A total of 24 benthic samples were collected from the low-tide mark along an 800 m transect, using a standard corer methodology46 , from marine sandy beach substrata in Prestwick (three every 100 m between 55°30.481′N, 4°37.489′W and 55°30.194′N, 4°37.368′W) and a further three from Littlehampton (50°48.021′N, 00°32.530′W), UK, during the summer of 2007. The latter sampling site was used as a geographically disparate out-group comparison. For the sequencing analysis, each biological sample comprised three pooled 44 mm diameter×100 mm benthic samples taken approximately 10 m apart. An additional core was taken for sediment analysis. All samples were immediately fixed in 500 ml storage pots containing 300 ml of DESS (20% DMSO and 0.25 M disodium EDTA, saturated with NaCl, pH 8.0)47 .
The meiofaunal size fraction was mechanically separated from the sand and concentrated by decanting five times with filtered tap water through a 45 μm filter. Subsequent separation from fine silt was achieved by repetitive centrifugation in 1.16 specific gravity LUDOX-TM solution48 . Following centrifugation, each sample was retained on a distinct mesh sieve, which was then folded, sliced and placed in a 15 ml falcon tube and kept at −80 °C until DNA extraction. Samples were lysed overnight at 55 °C in lysis buffer (100 mM Tris–HCl, pH7.5; 100 mM NaCl; 100 mM EDTA; 1% SDS, 500 μg ml−1 proteinase K), assisted by spinning wheel mixing, and DNA extracted with the QIAamp DNA Blood Maxi Kit (Qiagen) following the manufacturer's protocol.
The meiofaunal size fraction was mechanically separated from the sand and concentrated by decanting five times with filtered tap water through a 45 μm filter. Subsequent separation from fine silt was achieved by repetitive centrifugation in 1.16 specific gravity LUDOX-TM solution48 . Following centrifugation, each sample was retained on a distinct mesh sieve, which was then folded, sliced and placed in a 15 ml falcon tube and kept at −80 °C until DNA extraction. Samples were lysed overnight at 55 °C in lysis buffer (100 mM Tris–HCl, pH7.5; 100 mM NaCl; 100 mM EDTA; 1% SDS, 500 μg ml−1 proteinase K), assisted by spinning wheel mixing, and DNA extracted with the QIAamp DNA Blood Maxi Kit (Qiagen) following the manufacturer's protocol.
