ANALYSIS OF THE SPATIAL VARIABILITY IN ABUNDANCE AND AGE STRUCTURE OF2 INFAUNAL BIVALVES, CERASTODERMA-EDULE AND C-LAMARCKI, USING HIERARCHICAL SAMPLING PROGRAMS
M. Lindegarth et al., ANALYSIS OF THE SPATIAL VARIABILITY IN ABUNDANCE AND AGE STRUCTURE OF2 INFAUNAL BIVALVES, CERASTODERMA-EDULE AND C-LAMARCKI, USING HIERARCHICAL SAMPLING PROGRAMS, Marine ecology. Progress series, 116(1-3), 1995, pp. 85-97
Spatial variability in abundance and age distribution of 2 infaunal bi
valves, Cerastoderma edule (Linnaeus, 1785) and C. lamarcki (Reeve, 18
45), were quantified using hierarchical sampling programs. The scales
investigated ranged between 100 and 10(5) m. Analyses of variance reve
aled significant variability in abundance among sites within bays (sim
ilar to 100 m apart) for both species and also among bays (similar to
1 km apart) for C. lamarcki. Mean age varied at several spatial scales
. For both species, however, the scale contributing most to the variat
ion was bays, which provided about 40 % of the total variation for eac
h species. Randomization procedures were used to test the generality o
f previous observations of non-random distributions of year classes (n
amely number of year classes and dominance by single year classes). Th
ese analyses showed that for both species a spatial unit contained sig
nificantly fewer year classes and the most abundant year class was sig
nificantly more abundant than expected by chance. These results were c
onsistent for all spatial scales except among plots (similar to 10(1)
m apart) in C. lamarcki. The necessity to assess spatial patterns at a
wide range of spatial scales is emphasized. Potentially important pro
cesses (focusing on larval supply and recruitment) which generate the
observed patterns and general implications of spatial variability are
discussed.