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Sea turtles are at the crossroads of marine ecology, species protection, and nature conservation. And, as any crossroads, they tend to be difficult to navigate and accident-prone. These animals can therefore be taken as a case study of how we integrate our efforts at all levels and as a test of how good we have become in translating our knowledge (or lack thereof) into reasonable action. In this tack, some will say that the first step to successful management action is knowledge. Let's assume for the moment that this is true.

This book is the third volume on sea turtles in a CRC Marine Science/Marine Biology Series and is a mixture of chapters on new topics and of chapters updating the information presented in the two earlier volumes. It boasts 33 contributing authors and spans the full range from anatomy and physiology to fisheries bycatch and climate change. Several underlying aspects permeate the book. Almost every chapter:

  1. (a)
    emphasizes that gaining knowledge often involves invasive techniques, which are problematic due to the protected status of all sea turtle species;
  2. (b)
    uses some variation of the phrase ‘…however, we still know far too little…’ and outlines future research needs in a ‘Conclusions’ subchapter;
  3. (c)
    underlines the practical aspect of the respective topic in relation to conservation efforts.

A case in point is Chapter 1 ‘Physiology as Integrated Systems’. It for example treats the issues of cold-stunned animals and the response to oil pollution (Deepwater Horizon) as physiological components of conservation efforts. It also addresses a range of other issues, most interestingly if only briefly, amazing anoxia tolerance in relation to purported lengthy dives of days to weeks associated with seasonal burial in the seafloor substrate.

Chapter 2 (Vision) is interesting in that, considering the exposure of sea turtles to highly varied visual habitats, their eyes are not very good, for example in dim light. The phenomenon of ‘light-trapping’ – artificial lights that are directional and provide little illumination of surrounding features – is a phenomenon of clear conservation interest: it is disheartening how even ‘harmless’ lights completely mis-orient hatchlings on their way to the sea.

The ‘anatomical bread-and-butter’ chapters are rounded off by ‘The skeleton’ (Chapter 4), which stands out for its outstanding series of wonderfully illustrative CT scans – many in color and ‘3D’ – on every page. How can a chapter like this be relevant to conservation? The information presented here provides a basis for determining how to handle injured and sick turtles, e.g. surgical versus medication treatments. And a basis for answering the questions most posed to the author: ‘what bone is this?’ or ‘is what is on this radiograph/CD normal?’

A sister chapter (Chapter 14) on ‘Free-ranging sea turtle health’ deals with diseases and survivorship along with the factors determining them. This is apparently an understudied area of epidemiology and veterinary medicine. I was surprised that so little new information is available on fibropapillomatosis and that so little space was devoted to dead sea turtles and postmortem examination: more information would have been highly useful to field researchers confronted with dead adult turtles washed ashore.

This underlines a central question in sea turtle conservation: what is the use of protecting nesting beaches and promoting hatchling success if more adult sea turtles are being killed at sea than are being produced? Chapter 12 on fisheries bycatch addresses this critical issue for sea turtles (along with whales, dolphins, fish, etc.), starting with a conceptual model (p. 330). Direct mortality in various fishing gears and the issue of post-capture mortality are raised (what a surprise to read ‘another knowledge gap’…). The authors apparently see some light at the end of the tunnel and place their bets on new bycatch reduction measures, nonetheless admitting that although some fleets require and enforce bycatch reduction measures, the vast majority do not. They mention ‘integrated multi-species catch management’ and cite the Eastern Australian longline fishery, which combines satellite tracking, remote sensing, tiered fishing zones, and ‘potential economic yield given real-time quota levels’. Of course, this requires abundant high-resolution data that are difficult to develop and apply. The map of globally documented bycatch records of sea turtles (p. 336) is disquieting. The information that some of the most effective bycatch reduction technologies and strategies were invented and designed by fishers is important.

Chapter 3 on ‘natal homing and imprinting’ is interesting because our explanations for how sea turtles find their way back to natal beaches is apparently still being formulated in the framework of hypotheses! The status at the moment is that long-distance homing involves geomagnetic imprinting, with short-distance homing perhaps involving chemical cues. We can only hope that compulsory pinpoint homing does not exist because, as the authors point out, particular nesting areas are repeatedly destroyed by storms, erosion, and flooding. I was surprised that they neglect to mention the similar effect of major anthropogenic changes such as the batteries of hotels, restaurants and bars, for example on the beaches I work on in Turkey.

A key question posed by the public is why sea turtles (and saving them) are important. Chapter 10 on the ecological roles of sea turtles is an ideal source of information. Even experts might not be able to list by heart all the interesting points made here. One of the roles, that of serving as a substrate for epibionts, is treated separately in Chapter 15 (epibioisis). The full range of associations is presented (up to 200+ organisms on the loggerhead Caretta caretta for example), ranging from facultative to obligate ‘chelonophilic’ species. The conservation connection – the epibionts provide data on where the turtles foraged. These considerations lead to a conceptual model (p. 409) and a lengthy bibliography by geographic region.

Another role of sea turtles – serving as hosts for parasites – is treated in Chapter 16. Although the focus is on Florida and therefore mostly loggerheads – which as omnivores have the greatest number of parasites – the author provides an impressive list of parasites, including an astounding array of trematodes presented in color plates spanning four full pages.

A hot topic and timely contribution (Chapter 13) is that on climate change and marine turtles (which is it now, sea turtles or marine turtles?). Simply put, many marine habitats such as seagrass meadows and coral reefs, but also shallower benthic communities and the pelagic zone, will be altered according to climate change scenarios. Although sea turtles have survived several large-scale climatic and sea level changes over geological history, such processes are today being synergistically affected by the ‘human dimension’ (p. 373). Nowhere will this effect be more evident than on sandy beaches. The authors outline these facets, including severe weather events, precipitation and ocean circulation, ending – as most chapters – with management-related considerations and bemoaning the constraints to management due to a lack of knowledge on a half-dozen levels.

The remaining chapters deal with the newest information on age estimation (Chapter 5: several methods available, none perfect); molecular genetics (Chapter 6: dramatic increase in number of papers, but much still to be done in this field ‘to contribute to their conservation’; surprisingly not one mention of Chelonia mydas agassizii); the oceanic habits and habitats of leatherbacks (Chapter 7: management priority – fisheries mortality reductions in high-use areas; important data ‘virtually non-existent’) and loggerheads (Chapter 8: ‘knowledge gaps remain and many management questions are yet to be answered’); feeding biology (Chapter 9: ending in a call for more studies into diet selection and feeding physiology and incorporation of emerging techniques and technologies); and persistent organic pollutants (Chapter 11: clear exposure to POPs, where body condition must be considered; more directed studies should include endpoints important to conservation managers).

All that being said, we are clearly killing the turtles off faster than we are gaining knowledge about them, so our information is always one step behind. On one hand, this makes the book very timely, on the other, this reviewer takes exception to any interpretation that knowledge is the first step to successful action: lack of sufficient knowledge simply cannot be brought forward as a reason for minimal, cautious or no action. How much knowledge do we need to take action? Of course any information is good and can help ‘optimize’ conservation measures (i.e. getting the most for your dollar?). The reason why sea turtle populations are in dire straits, however, is not a lack of knowledge, but, to put it politely, an incorrect set of priorities or, more brutally, convenience and greed. I therefore argue here for an approach transcending knowledge and relying on human intuition and simple good common sense. We must make every attempt to minimize anthropogenic disturbance and let nature run the most undisturbed course it can. Surprisingly, this important conclusion was not drawn at the end of any chapter.

Looking forward to Volume IV!