The Biology of Sea Turtles, volume III

It's getting better! This is not surprising considering the highly skilled team of editors and authors; the third volume of Biology of Sea Turtles should be on the shelf of every sea turtle biologist. The book is presented in 16 chapters, covering many aspects, from morphology to physiology and genetics, to organic pollutants and fisheries bycatch mitigation. Previous volumes have inspired many sea turtle scientists and conservation practitioners, myself included. When reviewing the third volume my first steps in sea turtle ecology came to mind, back to 1997 while still an undergraduate student, reading the recently released inaugural volume (Lutz & Musick 1997). At that time I was enthusiastic while reading the landmark chapter 8, by Bjorndal (1997) on foraging ecology and nutrition of sea turtles, which guided my earlier career on the dietary studies of sea turtles). Chapter 15 (Lutcavage et al. 1997) on human impacts, had a similar effect as it was also a reference point for my earlier studies on pollution and turtles. With similar enthusiasm, researchers have now updated several of these topics in the third volume, for instance Jones & Seminoff revise feeding biology in Chapter 9, and Heithaus in Chapter 10 deals with a different perspective of a similar subject: sea turtles as prey, consumers, and their ecological role in marine ecosystems.

The number and range of global locations of researchers studying sea turtles is vast, resulting in an immense and diverse body of knowledge having been produced from 1996 to 2013, the period between volumes I and III. As a consequence, important new findings are included in this latest volume, several based on methodologies only used intensively on sea turtle ecology in recent times, such as stable isotopes and trace elements. The growing use of remote sensing devices for tracking and collecting behavioural data, such as diving and general activity patterns, despite not being treated in a separate chapter, permeate many chapters. Such methods have been instrumental in clarifying poorly known aspects, such as the “lost years”. The current volume reports for the first time on marine tracking of neonates and early stages up to 7 months, providing some answers for very old questions (Mansfield & Putman, Chapter 8).

Topics that had received much attention from researchers in recent years, such as skeletochronology (Chapter 5), fisheries bycatch (Chapter 12), natal homing and imprinting (Chapter 3), sea turtle health (Chapter 14), and genetics (Chapter 6), treated briefly or with different perspectives in volumes I and II, having been updated in the current volume. Some other hot topics such as climate change are now covered, while traditional research areas, such as epibionts (Chapter 15) and parasites (Chapter 16), had to wait until volume III to receive specialized attention, with in-depth revisions. In addition, several chapters are richly illustrated with color figures, of note is Chapter 16 with illustrations of parasites, and Chapters 7 and 8, both with nice maps depicting tracking and oceanic habitats of leatherback Dermochelys coriacea (Vandelli, 1761), and loggerhead Caretta caretta Linnaeus, 1758, respectively.

Looking at the three volume series of Biology of Sea Turtles, clear developments in the field can be seen, with a range of paradigms being revisited and revised in the last volume, for instance ontogeny and individual specialization. The understanding of diet, once regarded as strictly defined for each species, has changed: now we know that adult green sea turtles, Chelonia mydas (Linnaeus,1758), are not strictly herbivorous, hawksbill sea turtles, Eretmochelys imbricata (Linnaeus, 1766), are not strictly spongivores, with some populations relying heavily on algae (Chapter 9, see also Bell 2013). Similarly, the generalized concept of the life-cycle, with the supposedly iconic change from offshore to neritic habitats, is now recognized to be much more variable, with considerable diversity among and within populations in the oceanic-coastal paradigm; for example, some individual adult and large subadult green and loggerhead sea turtles commute between these major marine environments. Additionally, adult leatherbacks frequently inhabit continental shelf waters off eastern Canada as well as eastern and western USA, instead of remaining exclusively in pelagic habitats, as was once thought. Although it is still useful to classify individuals or populations as inhabiting certain categories of marine environments, individual specialization and differences in habitat use are significant variants from the conventional paradigm (e.g. Mansfield & Putman, Chapter 8; Saba, Chapter 7).

The nationalities of the 33 authors, are strongly biased with 31 (94%) from the USA or Australia; only one author is from Europe and another one (or two, labeled with both Europe and South America affiliation) from South America. Despite the fact that many sea turtle researchers usually carry out studies in several countries during their careers, it is not surprising that study cases and bibliography are strongly skewed towards colleagues from the same country as authors and the editors. A broader geographic representation in authors would certainly benefit future publications of this nature, perhaps by including co-authorship from different places, which would facilitate including different points of view. There are very few minor mistakes, but a few that warrant mention are some references quoted in text, but lacking in bibliographic lists (e.g. Chapter 9), format problems such as table alignment (e.g. bottom of Table 9.3), and conceptual mistakes, e.g. in Table 9.2 “… Xeric (i.e., wet [sic]) habitats … mesic (i.e. dry [sic]) habitats”.

All three volumes, and the third in particular, end with recommendations for further research, the need for methodology improvements and key questions to be addressed. This is a valuable approach, and it makes the current volume a valuable guide, as well as an inspiration, for the current and next generation of sea turtle scientists.

Overall, in my opinion the current book should be compulsory reading for researchers, managers and conservationists who deal with marine turtles and their habitats. I cannot wait until vol. IV is available! Maybe in the future, among other new topics, or old ones still not fully covered in previous volumes, we will learn that “lost years” are no longer a black box, and hopefully we will read a chapter consolidating cases for encouraging upward trends in abundance of sea turtles, as already seen for some populations.

Leandro Bugoni

Professor of Ecology

Universidade Federal do Rio Grande – FURG

Rio Grande, RS, Brazil

Waterbird and Sea Turtle Laboratory

Email: [email protected]

© 2014 Leandro Bugoni