Publication Abstract

The ups and downs of benthic ecology: considerations of scale, heterogeneity and surveillance for benthic–pelagic coupling

D. Raffaelli , E. Bell, G. Weithoff, A. Matsumoto, J.J. Cruz-Motta, P. Kershaw, R. Parker, D. Parry and M. Jones

The seabed is the most extensive habitat on the planet. It occupies at least 75% of the Earth's surface, far more if the planar areas of the shelves and slopes are taken into account. It follows that fluxes of materials across the sediment-water interface, and the mechanisms that mediate and constrain those fluxes, are likely to have global significance. Just how important the seabed is globally has been costed for nutrient cycling, which for marine shallow water systems is >US$ 40,000 ha^-1year^-1, 86% of the value of this service for all terrestrial and aquatic systems (Constanza et al., 1997). To this must be added the smaller areas (<1%) occupied by the sediment-water interface of wetlands, lakes and rivers, where local fluxes can be high and their significance belies their lesser size. However, what must also be taken into account, but is often overlooked, is the contribution of living benthic particles to pelagic systems, particularly planktonic, a process which is likely to profoundly influence the dynamics of water column populations and communities (see below). Benthic organisms are often also key drivers of biogeochemical fluxes through their bioturbatory activities in sediments. An understanding of the linkages between the fluxes of inorganic materials, the fluxes of living particles and benthic patterns, and processes within the sediment will be central to a proper evaluation of the significance of the benthic environment in marine ecosystems.

These issues were the focus of a workshop held at Aberdeen 25th-29th March 2002, as part of a larger meeting Benthic dynamics: in situ surveillance at the sediment-water interface. The workshop specifically identified scaling, heterogeneity and the coupling of benthic and pelagic systems, focusing on the flux of living particles, as pressing research issues. In presenting the output from that workshop, we are only too aware that the area of benthic-pelagic coupling is not novel and that several excellent reviews of the topic already exist (e.g. Boero and Graf; Marcus and Boero, 1998). Similarly, many of the issues of scale and heterogeneity which are so pertinent to benthic ecology have been discussed at considerable length by many authors (Botsford; Chase; Edmunds; Ellingsen; Gaston; He; Pascual; Pepin; Sponseller and Woodward), and a marine benthic focus is provided in a dedicated issue of this journal (Thrush and Warwick, 1998). It is not our purpose to duplicate these fine reviews, but to highlight the ways in which the themes of heterogeneity, scale and the coupling of benthic and pelagic processes might usefully inform one another. Specifically, we provide a brief review of benthic-pelagic coupling, identify issues of patchiness and scale pertinent to our theme, discuss ways in which the integration of these areas might yield new scientific insights and reflect on the potential of surveillance methodologies in this respect.

Reference:

D. Raffaelli , E. Bell, G. Weithoff, A. Matsumoto, J.J. Cruz-Motta, P. Kershaw, R. Parker, D. Parry and M. Jones, 2003. The ups and downs of benthic ecology: considerations of scale, heterogeneity and surveillance for benthic–pelagic coupling. Journal of Experimental and Marine Biology and Ecology, 285-286: 191-203.