Meeting Abstract
P3.69 Thursday, Jan. 6 Jaw muscle fiber type distribution in Hawaiian gobioid stream fishes: Histochemical correlations with feeding ecology and behavior MAIE, T.*; MEISTER, A.B.; LEONARD, G.L.; SCHRANK, G.D.; BLOB, R.W.; SCHOENFUSS, H.L.; Clemson Univ.; St.Cloud State Univ.; St.Cloud State Univ.; St.Cloud State Univ.; Clemson Univ.; St.Cloud State Univ. tmaie@clemson.edu
Differences in muscle fiber type distribution for axial muscles of Hawaiian gobioid stream fishes have previously been linked to differences in locomotor performance and behavior. Similarly, different feeding styles among these gobies may be, at least in part, related to fiber type differentiation in their jaw muscles. Diet and feeding styles found among these gobies are diverse, including an algae-grazing specialist (Sicyopterus stimpsoni), opportunistic omnivores (Lentipes concolor and Awaous guamensis), a detritivore (Stenogobius hawaiiensis), and a piscivorous predator (Eleotris sandwicensis). Using ATPase assays, we examined muscle fiber types of the sternohyoideus and adductor mandibulae (A1, A2, and A3) across all five species. These muscles exhibited consistent differentiation in fiber type across species. For example, A2 had a greater proportion of white muscle fibers than A3 in all species. This distinction between A2 and A3 function differs from that shown by comparisons of lever mechanics, in which A3 has a greater velocity advantage in all five species. One distinction found among the species was that A. guamensis and S. hawaiiensis had a lower proportion of white muscle fibers in all jaw muscles than L. concolor, S. stimpsoni, and E. sandwicensis. The latter three species may share a higher proportion of fast-twitch muscles related to the demands of rapid predatory strikes or feeding in fast water. Thus, like the axial muscles, the different functional demands posed by variation in the feeding styles of Hawaiian stream gobies may be reflected in the proportions of muscle fiber types. NSF grants IOS-0817911, IOS-0817794.
