. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ^ 2-° 1 i H H b ^H - - Anacortes Marina: 100-cm depth. r~ 300 Experimental tank: 5-cm depth 400 500 600 700 300 400 500 600 700 Wavelength (nm) Figure 3. Irradiances at 5, 50, and 100 cm in Skyline Marina and in the flow-through seawater tank used for laboratory experiments (5-cm depth). Due to instrument constraints, we were unable to measure the UV-B below 300 nm. Lines on the figures between 290 and 300 nm are extrapolated second-order regressions from the data for 300 to 320 nm. is that the absorbance we
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ^ 2-° 1 i H H b ^H - - Anacortes Marina: 100-cm depth. r~ 300 Experimental tank: 5-cm depth 400 500 600 700 300 400 500 600 700 Wavelength (nm) Figure 3. Irradiances at 5, 50, and 100 cm in Skyline Marina and in the flow-through seawater tank used for laboratory experiments (5-cm depth). Due to instrument constraints, we were unable to measure the UV-B below 300 nm. Lines on the figures between 290 and 300 nm are extrapolated second-order regressions from the data for 300 to 320 nm. is that the absorbance we saw came from cell secretions known as "ornaments" (Cloney, 1990). Embryonic test cells produce ornaments that are deposited on the larval tunic of C. inflata and other ascidians (Cloney and Cavey, 1982; Cloney, 1994). The ornaments are composed largely of opal, a form of silicon dioxide (Monniot et al, 1992). It is unlikely that the opal alone absorbs UV, but if the orna- ments contain other UV-absorbing substances, they might provide larvae with some protection (R. A. Cloney, pers. comm.). With little structural or chemical protection, C. inflata appears vulnerable to UV damage in all life-history stages. Embryos were the most vulnerable. Even short exposures caused developmental abnormalities; after only 30 min of laboratory UV exposure, many embryos arrested at the morula stage. This agrees with Jeffrey (1990), who also found that UV-irradiated ascidian embryos failed to gastru- late. Although embryos were most sensitive to UV, larvae, juveniles, and adults were also affected. We suggest that the unique life-history characteristics of C. inflata allow the populations to persist in shallow habitats despite this vul- nerability. n Without UV-absorbing Plexiglas With UV absorbing Plexiglas - & - Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearan
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
