Benthic Foraminiferal Dynamics in Reef-Associated Sediments of Jobos Bay, Puerto Rico: 2018–2019

Jobos Bay, southeastern Puerto Rico, experiences strong environmental gradients between an historically impacted coastal-plain and oligotrophic Caribbean waters. The coastal zone is dynamic both seasonally and interannually. During 2018–2019, water quality, sediments, and benthic-foraminiferal assemblages were assessed from fore- and back-reef sites off three cays that separate Jobos Bay from Caribbean waters. Temperature and salinity reflected seasonal variations, inorganic nitrogen indicated terrestrial runoff, and sediment texture reflected influence of winds and wave energy. Foraminiferal assemblages in the fore-reef were dominated by Amphistegina while taxa such as Quinqueloculina and Discorbis dominated back-reef sediments. Low test densities reflected the influence of wave energy in predominantly siliciclastic sediments. Interannual differences in sediment textures and assemblages collected during comparable months reflected timing of storm passages. The prevalence of algal symbiont-bearing taxa in fore-reef sites indicated suitable water quality for reef accretion. This study of Jobos Bay foraminiferal assemblages provides baseline data on seasonal and interannual variability.