Coastal Lagoons – Critical Habitats of Environmental Change. Edited by Michael J. Kennish and Hans W. Paerl
Boca Raton, FL, CRC Press, Taylor & Francis Group, 2010. 558 pp., ISBN 978-1-4200-8830-4. US$95.96 (hardback)
This book forms part of the popular CRC Press Marine Science Series and is edited by two leading estuarine and coastal scientists from the USA, namely Michael Kennish and Hans Paerl. The contents of the book were largely dictated by papers presented at the nineteenth Biennial Conference of the Estuarine Research Federation held at Rhode Island in November 2007 during a special session titled Human and Climatic Factors Affecting Eutrophication of Coastal Lagoonal Systems. Not surprisingly, the overwhelming majority of the contributors to the book are from North America, especially the east coast, with some important chapters from scientists based in Europe and Asia. Only two of the 20 chapters are from the Southern Hemisphere (South America and Australia), which reflects the fact that only seven of the 93 contributors to the book are from south of the Equator. Consequently the insights provided by the book into environmental change in coastal lagoons are biased towards the Northern Hemisphere but are, I suspect, just as relevant to similar ecosystems in the Southern Hemisphere. Despite the above limitation, I have no hesitation in recommending the purchase of Coastal Lagoons by estuarine and coastal scientists and tertiary institution libraries around the world.
As would be expected from a special session on eutrophication in coastal lagoons, there are a number of case studies which show unequivocally that many lagoons around the world are experiencing severe eutrophication, and that overall this problem is escalating rather than declining. The case studies cover both natural and human-induced changes, especially the chemical and ecological responses to pollution and nutrient enrichment. There is a strong emphasis on indicators of eutrophic conditions as well as the influence of natural drivers of ecosystem change such as storms and droughts. The use of innovative tools and approaches in an attempt to assess both natural and human driven change is to be commended, especially as the separation of the ecological responses due to these two drivers is often very difficult to determine with a high degree of certainty. Despite these difficulties, most chapters in the book tackle the issue of natural and/or anthropogenic induced change from a strong scientific base and leave the reader with a much better understanding of the issues influencing the study systems. Unfortunately, very few chapters follow these changes beyond plants (phytoplankton, microphytobenthos, macroalgae and/or submerged macrophytes) and those that do tend to deal with the impacts on invertebrates, fishes or birds in a fairly superficial manner. This is probably largely attributable to the difficulties and complexity of tracing the exact impacts of eutrophication on higher trophic levels and also to the lack of suitable field and laboratory data on these components.
The book contains numerous examples of biotic and habitat responses to changing conditions in estuarine lagoons. Chapter 2 highlights the differential impacts of increasing tropical storms and hurricanes on phytoplankton community composition and productivity in Pamlico Sound; Chapter 3 investigates the interplay between benthic microalgae and macroalgae and hypothesizes that increased eutrophication will favour macroalgal development and thereby reduce the role of nitrogen uptake by microalgae in Virginia coastal bays; Chapter 5 places an emphasis on the very varied responses by phytoplankton to a range of nutrient loading scenarios that lead to blooms in both lagoons and river-dominated estuaries; Chapter 6 takes the effect of long-term hazardous algal blooms one step further and documents increasing concentrations of brown tide in Laguna Madre associated with decreasing abundance, biomass and diversity of the macrofauna; Chapter 8 highlights seagrass decline in selected New Jersey coastal lagoons associated with increasing eutrophication and the development of phytoplankton and benthic macroalgal blooms; Chapter 10 tracks the shift in southern California lagoons from phytoplankton and microphytobenthos-based systems towards a macroalgal-dominated community, primarily as a result of increased nitrogen loading from highly developed catchment areas; Chapter 11 documents the increasing anthropogenic nutrient enrichment of some coastal lagoons in Egypt's Nile Delta and makes the point that, although some of these lagoons are still productive, they are close to tipping points. Chapters 12–16 and 19 provide a similar message of increased nutrient loading and eutrophication of coastal lagoons in America, Europe and Asia. Chapters 17 and 20 follow a slightly different approach and emphasize the role of freshwater inflow on nutrient loading and ecological processes within the Patos Lagoon and various Texas lagoons, respectively.
One of the advantages of a book of this nature is that it brings together the recent work of leading experts in the field of coastal lagoon research into one volume. Although each chapter tends to focus on a particular system or aspect of research within this field, the major findings of these chapters are neatly summarized by the editors who also provide an overview of the knowledge and challenges that face scientists and managers who work in these important and often highly impacted ecosystems. In particular they provide a very useful table that lists six major and six less serious stressors on estuaries, including coastal lagoons, and which pose a threat to the ecological integrity of these systems. This table serves to focus the attention of scientists towards the issues that really matter, thereby mapping out the areas that require priority research attention if we are to achieve lasting health and viability of our coastal lagoons. The establishment of Long-Term Ecological Research sites, as proposed by Philippart and Epping in Chapter 16, is also fully supported. Not only will such sites provide long-term monitoring opportunities, they should also act as focal points for field experiments and the teaching of how changes in nutrient inputs brought about anthropogenic activities impact on ecosystem functioning.
An issue that this book raised for me was the diverse nature of coastal lagoons and the very loose definition that appears to be applied to these systems. When compared with other aquatic habitats, coastal lagoons (as defined in Chapter 1) seem to range from marine dominated systems that are separated from the sea by only a series of islands, through a series of true estuarine lagoons, to freshwater lagoons that were once connected to the sea but are now permanently isolated from the marine environment by vegetated dune barriers. Clearly the structure and functioning of lagoons at the two extremes of this continuum are very different and could almost be likened to the differences between an estuary and a freshwater coastal lake. Perhaps the time has come to separate out the different types of coastal lagoons using new terminology that recognizes these fundamental differences. These new definitions will hopefully lead us to the conclusion that systems such as Virginia coastal bays and the Wadden Sea, although important transitional waters, should not be classified as coastal lagoons. In the meantime, this book provides us with a wonderful insight into the range and complexity of these fascinating coastal habitats, and highlights the challenges that we face in maintaining the ecological integrity of these systems in the face of increasing anthropogenic disturbances.
Alan K. Whitfield
Chief Scientist
South African Institute for Aquatic
Biodiversity (SAIAB)
Grahamstown, South Africa
E-mail: [email protected]
© 2011 Alan K. Whitfield