Estuarine foraminifera as an effective measure of benthic ecological quality status in Jobos Bay, Puerto Rico) Benjamin G. Shirey1-2, Michael Martínez-Colón1*, Charles Jagoe1, Olugbenga T. Fajemila3, Angel Dieppa4, and Benjamin Mwashote1 School of the Environment, Florida A&M University, Tallahassee, FL, USA, michael.martinez@famu.edu 2 AUT Lab for Cephalopod Ecology and Systematics (ALCES), Department of Environmental Science, Auckland University of Technology, Auckland 1010, New Zealand 3 Department of Geological Sciences, Osun State University, Osogbo 230261, Nigeria 4 Jobos Bay National Estuarine Research Reserve, Aguirre, PR, USA *corresponding author
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ABSTRACT: This study investigated the effects of potentially toxic elements (PTEs) on the spatial distribution of benthic foraminifera in Jobos Bay, a National Estuarine Research Reserve in Puerto Rico. High PTE total concentrations (Cr-Cu-Zn-Mn-Hg) clustered around anthropogenic sources where “moderately polluted” to “moderate-heavily polluted” conditions prevail. The spatial distribution of the foraminiferal ecological indices mainly followed trends in bioavailable (exchangeable and organic-bound) PTEs. Ammonia (T1) (36%) was the most abundant foraminifera with species richness and diversity being characteristically low for an impacted estuary in Puerto Rico. Based on the Foram Stress Index, the ecological quality status (EcoQ) of the benthic environment varied according to PTE pollution and water quality levels with a “heavy polluted” (EcoQ “poor”) Inner Bay area (east coast) proximal to multiple non-point sources of pollution while conditions improved towards “moderately polluted” (EcoQ “moderate”) in the Open Bay area. The Restricted area (west coast of the bay) which received direct effluents of raw sewage was exposed to higher organic-bound bioavailable PTE concentrations coupled with more corrosive and less oxygenated bottom waters in some areas. This variability was reflected in the “heavy polluted” (EcoQ “poor”) and “azoic” (EcoQ “bad”) conditions where several sites were barren with respect to porcelaneous taxa in addition to Ammonia (T1) being almost absent in one sample. Keywords: trace metals, Caribbean, biological indices, ecosystem health, EcoQ.
INTRODUCTION It is well known that estuaries serve an inadvertently dual purpose as a sink or source of pollutants. Their fate and transport are governed by the dynamic equilibrium between water quality, sediments, and biota especially at the sediment water interface. The JBNERR (Jobos Bay National Estuarine Research Reserve) was established in 1981 and is an estuarine ecosystem located to the south coast of Puerto Rico. Like any estuarine setting in a small island, it has been impacted by numerous pointand non-point sources of pollution (text-fig. 1). For example, a landfill, residential areas, tire recycling, two power plants, power station, abandoned sugar mill, sewage, as well as pharmaceutical manufacturers (Baxter and Pfizer) are found within the watershed and some in proximity to the shoreline (Whitall et al. 2011; JBNERR 2017). Previous studies have documented organic pollutants (Aldarondo-Torres et al. 2010; Whitall et al. 2011; Pait et al. 2007; 2012) and PTEs (Potentially Toxic Elements) (e.g., Se, Cr, Cu, Zn) (Zitello et al. 2008; Aldarondo-Torres et al. 2010; Whitall et al. 2011; Apeti et al. 2012) in the sediments as well in the tissues of organisms. It is known that JBNERR has a rich history of pollution, and this was confirmed by Alegría et al. (2016) who documented changes in the use of PCBs (Polychlorinated biphenyl) from a sediment core that was radiometrically dated to 1939. More recently, a study by Martínez-Colón et al. (2021) documented the bioaccumula-
tion of PTEs (Cd-Ba-V-Cu-Zn-As-Se) into the black mangrove and its subsequent bioavailability and bioconcentration in the soft tissues of fiddler crabs via trophic transfer. Meiofaunal communities thrive and respond to bioavailable PTEs. These ecological responses are advantageous especially when r-type strategists serve as sentinels of environmental stress (e.g., Elliott and Quintino 2007; Wang et al. 2023) as well as for PTE pollution given their opportunistic or resilient behaviour. According to the definition of Heink and Kowarik (2010), an ecological indicator is a species used to evaluate the environmental conditions of an area as well as any spatial changes. BF (benthic foraminifera) are heterotrophic single-celled organisms that have been used for this purpose by numerous authors (e.g., Watkins 1961; Bouchet et al. 2012; Jorissen et al. 2018; Martins et al. 2020). Different BF taxa can be sensitive to indifferent (k-type strategist) or tolerant (r-type strategist) (Hallock 1985; Hallock et al. 1991; 2003; Martins et al. 2019; Bayrón-Arcelay et al. 2020; Benedetti and Papazzoni 2022) towards natural (e.g., Prazeres et al. 2020; Rosa-Marín et al. 2024) as well as anthropogenic (e.g., Watkins 1961; Marques et al. 2019; O’Malley et al. 2021) stressors. These organisms are ubiquitous in marine settings (deep vs shallow) however in tropical estuarine environments their community structures are unique, typically with low diversities and the dominance of
Micropaleontology, vol. 71, no. 2, text-figures 8, plate 1, pages 167–181, 2025 https://doi.org/10.47894/mpal.71.2.03
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