The study of meiofauna is a late component of benthic research, despite the fact that meiobenthic animals have been known since the early days of microscopy (meiofauna and meiobenthos are largely used in this book as synonyms). While the terms macrofauna and microfauna had been long established, it was not until 1942 that “meiofauna” was used by Mare to define an assemblage of mobile or hapto-sessile benthic invertebrates (meiobenthos) distinguished from macrobenthos by their small size. Earlier, most researchers had referred to typical meiobenthic animals as microfauna. Derived from the Greek μεloς meaning smaller, members of the meiofauna are mobile, sometimes also hapto-sessile benthic animals, smaller than macrofauna, but larger than microfauna (a term now restricted mostly to Protozoa). Today, the size boundaries of meiobenthos are based on the standardized mesh width of sieves with 500 µm (1000 µm) as upper and 42 µm (63 µm) as lower limits: all fauna passing the coarse sieve, but retained by the finer sieve during sieving is considered meiofauna. In a recent move, a lower size limit of 31 gm has been suggested by deep-sea meiobenthologists in order to quantitatively retain even the smallest meiofauna organisms (mainly nematodes). The significance of what began as a subjective defined size-range of benthic invertebrates has since been supported by more extensive studies on the size spectra of marine benthic fauna (Schwinghamer 1981a; Warwick 1984; Warwick et al. 1986a), which will be described later.
KeywordsDetailed Reading French Atlantic Coast Lower Size Limit River Shore Coarse Sieve
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