Avicennia germinans (black mangrove) is specifically adapted to the estuarine environments off the coast of the southern United States and in the tropical regions of the Caribbean and Eastern Africa. Black mangroves are viviparous, with propagules germinating on the parent tree followed by a floating dispersal stage. Once the propagules reach a suitable environment, the seed will take root. Many abiotic factors may influence the successful establishment of propagules in the field, and greenhouse studies are one tool to investigate the importance of various abiotic conditions. However, the methods for establishing seedlings in order to conduct effective greenhouse studies are not well standardized. The purpose of this research was to understand mangrove seedling response to different greenhouse conditions, including distinct substrates and watering regimes. Seedlings were collected from the field and transplanted into four different substrate conditions: sand, nutrient-amended sand, a mixture of sand and potting soil, and potting soil. As for the watering conditions used, there were non-flooded conditions and semi-flooded conditions. Over the course of three weeks, a rapid decline of seedling health, as measured with an index of leaf color, was observed across all experimental treatments. However, the sand-only substrate (without  nutrient or potting soil amendments) had the least dramatic decline, suggesting that the sand medium, which was most similar to the substrate from the field, was the most ideal out of the four. There were smaller differences among watering regimes,  where a decline was seen for the non-flooded seedlings after two weeks, and the flooded conditions remained more stable. The rapid overall seedling decline suggests transplant shock, indicating that effective greenhouse studies should germinate seeds in pots rather than collecting seedlings directly from the field.    

Primary Presenter: Lizmar Luna, University of Puerto Rico in Humacao (lizmar.luna@upr.edu)

Authors:

Marissa Palmer, Texas A&M Galveston  (mpalmer1@tamu.edu)

Anna Armitage, Texas A&M Galveston  (armitaga@tamug.edu)