Flexibility of size of gills and palps in the Sydney rock oyster Saccostrea glomerata (Gould, 1850) and the Pacific oyster Crassostrea gigas (Thunberg, 1793)

• Main Authors: Honkoop, PJC, Bayne, BL, Drent, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2003
• Subjects: gill size; growth; oysters; palp size; phenotypic flexibility; species comparison; SUSPENSION-FEEDING BIVALVES; FILTRATION-RATE; PALLIAL ORGANS; MYTILUS-EDULIS; IN-VIVO; MUSSEL; COMMERCIALIS; BEHAVIOR; SESTON; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://hdl.handle.net/11370/f091f651-ed3d-4c7b-9b5c-f99bf9449aa8; https://research.rug.nl/en/publications/f091f651-ed3d-4c7b-9b5c-f99bf9449aa8

in some estuaries along the East Coast of Australia, the native Sydney rock oyster, Saccostrea glomerata, and the introduced Pacific oyster, Crassostrea gigas, live together in the same areas. Generally, growth of C. gigas is faster than that of S. glomerata. A study was done to reveal whether morphological differences of the main feeding organs, the gills and palps, could explain differences in rate of growth. Held at three different stocking densities, oysters were regularly sampled during a period of 9 months. On each of four sampling times, the ash-free dry mass (AFDM) of the gills (which is related to gill area and pumping rate), palps and of the remaining tissues was measured. Subsequently, the relative mass of gills (mass of gills/total mass) and palps (mass of palps/total mass) and the gill-to-palp ratio were determined. Density had no effect on these parameters, suggesting that an expected smaller supply of food at high densities did not result in larger gills to be able to collect more food per unit time. Mass of gills and palps, as well as their relative mass, were variable in time; increases as well as decreases were observed, indicating that sizes of gills and palps were flexible and thus were not a constant proportion of total body mass or related to size of shells. Differences between species were most striking. Although both species could change the size of gills and palps, the variability of these over time was much larger for C. gigas than for S. glomerata. This suggests that C. gigas may respond better to changes in its environment than S. glomerata. The gill-to-palp ratio of S. glomerata was constant over time, whereas it was variable for C. gigas. Relatively larger gills mainly caused this variability. It was shown that the ratio of S. glomerata was independent of total body mass, whereas lighter C. gigas had a much larger ratio relative to heavier individuals. This means that light (but not necessarily small) C. gigas are able to collect more food per unit time than larger ones. In both ...