Long-term field study of sea kraits in New Caledonia: fundamental issues and conservation

This short review focuses on the findings associated with a long-term field study on two species of sea kraits in New Caledonia. Since 2002, more than 30 sites in the lagoon have been sampled, and in most places mark-recapture was implemented. We collected detailed data on more than 14,000 marked individuals (>6000 recaptures) and used different techniques (stable isotopes, bio-logging, analyses of diet). The objective was fundamental: to examine how amphibious snakes cope with both terrestrial and aquatic environments. As access to abundant food is likely the main evolutionary driver for the return transition toward the sea in marine tetrapods, foraging ecology was an important part of the research and novel information was obtained on this subject. Rapidly however, field observations revealed the potential interest of sea kraits for conservation issues. Our results show that these snakes are useful bio-indicators of marine biodiversity; they also provide a useful signal to monitor levels of contamination by heavy metals in the lagoon, and more generally as a means of studying the functioning of reef ecosystems. Importantly, anecdotal observations (e.g., a krait drinking during rain) provided unsuspected physiological insights of general importance to fundamental problems and conservation. One of the lessons of this long-term study is that key results emerged in an unexpected way, but all were dependent on intensive field work.