1. Habitats
Habitat suitability for freshwater fish in rivers and streams
Aquatic invertebrate species composition and diversity in standing waters
Multi habitat use of coral reef fish in tropical coastal habitats
2. Species
Understanding patterns in species distribution from traits
Thermal tolerance and oxygen limitation in aquatic ectotherms
3. Conservation Biology and Restoration Ecology
Mechanisms and constraints in the conservation and recovery of animal communities
1. Habitats
Habitat suitability for freshwater fish in rivers and streams
Spatiotemporal gradients in streams and rivers provide suitable habitat conditions for many different fish species. Knowledge on the conditions required by each species at various stages of its lifecycle contributes to our understanding of the importance of habitat connectivity and habitat heterogeneity for their continued coexistence.
Field research investigating patterns in habitat use and growth of different fish has shown that tributaries may contribute to riverine fish stocks by supplementing habitat for spawning and growing (Pollux et al. 2006). Within streams, passages may improve fish migrations for characteristic species and create more opportunities for fish species by providing additional habitat space (Dorenbosch et al. 2005). Differences in the regional distribution of three stream fish species could be linked to their biological traits (Verberk et al. 2004). Stream mouths, the transitional habitat where streams discharge into the river, were the subject of a separate investigation. These transitional habitats harboured a diverse fish assemblage, with in fish species associated with either the upstream stream or the downstream river contributing to these rich assemblages (Dorenbosch et al. 2006; Verberk et al. 2006).
During these studies I mainly collaborated with Bart Pollux and Martijn Dorenbosch. I was also involved with the Reinier de Nooij on his study on the importance of the hydrodynamical gradient for endangered and protected riverine species, including riverine fish (de Nooij et al. 2006) and participated with Rob Lenders on his research focusing on the historical decline of the Atlantic Salmon in the rivers Rhine and Meuse (Lenders et al. 2008). Recently, an applied study into the effectivity of newly created habitats in floodplain was performed (Dorenbosch et al. 2011), which was an active collaboration with Jan Kranenbarg, Frank Spikmans, Nils van Kessel, Martijn Dorenbosch and Rob Leuven.
Selected publications on this topic:
Verberk WCEP, van den Munckhof PJJ & Pollux BJA (2004) Veranderingen in het beekdallandschap van de peelregio Deel II: Grenzen aan het verspreidingsgebied in Limburg van de Driedoornige stekelbaars, de Tiendoornige stekelbaars en het Bermpje. Natuurhistorisch Maandblad 93: 328-333.
Dorenbosch M, Verberk WCEP & Pollux BJA (2005) Veranderingen in de visgemeenschap van de Oostrumsche beek – een evaluatie van de herinrichting vijf jaar na uitvoering. Natuurhistorisch Maandblad 94: 29-32.
Pollux BJA, Korosi A, Verberk WCEP, Pollux PMJ & van der Velde G (2006) Reproduction, growth, and migration of fishes in a regulated lowland tributary: Potential recruitment to the river Meuse. Hydrobiologia 565: 105-120.
Dorenbosch M, Verberk WCEP & Pollux BJA (2006) De visfauna van beekmondingen in Limburg Deel 1. Vergelijking tussen beekmondingen. Natuurhistorisch Maandblad 95: 93-97.
Verberk WCEP, Dorenbosch M & Pollux BJA (2006) De visfauna van beekmondingen in Limburg Deel 2. Vergelijking tussen beekmondingen en bovenstroomse beekdelen. Natuurhistorisch Maandblad 95: 173-177.
de Nooij RJW, Verberk WCEP, Lenders HJR, Leuven RSEW & Nienhuis PH (2006) The importance of hydrodynamics for protected and endangered biodiversity of lowland rivers. Hydrobiologia 565: 153-162.
Lenders HJR , Chamuleau T & Verberk WCEP (2008) Historical decline of Atlantic salmon in NW-Europe. In: van Os AG (Ed) Proceedings NCR-days 2007 – a sustainable river system ?! NCR, Delft. Pp. 58-59.
Dorenbosch M, N van Kessel, J Kranenbarg, F Spikmans, WCEP Verberk & RSEW Leuven (2011) Nevengeulen in uiterwaarden als kraamkamer voor riviervissen. Rapport Natuurplaza: Stichting RAVON, Stichting Bargerveen, Radboud Universiteit Nijmegen en Natuurbalans – Limes Divergens, Nijmegen.
Aquatic invertebrate species composition and diversity in standing waters
Aquatic macroinvertebrates play a central role in water management issues; they are frequently used as a tool to measure the ecological quality and the conservation or restoration of invertebrate populations is increasingly mentioned explicitly as one of the management aim.
Comparative research on several bog landscapes highlighted the importance of habitat heterogeneity, which encompassed variation in acidity, nutrient status and the size of the various water bodies (Verberk et al. 2006). As degradation results in a loss of habitat heterogeneity, within the context of nature restoration, it is important to know how heterogeneity can be strengthened or how restoration efforts can be adapted so that at least they do not induce a further homogenization. Using field studies, we investigated the response of invertebrate communities to the effects of rewetting of raised bogs (Verberk et al. 2010) and dredging of fen marshes (Verberk et al. 2007) and made comparisons in more pristine systems (Lamers et al. 2006; van Duinen et al. 2002). Additional field research focused on seasonal changes in different types of water body, to obtain information on life-history events (Verberk et al. 2005) and migration events (Verberk & Esselink 2005). Species attributes on life-history, morphology and physiology (species traits) were used to understand patterns in species occurrence (Verberk et al. 2008) and predict species responses to restoration management (Van Kleef et al. 2006), see also the theme “Understanding patterns in species distribution from traits”.
During these studies I mainly collaborated with Gert-Jan van Duinen and Hein van Kleef and participated in their research on raised bogs and moorland pools, respectively. The research on fen bogs was part of a larger research effort, coordinated by Leon Lamers.
Selected publications on this topic:
van Duinen GA, Brock AMT, Kuper JT, Peeters TMJ, Smits MJA, Verberk WCEP & Esselink H (2002) Important keys to successful restoration of characteristic aquatic macroinvertebrate fauna of raised bogs. In: Schmilewski G & Rochefort L (Eds) Proceedings of the International Peat Symposium: Peat in horticulture – Quality and environmental challenges. International Peat Society, Jyväskylä, Finland. Pp. 292-302.
Verberk WCEP & Esselink H (2005) Aggregation of water beetles: mechanisms of dispersal. Proceedings of the Section Experimental and Applied Entomology of the Netherlands Entomological Society (NEV) 16: 51-61.
Verberk WCEP, van Kleef HH, Dijkman M, van Hoek P, Spierenburg P & Esselink H (2005) Seasonal changes on two different spatial scales: response of aquatic invertebrates to water body and microhabitat. Insect Science 12: 263-280.
van Kleef HH, Verberk WCEP, Leuven RSEW, Esselink H, van der Velde G & van Duinen GA (2006) Biological traits successfully predict the effects of restoration management on macroinvertebrates in shallow softwater lakes. Hydrobiologia 565: 201–216.
Lamers LPM, Geurts J, Bontes B, Sarneel J, Pijnappel H, Boonstra H, Schouwenaars J, Klinge M, Verhoeven J, Ibelings B, van Donk E, Verberk WCEP, Kuijper B, Esselink H & Roelofs J (2006) Onderzoek ten behoeve van het herstel en beheer van Nederlandse laagveenwateren (eindrapportage 2003-2006). Ministerie van LNV, Directie Kennis, Ede. 260pp + bijlagen.
Verberk WCEP, van Duinen GA, Brock AMT, Leuven RSEW, Siepel H, Verdonschot PFM, van der Velde G & Esselink H (2006) Importance of landscape heterogeneity for the conservation of aquatic macroinvertebrate diversity in bog landscapes. Journal for Nature Conservation 14: 78-90.
Verberk WCEP, Kuper JT, Lamers LPM, Christianen MJA & Esselink H (2007) Restoring fen water bodies by removing accumulated organic sludge: what are the effects for aquatic macroinvertebrates? Proceedings of the Section Experimental and Applied Entomology of the Netherlands Entomological Society (NEV) 18: 115-124.
Verberk WCEP, Siepel H & Esselink H (2008) Applying life-history strategies for freshwater macroinvertebrates to lentic waters. Freshwater Biology 53: 1739-1753.
Verberk WCEP, Leuven RSEW, van Duinen GA & Esselink H (2010) Loss of environmental heterogeneity and aquatic macroinvertebrate diversity following large-scale restoration management. Basic and Applied Ecology 11: 440-449.
Multi habitat use of coral reef fish in tropical coastal habitats
Juveniles of many coral reef fish are found in high densities on shallow coastal habitats such as mangroves and seagrass beds. These shallow coastal habitats may provide favourable conditions for juvenile growth (low predation, high resource availability) and consequently provide essential nursery grounds for several of fish species.
To quantify the dependence of coral reef fish on shallow coastal habitats we investigated habitat use between different life stages (larvae, juvenile, subadult, adult) for various fish species using field observations, dietary analysis and stable isotope analysis. A variety of habitats was investigated, ranging from seagrass and algal beds, rocky shallow notches, mangroves, and coral reefs at different depths (Nagelkerken et al. 2000a). Nocturnal differences in habitat use (Nagelkerken et al. 2000b) and dietary analysis (Nagelkerken et al. 2006) were used to substantiate the dependence of coral fish species on specific habitats. By analyzing spatiotemporal patterns in newly settled fish, the degree to which larvae actively select for the habitats that they occupy as juveniles could be ascertained (Pollux et al. 2007). Additional investigations focused on how size distributions of juvenile fish in mangroves and seagrass beds were affected by the configuration of these habitats (distance and connectivity of to the reef), mainly through the effects of predation (Dorenbosch et al. 2007).
During these studies I participated in the PhD research of Ivan Nagelkerken and Martijn Dorenbosch on the nursery function and connectivity of coastal habitats for coral reef fish and additionally I collaborated with Gerard van der Velde and Bart Pollux.
Selected publications on this topic:
Nagelkerken I, Dorenbosch M, Verberk WCEP, Cocheret de la Morinière E & van der Velde G (2000) Importance of shallow-water biotopes of a Caribbean bay for juvenile coral reef fishes: patterns in biotope association, community structure and spatial distribution. Marine Ecology Progress Series 202: 175-192.
Nagelkerken I, Dorenbosch M, Verberk WCEP, Cocheret de la Morinière E & van der Velde G (2000) Day-night shifts of fishes between shallow-water biotopes of a Caribbean bay, with emphasis on the nocturnal feeding of Haemulidae and Lutjanidae. Marine Ecology Progress Series 194: 55-64.
Nagelkerken I, van der Velde G, Verberk WCEP & Dorenbosch M (2006) Segregation along multiple resource axes in a tropical seagrass fish community. Marine Ecology Progress Series 308: 79-89.
Dorenbosch M, Verberk WCEP, Nagelkerken I & van der Velde G (2007) Habitat configuration influences connectivity between fish assemblages of Carribbean seagrass beds, mangroves and coral reefs. Marine Ecology Progress Series 334: 103-116.
Pollux BJA, Verberk WCEP, Dorenbosch M, Cocheret de la Morinìere E, Nagelkerken I & van der Velde G (2007) Habitat selection during settlement of three Caribbean coral reef fishes: Indications for directed settlement to seagrass beds and mangroves. Limnology and Oceanography 52: 903-907.
2. Species
Understanding patterns in species distribution from traits
The adaptations of a species underlie its ability to deal with environmental problems and opportunities. Information of a species’ biology may therefore be used to construct a framework of causal mechanisms to understand and predict how abiotic and biotic factors drive species distribution patterns.
Information on species traits (attributes related to its life-history, physiology and morphology) was extracted from the literature to unravel the causal mechanisms underlying species occurrences. Selection pressures do not operate on single traits, but on organisms carrying multiple traits. Consequently, species-environment relationships are best understood from co-evolved sets of traits which constitute the life-history strategy of a species (Verberk et al. 2008; Verberk 2009). In this way, species traits can be used to define habitat suitability in an alternative way from the circular -yet surprisingly commonplace- reasoning that the most suitable habitat is where species is most abundant (Verberk et al. 2004; Verberk 2008). allows species abundance and distributions to be better understood and predicted (Verberk et al. 2010a). The trait based approach was also successfully applied in the restoration management of moorland pools, chalk grasslands and a heterogeneous bog remnant (van Kleef et al. 2006; Verberk et al. 2010b; van Noordwijk et al. 2012).
I developed the life-history strategies in close collaboration with Henk Siepel and participated in the PhD research of Hein van Kleef and Toos van Noordwijk to apply this approach to chironomids in moorland pools and ants in chalk grasslands, respectively.
Selected publications on this topic:
Verberk WCEP, Pollux BJA & van den Munckhof PJJ (2004) Veranderingen in het beekdallandschap van de peelregio Deel I: Een ecologische analyse voor de Driedoornige stekelbaars, de Tiendoornige stekelbaars en het Bermpje. Natuurhistorisch Maandblad 93: 301-310.
van Kleef HH, Verberk WCEP, Leuven RSEW, Esselink H, van der Velde G & van Duinen GA (2006) Biological traits successfully predict the effects of restoration management on macroinvertebrates in shallow softwater lakes. Hydrobiologia 565: 201–216.
Verberk WCEP (2008) Matching species to a changing landscape – Aquatic macroinvertebrates in a heterogeneous landscape. PhD Thesis, Radboud Universiteit, Nijmegen.
Verberk WCEP, Siepel H & Esselink H (2008) Life-history strategies in freshwater macroinvertebrates. Freshwater Biology 53: 1722-1738.
Verberk WCEP (2009) Overlevingsstrategieën koppelen soorten aan hun landschap. Entomologische Berichten 69: 122-128.
Verberk WCEP, van der Velde G & Esselink H (2010a) Explaining abundance-occupancy relationships in specialists and generalists: a case study on aquatic macroinvertebrates in standing waters. Journal of Animal Ecology 79: 589-601.
Verberk WCEP, Leuven RSEW, van Duinen GA & Esselink H (2010b) Loss of environmental heterogeneity and aquatic macroinvertebrate diversity following large-scale restoration management. Basic and Applied Ecology 11: 440-449.
van Noordwijk CGE, Boer P, Mabelis AA, Verberk WCEP & Siepel H
(2012) Life-history strategies as a tool to identify conservation
constraints: A case-study on ants in chalk grasslands.Ecological Indicators 13(1): 303-313.
Thermal tolerance and oxygen limitation in aquatic ectotherms
Studies on the respiratory biology of marine taxa have led to the hypothesis that oxygen may become limiting at extreme temperatures, setting whole animal thermal tolerance limits This perspective may allow the prediction of a species’ thermal vulnerability from their morphological and physiological traits that are related to oxygen supply and demand.
Using a combination of laboratory experiments and field data, I investigate if thermal tolerance limits in aquatic ectotherms be understood in terms of oxygen shortage arising from a mismatch between oxygen supply and oxygen demand (Verberk & Bilton 2009). To investigate the effect of water temperature on environmental oxygen supply I revisited the question whether partial pressure or solubility limits oxygen supply in nature, something which has been actively debated for more than a decade. By returning to first principles of gas diffusion, I resolved this question (Verberk et al. 2011); both pO2 and solubility contribute to environmental oxygen supply and that owing to higher diffusivity there is more oxygen available in warmer habitats (which is exactly opposite to current wisdom). Observed oxygen shortages arise due to (non-lineair) increases in oxygen demand with warming. Although organisms may adjust oxygen demand, they are constrained by the oxygen available in their environment. Our discovery that oxygen supply is actually higher in warmer habitats, may shift our understanding of how oxygen shapes aquatic communities and has consequences for our understanding of how thermal limits may arise, and our ability to predict the impacts of climate change. Recent experimental results from stonefly nymphs likewise supported the importance of both oxygen supply and oxygen demand in setting thermal limits, providing the first formal demonstration of oxygen limitation in a tracheate (Verberk & Bilton, 2011). These results on aquatic nymphs contrast with recent studies on terrestrial arthropods. Our proof of principle suggests that many insects may be affected by oxygen limitation as many live in aquatic or essentially aquatic environments (e.g. endophytic species, rotten fruit specialists, etc.) at some stage during their life cycle.
This research is performed in collaboration with David Bilton, Piero Calosi and John Spicer.
Selected publications on this topic:
Verberk WCEP & Bilton DT (2009) Oxygen deficiency under elevated temperatures: a mechanism connecting the response of stream ectotherms to global warming? Comparative Biochemistry and Physiology Part A 153: S169.
Verberk WCEP, Bilton DT, Calosi P & Spicer JI (2011) Oxygen supply in aquatic ectotherms: Partial pressure and solubility together explain biodiversity and size patterns. Ecology 92: 1565-1572. [doi:10.1890/10-2369.1]
Verberk WCEP & Bilton DT (2011) Can oxygen set thermal
limits in an insect and drive gigantism? PLoS One, 6(7), e22610.
3. Conservation Biology and Restoration Ecology
Mechanisms and constraints in the conservation and recovery of animal communities
Improving the effectivity of restoration management requires an understanding of the causal mechanisms explaining how the system naturally functions, how it is impacted and how it can be restored.
A combination of desk studies and field studies is used to gain insight in the key factors that explain why species have declined and how to improve the effectiveness of efforts taken in the fields of conservation biology and restoration ecology. Desk studies are used to collate and synthesize the information available, identify gaps in knowledge and outline the type of research that is required to fill in these knowledge gaps. Such desk studies are usually confined to a discrete habitats or landscape, for example coppice woodlands (Bobbink et al. 2008),valleys of lowland streams (Aggenbach et al. 2009), fen marshes (Antheunisse et al. 2008) and rivers (Verberk et al. 2009a). Field studies aim to unravel the causal mechanisms underlying the suitability of a species’ habitat, yet are driven by applied questions from the field, thus bridging the gap between fundamental and applied research. I have been involved with research on riverine fish (see the theme “Habitat suitability for freshwater fish in rivers and streams”), aquatic invertebrates (see the theme “Aquatic invertebrate species composition and diversity in standing waters”) and terrestrial invertebrates in chalk grasslands (Smits et al. 2009). In addition, I helped develop theoretical concepts for the practice of restoration management on how to deal with differences in scale and land use among species and the importance of habitat heterogeneity (Verberk & Esselink 2003; Verberk et al. 2009b; Verberk, 2011) as well as the use of life-history strategies to capture the causal mechanism underlying species-environment relationships thereby potentially being capable of transforming the descriptive field studies in applied ecology into a predictive science (see the theme “Understanding patterns in species distribution from traits”; Verberk 2010).
I have been fortunate to have collaborated with many people with a strong passion for nature conservation, research or both. Far too many to mention here individually, except for Hans Esselink with whom I have worked intensively. His compassion, tenacity and insight have been inspirational. With his untimely death in 2008 Nature has lost a valuable ally.
Selected publications on this topic:
Verberk WCEP & Esselink H (2003) Faunaherstel vereist de integratie van landschapsecologie en dierecologie. Landschap 20: 3-7.
Antheunisse AM, Verberk WCEP, Schouwenaars JM, Limpens J & Verhoeven JTA (2008) Preadvies laagveen- en zeekleilandschap - een systeemanalyse op landschapsniveau. Ministerie van LNV, Directie Kennis, Ede. 115pp + bijlagen.
Bobbink R, Bijlsma RJ, Brouwer E, Eichhorn K, Haveman R, Hommel P, van Noordwijk CGE, Schaminée JHJ, Verberk WCEP, de Waal R & Wallis de Vries MF (2008) Preadvies hellingbossen in Zuid-Limburg. Ministerie van LNV, Directie Kennis, Ede. 106pp.
Aggenbach CJS, Groenendijk D, Kemmers RH, van Kleef HH, Smolders AJP, Verberk WCEP & Verdonschot PFM (2009) OBN-preadvies beekdallandschap. Ministerie van LNV, Directie Kennis, Ede. 151pp + bijlagen.
Smits NAC, van Noordwijk CGE, Bobbink R, Esselink H,Huiskes R, Kuiters L, Ozinga W, Schaminée J, Siepel H, Verberk WCEP & Willems J (2009) Onderzoek naar de ecologische achteruitgang en het herstel van Zuid-Limburgse hellingschraallandcomplexen. Ministerie van LNV, Directie Kennis, Ede. 153pp + bijlagen.
Verberk WCEP, Helmer W, Sýkora KV, Leuven RSEW, Saris FJA, Wolfert HP & Hekhuis H (2009a) Kansen voor verder herstel van het rivierenlandschap. De Levende Natuur 110: 148-152.
Verberk WCEP, Grootjans AP & Jansen AJM (2009b) Natuurherstel: van standplaats naar landschap. De Levende Natuur 110: 105-110.
Verberk WCEP (2010) Life-history strategies: a fresh approach to causally link species and their habitat. In: Carlo F de & Bassano A (eds) Freshwater Ecosystems and Aquaculture Research. Nova Publishers, New York. ISBN: 978-1-60741-707-1
Verberk WCEP (2011) Gidssoorten wijzen de weg naar herstel. De Levende Natuur 112: 152-156.