Recent changes in the contributions of river Rhine and North Sea to the eutrophication of the western Dutch Wadden Sea

Jonge, Victor N. de; Bakker, Joop F.; Stralen, Marnix van

doi:10.1007/bf02092145

Cited by 61 publications

(27 citation statements)

References 23 publications

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“…Hawkins et al (1996) found that mussels are able to cope with high silt concentrations and can adapt to short-term changes in silt-related food quality, by altering their feeding behaviour (Bayne 1998, Hawkins et al 1998). This adaptability was demonstrated for a range of SPM levels (10−90 mg l −1 ) that is very similar to the natural range reported for the Marsdiep area in the Wadden Sea (De Jonge et al 1996). Although mussel populations can persist under these conditions, inorganic matter reduces food quality and thus mussel growth rates in shellfish production (Newell et al 1998, Scholten & Smaal 1999.…”

Section: Factors That Determine Mussel Survival On Natural Mussel Bedsupporting

confidence: 71%

Population dynamics of subtidal blue mussels Mytilus edulis and the impact of cultivation

Stralen¹,

Wijsman²,

Herman³

et al. 2017

Aquacult. Environ. Interact.

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Fishery on subtidal mussel beds and subsequent relying on culture plots in the same system is a common practice in bottom mussel culture. We address factors that determine the population dynamics of subtidal blue mussels Mytilus edulis L. and to what extent total (natural plus cultured) subtidal mussel biomass in the system is affected by fishery practices. Mussel size and density of spatially segregated natural and cultured subtidal mussel populations in the western Wadden Sea were measured over time in 2 field studies. Spatial patterns in survival rates showed better spat survival in areas with lower salinity and lower density of sea stars Asterias rubens. This suggests that mussel survival is negatively related to sea star distribution which is to a large extent controlled by salinity. The Asterias−Mytilus relation in the Wadden Sea is an example of the concept that environmental stress determines the successes of the prey by affecting the prey− predator relationship. Natural beds that escape predation are found at lower salinities, and mussels on these beds showed low growth rates, also because of lower food quality in these areas. Mussel culture is strongly affecting the population dynamics of the subtidal mussel population, through relay of mussels from natural mussel beds to culture plots. This activity increases mussel growth and survival, because food quality on culture plots is high and predation is controlled. Despite harvesting, mussel biomass production on culture plots was higher than on natural mussel beds, enhancing total subtidal mussel stock.

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Section: Factors That Determine Mussel Survival On Natural Mussel Bedsupporting

confidence: 71%

Population dynamics of subtidal blue mussels Mytilus edulis and the impact of cultivation

Stralen¹,

Wijsman²,

Herman³

et al. 2017

Aquacult. Environ. Interact.

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show abstract

“…This situation is aggravated in the Wadden Sea where not only local primary production but also the import of primary produced organic matter from off-shore areas outside the Wadden Sea proper determines the eutrophication status (van Beusekom and de Jonge 2002). Nitrite and ammonium values during autumn and chlorophyll levels during summer may be better eutrophication indicators as they show good correlations with riverine TN discharge (van Beusekom et al 2001(van Beusekom et al , 2005a The difficulty in identifying a decreasing trend in winterly nitrate concentrations contrasts with a clear decrease in phosphate concentrations in the Wadden Sea that was already observed during the 1990s (de Jonge et al 1996;Cadée and Hegeman 1993). The reason for this discrepancy may be two-fold.…”

Section: Implications For Coastal Management and Monitoringmentioning

confidence: 98%

Long-term variability of winter nitrate concentrations in the Northern Wadden Sea driven by freshwater discharge, decreasing riverine loads and denitrification

2007

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The hypothesis of a recent reversal in the eutrophication of the Wadden Sea and the potential of inshore waters in denitrification is explored. Salinity, temperature and nitrate concentrations in the List Tidal Basin (Northern Wadden Sea) have been measured about twice weekly since 1984. Salinity has a clear seasonal cycle with lowest salinities of about 27 in late winter and highest salinities of about 31 in summer. Mean annual deviations from the long-term mean salinity correlate significantly with riverine freshwater discharge. Winter nitrate concentrations are generally high (about 50 lM on average). The major part of the variability is related to salinity (*35%). Temperature had a minor impact (*1%). Superimposed on this, a long-term decrease of about 1 lM per year was found. Together, these processes account for about 45% of the nitrate variability. The long-term decrease of about 2% per year is similar to continental riverine trend in total nitrogen loads. In contrast to the List Tidal Basin, salinity explained more than 90% of nitrate variability in the off-shore German Bight. Salinity (30) normalised winter nitrate data of the German Bight also show a long-term decreasing trend. Most of the List Tidal Basin data are either on or below the nitrate-salinity relation found in the German Bight. This observation suggests that denitrification has a major impact on the winter nitrate concentrations in the Northern Wadden Sea compared to the German Bight. It is hypothesised that a large part of the unexplained variability is related to weather-dependent changes in residence time of tidal water masses in the Wadden Sea and circulation patterns within the German Bight.

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“…Although Chl-a concentrations and primary production have been subject to much research in the Wadden Sea for a long time (Cadée and Hegeman 2002;De Jonge et al 1996;Cadée 1986, Postma 1954, the system remains complex and is still not completely understood. Top-down control by predators for example makes the response of phytoplankton to nutrient reduction unpredictable (Philippart et al 2007).…”

Section: ¡1mentioning

confidence: 99%

A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

et al. 2010

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The interpretation of optical remote sensing data of estuaries and tidal Xat areas is hampered by optical complexity and often extreme turbidity. Extremely high concentrations of suspended matter, chlorophyll and dissolved organic matter, local diVerences, seasonal and tidal variations and resuspension are important factors inXuencing the optical properties in such areas. This review gives an overview of the processes in estuaries and tidal Xat areas and the implications of these for remote sensing in such areas, using the Wadden Sea as a case study area. Results show that remote sensing research in extremely turbid estuaries and tidal areas is possible. However, this requires sensors with a large ground resolution, algorithms tuned for high concentrations of various substances and the local speciWc optical properties of these substances, a simultaneous detection of water colour and land-water boundaries, a very short time lag between acquisition of remote sensing and in situ data used for validation and suYcient geophysical and ecological knowledge of the area.

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Recent changes in the contributions of river Rhine and North Sea to the eutrophication of the western Dutch Wadden Sea

Cited by 61 publications

References 23 publications

Population dynamics of subtidal blue mussels Mytilus edulis and the impact of cultivation

Population dynamics of subtidal blue mussels Mytilus edulis and the impact of cultivation

Long-term variability of winter nitrate concentrations in the Northern Wadden Sea driven by freshwater discharge, decreasing riverine loads and denitrification

A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

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