Contribution of Melampus coffeus (Gastropoda, Ellobiidae) to leaf litter decomposition in the middle estuary of the Pacoti river, Ceará, Brazil

The leaf litter decomposition in the middle estuary of the Pacoti river was studied in the presence and absence of the gastropod Melampus coffeus (Linnaeus, 1758), aiming at examining the contribution of this invertebrate to the organic matter cycling in mangroves ecosystems. The local population density of M. coffeus and leaf distribution based on wet biomass, dry biomass, and abundance, were estimated. A field experiment was conducted using samples of Rhizophora mangle (Rhizophoraceae) leaves (with similar color, and wet and dry biomass) equally distributed in 64 leaf litter cages. Groups of 14 individuals of M. coffeus were placed in 32 of these cages. The experimental cages were equally distributed with their respective control cages (leaves only) in the field among four points, totaling 64 cages. During eight weeks four pairs of cages (experimental and control) were collected weekly. Once collected, the leaves showing signs of grazing by M. coffeus were counted. The wet and dry biomasses of samples were also determined. Although M. coffeus can contribute to leaf litter degradation, in this study, its effect on leaf degradation was not significant when comparing experiment and control groups during the experimental time in the studied area.

Leaves; macrodetritivores; mangroove; Rhizophora mangle