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Meiofauna and solute transport in marine muds
Author(s) -
Aller Robert C.,
Aller Josephine Y.
Publication year - 1992
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1992.37.5.1018
Subject(s) - meiobenthos , bioturbation , diffusion , q10 , environmental chemistry , ecology , chemistry , oceanography , environmental science , geology , biology , sediment , geomorphology , abundance (ecology) , respiration , botany , physics , thermodynamics
Meiofauna typically inhabit sedimentary zones having substantial concentration gradients in biogcochemically important solutes such as O 2 . Diffusion experiments with the conservative tracers Cl − and Br − demonstrate that natural populations of meiofauna (∼30–100 cm 3 ) can increase transport rates of these solutes by factors of ∼1.7–2.3 × (for T > 10°C) compared with uninhabited sediments. The effect varies seasonally, directly with temperature and probably with faunal composition. About 20–40% of the increase in transport is due to increased porosity (decreased tortuosity) caused by meiofaunal activities and would be accounted for in most estimates of diffusion. The remaining, larger portion, is apparently due more directly to biologically induced fluid motion and three‐dimensional diffusion. Transport coefficients can be resolved into two components with apparent activation energies of ∼3 and ∼10 kcal mol −1 (Q 10 ∼ 1.2 and 1.8, T = 10°–20°C), consistent with control by physical and metabolic processes. Measurements following addition of particular meiofaunal groups to otherwise natural populations suggest that nematodes, juvenile bivalves, and polychaetes have the greatest effect. Transport activities of meiofauna must stimulate solute fluxes and reaction rates, particularly aerobic decomposition and associated processes such as nitrification in the oxic zones of marine sediments. In contrast, macrofauna commonly enhance solute transport to a greater extent (2–10 ×) than do meiofauna and, while stimulating aerobic reactions, also dramatically promote anaerobic processes in organic‐rich deposits.