Overlapping microscale dispersion patterns of meiofauna and microphytobenthos

Microscale dispersion patterns of meiofauna and microphytobenthos from an oyster pond on the French Atlantic coast were studied through spatial autocorrelation analysis during 2 successive spring periods. Patch size was calculated using correlograms. Both microalgae genera and meiobenthos taxa (except turbellarians in May 1987 and single groups of harpacticoid copepods in April 1988) exhibited patchy distributions. Meiofauna patches ranged from 40 .mu.m) patches from < 4 to 113 cm2 and smaller cell (< 40 .mu.m) patches from < 4 to 79 cm2. High variability in patch size was observed between taxa or genera, between years, and a second aggregation level (small patches within large clumps) was shown by harpacticoid copepods. A log-log regression indicated positive spatial associations among meiofauna and microphytobenthos assemblages but not with nanophytobenthos (cells < 40 .mu.m). Furthermore, high complexity among microbiota interactions indicates that no single causative factors may explain observed patterns. When positive significant correlations between meiofauna taxa and microphytobenthos genera occurred, patch size was different. Hence no very close overlap was detected and microphytobenthos was thought to only partially influence meiofauna dispersion. However, selectivity of trophic interactions seems to exist and data support the hypothesis of meiofauna spatial patterns being generated by feeding preferences