheid van microplastics in haar wateren. Er was interesse in de volgende drie vragen: 1. Waar zit het microplastic? (in bagger en/of oppervlaktewater, in landelijk of stedelijk gebied?) In welke vorm wordt het plastic aangetroffen en in welke concentraties? 2. Waar komt het plastic vandaan? (effluent, landbouw, inlaat, etc.) 3. Wat doet het plastic in het systeem / wat zijn de effecten?

On behalf of the Office of Research and Risk Assessments (BuRO) of the Netherlands Food and Consumer Product Safey Authority (NVWA), IMARES conducted a species inventory in the Oyster basins in Yerseke and the surrounding area in the Eastern Scheldt, known to be subject to shellfish related activities. This inventory that was performed in September/October 2013 revealed 21 macro invertebrate species that are regarded as alien species. Five of these are assumed not to be present in the Wadden Sea and one species was discovered there once very recently. For all six alien species an assessment was performed to define the potential risk that they will reach the Wadden Sea and affect the local native ecosystem, which is described in this report.

Uit onderzoek verricht in het voorjaar van 2013 blijkt, dat grote hoeveelheden glasaal zich concentreerden rond het lozingspunt van de rioolwaterzuivering in Den Oever. Het is mogelijk dat onder de geconcentreerde glasalen verhoogde sterfte plaatsvindt vanwege gerichte predatie. In een onderzoek van beperkte opzet werd in het voorjaar van 2014 onderzocht of de rwzi-uitlaat in Den Oever als knelpunt voor de glasaalintrek geldt. Het onderzoek werd uitgevoerd door monitoring van met kleurstof gemerkte glasalen, waarnemingen met een akoestische onderwatercamera (DIDSON) en maagonderzoek van lokaal aanwezige potentiele predator vissen.

Harbour infrastructures, civil engineering structures and offshore structures are exposed to a very aggressive maritime environment. The local corrosion mechanism bio-corrosion or microbial influenced corrosion (MIC) seems to be the life determining failure mechanism for these structures. There is a need for durable solutions to protect and maintain these structures. Different corrosion protection methods and systems are commercially available but each application requires a specific protection system. The optimal solution is not available yet

Bij calamiteiten op zee kan vrijkomende olie leiden tot ernstige ecologische effecten. De Landelijke Coördinatiecommissie Milieu (LCM) maakt bij de 24/7 advisering voor Rijkswaterstaat Zee en Delta gebruik van ecologische kwetsbaarheidskaarten bij het besluit om detergenten bij een olieverontreiniging in te zetten. De kaarten maken gebruik van verspreidingsgegevens van zeevogels en aanwezigheid van vissen (viseieren en -larven, en paaigebieden) en zijn bedoeld om direct, in het eerste uur na een olieverontreiniging, informatie te geven over wat te verwachten valt aan ecologische kwetsbaarheid op de locatie van het incident. Onderhavig rapport beschrijft de update van deze kaarten voor drijvende olie en het ontwikkelen van vergelijkbare kaarten voor gedispergeerde olie. Oil spills at sea can cause serious ecological effects. The National Coordination Committee on the Environment (LCM) uses ecological vulnerability maps in its 24/7 advice for Rijkswaterstaat Sea and Delta. These maps are used in the decision whether or not to deploy detergents. The maps use monitoring data of seabirds and fish (abundance of fish eggs and larvae and presence of spawning grounds) and are intended to provide information on the ecological vulnerability at the location of the incident. The present report describes the update of these maps for oil slicks, and the development of similar maps for dispersed oil.

Vissen die in de Noordzee zwemmen hebben, anders dan vaak gedacht, amper plastic in hun maag. Wel zijn er verschillen tussen vissoorten: de maag van kabeljauw bevat iets vaker plastic dan gemiddeld, bij makreel werd niets gevonden. Dat blijkt uit onderzoek van IMARES Wageningen UR en Wageningen University. Het onderzoek wordt binnenkort gepubliceerd in het toonaangevende tijdschrift Environmental Science and Technology.

Persistent organic pollutants (POP), with well-known representatives as polychlorinated biphenyls (PCBs), dioxins, and brominated flame retardants as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCD), are still globally present in the marine environment, This despite the substantial reduction of application and emission that was achieved during the last decades. Apart from their persistency these compounds share low water solubility and a high lipophilicity which make that the highest concentrations in the aquatic environment are found in the organic matrix of sediments and in biota. Dissolved water concentrations are low. Hence, intake of contaminated food items forms the major source for POPs exposure of aquatic organisms, and through biomagnification the highest concentrations can be found in the tissue of top predators. POPs have the potency to cause a variety of toxic effects, among which endocrine disruption and teratogenic effects that especially apply to early life stages. As the early life stages of most fish species develop suspended in the water column, exposure to POPs may be considered relatively low, at least until the larvae start feeding after yolk absorption. However, POPs accumulated in the tissue of the mother are transferred to the eggs. The research presented in this thesis aims at the determination of the impact of such maternally transferred POPs on development and survival of fish early life stages, in order to assess if this exposure route can significantly impact the development of a fish population at current environmental concentrations, especially in combination with high fishing pressure. For this purpose a bioassay was developed with the common sole (Solea solea). The advantages for this research of this new bioassay above standard fish early life stage (ELS) tests are that sole is a native West European species that as all flatfishes undergoes an obvious metamorphosis. The test set-up includes this metamorphosis that is thyroid hormone mediated and therefore expected to be easily disrupted by POPs, based on research with amphibians. The prolonged Early Life Stage test (p-ELS) with sole is presented in chapter 2. Early life stages were exposed to a concentration series of the dioxin-like PCB 126 (3,3',4,4',5-pentachlorobiphenyl) in seawater until 4, 8,10 and 15 days post fertilisation (dpf). Subsequently the development of the larvae was registered under further unexposed conditions. The LC50s at the start of the free-feeding stage (12 dpf) ranged between 39 and 83 ng PCB 126/l depending on exposure duration. After the fish had completed the metamorphosis, the LC50 values ranged between 1.7 and 3.7 ng PCB 126/l for the groups exposed for 4, 8 and 10 dpf respectively. Thus exposure for only 4 days, covering only the egg stage, was sufficient to cause adverse effects during a critical developmental phase two weeks later. This study indicates that ELS fish tests that are terminated shortly after the fish becomes free-feeding underestimate the toxic potential of compounds with low acute toxicity such as PCBs. The internal dosages of these larvae at the end of the exposure, determined by means of an in-vitro gene reporter assays as dioxin-equivalent values (TEQ), revealed an internal lethal concentration, ILC50 of 1 ng TEQ/g lipid, which is within the same order of magnitude as TEQ levels found in fish from highly polluted areas. This suggests that larval survival of fish populations at contaminated sites can be affected by persistent compounds that are accumulated by the female fish and passed on to the eggs. Based on these first results the p-ELS test procedure was improved to reach a better control performance. The exposure period was terminated when all larvae had hatched (6 dpf), this in order to mimic exposure through maternal transfer as good as possible without exposing parent fish or manipulation the eggs. In a second test (Chapter 3) the eggs were exposed to a concentration series of methyltriclosan (MTCS), a metabolite of triclosan (TCS) that is commonly used as bactericide in a wide variety of human care products. MTCS and TCS are discharged with waste water, bioaccumulate in fish tissue, and are known to have the potency to disrupt the thyroid hormone system. Mortality occurred in the higher treatment levels until 20 dpf. Indications for thyroid hormone disruption were not observed; all surviving larvae completed metamorphoses without problems. Internal effect concentrations, reached in larvae at the end of the exposure (6 dpf), were 5.8 mg/g lipid weight (lw) and 2.1 mg/g lw for ILC50 and ILC10 respectively. These internal effect concentrations are at least 200 times higher than concentrations that due to maternally transfer can be expected in the eggs of highly exposed fish in a field situation. Our results thus do not indicate a high risk from maternally transferred MTCS for fish at the current field concentrations. In order to get more insight in the fate of the POPs in the larvae, in Chapter 4 the existing bioaccumulation model OMEGA was adjusted for sole early life stages and validated with experimental data with PCBs. This study revealed, that tissue concentrations of compounds with log Kow>6, peak in the tissues of developing sole at the end of the yolk-sac stage, when lipid reserves are depleted. As a result, just before the larvae become free feeding, the peak tissue concentrations of the pollutants in the larvae exceed that of the adult fish. This also explains at least partly, the delayed effects that were observed in Chapter 2 (and 5). Chapter 5 assesses the likelihood that early life development of fish from contaminated areas is affected by maternally transferred POPs. Following the p-ELS test protocol, effects on sole larvae were determined for the dioxin-like PCB 126, the technical PCB-mixture Arochlor 1254, PBDEs and HBCDs, for an artificial mixture of PCBs and PBDEs, and for ‘field mixtures’ extracted from sole collected from the North Sea and in the contaminated Western Scheldt estuary. As was earlier observed with PCB126 and MTCS, exposure to PCBs, PBDEs and the artificial and field mixtures caused mortality that started to occur shortly after the larvae became free-feeding and continued to increase until the onset of metamorphoses. The effects induced by the field mixtures correlated well with the ∑PCB concentrations in the tissue of the exposed larvae. No indications were found for synergistic effects or for substantial contribution of other (unknown) substances in the field mixtures. HBCD did not induce toxic effects. POP levels in sole from Western Scheldt estuary are about 20 times lower than the ILC50, the larval tissue concentration that produced 50% early life stage mortality. Levels in North Sea sole are an order of a magnitude lower. Chapter 6 describes a risk assessment for toxicant induced larval survival for European eel (Anguilla anguilla). Eels are considered sensitive for the effect of POPs that can accumulate to high levels in their lipid rich tissue. During spawning migration without feeding high lipophilic dioxin-like POPs in the eel’s tissue were estimated to increase 1.33 or 2 fold, due to weight loss. As no toxicity data are available for eel larvae, the critical egg concentrations for larval survival was estimated from a sensitivity distribution based on literature data of other species. It was assumed that eel larvae belong to the 5% or 1% most sensitive teleost fish species. Given concentrations of dioxin-like pollutants as reported for European eel, and following the worst case scenarios with respect to sensitivity of the larvae and bio amplification during migration, it can be expected that larvae of eel from highly contaminated locations in The Netherlands and Belgium will experience more than 50% mortality due to maternally transferred dioxin-like toxicants. Chapter 7 explores the potential impact of (toxicant induced) early life stage mortality on the population development of sole by application of a simple age structured matrix model. The model is used to explore the population response to a combination of (toxicant induced) larval mortality and fishing-related mortality of mature fish. The results indicate that the impact of larval mortality that occurs before metamorphosis is very low, even in population subject to high fishing pressure. This is the result of the combination of a high fecundity and the fact that the larval mortality occurs before the moment when the number of recruits is limited by the carrying capacity of the nursery areas. When colonising the nursery areas the, until than pelagic sole larvae metamorphose into flatfishes with a benthic life style. The individuals hence concentrate from the three dimensional pelagic environment to a two dimensional benthic environment, which caused density dependent mortality. This concentration of early life stages is typical for flatfish. Mortality that occurs after the nursery areas are populated will have a more pronounced impact on population development. The results further imply that population development of pelagic fish species that do not concentrate in nursery areas, and species with low fecundity is more vulnerable for disturbance through mortality of early life stages. Chapter 8 synthesises and discusses the outcome of the research. It is stressed that short term fish tests, often covering only the embryonic development, will underestimate the real risk of lipophilic substances. Toxicity of these substances will peak after yolk sac absorption when these tests have already been ended. When the characteristics of the test substance are known this risk is predictable with for instance the ELS-OMEGA model. However, especially when mixtures of unknown composition (effluents, sediment extracts) are being tested one must realise that the contribution of lipophilic substances may be underestimated in test that are terminated before, or too soon after the fish larvae are free feeding. The absence of effects on metamorphosis in our P-ELS test is explained by the prediction of the ELS-OMEGA model that the POPs concentrations in the larvae, had reached too low concentrations at the moment of metamorphoses to disrupt the thyroid hormone system. This was due to passive excretion (for substances with log Kow

Om met zekerheid vast te kunnen stellen dat er geen negatieve effecten optreden op het mariene milieu n.a.v. de oever-verdediging in Ooster- en Westerschelde is door Rijkswaterstaat in 2009 een monitoringsprogramma opgezet. Vanwege kostenoverwegingen zijn monitoringsactiviteiten in 2012 ingeperkt. Wel zijn op de Zeelandbrug (Oosterschelde) mosselen (Mytilus edulis) en Japanse oesters (Crassostrea gigas) bemonsterd om inzicht te verkrijgen in gehalten aan zware metalen tweeëneenhalf tot drie jaar na het aanbrengen van de vooroeververdediging. Dit rapport beschrijft het resultaat van de verschillende toxiciteitstesten die uitgevoerd zijn in het laboratorium van IMARES Den Helder. Daarnaast worden de resultaten van de metaalanalyses in mosselen en oesters bemonsterd op de Zeelandbrug besproken waarbij ingegaan wordt op de jaarlijkse variatie in metaalconcentratie een mogelijke trend in de tijd.

Zeewaarts migrerende schieralen laten een gedragsverandering zien wanneer zij geconfronteerd worden met een lozingspluim van rwzi-effluent. Ruim de helft van de vissen verandert van zwemrichting en tracht langs de rand van de pluim te passeren. Het risico dat een permanente migratiebarrière ontstaat is bij de meeste rwzi's niet groot door het dynamische karakter van de lozingspluim. Bij rwzi's die lozen op wateren met een beperkt afvoerdebiet, kunnen wel migratiebarrières ontstaan, maar met relatief eenvoudige aanpassingen kan de kans daarop worden verkleind. De onderzoeksresultaten geven aan dat rwzi-effluentpluimen potentie hebben om te worden ingezet voor de geleiding van stroomafwaarts migrerende vissen naar een veilige route langs gevaarlijke situaties zoals koelwaterinlaten, gemalen en waterkrachtcentrales.