105.1 Saturday, Jan. 7 Cold-exposure compromises feeding resistance toward seaweed secondary metabolites in the sea urchin Arbacia punctulata. CRAFT, Jonathan D*; DELORENZO, ME; SOTKA, EE; College of Charleston email@example.com
Ambient temperature and plant secondary metabolites are common stressors for herbivores, but there are more examples of their independent, rather than combined, effects. We assessed whether evolutionary history, temperature, and seaweed secondary metabolites could explain feeding behaviors in subtropical (27°N) and temperate (41°N) lineages of the sea urchin Arbacia punctulata. We simultaneously acclimatized individuals of both lineages to three temperatures (15ºC, 22ºC and 27°C) and measured feeding in response to Dictyota pulchella metabolites. Temperate individuals ate lower proportions of D. pulchella-coated food than did subtropical individuals, and the proportion was consistently low across all temperatures. Subtropical individuals consumed less D. pulchella-coated foods when held at 15ºC relative to 22ºC or 27ºC. When isolated with either control or D. pulchella-coated foods, the consumption rates of temperate urchins were additively decreased by D. pulchella secondary metabolites and decreasing temperature. Whereas these factors caused a synergistic decrease in the feeding rate of the subtropical urchins. The feeding rates and preferences of subtropical individuals were reduced at 15ºC relative to warmer temperatures. Subtropical A. punctulata rarely experience temperatures below 19ºC, thus, this population may have been cold-stressed. Cold-stress was independently suggested by higher glutathione S-transferase levels in Subtropical urchins at 15°C than at 27°C. Thus, subtropical A. punctulata are more resistant to metabolites of the tropical D. pulchella than temperate individuals, and cold-stress can compromise this feeding resistance.