Meiofaunal thiobios and “the Arenicola negation”: Case not proven

It has been alleged recently that the distribution of meiofauna around Arenicola burrows disproves the existence of a specifically anaerobic marine meiofauna. Critical appraisal of the evidence on which this denial was based shows that the conclusion was untenable. It may have arisen mistakenly from inadequate sampling of the burrow micro habitats, from lack of complementary data on burrow wall oxygen regime and from prejudgement (by denying the possibility of primary anaerobiosis) of the reasons why species held to be anaerobic by other authors occur in proximity to oxic conditions. These points and some new data on Arenicola burrow oxygenation are discussed. It is shown that at present the evidence from meiofaunal distribution around Arenicola burrows may be taken as much in favour of thiobiotic theories as against them.