Food Webs of Shallow Subtidal Marine Ecosystems

To some ecologists, food webs and the diagrams associated with them represent the underpinnings of a grand unifying theory of ecology, the culmination of years of field study by numerous investigators, and a gateway to the creation of synthetic models and other predictive tools for resource management; but for others, they are naive and dangerous oversimplifications and the associated diagrams and models are merely the Tinkertoys of reductive, impatient investigators. Clearly, both views have their merits. Like many paradigms and heuristic tools in ecology, the popularity of food webs has waxed and waned. Nevertheless, the dynamic debate arising from the intellectual tension between these two positions could foster the progress in ecological research needed to produce a holistic approach that would enable ecologists to deliver the sound predictions demanded by resource users and managers. However conscientious, any rush to abandon these tools, and thereby avoid the simplification of complex processes, would only serve to delay the development of the holism needed to improve the management of our natural resources. Consequently, we need to periodically revisit and revise our conceptualization of the food webs we study, to consider anew the insights they might generate, and to assess their relevance to the twofold task of improving our understanding of the impact of human activities on global and regional ecosystems and then determining how best to manage them. In the past few decades, investigation into the ecology of shallow subtidal ecosystems has increased greatly, thanks to the advent and popularization of SCUBA diving and our consequent ability to conduct field studies in these physically challenging environments. These studies have expanded our understanding of the enormous impact of human activities on these ecosystems, as well as the long-term consequences of resource extraction. Without such studies, the impact of humans on these cryptic ecosystems would remain largely unknown and the observed changes in resources would seem mysterious and often inexplicable. In many cases, this new recognition of the strong effect of human activities became the impetus to create protected areas that maintain the food web or re-create new webs that minimize human influences. To stimulate further development of ecological holism, I invited several investigators working in disparate subtidal ecosystems to present a brief description of their research on the food webs in their study areas and to place these concepts into the historical context of ecological investigation. Authors were asked to identify the important issues in this arena that are not well understood and to focus on current areas of investigation. They were to assume that food webs would be revised as additional information became available. The papers that follow are the result of this initiative and offer a simple overview of our understanding of some of the most well-studied subtidal food webs. Changes in the ecological view of these food webs and the web structures themselves over time under natural and human influences are also presented. The early insights into human influences on subtidal ecosystems are important. However, given the short-term nature of most of these studies, it is difficult to determine to what extent natural variability contributes to the changes and what the resilience and recovery potential of these ecosystems may be. The coral reefs of the eastern Pacific, as described by Glynn (this issue), are a good exReceived 22 April 2003; accepted 23 April 2003; published online 27 April 2004. Corresponding author; e-mail: crcp@africaonline.co.ke Ecosystems (2004) 7: 321–322 DOI: 10.1007/s10021-004-0065-3 ECOSYSTEMS