Introduction

The idea of producing a new book of seagrass methods arose from a series of meetings of the International Seagrass Biology Workshop (ISBW). The need for updated methods first emerged at ISBW-2 in Australia, 1996; Professor C. Peter McRoy expressed the need to update our knowledge of research methods through a revision of “Seagrass Research Methods” (Phillips and McRoy 1990). The concept of developing a publication of methods more broadly applicable to seagrass research in a global context was raised at ISBW-3 in the Philippines, 1998. That workshop recognised the need for an updated set of methodologies suitable for a range of environments, from tropical to temperate and from estuarine to deep water. By the time of ISBW-4, in France, 2000, the global methods book was under way and draft chapters were discussed at the meeting.

The importance of seagrasses in coastal and near shore environments, and ultimately their contribution to the productivity of the world’s oceans, has become increasingly recognised over the last 40 years. In his keynote address at ISBW-3, Professor Ronald Phillips charted the development of seagrass research from its early taxonomic and descriptive phase before the 1970s to modem ecosystem approaches. He included the key role of Professor C. den Hartog’s 1970 monograph in providing the base systematic information for much of the recent world interest and research as well as the impetus of the 1973 International Workshop in Leiden, The Netherlands in recognising seagrasses as an important ecosystem.

McRoy (1996) pointed out that these two events also reflected the two streams of research that existed at the time: a classical academic approach and an ecosystem approach. The Leiden workshop led to the development of the journal Aquatic Botany in 1975 with Professor den Hartog as editor-in-chief. The journal fostered a merging of research approaches and has acted as a springboard for the development of new seagrass research and methods. Since the Leiden workshop in 1973, seagrass research has escalated rapidly in many parts of the world but particularly in Europe, the United States, Australia, Japan and the countries of the Indo-Pacific, most notably the Philippines. Seagrass science has progressed rapidly in the last three decades with further publications and books (McRoy and Helferrich 1977, Phillips and McRoy 1980, Hemminga and Duarte 2000).

Seagrasses provide food for sea turtles, nearly 100 fish species, waterfowl and for the marine mammals the manatee and the dugong; the latter is on the IUCN red list as vulnerable to extinction. Seagrasses also support complex food webs by virtue of their physical structure and primary production and are well known for their role as breeding grounds and nurseries for important crustacean, finfish and shellfish populations. Seagrasses are the basis of an important detrital food chain. The plants filter nutrients and contaminants from the water, stabilise sediments and act as dampeners to wave action. Seagrasses rank with coral reefs and mangroves as some of the world’s most productive coastal habitat and strong linkages among these habitats make the loss of seagrasses a contributing factor in the degradation of the world’s oceans.

In his summation at ISBW-3, Professor Phillips noted that seagrasses are a semipermeable filter, a buffer between the land and the marine environment and that this filter was becoming overloaded. He expressed the need for an integrated coastal zone management approach at an international, not just a national, scale. He applauded the trend for research scientists to be involved at committee levels with policy makers, politicians, business developers and administrators of government agencies as a way of developing an integrated ecosystem approach to seagrass management.

Importantly, McRoy noted the effect on seagrass research of the terms and the concepts of biodiversity and sustainable development. Both these concepts emerged from the UN Conference on Environment and Development (UNCED), otherwise known as the Earth Summit, which took place in Rio de Janeiro on 9-14 June 1992.

In the first decade of the new millennium, it is clearly time to approach seagrass ecology issues from an integrated and global perspective and to understand the role each country can play. The importance of a global approach is encapsulated in the 1992 Rio Declaration on Environment and Development, Principle 7 that says in part: “States shall cooperate in a spirit of global partnership to conserve, protect, and restore the health and integrity of the earth’s ecosystems.”

The discussions on producing a methods book for global seagrass research at ISBW-3 resulted in many scientists volunteering to contribute chapters. The vision was to provide the opportunity for seagrass scientists to publish a set of methods that would promote and stimulate seagrass research worldwide, to include both taxonomic and other academic approaches, address issues of coastal management, habitat quality and estimation of change and mapping, and provide a set of tools to study various aspects of seagrass as a functional ecosystem. Foremost in the group discussion was the spirit of global partnership and the dream of being able to initiate coordinated global seagrass monitoring (e.g., SeagrassNet and Seagrass-Watch) and, in the future, to produce a meaningful “Seagrass Global Report Card” based on standard methodologies.

As editors, our approach has been to ask for the most globally useful techniques, not necessarily the newest methods or those requiring equipment available only to the economically privileged. To meet the real world limits of page length, we asked authors to present the most useful primary methods and to reference other techniques considered important. In editing we have tried our best to make the information relevant to as much of the planet as possible, discouraging methods that need chemicals not widely available or destructive field collection not permitted in some countries. We assembled 51 authors from around the world, representing temperate and tropical areas as well as both hemispheres, to produce a useful and comprehensive a set of seagrass research methods.

The book is organised into three sections. The first section has three chapters that discuss our knowledge of the world’s seagrasses. Chapter 1 summarises the current world distribution of seagrass and the gaps in our knowledge of distribution. It lists, for the newcomer to seagrass research, which of the seagrass species (from five Families: Zosteracea, Posidoniaceae, Cymodoceaceae, Hydrocharitaceae, and Ruppiaceae) can be expected within 10 geographic regions and discusses the factors that influence seagrass distribution from several perspectives, including physical parameters and anthropogenic stressors. Chapter 2 provides a key and descriptions of the seagrass species. The actual number of seagrass species is a matter of debate, depending in part on their proximity to the marine environment and on the level of discrimination in physical taxonomy and genetics. There are unresolved differences of opinion among seagrass scientists as to what species to include as seagrass. As recommended at ISBW-4, the genus Ruppia is accepted as a seagrass throughout most of the book, although not included in the classical key of Chapter 2. Species such as those of the genera Lepilaena and Potomogeton are largely freshwater species and are considered as co-occurring rather than true seagrasses and referred to as such. The defining feature of a submerged marine angiosperm is an ability to flower and produce viable fruits and seeds while submerged in the marine environment. The quantification of fruit and seed production is essential in understanding the dispersal, colonization, and recruitment dynamics of different seagrass species. Chapter 3 describes the extent of the somewhat limited knowledge of sexual reproduction in seagrasses. The chapter details the regions of the world for which we have phenological information and the large gaps in our knowledge that need to be filled.

Chapters 4 to 20 discuss the measurement of physical parameters in seagrasses, including temperature, salinity and water movement, sediment characteristics, light, and water quality. All these physical parameters regulate plant and animal activity and are often determinants of seagrass distribution.

The book closes with three chapters that examine mechanisms for sustaining and improving seagrass habitat worldwide through protection and repair. These chapters address Professor Phillip’s request that seagrass scientists develop an integrated approach to seagrass management and engage with government processes. Chapter 21 addresses mechanisms for improving the quality of the environment to better support seagrass. Chapter 22 discusses seagrass transplanting and restoration within the context of rapid coastal alterations worldwide. The book’s final chapter (Chapter 23) summarises methods used around the world to protect seagrasses, emphasising that each community, each jurisdiction, and each seagrass area is different and so it is not possible to prescribe a single formula for seagrass protection. It emphasises that to achieve protection and conservation it is necessary to elevate seagrass issues to the same level that coral reefs and rainforests occupy in a global political sense. Global concern for the seagrass environment must be matched...