waders and their estuarine food supplies - Vlaams Instituut voor de ...

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size (mm)
Fig. 3. Cerasioderma edule. Frequency disinhution of depth per
size da— in vv inter tgrey histograms: n = 453) and in summer (hlack
histograms; n = 835). Mean depth indicated. Table 2 give- statistical
analysis.
SIPHON SIZE AND DEPTH IN BENTHIC BIVALVES
size (mm)
ber-March) and a summer period (July to September)
during which, according lo a preliminary analysis, the
bivalves remained al a similar depth. SPSS (Nie el al.
1975) was used for all statistical analyses.
Results
Burying depth and shell size
The depth measurements of Mya are given in lig. 2.
The relation between burying depth and shell si/e can
be described by an S-curve. Mya < 10 mm live in the
upper 2 cm of the substrate. They increase their depth
when they grow from 10 to 40 mm and remain al the
same depth level when > 50 mm. In winter Mya live
\(Wc deeper than in summer.
Cerastoderma remain near the surface, but there is
an increase of depth with size and their burying depth
in winter is larger than in summer (Fig. 3).
Large Macoma live deeper in the substrate than
smaller ones, but the depth remains the same for all animals
> 10 mm (Fig. 4). In summer Macoma > 10 mm
live at a depth of 2 cm compared to ail average of 5 cm
in winter.
Fig. 4. Macoma balihica. Frequency distribution ol depth per size class in vv Inter (grey histogtams; n = I609i and in summer (black hi-l.icrain-;
n = 67111 Mean depth indicated. Tahle 2 gives Statistical analysis.
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