The Distribution of Halacaridae (Acari: Prostigmata) Among Macroalgae on Sheltered Rocky Shores

Abstract

Clumps of macroalgae on sheltered shores exposed at low tide provide a mosaic of micro-habitats for halacarid mites. The predominant pattern is one of zonation, with the level of high water neap tides limiting the distribution of many species of Halacaridae. Within emersed clumps of macroalgae four micro-habitats are recognized: the dry surface layer of the clump; damp fronds within the clump retaining surface moisture; lower stipes and holdfasts; the surface of the substratum between the holdfasts. Halacaridae are spatially segregated, different species being associated with different micro-habitats within clumps. This has implications for the way in which intertidal phytal meiofaunal communities are sampled. In general damp fronds from within seaweed clumps are collected. Species characteristically associated with stipes, holdfasts and the substratum beneath the clumps are probably under-represented in the majority of collections, and may, therefore, be considered rare.

A dataset of European marine mites (Trombidiformes, Halacaridae)

“…Because most of these papers reported single or very few records for a selected group of species (e.g., André 1939, 1940, 1941, 1942, Bartsch 1982, 1983a, 1983b, 1987, 1989b, 1992, 1998a or a given geographic area (e.g., Bartsch 1975aBartsch , 1975bBartsch , 1976aBartsch , 1976bBartsch , 1979Bartsch , 1980Bartsch , 1985Bartsch , 1991Bartsch , 1996a but do not addressed the whole halacarid communities, our dataset does not allow to unequivocally report species' absences nor precise species' abundances. We only recovered eight ecological studies that analysed halacarids at the community level, providing a standardised sampling effort and a robust estimation for abundances allowing for reliable comparisons in the future (Bartsch 1978, Pugh and King 1985, Somerfield and Jeal 1995, 1996, Riesgo et al 2010, Martínez, García-Gómez et al 2021, García-Gómez et al 2022.…”

“…Most of the research has been performed in the intertidal zone, while surveys in deeper waters are infrequent. Likewise, the halacarid fauna present on algae (Bartsch 1978, 2004, Pugh and King 1985, Somerfield and Jeal 1995, 1996 has been comprehensively sampled, whereas the nature of the relationship between mites and other animal hosts (e.g. sponges, hydrozoans, bryozoans, barnacles, mussels, polychaetes, crustaceans) is unknown for most of these associations, as live observation of living material has not been executed (Chatterjee 2020(Chatterjee , 2021a(Chatterjee , 2021b(Chatterjee , 2021c.…”

Meiofauna Techniques

“…It may be possible to detach a portion of the substratum from a known area, or to collect a standard volume of the substratum, but in either case the degree to which samples may be regarded as quantitative is questionable. Such problems may be exacerbated by the fact that many meiofaunal organisms have quite specific microhabitat requirements, as such they may not be distributed evenly throughout the substratum (Somerfield & Jeal, 1996). To overcome these problems, one approach is to use artificial substratum units (ASUs).…”