Sample Processing
Gut content samples were collected via lavage (stomach pump, Artim et.
al 2017), dissection, or feces collection. Fish that were large enough
to have surgical tubing (either 6mm or 3mm outer diameter) safely
inserted were gut lavaged. They were then returned to the location on
reef where they were caught after recovering in an aerated bin of fresh
seawater. Fish that were too small to be lavaged were brought back to
the lab and humanely euthanized prior to dissection. However, when
possible, fish were placed in aerated tanks for ~24hrs
and allowed to defecate. Fecal matter was collected, and the fishes were
subsequently returned to the same area reef where they were caught.
Samples were screened with a dissecting scope. Since their chitinous
exoskeletons are not able to be digested, remnants of gnathiids
(specifically the heads, Fig. 1), can be reliably identified by any of
the sample collection methods detailed above.