AB 6:289-302 (2009)  -  DOI: https://doi.org/10.3354/ab00126

ABSTRACT: To examine the trophic relationship between the sea squirt Halocynthia roretzi and the Pacific oyster Crassostrea gigas cocultured in suspension, their δ¹³C and δ¹⁵N values were monitored monthly on the southern coast of Korea for a period of 2 yr. Suspended particulate organic matter was fractionated as coarse (>20 µm, CPOM) and fine particles (<20 µm, FPOM), and the seasonal variations in the δ¹³C and δ¹⁵N were determined. CPOM δ¹³C was slightly more variable than FPOM δ¹³C over the sampling period, whereas δ¹⁵N varied less for CPOM than for FPOM. Co- and monocultured sea squirts had a less variable δ¹³C, but a more variable δ¹⁵N than cocultured oysters over the sampling period. The δ¹³C and δ¹⁵N of cocultured sea squirts were consistently lower than those of cocultured oysters. The more pronounced difference in the δ¹³C between the cocultured suspension feeders was attributed to a striking isotopic change in oysters during their autumn to winter growing period. Differences in the δ¹³C were significant between co-, monocultured, and wild sea squirts, but not between co- and monocultured oysters. These suspension feeders can use different POM size fractions within the same habitat. The marked ¹³C-enrichment in oyster tissues, particularly during their fast growing period, may result from their strong selectivity of diatoms. In contrast, both the ¹³C- and ¹⁵N-depleted values in cocultured sea squirts indicate the importance of pico-/nano-size fractions as their dietary components. Size-related patterns in food resource exploitation between the cocultured suspension feeders may be due to different particle capture mechanisms.

KEY WORDS: Halocynthia roretzi · Crassostrea gigas · Coculture · Stable isotopes · Trophic relationship · Food partitioning

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Cite this article as: Kang CK, Choy EJ, Hur YB, Myeong JI (2009) Isotopic evidence of particle size-dependent food partitioning in cocultured sea squirt Halocynthia roretzi and Pacific oyster Crassostrea gigas. Aquat Biol 6:289-302. https://doi.org/10.3354/ab00126 Export citation Share:    Facebook - - linkedIn