Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

Introduction

Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity.Edited by John Stockner. American Fisheries Society, Symposium 34, Bethesda, Maryland. 2003. 285 pages. $60.00 (paper) ($42.00 to AFS members).

This book is a compilation of the papers presented at a 2001 conference of the same title. The 21 papers are organized into five sections: “Background and Historic Perspective,” “Ecosystem Responses,” “Replacing Lost Nutrients: Stream and Lake Fertilization,” “Method Refinement,” and “Innovative Ecosystem Management.” In a preface, Ashley and Stockner provide supplemental information on the development of the conference.

The papers in the opening section set the stage. Stockner and Ashley contribute an overview of the role and importance of salmon nutrients, particularly in oligotrophic ecosystems, and place that role in the context of strong societal desires to reduce nutrient input into freshwater ecosystems. Murota provides an interesting perspective on the roles of anadromous salmonids, marine fisheries, and marine-derived guano in phosphorus uploading; this paper does an admirable job of putting the issue into a global perspective and includes an acknowledgement of the potential but largely unstudied role of nonsalmonid anadromous species. Thomas et al. try to assess the historic contribution of marine-derived nutrients (MDN) to Idaho streams.

The four chapters on ecosystem response cover such topics as the isotopic evidence for the enrichment of a variety of recipient components in riparian zones, utilization by wildlife, aquatic animal colonization, and hyporheic transfer of MDN. Collectively, these chapters give a strong sense of the ecosystemic role played by salmon returning to natal streams.

Seven papers focus on fertilization studies. Five of them review the results of recently completed or ongoing fertilization experiments. Convincing evidence is provided that fertilization increases primary productivity as well as salmonid production, particularly in the juvenile stages. A paper by Volk et al. on the role of red alder Alnus rubra adds a very interesting ecosystem perspective.

The section on methods refinement contains three papers, one dealing with methods for determining the trophic-level implications of salmon-derived nutrients and the other two relating to nutrient application techniques and protocols. I was slightly disappointed that neither the author nor the book's editor chose to deal with the acronym inconsistency introduced in the trophic-level implications paper. The MDN earlier defined as marine-derived nutrients (P and N) gets redefined in this chapter as marine-derived nitrogen.

A very positive contribution of this book is the final section on innovative ecosystem management. The three papers in this section place fertilization and potential management measures in proper perspective. Knudsen et al. introduce a life history approach to salmon escapement management. While recognizing the limitations and assumptions of their model, the authors provide a stepwise framework that requires one to view the role of nutrients in the context of all management actions affecting the various life history survival rates. Michael provides a complementary view of the importance of understanding the entire ecosystem pertaining to salmon management, including humans, when developing escapement goals. The final paper by Lackey places the issue of nutrient enrichment for the purpose of enhancing salmonid populations into the broader societal context (particularly in the USA) of public policy and regulatory responsibilities for clean waters. Lackey (2003) provides a synopsis of this chapter that summarizes the key policy questions in a recent issue of Fisheries.

I found this book and the topic it covered extremely interesting. It did a nice job of providing an overarching framework, a good synopsis of the issue on a large scale, and a balance of recently completed or in-progress research results. Perhaps most importantly, the book provides an ecosystem framework for its subject. I recommend this book and encourage readers to read it in its entirety.