What is a Bone Atlas?

To understand the trophic structure of an ecosystem one needs to identify not only the ‘eaters’ but also what has ‘been eaten’. Tracey Sutton is leading work to develop a unique valuable tool to facilitate this process.

By Elinor Bartle with Tracey Sutton and Amy Heger.

Information about what has been eaten is gleaned from gut-contents studies. Unfortunately, although many fish swallow their prey whole, this does not often remain “whole” but the time the contents are actually studied. Prey items such as fish contain indigestible parts such as bones, teeth, eye lenses etc.

Tracey Sutton is leading a project to quantify information about the indigestible matter in gut contents by documenting images of a large collection of “indigestible” fish material to make a reference – a “Bone Atlas” – to facilitate this difficult identification work.

The experienced engineering and technical staff at Bergen Museum began the work by selecting fishes from the huge G.O.Sars collection from summer 2004. After being measured and documented, each fish was placed in a special solution that dissolved the flesh leaving nothing but bones and indigestible material.

The fragments include jaw bones, teeth, cranial bones, otoliths and eyes. Much of this material is species-specific in terms of shape, number of teeth etc. Researchers are working to determine defining characteristics for all the various bone fragments.

“It is like fingerprinting,” explains Sutton. This preparatory work is a tremendous project and since the summer of 2004 about 340 specimens have been prepared including over 200 species.

The next step in the “Atlas” work is to make the material more universally accessible because few researchers can afford to actually come to Bergen Museum to examine the bones directly.

Amy Heger was in the final stages of her PhD work when the MAR-ECO participants met for the annual meeting summer 2006 in Aberdeen. At some of the group meetings she heard about the idea for the “Bone Atlas” project and volunteered to help with its realization.

Heger came to Norway January 2007 to work with Sutton for several weeks. She was responsible for photographing the individual bone fragments for the catalogue.

Professor Endre Willassen and Dr. Jon Kongsrud kindly allowed her to utilize their high-resolution digital macro-photography setup for this endeavor. The camera was linked to software that enabled photographs to be automatically viewed, named and organized into folders.

Over the course of two weeks Heger photographed and catalogued the bones selected by Sutton as “diagnostic for the species.”  At the same time, Sutton studied the bones under the microscope, making detailed measurement for length/weight relationships and searching for characteristic features.

When finished the Atlas will be an invaluable reference for researchers building up more complete trophic pictures of life in the open ocean and deep sea.

In addition to support from the MAR-ECO Project, this work was funded by:

• US National Science Foundation Biological Oceanography Program
• Norway-America Marshall Fund Program