P3.114 Friday, Jan. 6 Magnitude of specific dynamic action response in larvae of the sea urchin Lytechinus variegatus GENOVESE, C.B.*; MORAN, A.L.; Clemson University; Clemson University email@example.com
Specific dynamic action (SDA) is defined as an increase in the metabolic response of an organism following a meal. Typically, an individual’s metabolic rate will increase rapidly, peak, and then slowly return to pre-feeding levels. SDA has been attributed to an array of physical processes necessary to obtain, digest, absorb, and assimilate food. Evidence of the response has been documented in a variety of species, both vertebrate and invertebrate, with the percent increase ranging from as low as 25% to over 600% in some studies. Given that the metabolic capacity of an individual is limited, such a response may have a critical impact on the energy budget of an organism, as the energy allotted to SDA may reduce the energy available for other aerobic activities. A majority of studies on specific dynamic action have focused on adult organisms, and little research has been performed on larval stages. Planktonic larval populations determine the success of the adult population; however, relative to adult stages, few studies have attempted to describe their metabolic response to food. This study focused on the larvae of the sea urchin Lytechinus variegatus; a marine invertebrate with a broad distribution and planktotrophic, feeding larvae. Using a μBOD method to measure oxygen consumption, postprandial metabolic rates were characterized to determine the magnitude of the SDA response in the larvae. Rates were measured for 24 hours post-feeding, during which the larvae approximately doubled their pre-feeding rates. Further studies on how meal size and composition affect the response, as well as the effects of environmental conditions, will aid in our understanding of the physiological and ecological significance of the SDA response in the life histories of marine invertebrate larvae.