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Succession of Macroinvertebrates in Playas of the Southern High Plains, USA

1998; University of Chicago Press; Volume: 17; Issue: 4 Linguagem: Inglês

10.2307/1468364

1937-237X

Daryl Moorhead, Dianne L. Hall, Michael R. Willig,

Marine Biology and Ecology Research

Playas are seasonal wetlands that constitute the principal surface-water features of the semiarid, Southern High Plains, USA. They are shallow pools that usually persist for 2-4 mo following inundation by spring rains. The development of macroinvertebrate assemblages in 10 playas located in West Texas was examined during the summer of 1994. Playas were sampled 3 times at approximately monthly intervals, beginning shortly after initial inundation in early May. All playas were dry within 90 d. Species richness and diversity (Fisher's log-series α) increased significantly over time (p < 0.05). Thirteen of the 16 species representing at least 1% of collected individuals, showed significant differences in abundances over time (p < 0.05). Some taxa increased in abundance (especially insects), whereas others decreased (most crustaceans). Trophic structure of assemblages also changed over time, with a significant reduction in the abundances of detrivores (p < 0.05) and filter-feeders (p < 0.05) occurring concurrently with an increase in the abundance of predators (p < 0.05). The composition of macroinvertebrate assemblages became more similar among playas over time (Ochai's index, p < 0.05), and changes in composition within individual playas tended to decrease with time (p < 0.05). These results suggest a rapid development of macroinvertebrate assemblages in playas, begining with early dominance of crustacean detritivores and filter-feeders (e.g., phyllopods and ostracods), followed by later dominance of herbivorous and predaceous insects (e.g., hydrophilids and notonectids). Increases in species richness, diversity, and similarity in assemblage composition among playas over time are consistent with a pattern of progressive colonization by a finite set of species capable of exploiting these ephemeral habitats.