Flowering, seed production, predation and recruitment of Posidonia australis



The drivers and bottlenecks of sexual reproduction in seagrasses are a crucial element in their conservation and restoration, determining resilience over ecological and evolutionary timescales. We collected flowering, seed production, and seedling establishment data for the seagrass Posidonia australis annually between 2013-2018 in meadows at six locations around Rottnest Island, Western Australia. We present data on inflorescence and vegetative shoot density, reproductive effort, flower and seed density, seed to ovule ratio, seed predation, and seedling survival. We found variable annual rates of flowering and seed production among meadows and between years. Some meadows, however, flowered more intensely and produced more seeds across the years of the survey. Inter-site and inter-annual variation in seed production, the stochastic nature of weather during seed release, and the large, but variable, impact of seed predation are likely the principle drivers of successful recruitment into established meadows and in colonising unvegetated sands. We propose that for the long-lived and persistent P. australis, variable annual reproductive investment increases the probability of low levels of continuous recruitment from seed in this seagrass, despite high rates of abiotic and biotic disturbance at seedling, shoot and patch scales.
Date made available18 Jul 2022

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