‘State of Lake Superior’: A review

Edited by M. Munawar and I.F. Munawar, 2009. Published by Ecovision World Monograph Series, Aquatic Ecosystem Health & Management Society, Canada. 704 pgs., 157 figures, 60 tables, indices, ISBN 978-81-7898-592-3.As the largest of the Great Lakes, Lake Superior presents a formidable task to researchers. Whole lake explorations require large vessels and large budgets. Because of its almost marine size and depth, Lake Superior does not give up information easily which explains why major investigations into limnology and fisheries have been few and fairly recent. Results from the Upper Lakes Reference Group studies of the early 1970s were published in 1978 by the Journal of Great Lakes Research in a special issue ‘Limnology of Lake Superior’ (IAGLR, 1978). Results presented at a conference held in Houghton, Michigan in 2002 were published in Aquatic Ecosystem Health and Management (AEHMS, 2004) and in a special issue of the Journal of Great Lakes Research (IAGLR, 2004).The ‘State of Lake Superior’ is the latest volume of the Ecovision World Monograph Series published by AEHMS. It is edited by M. Munawar and I. F. Munawar and completes the cycle of volumes on state of the Great Lakes published between 1995 and 2009. It is noteworthy that Dr. M. Munawar was the editor of the first major publication on Lake Superior published by the Journal of Great Lakes Research in 1978. The current volume is a rich compendium of diverse interests in a common resource. It is not an easy task to produce a cohesive treatise on such a complex ecosystem and Dr. Munawar is to be commended for bringing a group of scientists together to complete this excellent benchmark of past and current knowledge. At over 700 pages, the volume is the largest in the Great Lake state series; very fitting as Lake Superior is the largest Great Lake. The book consists of 20 chapters authored by 37 scientists from 13 laboratories and universities in U.S. and Canada. It is divided into two main sections, Physical and Chemical Regimes (8 chapters) and Food Web Dynamics (12 Chapters).Chapters in the first section cover physical limnology, ice cover, isostatic rebound, nutrients, carbon, mining and contaminant modelling. The opening chapter by Schertzer and Rao (Environment Canada) is a comprehensive overview of past and current research in climatology, hydrology, thermal structure, currents and hydrodynamic modelling. The paper provides basic understanding of complex physical interactions important to biological distributions and processes in this large, deep lake. Raymond Assel (NOAA-GLERL), the ‘grand old man of Great Lake's ice’, presented information on ice cover climatology since David Phillip's 1978 survey (Phillips, 1978), including potential ice cover under climate warming scenarios. Norton (Penn State Erie) used models and GIS to calculate the paleotopography for the Lake Superior basin at 500 year intervals from 9500 years BP to present. Urban (Michigan Technological University) discussed nutrient and carbon cycling in two lengthy papers. In a review and update of nutrient cycling he reported that phosphorus has declined four-fold since the 1950s in response to reduced inputs and that nitrates increased four-fold between 1900 and 1980 in response to atmospheric loadings. The carbon cycling paper is an ambitious and successful attempt to evaluate pathways for carbon flow through the food web and spatially through the lake. The influence of hydrology and land use on nutrient variability in coastal wetlands of western Lake Superior is discussed in a chapter by Morrice et al. (EPA-Duluth). Kerfoot and Jeong (Michigan Technological University) and Robbins (NOAA-GLERL) have contributed a milestone summary of mining operations in the Lake Superior Basin and their impacts on the lake. It is the longest chapter (63 pages) in the book and is a comprehensive review of historic and current operations and environmental perturbations. The authors highlight problems and remedial progress with copper mining in the Keweenaw Peninsula. They have included a useful appendix of watershed mining activity in Canada and the U.S. I found this chapter very interesting. In a former life I was a credit officer with a large bank in Toronto. Included in my “portfolio” were many mining accounts. The bottom line was king. As in the other major resource industries (logging, pulp and paper, fisheries), there were virtually no regulations or concerns about negative impacts to the environment. This lack of policy is well reflected in the perturbations described in this chapter. The final chapter in the first section is a modelling study of contaminant behaviour in Lake Superior. Rowe et al. (Michigan Technological University) used a mass-balance model to determine major routes of entry and mechanisms of loss of PCBs, PBDEs and mercury.Chapters under Food Web Dynamics cover the microbial loop, phycology, zooplankton, nearshore water quality and plankton, benthic macroinvertebrates, fish communities, birds and food web modelling. Munawar et al. (Fisheries and Oceans Canada) provided a detailed analysis of the microbial food web from bacteria to nanoflagellates and ciliates and concluded that energy transfer is predominately autotrophic. Their results indicated Lake Superior remains a cold stenothermic and ultra-oligotrophic ecosystem. As in all of the ‘state of lake’ volumes, Munawar and Munawar have contributed a lengthy and detailed report on phytoplankton communities. The most recent samples were taken from Lake Superior in 2001 which indicates the difficulties and expense of undertaking a major lakewide survey in such a large lake. Their analysis included phytoplankton biomass, size structure, species composition and primary productivity. Comparisons with surveys of 1973 and 1983 indicated a 10-fold increase in mean biomass and a 37 percent increase in average size of algae between 1973 and 2001. In the same period, primary productivity declined 50 percent. The authors suggested that these and other functional changes may be related to a 5C increase in summer temperature.Three chapters are concerned with zooplankton in Lake Superior which is characterized by one of the most diverse communities in the Great Lakes. Kerfoot et al. suggest that a new concept, metacommunity, be applied to ease our understanding of complex interactions between the lake's embayment, coastal and open-water zooplankton communities. They advocate the use of ‘metacommunities’ as a spatial structure to encompass local communities connected to other local communities by dispersal and suggest the concept could be applied in Lake Superior and the other Great Lakes. The established relationship between zooplankton communities and planktivory has been studied further by Gorman et al. (Ashland Biological Station) in four inshore ecoregions of Lake Superior over a 12 year period. The principal planktivore was Lake Herring, in turn preyed upon by Lake Trout. The authors suggest that an improved understanding of zooplankton productivity and planktivory will assist managers to determine the size of sustainable Lake Trout populations. In a 2004 inshore study using towed electronic sensors, Yurista and Kelly (EPA Duluth) determined spatial patterns in temperature, specific conductance, percent light transmittance, fluorescence and zooplankton biomass. Comparisons with fixed point samples indicated that the technology can provide rapid high-resolution assessment of water quality and plankton in the Great Lakes. In a sole benthos chapter, Scharold et al. (EPA Duluth, NOAA-GLERL) examined the status of benthic macroinvertebrates in inshore US waters. Changes in abundance and community composition were evaluated in 1994, 2000 and 2003 and indicated that the assemblage was stable over the period.The importance of the fish community in Lake Superior is highlighted with the inclusion of three chapters. Changes in the nearshore fish community were monitored by Gorman and Hoff (Ashland Biological Station) during 1978 to 2003. From low levels in the mid 1900s (Lawrie and Rahrer, 1972), native Lake Trout and Lake Herring stocks have recovered in the past 20 years. However, the authors predict that community biomass will continue to fluctuate, possibly with a downward trend. In a multivariate analysis of the ten predominate taxa of the benthic fish community in western Lake Superior during 1972 to 1995, Hoff determined three significantly different assemblages in shallow, intermediate and deeper depths. He concluded that management objectives could be developed for each assemblage and taxa. Mandrak (Fisheries and Oceans Canada) reviewed the past and present fish fauna in Lake Superior and offered predictions for the future. Diversity of the fauna is the lowest in the Great Lakes. The author described how the fauna has changed over time and why. About one-third of the paper is devoted to future fauna. Some native species will be lost and some non-native species will be gained in response to habitat degradation, augmentation of invasion vectors and expansion of distribution ranges through climate warming.Bird life in the Lake Superior watershed is addressed in two chapters. Hoff (Ashland Biological Station) and Van Stappen (National Park Service – Bayfield) analyzed breeding bird community structure and trends in abundance in the Apostle Island area during 1991 to 2000. Some species are declining due to loss of specific habitats. The authors recommend that land managers emphasize conservation of specific forest, savanna, and sandscape areas in the Apostle Islands, Lake Superior basin and the U.S. Morris (Brock University) and others (Canadian Wildlife Service) review census and distribution data on five species of colonial waterbirds nesting in Canadian and US waters of Lake Superior from 1976 to 2000. Abundance of all five species increased but with wide variation in the annual increase rate. Of concern is the substantial increase in the number of breeding pairs of Double-Crested Cormorants (as in the other Great Lakes) and the authors suggest the need for management protocols.Tim Johnson (OMNR) has provided a valuable synthesis of trophic linkages in the Lake Superior food web using empirical and modelling information from 1970 to 2003. Results of early studies by the Upper Lakes Reference Group were summarized in IAGLR (1978). Our understanding of the biota and trophic relationships has increased greatly since then but Johnson considers that knowledge of lower trophic levels remains weakest.The volume includes a taxonomic index, useful to those seeking species information, and a subject index. The editing throughout the book has been tight.In the Foreword to the volume, Henry Regier, CM, has written an elegant excursion into origins and uses of the term ‘ecosystem’ and its application to Lake Superior. In the Preface, Jim Kitchell exhibits his comprehensive knowledge of the lake. It is noteworthy that his contributions to the science of Lake Superior are referenced in many of the chapters. Dr. Munawar has dedicated the book to Richard Vollenweider, his mentor, and to Ginette Dupuis, a co-recipient with him of the Chandler-Misener Award.The authors, the editors Drs. M. Munawar and I.F. Munawar, and the editorial staff are commended for this excellent addition to the Great Lakes series. Many of the chapters include long-term data sets. As a champion of the importance of historic data, the late Kenneth Loftus, former Director of Fisheries Research (OMNR), would be pleased.J. LeachResearch Scientist Emeritus, Ontario Ministry of Natural Resources, joeleach@sympatico.ca

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