Changes in seagrass genotypic diversity over a four-year time span

The seagrass Halodule wrightii is a vital part of Texas Gulf Coast ecosystems. Genetic diversity is associated with many positive traits, and a decrease could result in a decline in the viability of the overall plant population. We examined genotypic diversity (R) in a population of Halodule wrightii from Oso Bay, Tx, and compared the results to those collected in 2017 and 2019 from the same location. Past results indicated low to moderate genotypic diversity in this population and a lack of an evident seed bank. In 2021, we were only able to collect samples from 25 out of 48 positions, representing a 49% loss of seagrass coverage since 2019. We found that, over this time period, 11 genotypes were lost, and 9 new genotypes were gained. The genotypic diversity estimate for 2021 (R = 0.25) was similar to that of 2017 and 2019 (0.22 and 0.24, respectively). Our results indicate that Halodule wrightii is able to maintain genotypic diversity over time, despite a significant decline in population size and lack of an evident seedbank.