Articles | Volume 10, issue 3
https://doi.org/10.5194/os-10-357-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/os-10-357-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Numerical modelling of physical processes governing larval transport in the southern North Sea
M. C. H. Tiessen
Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
L. Fernard
Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK
T. Gerkema
Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
J. van der Molen
Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK
P. Ruardij
Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
H. W. van der Veer
Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
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Anna-Selma van der Kaaden, Dick van Oevelen, Christian Mohn, Karline Soetaert, Max Rietkerk, Johan van de Koppel, and Theo Gerkema
Ocean Sci., 20, 569–587, https://doi.org/10.5194/os-20-569-2024, https://doi.org/10.5194/os-20-569-2024, 2024
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Cold-water corals (CWCs) and tidal waves in the interior of the ocean have been connected in case studies. We demonstrate this connection globally using hydrodynamic simulations and a CWC database. Internal-tide generation shows a similar depth pattern with slope steepness and latitude as CWCs. Our results suggest that internal-tide generation can be a useful predictor of CWC habitat and that current CWC habitats might change following climate-change-related shoaling of internal-tide generation.
Anna-Selma van der Kaaden, Sandra R. Maier, Siluo Chen, Laurence H. De Clippele, Evert de Froe, Theo Gerkema, Johan van de Koppel, Furu Mienis, Christian Mohn, Max Rietkerk, Karline Soetaert, and Dick van Oevelen
Biogeosciences, 21, 973–992, https://doi.org/10.5194/bg-21-973-2024, https://doi.org/10.5194/bg-21-973-2024, 2024
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Combining hydrodynamic simulations and annotated videos, we separated which hydrodynamic variables that determine reef cover are engineered by cold-water corals and which are not. Around coral mounds, hydrodynamic zones seem to create a typical reef zonation, restricting corals from moving deeper (the expected response to climate warming). But non-engineered downward velocities in winter (e.g. deep winter mixing) seem more important for coral reef growth than coral engineering.
Dirk S. van Maren, Christian Maushake, Jan-Willem Mol, Daan van Keulen, Jens Jürges, Julia Vroom, Henk Schuttelaars, Theo Gerkema, Kirstin Schulz, Thomas H. Badewien, Michaela Gerriets, Andreas Engels, Andreas Wurpts, Dennis Oberrecht, Andrew J. Manning, Taylor Bailey, Lauren Ross, Volker Mohrholz, Dante M. L. Horemans, Marius Becker, Dirk Post, Charlotte Schmidt, and Petra J. T. Dankers
Earth Syst. Sci. Data, 15, 53–73, https://doi.org/10.5194/essd-15-53-2023, https://doi.org/10.5194/essd-15-53-2023, 2023
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This paper reports on the main findings of a large measurement campaign aiming to better understand how an exposed estuary (the Ems Estuary on the Dutch–German border) interacts with a tidal river (the lower Ems River). Eight simultaneously deployed ships measuring a tidal cycle and 10 moorings collecting data throughout a spring–neap tidal cycle have produced a dataset providing valuable insight into processes determining exchange of water and sediment between the two systems.
Johan van der Molen, Sjoerd Groeskamp, and Leo R. M. Maas
Ocean Sci., 18, 1805–1816, https://doi.org/10.5194/os-18-1805-2022, https://doi.org/10.5194/os-18-1805-2022, 2022
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We studied the long-term mean flow through the Marsdiep tidal inlet in the Dutch Wadden Sea. We found that this flow, which is important for sediment, salt and nutrient balances, is reversing from net outflow to inflow. We hypothesise changes in tides in the North Sea caused this, due to increased stratification in response to global warming. Hence, we expect permanent inflow conditions within 1 decade, with potential effects on the sediment balance and the ecosystem of this World Heritage Site.
Long Jiang, Theo Gerkema, Jacco C. Kromkamp, Daphne van der Wal, Pedro Manuel Carrasco De La Cruz, and Karline Soetaert
Biogeosciences, 17, 4135–4152, https://doi.org/10.5194/bg-17-4135-2020, https://doi.org/10.5194/bg-17-4135-2020, 2020
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A seaward increasing chlorophyll-a gradient is observed during the spring bloom in a Dutch tidal bay. Biophysical model runs indicate the roles of bivalve grazing and tidal import in shaping the gradient. Five common spatial phytoplankton patterns are summarized in global estuarine–coastal ecosystems: seaward increasing, seaward decreasing, concave with a chlorophyll maximum, weak spatial gradients, and irregular patterns.
Long Jiang, Theo Gerkema, Déborah Idier, Aimée B. A. Slangen, and Karline Soetaert
Ocean Sci., 16, 307–321, https://doi.org/10.5194/os-16-307-2020, https://doi.org/10.5194/os-16-307-2020, 2020
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A model downscaling approach is used to investigate the effects of sea-level rise (SLR) on local tides. Results indicate that SLR induces larger increases in tidal amplitude and stronger nonlinear tidal distortion in the bay compared to the adjacent shelf sea. SLR can also change shallow-water tidal asymmetry and influence the direction and magnitude of bed-load sediment transport. The model downscaling approach is widely applicable for local SLR projections in estuaries and coastal bays.
Thodoris Karpouzoglou, Brigitte Vlaswinkel, and Johan van der Molen
Ocean Sci., 16, 195–208, https://doi.org/10.5194/os-16-195-2020, https://doi.org/10.5194/os-16-195-2020, 2020
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Sustainable operation of floating solar platforms requires knowledge of effects on the marine ecosystem. We modelled effects on water flow and algae growth in a coastal sea. Algae growth was reduced depending on the local currents and on the density of coverage with platforms. The model represented platforms distributed evenly over areas of hundreds of square kilometres. For smaller-scale cases, effects may be smaller, and for more detailed understanding, three-dimensional models are needed.
Thomas Frederikse and Theo Gerkema
Ocean Sci., 14, 1491–1501, https://doi.org/10.5194/os-14-1491-2018, https://doi.org/10.5194/os-14-1491-2018, 2018
Johan van der Molen, Piet Ruardij, Karen Mooney, Philip Kerrison, Nessa E. O'Connor, Emma Gorman, Klaas Timmermans, Serena Wright, Maeve Kelly, Adam D. Hughes, and Elisa Capuzzo
Biogeosciences, 15, 1123–1147, https://doi.org/10.5194/bg-15-1123-2018, https://doi.org/10.5194/bg-15-1123-2018, 2018
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Macroalgae farming may provide biofuel. Modelled macroalgae production is given for four sites in UK and Dutch waters. Macroalgae growth depended on nutrient concentrations and light levels. Macroalgae carbohydrate content, important for biofuel use, was lower for high nutrient concentrations. The hypothetical large-scale farm off the UK north Norfolk coast gave high, stable yields of macroalgae from year to year with substantial carbohydrate content.
David A. Ford, Johan van der Molen, Kieran Hyder, John Bacon, Rosa Barciela, Veronique Creach, Robert McEwan, Piet Ruardij, and Rodney Forster
Biogeosciences, 14, 1419–1444, https://doi.org/10.5194/bg-14-1419-2017, https://doi.org/10.5194/bg-14-1419-2017, 2017
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This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea. These observations were used to validate two physical–biogeochemical ocean model simulations, each of which used different variants of the widely used European Regional Seas Ecosystem Model (ERSEM). The results suggest the ability of the models to reproduce the observed phytoplankton community structure was dependent on the details of the biogeochemical model parameterizations used.
Borja Aguiar-González and Theo Gerkema
Nonlin. Processes Geophys., 23, 285–305, https://doi.org/10.5194/npg-23-285-2016, https://doi.org/10.5194/npg-23-285-2016, 2016
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We derive a new two-fluid layer model consisting of forced rotation-modified Boussinesq equations for studying the limiting amplitudes of tidally generated fully nonlinear, weakly nonhydrostatic dispersive interfacial tides and solitons. Numerical solutions show that solitons attain in some cases a limiting table-shaped form, but may also be limited well below that state by saturation of the underlying quasi-linear internal tide under increasing barotropic forcing.
Johan van der Molen, Piet Ruardij, and Naomi Greenwood
Biogeosciences, 13, 2593–2609, https://doi.org/10.5194/bg-13-2593-2016, https://doi.org/10.5194/bg-13-2593-2016, 2016
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The potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth were studied using a 3-D hydrodynamics–biogeochemistry model. A realistic 800 MW scenario suggested minor effects on tides and biogeochemistry. A massive-expansion 8 GW scenario suggested effects over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, the latter through clearer waters and increased primary production with associated increases in fauna.
Momme Butenschön, James Clark, John N. Aldridge, Julian Icarus Allen, Yuri Artioli, Jeremy Blackford, Jorn Bruggeman, Pierre Cazenave, Stefano Ciavatta, Susan Kay, Gennadi Lessin, Sonja van Leeuwen, Johan van der Molen, Lee de Mora, Luca Polimene, Sevrine Sailley, Nicholas Stephens, and Ricardo Torres
Geosci. Model Dev., 9, 1293–1339, https://doi.org/10.5194/gmd-9-1293-2016, https://doi.org/10.5194/gmd-9-1293-2016, 2016
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ERSEM 15.06 is a model for marine biogeochemistry and the lower trophic levels of the marine food web. It comprises a pelagic and benthic sub-model including the microbial food web and the major biogeochemical cycles of carbon, nitrogen, phosphorus, silicate, and iron using dynamic stochiometry. Further features include modules for the carbonate system and calcification. We present full mathematical descriptions of all elements along with examples at various scales up to 3-D applications.
Bastien Y. Queste, Liam Fernand, Timothy D. Jickells, Karen J. Heywood, and Andrew J. Hind
Biogeosciences, 13, 1209–1222, https://doi.org/10.5194/bg-13-1209-2016, https://doi.org/10.5194/bg-13-1209-2016, 2016
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In stratified shelf seas, physical and biological conditions can lead to seasonal oxygen depletion when consumption exceeds supply. An ocean glider obtained a high-resolution 3-day data set of biochemical and physical properties in the central North Sea. The data revealed very high oxygen consumption rates, far exceeding previously reported rates. A consumption–supply oxygen budget indicates a localized or short-lived resuspension event causing rapid remineralization of benthic organic matter.
J. van der Molen, J. van Beek, S. Augustine, L. Vansteenbrugge, L. van Walraven, V. Langenberg, H. W. van der Veer, K. Hostens, S. Pitois, and J. Robbens
Ocean Sci., 11, 405–424, https://doi.org/10.5194/os-11-405-2015, https://doi.org/10.5194/os-11-405-2015, 2015
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The reproduction, survival, and transport of the comb jelly Mnemiopsis leidyi was studied with three models in the Scheldt estuaries and the southern North Sea. The results suggest that (a) the estuaries can retain an overwintering population and seed offshore populations; (b) M. leidyi can survive in the North Sea, and be transported between coastal inlets; and (c) M. leidyi cannot reproduce well in the North Sea, but this might change with global warming. The models need further improvement.
M. Duran-Matute, T. Gerkema, G. J. de Boer, J. J. Nauw, and U. Gräwe
Ocean Sci., 10, 611–632, https://doi.org/10.5194/os-10-611-2014, https://doi.org/10.5194/os-10-611-2014, 2014
Related subject area
Approach: Numerical Models | Depth range: All Depths | Geographical range: Shelf Seas | Phenomena: Current Field
Investigating the relationship between volume transport and sea surface height in a numerical ocean model
The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation
Deep ocean exchange with west-European shelf seas
Evaluating two numerical advection schemes in HYCOM for eddy-resolving modelling of the Agulhas Current
Estee Ann Vermeulen, Björn Backeberg, Juliet Hermes, and Shane Elipot
Ocean Sci., 15, 513–526, https://doi.org/10.5194/os-15-513-2019, https://doi.org/10.5194/os-15-513-2019, 2019
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This modelling study aimed to recreate the Agulhas Current transport proxy within a regional HYCOM simulation of the Agulhas Current system, attempting to test the validity of the underlying assumptions on which the satellite-altimeter proxy was based. Results showed that the proxy is sensitive to subsurface variability in the model but that the proxy remained robust regarding the time periods needed to build a sufficient linear relationship between transport and sea surface height slope.
R. P. Matano, E. D. Palma, and A. R. Piola
Ocean Sci., 6, 983–995, https://doi.org/10.5194/os-6-983-2010, https://doi.org/10.5194/os-6-983-2010, 2010
J. M. Huthnance, J. T. Holt, and S. L. Wakelin
Ocean Sci., 5, 621–634, https://doi.org/10.5194/os-5-621-2009, https://doi.org/10.5194/os-5-621-2009, 2009
B. C. Backeberg, L. Bertino, and J. A. Johannessen
Ocean Sci., 5, 173–190, https://doi.org/10.5194/os-5-173-2009, https://doi.org/10.5194/os-5-173-2009, 2009
Cited articles
Aldridge, J., van der Molen, J., and Forster, R.: Wider ecological implications of Macroalgae cultivation, ISBN: 978-1-906410-38-4, 95 pp., The Crown Estate, Lowestoft, UK 2012.
Bergman, M. J. N., Veer, H. W., and Zulstra, J. J.: Plaice nurseries: effects on recruitment, J. Fish Biol., 33, 201–218, 1988.
Boero, F., Bouillon, J., and Gravili, C.: The life cycle of Hydrichthys mirus (Cnidaria: Hydrozoa: Anthomedusae: Pandeidae), Zool. J. Linn. Soc., 101, 189–199, 1991.
Bolle, L. J., Dickey-Collas, M., van Beek, J. K. L., Erftemeijer, P. L. A., Witte, J. I. J., van der Veer, H. W., and Rijnsdorp, A.: Variability in transport of fish eggs and larvae. III. Effects of hydrodynamics and larval behaviour on recruitment in plaice, Mar. Ecol. Prog. Ser., 390, 195–211, 2009.
Borley, J. O.: Report on the Experimental Transplantation of Plaice to the Dogger Bank Carried Out by the Marine Biological Association in the Years 1904–8, 79 pp. Lowestoft Laboratories, Lowestoft, UK, 1919.
Burchard, H. and Bolding, K.: GETM – A general estuarine transport model, Scientific documentation (Technical report No. EUR 20253 EN), European Commission, 2002.
Coombs, S. H., Nichols, J. H., and Fosh, C. A.: Plaice eggs (Pleuronectes platessa L.) in the southern North Sea: abundance, spawning area, vertical distribution, and buoyancy, J. du Cons., 47, 133–139, 1990.
Creutzberg, F., Eltink, A. T. G. W., and van Noort, G. J.: The migration of plaice larvae Pleuronectes platessa into the western Wadden Sea, in: Proc. 12th Europ. Mar. Biol. Symp. Presented at the Physiology and behaviour of marine organisms, edited by: McLusky, D. S. and Berry, A. J., Pergamon Press, New York, 243–251, 1978.
Dale, B.: Dinoflagellate cysr analysis of upper quaternary sediments in core GIK-15530-4 from the Skagerrak, Nor. Geol. Tidsskr., 65, 97–102, 1985.
De Graaf, M., Jager, Z., Vreugdenhil, C. B., and Elorche, M.: Numerical simulations of tidally cued vertical migrations of flatfish larvae in the North Sea, Estuar. Coast. Shelf S., 59, 295–305, 2004.
Dickey-Collas, M., Bolle, L. J., van Beek, J. K. L., and Erftemeijer, P. L. A.: Variability in transport of fish eggs and larvae. II. Effects of hydrodynamics on the transport of Downs herring larvae, Mar. Ecol. Prog. Ser., 390, 183–194, 2009.
Fox, C. J., Mccloghrie, P., Young, E. F., and Nash, R. D. M.: The importance of individual behaviour for successful settlement of juvenile plaice (Pleuronectes platessa L.): a modelling and field study in the eastern Irish Sea, Fish. Ocean., 15, 301–313, 2006.
Fox, C. J., McCloghrie, P., and Nash, R. D. M.: Potential transport of plaice eggs and larvae between two apparently self-contained populations in the Irish Sea, Estuar. Coast. Shelf S., 81, 381–389, 2009.
Gräwe, U. and Burchard, H.: Storm surges in the Western Baltic Sea: the present and a possible future, Clim. Dynam., 39, 165–183, 2011.
Harding, D., Nichols, J. H., and Tungate, D. S.: The spawning of plaice (Pleuronectes platessa) in the southern North Sea and English Channel, Rapp. Procès Verbaux Réunions Cons. Int. Pour Explor. Mer, 172, 102–113, 1978.
Hufnagl, M., Peck, M. A., Nash, R. D. M., Pohlmann, T., and Rijnsdorp, A. D.: Changes in potential North Sea spawning grounds of plaice (Pleuronectes platessa L.) based on early life stage connectivity to nursery habitats, J. Sea Res., 84, 26–39, 2013.
Hunter, J. R., Craig, P. D., and Philips, H. E.: On the use of random walk models with spatially variable diffusivity, J. Comput. Phys., 106, 366–376, 1993.
Janssen, F., Schrum, C., and Backhaus, J. O.: A climatological data set of temperature and salinity for the Baltic Sea and the North Sea, Dtsch. Hydrogr. Z., 51, 5–245, 1999.
Lacroix, G., Maes, G. E., Bolle, L. J., and Volckaert, F. A. M.: Modelling dispersal dynamics of the early life stages of a marine flatfish (Solea solea L.), J. Sea Res., 84, 13–25, 2013.
Leggett, W. C. and Deblois, E.: Recruitment in marine fishes: Is it regulated by starvation and predation in the egg and larval stages?, Neth. J. Sea Res., 32, 119–134, 1994.
Lenhart, H.-J., Mills, D. K., Baretta-Bekker, H., van Leeuwen, S. M., van der Molen, J., Baretta, J. W., Blaas, M., Desmit, X., Kühn, W., Lacroix, G., Los, H. J., Ménesguen, A., Neves, R., Proctor, R., Ruardij, P., Skogen, M. D., Vanhoutte-Brunier, A., Villars, M. T., and Wakelin, S. L.: Predicting the consequences of nutrient reduction on the eutrophication status of the North Sea, J. Mar. Syst., 81, 148–170, 2010.
Loots, C., Vaz, S., Koubbi, P., Planque, B., Coppin, F., and Verin, Y.: Inter-annual variability of North Sea plaice spawning habitat, J. Sea Res., 64, 427–435, 2010a.
Loots, C., Vaz, S., Koubbi, P., Planque, B., and Koubbi, P.: Spawning distribution of North Sea plaice and whiting from 1980 to 2007, J. Oceanogr., Research and Data, 3, 77–95, 2010b.
Niiler, P. P., Sybrandy, A. S., Bi, K., Poulain, P. M., and Bitterman, D.: Measurements of the water following capacity of holeysock and tristar drifters, Deep Sea Res., 42, 1951–1964, 1995.
Otto, L., Zimmerman, J. T. F., Furnes, G. K., Mork, M., Saetre, R., and Becker, G.: Review of the physical oceanography of the North Sea, Neth. J. Sea Res., 26, 161–238, 1990.
Rijnsdorp, A. D., van Stralen, M., and van der Veer, H. W.: Selective Tidal Transport of North Sea Plaice Larvae Pleuronectes platessa in Coastal Nursery Areas, T. Am. Fish. Soc., 114, 461–470, 1985.
Rochette, S., Huret, M., Rivot, E., and Le Pape, O.: Coupling hydrodynamic and individual-based models to simulate long-term larval supply to coastal nursery areas, Fish. Oceanogr., 21, 229–242, https://doi.org/10.1111/j.1365-2419.2012.00621.x, 2012.
Ruardij, P., Veldhuis, M. J. W., and Brussaard, C. P. D.: Modeling the bloom dynamics of the polymorphic phytoplankter Phaeocystis globosa: impact of grazers and viruses, Harmful Algae, 4, 941–963, 2005.
Savina, M., Lacroix, G., and Ruddick, K.: Modelling the transport of common sole larvae in the southern North Sea: Influence of hydrodynamics and larval vertical movements, J. Mar. Syst., 81, 86–98, 2010.
Sinclair, M.: Marine populations: an essay on population regulation and speciation, Books in recruitment fishery oceanography, Washington Sea Grant Program?: Distributed by University of Washington Press, Seattle [Wash.], 1988.
Sündermann, J. and Pohlmann, T.: A brief analysis of North Sea physics, Oceanologia, 53, 663–689, 2011.
Talbot, J. W.: The dispersal of plaice eggs and larvae in the Southern Bight of the North Sea, J. Cons., 37, 221–248, 1977.
Taylor, N., Fox, C. J., Bolle, L., Dickey-Collas, M., Fossum, P., Kraus, G., Munk, P., Rolf, N., van Damme, C., Vorbach, M., Taylor, N., Fox, C. J., Bolle, L., Dickey-Collas, M., Fossum, P., Kraus, G., Munk, P., Rolf, N., van Damme, C., and Vorbach, M.: Results of the Spring 2004 North Sea Ichthyoplankton Surveys. The distribution of fish eggs and larvae from the International Ichthyoplankton Survey, 2007.
Thorson, G.: Some factors influencing the recruitment and establishment of marine benthic communities, Neth. J. Sea Res., 3, 267–293, 1966.
Van der Molen, J., Rogers, S. I., Ellis, J. R., Fox, C. J., and McCloghrie, P.: Dispersal patterns of the eggs and larvae of spring-spawning fish in the Irish Sea, UK, J. Sea Res., 58, 313–330, 2007.
Van der Veer, H. W.: Immigration, settlement and dependent mortality of a larval and early post-larval 0-group plaice (Pleuronectes platessa) population in the western Dutch Wadden Sea, Mar. Ecol. Prog. Ser., 29, 223–236, 1986.
Van der Veer, H. W. and Leggett, W. C.: Recruitment, in: Flatfishes, edited by: Gibson, R. N., Blackwell Science Ltd, Oxford, UK, 120–137, 2005.
Van der Veer, H. W. and Witte, J. I. J.: Year-class strength of plaice Pleuronectes platessa in the Southern Bight of the North Sea:a validation and analysis of the inverse relationship with winter seawater temperature, Mar. Ecol. Prog. Ser., 184, 245–257, 1999.
Van der Veer, H. W., Ruardij, P., Van den Berg, A. J., and Ridderinkhof, H.: Impact of interannual variability in hydrodynamic circulation on egg and larval transport of plaice Pleuronectes platessa L. in the southern North Sea, J. Sea Res., 39, 29–40, 1998.
Van der Veer, H. W., Geffen, A. J., and Witte, J. I. J.: Exceptionally strong year classes in plaice Pleuronectes platessa:are they generated during the pelagic stage only, or also in the juvenile stage?, Mar. Ecol. Prog. Ser., 199, 255–262, 2000.
Van der Veer, H. W., Bolle, L. J., Geffen, A. J., and Witte, J. I. J.: Variability in transport of fish eggs and larvae. IV. Interannual variability in larval stage duration of immigrating plaice in the Dutch Wadden Sea, Mar. Ecol. Prog. Ser., 390, 213–223, 2009.
Van Leeuwen, S. M., van der Molen, J., Ruardij, P., Fernand, L., and Jickells, T.: Modelling the contribution of deep chlorophyll maxima to annual primary production in the North Sea, Biogeochemistry, 113, 137–152, 2012.
Wolk, F.: Three-dimensional Lagrangian Tracer Modelling in Wadden Sea Areas (Diploma thesis), Carl von Ossietzky University, Oldenburg, 2003.
Zijlstra, J. J.: On the importance of the Waddensea as a nursery area in relation to the conservation of the southern North Sea fishery resources, Symp. Zool. Soc. Lond., 19, 233–258, 1972.