Meiofaunal Colonization of Decaying Leaves of the Red Mangrove Rhizophora mangle, in Southwestern Puerto Rico

Abstract

This study targeted the successional,trophic and taxonomic aspects of nematode assemblages inhabiting fallen Rhizophora mangle leaves in an experiment repeated during two consecutive years. Four replicates of four leaves each were secured near the mangrove prop roots at Magueyes Island, southwestern Puerto Rico. At biweekly intervals, one leaf from each replicate was removed and selected meiofauna were enumerated. The two most abundant taxa were harpacticoid copepods (max. 228/leaf) and nematodes (max.182/leaf). Significant differences between sample times were observed. Copepod and nematode densities for these times were compared using a two-way, crossed ANOSIM (global R = 0.327, significance level of 0.1%). Both nematode and copepod densities increased as leaves decayed. The leaf size had no significant effect on meiofaunal densities, an observation consistent with previous studies. We identified 25 nematode species of 25 genera, with the most abundant taxa being Adoncholaimus and Dichromadora. The most frequently encountered taxa in leaves were Haliplectus (58.62%), Dichromadora (65.52%), Adoncholaimus (41.38%), and Oncholaimus (41.38%). When we assigned nematode species to feeding groups, omnivores/predators accounted for >30% of the nematode abundance. Together, the omnivores/predators and the epigrowth feeders accounted for >63% the species richness and >72% of the species abundance. No successional patterns were detected between the nematode feeding groups. Diversity indices were not significantly different within and between years. The successional patterns of colonizing nematodes did not follow the patterns observed in classical succession studies in terrestrial habitats.