Meeting Abstract
P3.129 Wednesday, Jan. 6 Temperature and size-dependent growth in a marine ectotherm: the green sea urchin Strongylocentrotus droebachiensis. BRASILI, A.*; JOHNSON, A.S.; ELLERS, O.; Bowdoin College; Bowdoin College; Bowdoin College abrasili@bowdoin.edu
Temperature alters growth of ectothems, but growth also depends on size. We examine the scaling of growth, size and metabolic rate of the green sea urchin, Strongylocentrotus droebachiensis. We are growing 468 urchins ranging in weight from 0.02 to 295 g (0.42-8.97 cm diameter) in six tanks at three different temperatures (7, 14 and 17oC). Urchins are weighed once per month and will be in their 5th month of growth by January 2009. There is a lag phase in the growth of the smallest urchins (< 2 cm diameter) and accordingly we use the gamma function (Ellers and Johnson, 2009) to describe growth rate as a function of size. After the first month of growth, analysis of residuals from the fit of the gamma function to the pooled data revealed significant differences between temperatures. These differences are size-dependent: the urchins still in the growth lag grew fastest at 14oC and most slowly at 7oC, whereas urchins larger than 4 cm diameter grew fastest at 7oC and most slowly at 17oC. All urchins will be past the growth lag by November, at which time we will fit the growth data with the von Bertalanffy equation, which includes anabolic and catabolic coefficients and a metabolic exponent. We expect that this analysis will show that the anabolic and catabolic coefficients have different Q10 values, and consequently, urchins will grow to smaller sizes at higher temperatures. The predicted maximums for each temperature will be compared to the actual sizes at which the urchins stop growing to test this theoretical model for growth.
