A Guide to Southern Temperate Seagrasses

The global decline of seagrasses has been well documented (e.g. Short & Wyllie-Echeverria 1996), with growing focus on the loss of their implicit ecological functions (e.g. Waycott et al. 2009). This guidebook provides a scientifically grounded overview of the diversity of seagrasses in the southern temperate region, with incredible illustrations of the beauty and biology of these marine plants and their ecosystem roles. This guide goes beyond the standard guidebook: species names, short descriptions and species ranges. In addition, it offers ample species-specific biological and ecological detail to guide scientists, educators, managers and members of the general public with practical information for seagrass conservation, management and restoration. It is simple to use, but contains a wealth of descriptive information.

This guide builds on the global review of seagrasses presented in The World Atlas of Seagrasses (Green & Short 2003). It highlights the speciose seagrasses of the southern temperate bioregion, which occupies a large circum-global swath of the Southern Ocean, including coastlines in Australia, South America, Africa and New Zealand (bioregions are described in the guide, along with maps).

The introductory pages to this guide provide short overviews on important themes that are carried through the remainder of the guide: seagrass biology, taxonomy, habitats, ecology, associated fauna, human interactions, reproduction, evolution and distribution. These sections are written for a general audience, and for more detailed information, a short bibliography of pertinent literature is provided. The section on habitats, as well as the instructions for using the guide, are presented in a graphical style that is successfully used throughout the book for species descriptions and comparisons. The sections on taxonomy and evolution are more detailed than the other sections and are necessary to describe the classifications used (some species are presented as ‘complexes’ because their taxonomy is currently being resolved). These sections are quick and easy to read, and lead guide users to the core pages; an identification key and species-specific descriptions, grouped by families.

The identification key is based primarily on leaf morphology, making use of general descriptive attributes that are discernible to the naked eye; no cellular-level observations are needed. The key also presents a valuable educational opportunity by describing the key structural features of seagrass plants. In addition, two glossaries are provided to further define anatomical characteristics of these plants, and introduce the readers to seagrass terminology. The pictorial glossary is particularly well illustrated, and provides very good descriptions of plant parts, as well as important features such as reproductive structures. Great care has been taken to ensure that terminology, especially that used in the key, is well defined in the glossary. This will help to make this an important reference for practitioners and educators of marine biology and ecology.

The remainder of the guide follows from the key and homes in with more detailed information on particular Southern Ocean species grouped and colour-coded by common lineage: Cymodoceaceae, Posidoniaceae, Ruppiaceae, Hydrocharitaceae, Zosteraceae, Potamogetonaceae. In all, 21 species are described, including three ‘complexes’. For each, a brief species overview is provided, followed by more detailed information on species taxonomy/morphology, reproduction/seed morphology, distribution, habitat characteristics, key plant characteristics and their distinctive features. This provides critical biological information for managers, and important comparisons between species, which is critical for the mixed-species meadows that exist in southern temperate regions.

For all species groups, excellent illustrations demonstrate the diversity of plant forms. Even the least studied and less ornate groups are captured in glorious underwater imagery. For me these photographs, as well as the hand-drawn biological illustrations, were a highlight of this book. The detail and accuracy of the illustrations is impressive, and the two opaque inlays provide an artistic flourish to the guide. The illustrations are purposefully incorporated to highlight anatomical features in a manner that isn’t normally possible with most photographs. Similarly, great care has been taken with the graphics used throughout this book. These provide a comparative cross-species thread, linking their ecological role and evolutionary histories.

The care taken to assemble this guide is apparent, and the authors have clearly put their life’s work into seagrass science, as evidenced by the book’s foreword and preface. As a northern temperate seagrass ecologist, this guide made me yearn for an equally detailed guide to northern species. Until the publication of this guide, no concise field guides have been developed specifically for seagrasses that I am aware of. This book could easily provide a template for similar guides to other bioregions; however, they would likely have to be grouped into one or two editions, as the diversity in other regions is not nearly as great. With 40% of the global diversity, clearly the Southern Ocean was a good place to start, and this user-friendly guide provides a much-needed tool for the description, categorization and appreciation of seagrass species and their associated communities.

Margot Hessing-Lewis

Research Faculty Hakai Beach Institute, Calvert Island, BC, Canada

E-mail: [email protected]

© 2014 Margot Hessing-Lewis