Life Science Mass Spectrometry Facility
Investigating dietary niche width of beaked whales in the north Atlantic using stable isotopes
What Are Beaked Whales?
Beaked whales remain one of the least known families of large mammals. With an oceanic distribution and very long, deep foraging dives, it is inherently difficult to study their dietary preferences directly. Stomach contents analysis can provide some information on the types of prey consumed. However, such sources of data are not only few and far between but also subject to various unquantifiable biases. In particular, when an animal dies from an illness, it will not be certain that it fed normally immediately prior to death.
How Can Stable Isotope Analysis Help?
Stable isotope analysis provides a means to investigate foraging ecology that is not subject to the same types of biases as stomach contents analysis. In addition, as bone samples can be analysed, a large number of samples can be obtained from museum collections.
There was a positive relationship between body size and the d15N ratio which is an indicator of trophic level. This suggests body size plays an important role in determining the trophic level and prey size consumed by individual beaked whales. Moreover, it suggests that species can only co-exist it they have different body sizes, and therefore consume different sizes of prey. When the data from different species were compared, this was found to be correct and North Atlantic beaked whales could be divided into two groups, those that consume larger prey and those that consume smaller prey. Members of these two groups can occur in the same place at the same13 September, 2005
For more details contact:
Colin D. MacLeod,
School of Biological Sciences (Zoology),
University of Aberdeen,
Aberdeen, AB24 2TZ,