Macroecology of the European Soft Sediment Benthos: Insights from the Macroben Database
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Vol. 382: 287–296, 2009 MARINE ECOLOGY PROGRESS SERIES Published April 30 doi: 10.3354/meps07754 Mar Ecol Prog Ser OPENPEN Contribution to the Theme Section ‘Large-scale studies of the European benthos: the MacroBen database’ ACCESSCCESS Macroecology of the European soft sediment benthos: insights from the MacroBen database T. J. Webb1,*, I. F. Aleffi, J. M. Amouroux, G. Bachelet, S. Degraer, C. Dounas, D. Fleischer, A. Grémare, M. Herrmann, H. Hummel, I. Karakassis, M. Ke˛dra, M. A. Kendall, L. Kotwicki, C. Labrune, E. L. Nevrova, A. Occhipinti-Ambrogi, A. Petrov, N. K. Revkov, R. Sardá, N. Simboura, J. Speybroeck, G. Van Hoey, M. Vincx, P. Whomersley, W. Willems, M. W8odarska-Kowalczuk 1Department of Animal & Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK ABSTRACT: Macroecology provides a novel conceptual framework for analysis of the distribution and abundance of organisms at very large scales. Its rapid development in recent years has been dri- ven primarily by studies of terrestrial taxa; the vast potential of marine systems to contribute to the macroecological research effort remains largely untapped. International collaborative efforts such as MarBEF have provided fresh impetus to the collation of regional databases of species occurrences, such as the newly available MacroBen database of the European soft sediment benthic fauna. Here, we provide a first macroecological summary of this unique database. We show that in common with almost all previously analysed assemblages, the frequency distribution of regional site occupancies across species in the MacroBen database is strongly right-skewed. More unusually, this right skew remains under logarithmic transformation. There is little evidence for any major differences between higher taxa in this frequency distribution (based on the 8 animal classes for which we have sufficient data). Indeed, considerable variation in occupancy persisted across the taxonomic hierarchy, such that most variation occurred between species within genera. There was a weak positive relationship between local population density and regional occupancy across species, but this abundance–occu- pancy relationship varied considerably between higher taxa and between geographical areas. Our results highlight the potential of databases such as MacroBen to consolidate macroecological gener- alities and to test emerging theory. KEY WORDS: Marine macroecology · Macrobenthic · Europe · Large marine ecosystems · Species– range size distributions · Phylogeny · Abundance–occupancy relationships Resale or republication not permitted without written consent of the publisher INTRODUCTION Blackburn 2000, Blackburn & Gaston 2003). The impor- tance of a macroecological approach becomes still more Macroecology draws on insights from fields including apparent with the realisation that human impacts on ecology, biogeography, palaeontology, macroevolution ecological systems are detectable at the same very and applied statistics to understand how large-scale large scales that interest macroecologists (Chapin et al. processes affect the organisation of ecological systems 2000, Kerr et al. 2007), and that many of the most press- at multiple scales (Brown 1995, Gaston & Blackburn ing issues in applied ecology involve very general 2000, Blackburn & Gaston 2006). It has defined novel questions relating to habitat modification, invasive spe- and important concepts and methodological techniques cies, over-exploitation, pollution and climate change to describe the form and structure of large-scale eco- (Sutherland et al. 2006). In a marine context, consider- logical patterns and has developed in a relatively short able large-scale changes in ecosystems have already time into a thriving and productive discipline (Gaston & occurred without rigorous documentation (Jackson *Email: [email protected] Addresses for other authors are given in the Electronic Appen- © Inter-Research 2009 · www.int-res.com dix at www.int-res.com/articles/suppl/m382p221_app.pdf 288 Mar Ecol Prog Ser 382: 287–296, 2009 2001), which brings into sharp relief the need to under- also seen for species–abundance distributions; Gray et stand large-scale patterns of biodiversity that we may al. (2006) show that these are of similar form in a vari- better predict the consequences of current and future ety of marine and terrestrial taxa under similar sam- human-induced global change. pling regimes. Importantly, macroecological relation- A guiding principle of the macroecological approach ships such as the abundance–occupancy relationship is the search for generality — to what extent are large- are also observed in the sea (e.g. Foggo et al. 2003, scale patterns in the abundance and distribution of or- Fisher & Frank 2004, Blackburn et al. 2006), indicating ganisms consistent across taxa and environments? Cer- that similar processes may act on communities in both tain macroecological patterns and relationships appear environments. Efforts to increase communication be- to be very general. For instance, across a taxonomically tween marine and terrestrial ecological research com- constrained group of species, the frequency distribution munities (e.g. Stergiou & Browman 2005) are stimulat- of range sizes measured at regional to global scales will ing progress in marine macroecology, and this trend typically display a characteristic right skew: most spe- will only increase as national and international organi- cies are rare, but a few are extremely widely distributed sations consolidate the data collected by individual (Gaston 2003). Similar generalities are observed in re- research organisations into regional databases that lationships between geographic distribution and local provide a broader-scale overview of the distribution of population density (Gaston et al. 2000, Blackburn et al. marine diversity. The Marine Biodiversity and Ecosys- 2006). This so-called abundance–occupancy relation- tem Functioning EU Network of Excellence (MarBEF, ship is typically positive such that locally abundant spe- www.marbef.org) has been established specifically to cies tend to be geographically widespread (Gaston et investigate patterns of marine biodiversity, with an al. 2000, Blackburn et al. 2006), and is important as it emphasis on the analysis of large-scale patterns and provides a link between local and regional population processes that would not be tractable without such processes (Freckleton et al. 2005, 2006). international cooperation. An important caveat to the inferred generality of It is important to realise that macroecology is about such patterns, however, is that macroecology has more than simply describing patterns (Blackburn & developed as an overwhelmingly terrestrial discipline Gaston 2006), and recent efforts have shifted towards (Raffaelli et al. 2005, Clarke et al. 2007), whereas the seeking a mechanistic understanding of the processes sea is home to most of life’s higher-taxon diversity that drive these patterns. For instance, population (May 1994). Only a minority of studies making explicit models that view interspecific macroecological pat- reference to ‘macroecology’ have had a primarily terns as the result of intraspecific dynamics have pro- marine focus (Raffaelli et al. 2005), and just 18 of the vided a powerful approach for generating mechanistic 279 abundance–occupancy relationships reviewed by hypotheses (He & Gaston 2003, Freckleton et al. 2005, Blackburn et al. (2006) derived from marine or inter- 2006), and make testable predictions about the roles of tidal systems. This paucity of marine macroecological ecological and life history parameters in shaping studies can be partially explained by the particular macroecological patterns and relationships. Testing practical, logistical and financial challenges posed by these predictions in terrestrial systems has been lim- working in the marine environment that make the ited by the fact that parameters thought to be impor- kinds of datasets relied upon by terrestrial macroecol- tant in determining the form of macroecological pat- ogists (often compiled largely through the efforts of terns, such as colonisation ability, often do not vary committed volunteer naturalists) difficult to obtain for substantially within the highly mobile taxa (such as marine taxa. In addition, it can prove difficult to define birds) typically studied (Freckleton et al. 2005). Indeed variables crucial to macroecological analyses such as most macroecological datasets tend to be somewhat ‘range size’ and ‘population size’, particularly for taxonomically restricted, and thus encompass only lim- highly mobile pelagic taxa or for regions with (often ited functional diversity. This underlines the vast highly) incomplete sampling. Despite these difficulties, potential of macroecological studies of marine systems there exist several excellent macroecological studies of to aid in a more general understanding of macroeco- the marine environment (e.g. Li 2002, Foggo et al. logical process. The same sampling regime within a 2003, Macpherson 2003, Fisher & Frank 2004, Irigoien single marine habitat type will typically capture signif- et al. 2004, Jennings & Blanchard 2004, Hsieh et al. icant taxonomic diversity, recording species that differ 2006). In the main, these have tended to support gen- markedly in characteristics (e.g. larval dispersal poten- eral conclusions reached by terrestrial macroecologists tial) hypothesised to be important in determining on the basic form of the principal patterns. For in- large-scale