Abstract: | The bacterial communities associated with the cockle (Cerastoderma edule) were investigated at the individual level through a 10-month monitoring programme. Temporal changes and those changes associated
with a common parasite of the cockle, Bucephalus minimus, were investigated by monthly sampling of individuals, selected based on their shell length (cohort monitoring). Cockle bacterial
community abundance (CBCA) and diversity (CBCD) were estimated by epifluorescence microscopy counts and automated ribosomal
intergenic spacer analysis, respectively. CBCA showed a temporal pattern peaking at 30 × 106 cells per gram of cockle flesh and intervalval liquid in October and a significant 1.8-fold increase linked with B. minimus occurrence. CBCD was characterized by 112 ± 26 intergenic transcribed spacer (ITS) per individual and showed a relative homology
between individuals (52 ± 6%, Jaccard similarity) in spite of more than 30% of rare ITS. Consistent with an undisturbed evolution
of the condition index of the studied cohort individuals as an estimate of their physiological state, neither temporal nor
parasite-induced change in CBCA has been related to marked changes in CBCD. |