Sediment grain size distribution and composition of coastal environments at Jobos Bay National Estuarine Research Reserve, Puerto Rico

Estuaries remove sediments and pollutants from rivers and streams before they enter the ocean, resulting in cleaner water for humans and marine life. However, the health of estuaries has declined as a result of coastal development and climate change. This study focused on Jobos Bay National Estuarine Research Reserve (JBNERR) located in southeast Puerto Rico, conducting analyses of sediment texture and composition of surficial sediment samples from its coastal environments. In December 2023, three independent surficial sediment samples were collected from a total of 16 sites within JBNERR. Grain-size analysis included wet-sieving of 10 g to remove the mud fraction, followed by dry sieving of sand and coarser components. All size fractions were weighed, and grain-size percentages were calculated. Sediment samples were also assessed for calcium carbonate and organic matter content utilizing a Loss on Ignition (LOI) protocol. Overall, mud predominated in most of the sites, however, fine sand was common around the offshore cays, and both coarse and fine sand were found in anthropogenic impacted areas. The LOI analysis revealed higher percentages of calcium carbonate around the offshore cays, higher organic carbon and shell fragments in the mangrove area, and the predominance of siliciclastic in the anthropogenically impacted areas. This analysis of sediment composition and organic matter in Jobos Bay highlights variations among different habitats and sources. These results contribute essential information to support the management and conservation strategies that aim to preserve the diverse ecosystems of JBNERR, while also providing additional data for other studies being conducted in the estuary.

Presentation Preference: Poster

Primary Presenter: Xiomara Cruz, University of Puerto Rico (xiomara.cruz8@upr.edu)

Authors:

Angelique Rosa Marín, University of South Florida  (arosamarin@usf.edu)

Natalia López Figueroa, University of Florida  (natalia28@usf.edu)

Pamela Hallock, University of Florida  (pmuller@usf.edu)