Rob Witbaard
	Publications

 

Dr. Rob Witbaard
Researcher Marine Ecology		(North Sea) Benthic ecology   Shell growth   Sclerochronology   Arctica islandica                   Distribution             Effects fishing             Age and size             variation   Callianassa subterranea              Distribution NSea
Witbaard@nioz.nl +31(0)222-369537 +31(0)222-319674
Visiting address:	Postal address:	Research Interests Projects Links Publications
Landsdiep 4 NL-1797 SZ 't Horntje (Texel) The Netherlands   Tel. (+31) (0)222-369300 Fax: (+31) (0)222-319674	P.O. Box 59, NL-1790 AB Den Burg The Netherlands

 

Research Interests	Top ^
I was trained as a limnologist but became involved in research at the open North Sea. Up to now I worked on the ecology of benthic communities of coastal and off-shore, sub-tidal areas of the North Sea as well as on benthic communities at full oceanic depths. The emphasis of this work lies mainly on processes which structure benthic communities with the attention on processes of growth in relation to foodsupply. Interests range from bioturbation to community metabolism, population dynamics and shell growth and longevity of bivalves. Latter study initially focused on the ocean quahog, Arctica islandica. This work resulted in the defence of a PhD thesis  at the University of Groningen entitled “Tree of the sea”. Presently studies focus on the effect of resuspended material on the behaviour and performance of bivalve molluscs.

 

Projects

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CLIVAR Climate variability. Reconstruction of climatic variability on decadal scales on bases of the interannual variations in shell growth of Arctica islandica.   PROCS Processes at continental slopes Study to the fauna distribution along a depth gradient in the Faroer Shetland Channel and its possible relation with sediment resuspension by internal waves.   BENGAL Study on the seasonal input of fresh organic material to the benthic community at a 4800 m Deep abyssal site in the North Atlantic.   FROGS  Frogs: Frontal Organic Matter Governing Benthic Ecosystem Structures (New Zealand) NIWA-NIOZ cooperative research program on supply of phytodetritus along a depth gradient in New Zealand waters.     CurrentProjects                                                                                 ^Top   BSIK A6 / Senternovem The aim of this project is to get insight in how climate change might effect the performance growth and production of filter feeding bivalves in the coastal zone. The other part of the project focuses on the effect of climate change on the spatial distribution of  macrobenthic species in the context in spatial planning within the North Sea.   CASSIOPEIA. This is a national funded project under the umbrella of the European Science foundation (ESF). The aim of the project is to explore the possibilities of using the calcium isotope system within bivalves for environmental temperature reconstructions.   Building with Nature / Ecoshape . A consortium of institutes and commercial dredging companies cooperate to study the biological effects of near shore beach nourishments along the Dutch coast. Coming years the project will deal with effects of increased Suspended Particulate Matter (SPM) levels due to resuspension of bottom material on production and behavior of important near shore bivalves.   RWS-Ensis monitor. A pilot project to explore the effects of SPM on filtration rate of Ensis directus. This project is linked to Building with nature and ecoshape

 

Callianassa subterranea from the Frisian front.	Top ^
Burrows and entrances of callianassa in the Oystergrounds.   The Frisian Front area, north the Dutch barrier islands is a frontal area with a transition between the permanently mixed waters in the south and the summer stratified waters in the central Oyster grounds.. In the area increased primary production and a the strong environmental gradients (sediments, waterdepths) are reflected in the benthic community. In the silty, deeper areas north of 30 m depth contour several species of burrowing shrimps can be found. Most abundant is Callianassa subterranea. A full grown shrimp has a maximum size of approximately 4 cm. In the Frisian Front area, densities of 60 to over 100 / m² have been reported. The shrimps make extensive burrows underneath the sediment surface. A burrow consists of several vertical shafts and a living level with small chambers. In these chambers the animals can turn around since the connecting burrow parts are only a little wider than the animal in cross section. The biggest shrimps may burrow as deep as 60 cm deep. Smaller shrimps burrow less deep. So different sized animals live at different depths which make it possible that densities are so high. In quiet weather conditions the bottom surface is completely covered with small vulcano shaped mounts. In winter these mounts may disappear by the wave action which  flattens the seabed.     Density of Callianassa subterranea in the top 20 cm of the sediment at the Dutch continental shelf.   Each shrimp makes a separate burrow and each burrow has 1 or 2 exhalent openings and several inhalent openings (see photographs). The effect of all this burrowing is significant. Per square meter bottom surface many kilograms of sediment per year is expelled and reworked. As a result of the constant reworking of bottom sediments large amounts of fresh organic carbon become buried. The burrow walls cause at least a 1.5 fold increase of the water bottom interface. Together with the volume of sea water which is flushed through the burrows to keep oxygen levels high enough for survival, the burrows are important sites for nutrient exchange between bottom and water. In the burrows concentrations of major nutrients are indeed elevated. This implies that the shrimp community my play an important role in the nutrient regeneration in the area.

 

 

 

Arctica islandica	Top ^
Distribution	Top ^
At NIOZ the research on Arctica Islandica started with studying the occurrence, growth and population dynamics of Arctica islandica in the North Sea. Arctica islandica is a rather large bivalve mollusc occurring in the boreal shelf seas of the Atlantic Ocean.       Map of the northern Hemisphere centred around greenland, In blue the areas where Arctica can be found.   In the North Sea the species has a scattered distribution. In the shallow sandy coastal sector it has never been collected alive. North of the 30 meter depth contour it can be found virtually everywhere, although in low to very low densities. Densities in the Oyster Grounds and Frisian Front area are less then 1 individual / 10 m². This is low compared to the northern North Sea ( 30-300 m²) or the Baltic with 150 ind/m².       Although Arctica islandica is most often found in silty sediments it has been reported from sand to gravel sediments as well. Actually, shells collected from coarse sediments are often more robust and heavier and appear to grow faster.
Maximum reported age for this species is between 400 and  405 years for a specimen collected east of Iceland by the Bangor research group. . In the North Sea we have found a specimen of 167 years old. Because of its high longevity it is the ideal species to be used in studies which aim to reconstruct past environmental conditions. Arctica islandica has growth lines which are clear and well defined. So it can be used in a way similar to tree-rings.  Nowadays there are several labs who specialise in reconstructing past environments on basis of the growth lines of Arctica. (see below)  But other long lived shell species are  being used as well.
Genetic and morphological variation                                      ^Top
Both morphologically and genetically differences can be detected between Arctica islandica from different sub-areas. While the differences in shape can be the result of phenotypic plasticity, genetic studies suggest the existence of genetic differences as well, even within the North Sea (Holmes et al, 2003).
A dendrogram showing the genetic separation of geographically separated populations.
Age and Size distribution in the North Sea                          ^Top
In the south eastern part of the North Sea the population is dominated by full grown specimens, with shell heights normally over 50 mm.  Spat (~1mm) is regularly found but apparently are not able to survive. In the northern North Sea (Fladen Grounds) but also other areas, high densities of juvenile specimens (<50 mm) can be found.  In the Balthic sea the population is also dominated by juvenile specimens.
Bottom fisheries and Arctica islandica                                ^Top
Broken shells as by catch in a commercial trawl.   In the south eastern North Sea Arctica islandica heavily suffers from beam trawling. Studies have demonstrated that about 80 % of the by-catch of a (commercial) trawl is damaged. Most injuries are found on the posterior shell margin which is the area of the shell which is positioned at the sediment water interface. Tickler change in front of the net, which are  meant to  disturb bottom dwelling (flat)fish, cause the  damage to the shells. In the picture below the division of shell portions and the occurrence of injuries on the respective parts is depicted.         Schematic drawing how Arctica lives in the bottom. On the right side a pie diagram depicts the % of damage in corresponding shell part.   Other species are regularly found with scars as well.              Examples of injuries most likely caused by trawl passage, From left to right. Arctica islandica, Acanthocardia echinatum, Chlamys opercularis.   Often the injuries are so severe that  survival is unlikely. Some individuals however manage to repair the damage. In some shells the damage results in embedded sand-mud within the carbonate matrix. By counting the internal growth lines the year in which the damage was inflicted can be dated. Most shells from the SE north sea have more than one scar. It appeared that the frequency of scars increased with the increased fishing effort (with time) of the Dutch beam trawl fleet. A strong suggestion that both observations are linked to each other.       Drawing of a valve cross-section of Arctica islandica. Three years before it died sand was pushed in between the shell and the mantle tissue. The shell enclosed it by growing over it.     A Lesley matrix population model suggests that, if fishing mortality remains at today's level and no massive successful recruitment takes place before, the species will be virtually extinct (<1ind/10000m²) from the Frisian Front part of the Dutch continental sector of the North Sea shelf  by 2017.
Shellgrowth & Longevity Top ^
Under the seasonal influence of temperature and the availability of food, bivalves in the temperate climatic zone grow periodically. With that, they form internal growth lines similar to the growth rings in trees. These rings are often visible on the outside of a shell but in species which grow very old, it might be difficult to count the lines on the outside. To age such old shells, the growth lines in cross sections can be visualised by grinding and polishing shell cross sections and by application of the acetate peel method.
Annual internal growthlines a valve cross section of Arctica islandica
From shell size measurements and ring counts, ages and growth rates can be estimated. Many species grow much older than we expect. Because of its high longevity Arctica islandica is the ideal species to be used in studies which aim to reconstruct past environmental conditions. Arctica islandica has growth lines which are clear and well defined. So it can be used in a way similar to tree-rings.  Nowadays there are several labs who specialise in reconstructing past environments on basis of the growth lines of Arctica.  But other long lived shell species are  being used as well.
Example of bivalve species from the North Sea with maximum ages found so far.
Links                                                                                     ^Top
http://www.sos.bangor.ac.uk/research/php/theme.php?project=355 http://www.increments.de/

 

 

 

Publications                                                                         ^Top

Witbaard, R. and Duineveld, G. C. A. (1989). Some aspects of the biology and ecology of the burrowing shrimp Callianassa subterranea (Montagu) (Thalassinidea) from the southern North Sea. Sarsia  74: 209-219. Witbaard, R. and Duineveld, G. C. A. (1990). Shell growth of the bivalve Arctica islandica (L.) and its possible use for evaluating the status of the benthos in the subtidal North Sea. Basteria 54, 63-74. Witbaard, R. and Klein, R. (1993). A method to estimate the bottom trawl intensity independently fom fisheries itself by using internal mollucan growth lines. ICES  C. M. 1993/K:16 , 8pp. Witbaard, R. and Klein, R. (1994). Long-term trends on the effects of the southern North Sea beamtrawl fishery on the bivalve mollusc Arctica islandica L. (Mollusca, bivalvia). ICES J. mar. Sci. 51, 99-105. Witbaard, R., Jenness, M. I., Borg, K. v. d. and Ganssen, G. (1994). Verification of annual growth increments in Arctica islandica L. from the North Sea by means of oxygen and carbon isotopes. Netherlands Journal of Sea Research 33, 91-101. Witbaard, R. (1996). Growth variation in Arctica islandica L. (Mollusca): a reflection of hydrography-related food supply. ICES journal of Marine Science 53, 891-987. Witbaard, R., Franken, R. and Visser, B. (1997). Growth of juvenile Arctica islandica under experimental conditions. Helgolander meeresuntersuchungen 51, 417-431. Witbaard, R., Duineveld, G. C. A. and Wilde, P. A. W. J. d. (1997). A  long-term growth record derived from Arctica islandica (Mollusca, Bivalvia) from the Fladen Ground (northern North Sea). Journal of the Marine Biological association of the United Kingdom. 77, 801-816. Witbaard, R., Duineveld, G. C. A. and Wilde, P. A. W. J. d. (1999). Geographic differences in growth rates of Arctica islandica (mollusca: Bivalvia) from the North Sea and Adjacent  waters. Journal of the Marine Biological Association of the United Kingdom 79, 907-915. Weber, A., Witbaard, R. and Steenpaal, S. (2000). Patterns of Growth and undetectable Growth lines of Astarte sulcata (Bivalvia) in the Faroe-Shetland Channel. Senckenberg maritima 31, 235-244. Witbaard, R., Duineveld, G. C. A., Weele, J. A., Berghuis, E. M. and Reyss, J. P. (2000). The benthic response to the seasonal deposition of phytopigments at the Porcupine Abyssal Plain in the North East Atlantic. Journal of Sea Research 43, 15-31. Rabouille, C., Witbaard, R. and Duineveld, G. C. A. (2001). Annual and interannual variability of sedimentary recycling studied with a non-steady-state model: application to the North Atlantic Ocean (Bengal Site). Progress in Oceanography 50, 147-170. Ragueneau, O., Gallinari, M., Corrin, L., Grandel, S., Hall, P., Hauvespre, A., Lampitt, R. S., Rickert, D., Stahl, H., Tengberg, A. and Witbaard, R. (2001). The bentic silica cycle in the Northeast Atlantic: a;nnual mass balance, seasonality, and importance of non-steady-stat processes for the early diagenesis of biogenic opal in deep-sea sediments. Progress in Oceanography 50, 171-200. Witbaard, R., Duineveld, G. C. A. and Bergman, M. (2001). The effect of tidal resuspension on benthic food quality in the southern North Sea. Senckenbergiana marit., 31 (2): 31, 225-234. Witbaard, R., Duineveld, G. C. A., Kok, A., Weele, J. v. d. and Berghuis, E. M. (2001). The response of Oneirophanta mutabilis (Holothuroidea) to the seasonal deposition of phytopigments at the Porcupine Abyssal Plain in the Northeast Atlantic. Progress in Oceanography 50, 423-441. Holmes, S. P., Witbaard, R. and Meer, J. v. d. (2003). Phenotypic and genotypic population differentiation in the bivalve mollusc Arctica islandica (L.): results from RAPD analysis. Marine Ecology Progress Series 254, 163-176. Amaro, T., Duineveld, G., Bergman, M. and Witbaard, R. (2003). Growth variations in the bivalve Mya truncata: a tool to trace changes in the Frisian Front macrofauna (southern North Sea)? Helgoland Marine Research 57, 132-138. Witbaard, R. and Bergman, M. (2003). The distribution of Arctica islandica in the North Sea. What possible factors are involved?Journal of sea research 50; 11-25. Witbaard, R., Jansma, E. and Sass-Klaassen, U. (2003). Copepods link quahog growth to climate. Journal of Sea Research 50, 77-83. Witbaard, R. Daan, R. and Mulder, M., 2005. The mollusc fauna along a depth transect in the Faroe Shetland Channel; is there a relation with internal waves? Marine Biology Research, 1: 186-201. Witbaard R, Duineveld G.C.A., Amaro T., Bergman M.J.N.,2005 Growth trends in three bivalve species indicate climate forcing on the benthic ecosystem in the southeastern North Sea Climate Research 30:29-38 Epple, V.M. Brey, T. Witbaard, R. Kuhnert, H. Patzold, J. Sclerochronological records of Arctica islandica from the inner German Bight.” the Holocene 16(5): 763-769. Nodder, S.D, G.C.A. Duineveld, C.A. Pilditch, P.J. Sutton, P. Probert, M.S.S. Lavaleye, R.Witbaard, F.H. Chang, J.A. Hall, K.M. Richardson, 2007. Focusing of phytodetritus deposition beneath a deep-ocean front, Chatham Rise. Limnol. Oceanogr., 52(1), 299–314 Amaro, T.P.F.,  G.C.A. Duineveld, M.J.N. Bergman, R.Witbaard, 2007. The consequences of changes in abundance of Callianassa subterranea and Amphiura filiformis on sediment erosion at the Frisian Front (south-eastern North Sea). Hydrobiologia  589:273–285. Klünder, M.H., D. Hippler, R. Witbaard, D. Frei, 2008. Laser ablation analyses of bivalve shells- Archives of environmental information. Geological survey of Denmark and Greenland Bulletin, 15, 89-92. Hippler D., D. Buhl, R. Witbaard, D.K.  Richter, A. Immenhauser, 2009. Towards a better understanding of magnesium-isotope ratios from marine skeletal carbonates. Geochimica et Cosmochimica Acta, 73: 6134-6146. Butler, P. G., C. A. Richardson, J. D. Scourse, R. Witbaard, B. R. Schöne, N. M. Fraser, A. D. Wanamaker Jr., C. L. Bryant, I. Harris, and I. Robertson (2009), Accurate increment identification and the spatial extent of the common signal in five Arctica islandica chronologies from the Fladen Ground, northern North Sea, Paleoceanography, 24, PA2210, doi:10.1029 /2008PA001715. Witbaard, R. 2009, De Noordkromp. De Levende Natuur, Thema nummer de Noordzee. 6: 264-265. Witbaard, R. 2009.Inleiding Noordzee. In Europese Natuur in Nederland Natura 2000-gebieden van Zee en kust series editors J.A.M. Janssen & J.H.J. Schaminée. KNNV Uitgeverij, Zeist 2009. Witbaard, R. 2009.Doggers Bank. In Europese Natuur in Nederland Natura 2000-gebieden van Zee en kust series editors J.A.M. Janssen & J.H.J. Schaminée. KNNV Uitgeverij, Zeist 2009. Witbaard, R.& G.N.M. van Moorsel,  2009. Klaverbank. In Europese Natuur in Nederland Natura 2000-gebieden van Zee en kust series editors J.A.M. Janssen & J.H.J. Schaminée. KNNV Uitgeverij, Zeist 2009. Witbaard, R. 2009.Friese Front. In Europese Natuur in Nederland Natura 2000-gebieden van Zee en kust series editors J.A.M. Janssen & J.H.J. Schaminée. KNNV Uitgeverij, Zeist 2009.     Other. Witbaard, R. (1997). Tree of the Sea. The use of the internal growth lines in the shell of Arctica islandica (Bivalvia, Mollusca) for the retrospective assessment of marine environmental change. In Marine Ecology, pp. 149. Groningen: University of Groningen http://irs.ub.rug.nl/ppn/158547373 Witbaard, R. (1995). Measurements of burrows of Callianassa subterranea made in a meso. In: The applicability of mesocosm in North Sea eutrophication studies. Mesocosm research 1989. Eds F.C. van Duyl NIOZ Rapport 1991-5. Witbaard, R. Ecoprofiel Noordkromp, pp. 68. Texel: Netherlands Institute for Sea Research, Ministerie van verkeer en Waterstaat, Directoraat generaal rijkswaterstaat. Witbaard, R. and Klein, R., 1995.Long term trends in the effects of Beamtrawl fishery on the shells of Arctica islandica. NIOZ Rapport 1995-3. 15pp. Witbaard, R. and Klein, R., 1993. Long term trends in the effects of Beamtrawl fishery on the bivalve mollusc Arctica islandica L (Mollusca, Bivalvia). NIOZ Rapport 1993-12. 19pp. Witbaard, R. 2007. Evaluatie van streefdoelen voor de noordkromp-populatie op het Friese Front en in de Oestergronden, Imares rapport C041/07 Dalfsen, J.A. van &. R. Witbaard, 2007. Abelour Environmental Seabed Survey, UK 2007, 2007. Wageningen Imares rapport C016/08. 35pp. Dalfsen, J.A. van &. R. Witbaard, 2007. Environmental Seabed Survey, Captain WPPA Location  UK 2007, 2007. Wageningen Imares rapport C017/08. 50pp. Dalfsen, J.A. van &. R. Witbaard, 2007. Lochside  Environmental Seabed Survey, UK 2007, 2007. Wageningen Imares rapport C015/08. 42pp. Craeymeersch, J.A., R. Witbaard, E. Dijkman, H.W.G. Meesters, 2008. Ruimtelijke en temporele patronen in de diversiteit van de macrobenthische infauna op het Nederlands Continetaal Plat. 40pp. Lindeboom, H.J., R. Witbaard, O.G. Bos, H.W.G. Meesters, 2008. Gebiedsbescherming Noordzee. Habitattypen, instandhoudingsdoelen en beheersmaatregelen. Werkdocument 114 Wettelijke onderzoekstaken Natuur en Milieu, Wageningen, oktober 2008,45pp Witbaard, R. O.G. Bos, H.J. Lindeboom, 2008. Basisinformatie over de Borkummer Stenen, Bruine Bank en Gasfonteinen potentieel te beschermen gebieden op het NCP. Imares rapport C026/08, 37pp. Meesters, H.W.G. R. Ter Hofstede, C.M. Deerenberg, J.A.M. Craaymeersch, I.G. de Mesel, S.M.J.M. Brasseur, P.JH. Reijnders & R. Witbaard. 2008. Indicator system for biodiversity in Dutch marine waters. II Ecoprofiles of indicator species for Wadden Sea, North Sea and Delta area. Wageningen Wettelijke onderzoekstaken Natuur en Milieu, WOT rapport 82. 164pp. Jak, R.G, O.G. Bos, R. Witbaard, H.J. Lindeboom. 2009 Instandhoudingsdoelen Natura 2000-gebieden Noordzee. Imares rapport C065/09 177pp. Jak, R.G, O.G. Bos, R. Witbaard, H.J. Lindeboom. 2009 Bijlagen rapport bij Instandhoudingsdoelen Natura 2000-gebieden Noordzee. Imares rapport C065/09 177pp.