Meeting Abstract

28.1  Monday, Jan. 4  Determining diet over multiple timescales: isotopic turnover in mantis shrimp DEVRIES, M. S.*; LU, S.; MARTíNEZ DEL RIO, C.; DAWSON, T. E.; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of Wyoming; Univ. of California, Berkeley msdevries@berkeley.edu

The mantis shrimp species Neogonodactylus bredini (Stomatopoda) produces high accelerations and forces with hammer-like raptorial appendages that are thought to be specialized for smashing hard-shelled prey. Yet preliminary observations suggest that N. bredini consumes both hard- and soft-bodied prey. Stable isotope analysis (SIA) of different tissue types has been used to track changes in vertebrate diet over time, because different tissues assimilate nutrients, or “turnover,” at different rates. We tested whether muscle and hemolymph in N. bredini also exhibited different turnover rates. We measured how long it took for a known prey item to assimilate into the tissues by feeding individuals solely a marine snail, Tegula funebralis for 290 days and by periodically dissecting out muscle and hemolymph tissues for SIA of carbon and nitrogen. We then fit an isotopic incorporation model to the change in isotopic value for both tissues. A one-compartment model of turnover was well-supported by the data and revealed that average (±SD) incorporation of delta¹³C and delta¹⁵N was much faster in hemolymph than in muscle but that nitrogen was retained longer than carbon (delta¹⁵N = 52.3±21.5 days in muscle and 15.2±6.0 days in hemolymph; delta¹³C = 47.9±30.8 days in muscle and 3.8±2.2 days in hemolymph). Carapace length and weight did not change, suggesting that incorporation rates were due to catabolic turnover. To our knowledge, this study is the first to show different turnover rates between two tissue types in invertebrates. Short and long turnover rates allows for determining diet over short and long timescales in one individual. This technique will yield novel insights into whether N. bredini’s unique appendage morphology narrows or widens diet breadth over time.