Relationships between mangrove root system and benthic macrofauna distribution

Abstract

Despite the ability of mangrove trees to allocate a large proportion of the total biomass to the underground roots, little is known about the benthic macrofauna–root system relationships. We evaluated the above- and belowground structures of plants, soil properties, algal cover and their relationship with macrofauna as a function of soil strata (0–2.5, 2.5–5 and 5–10 cm) and distance (0–0.30 and 3–3.5 m) from trunks in three mangrove sites in southern Brazil. Coarse root biomass was higher near the trunks and in shallower layers, while fine root biomass predominated far from trunks and indifferent to the soil stratum. The macrofauna was more associated with changes in the root systems than with other soil properties. Most of the benthic taxa occurred in the upper layers of the soil (0–2.5 cm) and near trunks (< 0.30 m), where there was a lower proportion of fine roots. Fine root entanglement inhibited the presence of organisms with more complex body plans, which may hamper their locomotion and feeding activities. Therefore, the structure and function of macrofauna varied according to the depth stratum and distance from the trunks.