Proffitt, EdDoty, Jacob Kavanaugh2022-12-062022-12-062022-07-21https://hdl.handle.net/1969.6/94540A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Marine Biology from Texas A&M University-Corpus Christi in Corpus Christi, Texas.Anthropomorphic climate change has driven changes in the distribution of tropical species worldwide. Along the Texas Gulf coast, Avicennia germinans has progressed in a poleward expansion leading to a shift in species dominance from salt marsh flora to mangrove forest. Shifts from salt marsh dominance to mangrove dominance can lead to changes in species diversity, sediment chemistry, shoreline stabilization, and many more ecological functions. However, disturbance events (such as low temperature freeze events) can cause a mass mortality of tropical mangroves and drive shifts in dominance back to salt marsh flora. Directly following mass mortality inducing freeze events, population recovery will be largely dependent on the success and growth to reproductive age of black mangrove seedlings. Our study assessed the response of black mangrove young-of-the-year seedlings (green cotyledons attached) to an extreme low temperature disturbance event (Winter Storm Uri, Feb. 2021). We also quantified plant community structure following the mass mortality of black mangrove shrubs and its impacts on the ongoing regime shift along the Texas coast. Freeze disturbance affected shrub and seedling survival. In the Lower Laguna Madre (Boca Chica site) where freeze effects were minimal propagules recruiting any time that fall and winter survived and grew. At higher latitudes (Corpus Christi Bay & Matagorda Bay) where freeze effects were more severe, rooted seedlings died along with most adult shrubs and new colonization appeared to be by seedlings recruiting from propagules likely floating in the water at the time of the freeze. Growth of seedlings recruited prior (southernmost Boca Chica site) and after Uri (CC Bay and Matagorda Bay) were not significantly different. At freeze-disturbed sites 10-53% of new seedlings flowered within 16 months of the freeze event, while 0 % flowered at the non-disturbed southernmost location. As age of first reproduction is an important component of population growth, these results suggest that reproduction of 1 year old seedlings may be an important aspect of mangrove recovery and will contribute to the regime shift, barring additional hard freezes.41 pagesen-USThis material is made available for use in research, teaching, and private study, pursuant to U.S. Copyright law. The user assumes full responsibility for any use of the materials, including but not limited to, infringement of copyright and publication rights of reproduced materials. Any materials used should be fully credited with its source. All rights are reserved and retained regardless of current or future development or laws that may apply to fair use standards. Permission for publication of this material, in part or in full, must be secured with the author and/or publisher.This material is made available for use in research, teaching, and private study, pursuant to U.S. Copyright law. The user assumes full responsibility for any use of the materials, including but not limited to, infringement of copyright and publication rights of reproduced materials. Any materials used should be fully credited with its source. All rights are reserved and retained regardless of current or future development or laws that may apply to fair use standards. Permission for publication of this material, in part or in full, must be secured with the author and/or publisher.marine biologymangrovesmangrove seedlingsText