Journal of Foraminiferal Research, v. 54, no. 2, p. 95–106, April 2024
BENTHIC FORAMINIFERAL DYNAMICS IN REEF-ASSOCIATED SEDIMENTS OF JOBOS BAY, PUERTO RICO: 2018–2019 ANGELIQUE ROSA MARÍN1,2,*, PAMELA HALLOCK2 AND MICHAEL MARTÍNEZ-COLÓN1 ABSTRACT
bleaching events since the worldwide event in 1997–1998 (e.g., McClanahan, 2022; Shlesinger & van Woesick, 2023). In Puerto Rico, coral-reef ecosystems directly influence the economies of coastal communities, primarily through tourism and recreational activities. At the same time, coral reefs are threatened by human activities (e.g., Hernández-Delgado & Ortíz-Flores, 2022) that promote terrigenous sediment influx (Ramos-Scharrón et al., 2015; Ramos-Scharrón, 2021), nutrient pollution (Larsen & Webb, 2009), sewage pollution (Hernández-Delgado et al., 2011), non-point pollution sources (Bonkosky et al., 2009), and direct and indirect impacts from recreational activities (Webler & Jakubowski, 2016). Benthic foraminifers have been used for more than 50 years to provide insight into environmental changes, pollution, and climate change (e.g., Alve, 1995; Frontalini & Coccioni, 2011; Barbosa et al., 2012). They are useful as bioindicators because of their diversity in estuarine, coastal, and marine habitats, combined with their production of agglutinated or calcium carbonate (CaCO3) shells (commonly known as tests). The kinds of shells found in sediments can provide information about past environmental conditions (Barragán Montilla & Sanchez Quiñonez, 2021), types and rates of changes, and present conditions in a habitat (e.g., Oliver et al., 2014; Mathes et al., 2022). A variety of metrics (e.g., species richness and other diversity indices) are commonly used to evaluate foraminiferal assemblages (e.g., Murray, 1973, 2006; Hayek & Buzas, 2010; Gonzales et al., 2022). In addition, several indices specifically using benthic foraminifers to evaluate the health of coastal environments have been developed (e.g., Hallock et al., 2003; Schönfeld et al., 2012; El Kateb et al., 2020; Prazeres et al., 2020). Two studies (Donnelly, 1993; Oliver et al., 2014) off La Parguera, Puerto Rico, specifically contributed to the development and application of indices using benthic foraminifers in coral reef ecosystems. Hallock et al. (2003) used samples from La Parguera (Donnelly, 1993) and the Florida reef tract (Cockey et al., 1996) to develop a water-quality index known as “Foraminifera in Reef Assessment and Monitoring”, abbreviated as the FoRAM Index or FI. The FI reflects how reef water quality influences the occurrences of benthic foraminifers. Oliver et al. (2014) subsequently compared the FI with other environmental metrics, including coral cover, fish communities, and macrobenthic fauna, for La Parguera waters, finding that reefs exposed to more significant human disturbances had lower FI values (range of 2–3) indicative of deterioration, while those farther away (with less human disturbance) had higher FI values (4), indicating better water quality for coral survival and reef accretion.
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. INTRODUCTION BACKGROUND Tropical coral reefs are among Earth’s most vital marine ecosystems. Such reefs provide a wide array of ecosystem services that contribute to environmental and societal interests (e.g., Moberg & Folke, 1999; Eddy et al., 2021). Despite their importance, reefs are threatened by a wide range of global and local environmental stressors, both natural and anthropogenic (e.g., Beyer et al., 2018; Woodhead et al., 2019). Increasing concentrations of carbon dioxide in the atmosphere are driving ocean acidification and climate change, including rising seasurface temperatures (e.g., Hoegh-Guldberg et al., 2007, 2018). Terrestrial runoff increases after tropical storms and hurricanes, resulting in nutrient pollution and water-quality changes (e.g., increased water turbidity) on coral reefs (Takesue et al., 2021). Human influences from agriculture, industrial, and coastal development practices contribute to increases in turbidity, nutrients, and other chemical pollution (e.g., Wooldridge & Done, 2009; Lesser, 2021). In the past 50 years, coral-bleaching events associated with warmer sea-surface temperatures have increased from rare occurrences in the 1970s, to two significant events in the Caribbean in 1983 (Jaap, 1985) and 1987 (Lang et al., 1992), to multiple mass
STUDY SITE: JOBOS BAY NATIONAL ESTUARINE RESEARCH RESERVE
1
Florida Agricultural and Mechanical University, 1601 S. Martin Luther King Jr. Blvd., Tallahassee, FL 32307 2 College of Marine Science, University of South Florida, 830 1st St. S., St. Petersburg, FL 33701 * Correspondence author. E-mail: angeliquerosamarin@gmail.com
Jobos Bay National Estuarine Research Reserve (JBNERR), offshore from Salinas, Puerto Rico, is part of the U.S. National Estuarine Research Reserve system (Fig. 1A). Jobos Bay, located on the southeast coast, is the second largest estuary in
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