Distribution pattern and interaction of two infaunal bivalves, Tapes philippinarum (Adams and Reeve) and Anomalocardia squamosa (Linnaeus) (Bivalvia: Veneridae)
Lee, S.Y. (1996). Distribution pattern and interaction of two infaunal bivalves, Tapes philippinarum (Adams and Reeve) and Anomalocardia squamosa (Linnaeus) (Bivalvia: Veneridae). J. Exp. Mar. Biol. Ecol. 201(1-2): 253-273. https://dx.doi.org/10.1016/0022-0981(96)00015-9
In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more
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| Keywords |
Distribution > Ecological distribution
Distribution > Geographical distribution > Horizontal distribution
Distribution > Geographical distribution > Vertical distribution
Fauna > Aquatic organisms > Aquatic animals > Shellfish > Marine organisms > Marine molluscs
Spatial variations
Topographic features > Landforms > Coastal landforms > Beaches
Anomalodiscus squamosus (Linnaeus, 1758) [WoRMS]; Tapes (Ruditapes) philippinarum (A. Adams & Reeve, 1850) [WoRMS]
Marine/Coastal |
| Abstract |
The vertical and horizontal distribution patterns of two infaunal bivalves, Tapes philippinarum (Adams and Reeve) and Anomalocardia squamosa (Linnaeus) were investigated on a sheltered sandy shore in Hong Kong. Tapes philippinarum occurred at significantly higher densities and occupied a deeper stratum in the sediment than Anomalocardia squamosa, which is a species protected by a much thicker shell. Both species showed an aggregated pattern of spatial distribution over the scale of 101 to 10−2 m. There was no correlation between the densities of the two bivalves nor was there any relationship between body condition and burying depth of Tapes philippinarum. However, individuals of Anomalocardia squamosa residing in the 2–4 cm depth stratum had a significantly higher condition index than their counterparts in the 0–2 cm stratum. The three-dimensional distribution pattern of the two bivalves in relation to density and presence of the other species was investigated by using tagging experiments in the laboratory whereby the exact three-dimensional position of the individuals was recorded in the form of an x,y,z coordinate. The same relative vertical distribution pattern of the bivalves as in the field was maintained while nearest neighbour analysis using the three- (x,y,z coordinates) or two-dimensional (only the x,y coordinates) data yielded different conclusions about the distribution pattern of the bivalves. The three-dimensional analysis consistently suggested an aggregated pattern whereas horizontal distribution was mostly random in the sediment matrix. Both horizontal, vertical and total displacement by individuals of Tapes philippinarum, but not Anomalocardia squamosa, were significantly affected by manipulations of the densities of conspecifics and/or A. squamosa. The latter species, however, was responsive to manipulations in terms of their burying depth. Both species showed considerable movements over the 2-week experimental period. The presence of a predator Portunus pelagicus did not significantly change the vertical distribution pattern of the two bivalves but the mortality of Tapes philippinarum was significantly higher than that of Anomalocardia squamosa. The results suggest that short-term responses such as emigration may be an important response to potential competitive interaction among infaunal bivalves and that such interaction may reduce the usefulness of long-term indicators such as growth and mortality. Whereas burying depth of infaunal bivalves may be influenced intra-specifically by trade-off between predation risk and hunger level, the soft tissue: shell weight (≈ defence) ratio seems to be a more general predictor of vertical distribution in intra- as well as inter-specific comparisons. |
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