Rotifer occupancy and seasonal variation within Frullania eboracensis (Frullaniaceae) lobules

Document Type

Article

Publication Date

11-3-2025

Abstract

Bdelloid rotifers are well documented as inhabitants within lobules of the widely distributed epiphytic liverwort, Frullania eboracensis. This study provides a detailed description of rotifer occupancy within lobules near the shoot tip of F. eboracensis. The objectives of this study were to test whether rotifer density in lobules of F. eboracensis differed among tree species, understand how rotifers are distributed within F. eboracensis, the aggregations of lobule-dwelling rotifers, and how rotifer abundance is impacted by seasonality. The highest densities of rotifers within F. eboracensis lobules occurred on northern red oak (0.67 rotifers/lobule ± 0.069, mean and SE) and aspen (0.66 rotifers/lobule ± 0.046, mean and SE). Shoot tips of F. eboracensis were collected from five different tree species in fall 2014 to fall 2016. Rotifers had a higher probability of occupancy for the first 5-6 lobules, slowly declining thereafter. The probability of occupancy was significantly related to lobule sequence from the shoot tip (p<0.05, 95% CI-0.113 to-0.064) and branching level (p<0.05, 95% CI-0.984 to-0.195). Of all the rotifers counted within lobules, 34% were solitary, 23% were in pairs, 18% in trios, and 17% were in groups of five or more. Rotifer abundance was stable across the 1.5-year period, but there was a slight increase in density during the late fall and early winter. Studies of rotifers in other aquatic habitats emphasize considerable seasonal fluctuations in their populations, but the lack of competitors and limited predation within F. eboracensis lobules contributes to their stability. Anhydrobiosis also lessens the impact of drought and freezing temperatures on rotifer abundance.

Publication Title

Bryologist

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