. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 46 CLARK ET AL. 200 ^100 6 o> E x o o>. 15 20 25 30 TEMPERATURE (°C) 35 15 IO 0 500 1000 1500 IRRADIANCE JJE m2 s1 FIGURE 3. (Left) Effect of temperature on net alcohol-soluble (AS), net alcohol insoluble (AI) and dark (AI + AS) carbon fixation by Costasiella lilianae. (mean ± SD, n = 6). FIGURE 4. (Right) Effect of light intensity on carbon fixation rate in Costasiella lilianae. Regres- sion line calculated for interval of 25-1 5,000 ^t-m~2-s"' by method of least squares with semilogarithmic transformation: y = 2
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 46 CLARK ET AL. 200 ^100 6 o> E x o o>. 15 20 25 30 TEMPERATURE (°C) 35 15 IO 0 500 1000 1500 IRRADIANCE JJE m2 s1 FIGURE 3. (Left) Effect of temperature on net alcohol-soluble (AS), net alcohol insoluble (AI) and dark (AI + AS) carbon fixation by Costasiella lilianae. (mean ± SD, n = 6). FIGURE 4. (Right) Effect of light intensity on carbon fixation rate in Costasiella lilianae. Regres- sion line calculated for interval of 25-1 5,000 ^t-m~2-s"' by method of least squares with semilogarithmic transformation: y = 2608 log x + 2750, where x = DPM, y = intensity; r = .47. Relationship highly significant at p < .01. tions are believed to represent short chain (AS) and long chain (AI) photosynthetic products (Grant et al., 1976; Howard et al., 1977). Long-chain fractions are presumably used for structural synthesis (Grant et a/., 1976; Howard et al., 1977; Stirts and Clark, 1980). Hence, diversion of pho- tosynthates to somatic growth and gametogenesis is probably temperature depen- dent. Stirts and Clark (1980) noted similar thermal effects for Elysia tuca Marcus and Marcus. Dark fixation did not vary significantly with temperature (Fig. 3). Light intensity effects Carbon fixation approached saturation at fairly low irradiance levels, about 500 Ht-m~2-s~\ a third of peak in situ levels (Fig. 4). Fixation was substantial even at low intensities (25 ^-m~2-s~l), suggesting that light intensity is a minor limiting factor under natural conditions. No inhibition was noted at the highest irradiance levels. Digestive gland anatomy and fine structure A single duct of the digestive gland extended into each ceras (Fig. 5A) where it branched into a grape-like cluster of sacs. The diverticular sacs were lined by cells (Type 1) 20-30 yum wide, containing the plastids (Fig. 5B). Light microscopy showed the plastids as 3-7 jum bodies containing a single dark-staining pyrenoid. A second cell type (Type
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
