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Article

Persistent Pharmaceuticals in a South African Urban Estuary and Bioaccumulation in Endobenthic Sandprawns (Kraussillichirus kraussi)

by
Olivia Murgatroyd
1,
Leslie Petrik
2,
Cecilia Y. Ojemaye
3 and
Deena Pillay
1,*
1
Marine and Antarctic Centre for Innovation and Sustainability, Department of Biological Science, University of Cape Town, Cape Town 7701, South Africa
2
Environmental and Nano Science Group, Department of Chemistry, University of Western Cape, Cape Town 7535, South Africa
3
Environmental Humanities South, University of Cape Town, Cape Town 7701, South Africa
*
Author to whom correspondence should be addressed.
Water 2025, 17(15), 2289; https://doi.org/10.3390/w17152289
Submission received: 30 May 2025 / Revised: 28 July 2025 / Accepted: 29 July 2025 / Published: 1 August 2025
Browse Figure
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Abstract

Pharmaceuticals are increasingly being detected in coastal ecosystems globally, but contamination and bioaccumulation levels are understudied in temporarily closed estuaries. In these systems, limited freshwater inputs and periodic closure may predispose them to pharmaceutical accumulation. We quantified in situ water column pharmaceutical levels at five sites in a temporarily closed model urban estuary (Zandvlei Estuary) in Cape Town, South Africa, that has been heavily anthropogenically modified. The results indicate an almost 100-fold greater concentration of pharmaceuticals in the estuary relative to False Bay, into which the estuary discharges, with acetaminophen (max: 2.531 µg/L) and sulfamethoxazole (max: 0.138 µg/L) being the primary pollutants. Acetaminophen was potentially bioaccumulative, while nevirapine, carbamazepine and sulfamethoxazole were bioaccumulated (BAF > 5000 L/kg) by sandprawns (Kraussillichirus kraussi), which are key coastal endobenthic ecosystem engineers in southern Africa. The assimilative capacity of temporarily closed estuarine environments may be adversely impacted by wastewater discharges that contain diverse pharmaceuticals, based upon the high bioaccumulation detected in key benthic engineers.

1. Introduction

Diverse pharmaceuticals, including antibiotics, anti-inflammatory drugs, anti-depressants and analgesics, are used to treat human and animal ailments globally [1]. These pharmaceuticals have been detected with increasing frequency in aquatic ecosystems, leading to considerations of the ramifications being raised [1,2,3]. However, knowledge of pharmaceutical pollution differs among aquatic systems, with that of coastal ecosystems lagging behind that of freshwater environments [2]. The link between human settlements and pharmaceutical pollution, however, along with large, dense and growing human populations along coasts, highlights the need for improved understanding of coastal pharmaceutical pollution [2]. This point is especially relevant given that pharmaceuticals are often discharged via industrial, municipal and household sewage into coastal ecosystems and are often ineffectively removed by treatment plants [2,4]. Once discharged, pharmaceuticals in coastal systems can transform, bind to sediment and particulate matter and bioaccumulate [2,3]. While these pollutants may occur at low concentrations, they are designed to be biologically active at low levels [5], with the induction of stress and negative changes to organismal biology reported [6,7].
Within coastal ecosystems, pharmaceutical pollution has been investigated in several estuarine ecosystems [1], but equivalent research is lacking for temporarily closed estuaries (TCEs). These systems do not always discharge into oceans as sandbar formations at the mouth curtail marine–estuarine connectivity [8]. TCEs are, however, common in South Africa, Australia, south-eastern Brazil and Uruguay, south-western India, Sri Lanka, Portugal and the coastlines of California and Texas in the USA. In South Africa, TCEs account for 71% of estuaries, likely due to the semi-arid climate [8]. During closed phases of TCEs, which may persist for several months, material residence times typically increase due to restricted marine–estuarine connectivity [8,9]. This feature suggests that TCEs may be susceptible to accumulating pharmaceuticals, especially in urban and peri-urban settings, where high volumes of urban wastewater can be discharged into them [8,9].
South African TCEs, even those that have closed for several months, are commonly inhabited by endobenthic sandprawns (Kraussillichirus kraussi) [10]. Sandprawns are widely distributed in Southern Africa from Mozambique to Namibia [10] and are key benthic ecosystem engineers [11,12,13,14]. Sandprawns can also limit eutrophication-induced phytoplankton proliferation, likely due to phytoplankton adsorption onto burrow walls and consumption thereafter [15,16,17]. This finding also highlights the potential for water-borne pharmaceuticals to bioaccumulate in sandprawns due to their interactions with the overlying water column during phytoplankton consumption.
Estuarine pharmaceutical pollution is poorly researched locally and generally in Africa. However, the many millions of liters of inadequately treated wastewater that are discharged daily into South African estuaries [18] put into context the importance of quantifying estuarine pharmaceutical levels and consequences for estuarine biota. Rapid urbanization and the growth of unserviced, informal settlements, coupled with poor sanitation and improper wastewater disposal, contribute to accelerating water quality declines locally [19,20], but the problem is further compounded by poorly maintained, malfunctioning and overloaded WWTPs, along with regular power outages [9]. To aid in addressing knowledge gaps in pharmaceutical pollution locally, we quantified pelagic, sewage-related pharmaceutical concentrations in an urbanized estuary in the Western Cape of South Africa (Zandvlei Estuary) and in benthic sandprawns (K. kraussi) to provide baseline data on environmental pharmaceutical levels and bioaccumulation in a key ecosystem engineer. Specifically, we measured in situ levels of acetaminophen (analgesic; antipyretic), amitriptyline (antidepressant), bezafibrate (antilipemic), carbamazepine (anticonvulsant), diclofenac (anti-inflammatory), nevirapine (HIV treatment), and sulfamethoxazole (antibiotic). These chemicals have previously been detected in sewage [21,22] and in False Bay, into which the Zandvlei Estuary discharges, which allowed us to assess levels of these chemicals within the estuary and in the adjacent receiving marine environment [3]. We were also interested in quantifying levels of the selected pharmaceuticals that were present in sandprawn tissue and in the water column in the estuary.

2. Methods

2.1. Study Site

The Zandvlei Estuary is a shallow (mean water depth = 1.4 m), temporarily closed, urban system that is situated in Cape Town, South Africa (Figure 1) [15,23]. The estuary has been extensively anthropogenically modified [15], including the mechanical opening of the mouth during winter (high rainfall) and ±a week per month during summer (low rainfall) [15]. The Zandvlei Estuary is classified as eutrophic [23] due to high nutrient inputs, including from failing and aged sanitation infrastructure, unserviced communities and agricultural and urban runoff [15]. Frequent sewage spills due to malfunctioning WWTPs significantly contribute to eutrophication [9]. Dense aggregations (176/m2–240/m2) of the sandprawn, K. kraussi, inhabit the lower reaches of the system [15].

2.1.1. Field Sampling

Water samples for pharmaceutical quantification were collected following Ojemaye and Petrik (2021) [3] in winter (4 August) of 2022. Due to funding limitations, temporal replication of sampling could not be carried out, thus limiting generalization of the findings. Our previous studies showed that sediments showed intermediate contamination between water and biota; thus, sediments were not analyzed [3]. Glass bottles were first cleaned and dried overnight at 160 °C. Triplicate sub-surface (±20 cm deep) water samples (1 L) were collected from 5 sites in the Zandvlei Estuary (Figure 1) along with environmental data (water temperature, salinity, dissolved oxygen, pH and chlorophyll-a biomass; YSI 6600 Multiprobe, (YSI, Yellow Springs, OH, USA)). Water depth per site was measured using a weighted line marked at 30 cm intervals.
Ten sandprawns (4–8 cm from chela to telson; non-ovigerous) were collected using a stainless-steel prawn pump (length = 90 cm, diameter = 5 cm) in the sandprawn biotope (Figure 1; site 5). Sandprawns were individually enclosed in aluminum foil, transferred to Ziplock bags and placed in a cooler box on ice packs, along with water samples.

2.1.2. Pharmaceutical Preparation and Extraction

Pharmaceutical extraction followed Ojemaye and Petrik (2021) [3]. Water samples were filtered (particle retention 0.45 µm, GF/A 47 mm, cellulose) within 24 h and refrigerated (4 °C) for 5 days, followed by solid-phase extraction (SPE; 500 mg, 6 cc HLB extraction cartridges (Oasis HLB®, Waters, Milford, MA, USA), flow rate = 5 mL/min). Extraction cartridges were preconditioned with methanol (7 mL, HPLC-grade) and Milli-Q water (7 mL). Following extraction, cartridges were washed with methanol (5 mL, 40% v/v) and dried under a gentle stream of nitrogen. Analytes were thereafter eluted (2 mL methanol, flow rate = 1 mL/min), with eluates being dried under a nitrogen stream. Dried samples were reconstituted (100 µL methanol, 50 µL of internal standard mixture of 5 ng/L), then placed into individual 200 µm glass inserts within LC vials prior to LC-MS analysis.
Individual sandprawns were rinsed (Millipore water) and stored at −20 °C, freeze-dried for 5 days and ground. Pharmaceutical extraction was performed on three granulated sandprawn samples (±1 g dry weight (dw), n = 3) using methanol (3 mL, HPLC-grade). Each sample comprised 3 pooled sandprawns since individual sandprawns did not produce enough dry biomass for pharmaceutical extraction. The samples were then immersed in an ultrasonic bath (Bransonic MH Ultrasonic bath, Emerson, Danbury, CT, USA) for 30 min and centrifuged (8000 rpm; 10 min), followed by the supernatant being transferred into another tube. The process was repeated two more times; the supernatant was combined and made up to 10 mL with methanol. Then, 1 mL of the homogenized mixture was diluted with 9 mL of Millipore water, and SPE was carried out (200 mg, 6 cc HLB cartridges (Oasis HLB®) as described for the water sample analysis.

2.1.3. Pharmaceutical Analysis, Quality Control and Assurance

Pharmaceutical analysis (chemical identification and quantification) of water and sandprawn samples was performed using a Waters Aquity LC-MS (Liquid Chromatography-Mass Spectrometer) coupled with a Waters Xevo TQS Mass Spectrometer (Waters, Milford, MA, USA). Separation of sample compounds was achieved with a Waters Acquity C18 2.1 × 100 mm, 1.7 µm column. The chromatographic separation employed a mobile phase composed of solvent A (0.1% formic acid in water) and solvent B (0.1% formic acid in methanol). A 5 µL aliquot of each sample was injected into the LC/MS system. The total run time for each sample and standard was 12 min.
Quality control and assurance were conducted according to Ojemaye and Petrik (2021) [3]. Blank field samples (MilliQ water exposed to air and sunlight during sampling) were used as a control to assess potential contamination. Analytes were identified by qualitatively comparing chromatograph spectral peaks of the standard solution and the samples. The precision of the instrument was assessed by obtaining the relative standard deviation (%) of replicate injections of the standards and samples. The resulting relative standard deviation was <20%. Linearity was assessed using the obtained calibration curves and estimated using the coefficient of determination (r2), which ranged from 0.988 to 1.000 for each identified compound (Table 1). Accuracy was determined by comparing concentrations (20 ng/L and 100 ng/L) obtained in triplicate pre- and post-spiked estuarine water samples and expressed in recovery percentages (Table 1). The limit of detection (LOD) and limit of quantification (LOQ) were determined (Table 1) with the sample responses from the slope (S) and the standard deviation of the blank sample responses (α), where LOD = 3.3 α/S and LOQ = 10 α/S.

2.1.4. Bioaccumulation Factor

Bioaccumulation factors (BAFs) for each detected pharmaceutical in the Zandvlei Estuary were calculated by dividing contaminant concentrations in the sandprawn tissue by that of estuarine water (average values for site 5 from which sandprawns were collected). Contaminants were classified as either “bioaccumulative” (BAF > 5000 L/kg) or “potentially bioaccumulative” (2000–5000 L/kg) [24,25]. We calculated sandprawn BAFs using water column contaminant levels given previous research based on stable isotope analysis indicating that estuarine sandprawn diets comprise primarily pelagic particulate organic matter [26]. This finding aligns with our prior research showing the ability of sandprawns to reduce phytoplankton biomass under experimental conditions, likely through consumption following phytoplankton adsorption onto burrow walls [15,16,17].

2.2. Data Analysis

Spatial differences in water column pharmaceutical levels were assessed using Kruskal–Wallis tests since data did not meet the assumptions required for parametric testing (assessed using Q-Q Plots, K-S tests (normality) and Levene tests (homogeneity of variance). Where significant site effects were detected, post hoc Dunn’s tests were used to identify significant within-site differences. All data were analyzed using the data analysis platform R.

3. Results

Temperature, dissolved oxygen and pH were similar among sampling sites in the Zandvlei Estuary (Table 2). However, salinity and depth were more variable, with site 5 being shallowest (0.4 m) and having highest salinity (18.19; Table 2). The Chl-a concentration generally decreased from site 1 (81.6 µg/L) to site 5 (20.7 µg/L; Table 2).
In terms of total pharmaceutical concentrations, pelagic samples from Site 5 were the most contaminated of the five sampling sites (Table 2). Acetaminophen concentrations varied significantly among sites (Χ2 = 13.033, p = 0.011) and had the greatest concentrations among sampling sites (0.122 ± 0.0051 to 2.531 ± 0.0762 µg/L), while amitriptyline (0.0006 ± 0.00003 to 0.09 ± 0.0010 µg/L) and nevirapine (0.007 ± 0.0003 to 0.009 ± 0.0006 ug/L) were the least concentrated (Table 2). Acetaminophen concentrations were significantly greater in site 5 relative to sites 1 and 3 (post hoc Dunn’s test p < 0.001). Sulfamethoxazole concentrations were marginally unaffected by site (Χ2 = 8.633, p = 0.071), but levels were greater at site 5 relative to site 1 (post hoc Dunn’s test p = 0.030). Bezafibrate, carbamazepine, amitriptyline and diclofenac levels did not vary statistically among sites (p > 0.05; Table 2). Acetaminophen was also most concentrated in sandprawn samples (7.194 to 14.389 µg/g dw), followed by carbamazepine (1.879 to 5.695 µg/g dw), sulfamethoxazole (0.480 to 2.094 µg/g dw) and nevirapine (0 to 0.359 µg/g dw; Table 3). Variance in pharmaceutical concentrations was evident for the three sandprawn samples measured, suggesting within-population variability. The bioaccumulation factor for nevirapine was the greatest (43,775 kg/L), followed by carbamazepine (41,257 kg/L), sulfamethoxazole (7450 kg/L) and acetaminophen (4469 kg/L; Table 3). Of these pharmaceuticals, acetaminophen was potentially bioaccumulative in sandprawn samples, while the rest were bioaccumulative compounds. Diclofenac, amitriptyline and bezafibrate had the lowest bioaccumulation factors (Table 3) and were not bioaccumulative.

4. Discussion

Of the pharmaceuticals tested, acetaminophen levels were greatest across sampling sites in the Zandvlei Estuary, which reflects its widely prescribed- and non-prescribed usage in South Africa [27]. Sulfamethoxazole, carbamazepine and diclofenac were also abundant in the Zandvlei Estuary; these pharmaceuticals are similarly often prescribed, whilst diclofenac is available without prescription, and thus these compounds are prevalent in Cape Town’s sewage [21,22] and sewage-impacted water bodies worldwide [27,28,29]. The pharmaceutical concentrations recorded in the Zandvlei Estuary were greater than in the Sundays and Buffalo Estuaries in South Africa [30]. Pharmaceutical concentrations were also considerably greater than the Tejo Estuary, Portugal [31]; Jiulong River Estuary, China [32]; Long Island Sound Estuary, USA [33]; and the Sydney Estuary, Australia [34]. Relative to the above-mentioned systems, acetaminophen levels were over 100 times greater, and those of sulfamethoxazole, bezafibrate and carbamazepine were at least 5 times greater in the Zandvlei Estuary [31,32,33,34]. However, pharmaceutical concentrations were greater in the Umgeni and Warner Beach Estuaries in South Africa and Gazi Bay (coastal lagoon), Kenya, relative to the Zandvlei Estuary [35,36,37].
Noteworthy, however, was that pharmaceutical concentrations in pelagic samples from the Zandvlei Estuary were almost 100-fold greater than in False Bay, into which the estuary discharges [3]. To contextualize, sewage-related pharmaceuticals were detected in ng/L in False Bay but µg/L in the Zandvlei Estuary [3]. This finding highlights the potential for urbanized temporarily closed estuaries such as the Zandvlei Estuary to be sites of pharmaceutical accumulation. The order of magnitude increase in carbamazepine, sulfamethoxazole and acetaminophen levels in the Zandvlei Estuary relative to False Bay can be explained by dilution in False Bay, whilst higher material residence times, urbanization and sewage inputs into the Zandvlei Estuary are the most likely causes of the enhanced pharmaceutical concentrations detected.
Nevirapine, carbamazepine and sulfamethoxazole were bioaccumulative compounds in sandprawns (BAF > 5000 L/kg), whereas acetaminophen was potentially bioaccumulative (BAF = 2000–5000 L/kg). Although the BAFs we recorded need to be interpreted in the context of data being derived from one sampling period, the BAFs for acetaminophen and carbamazepine reported in the present study for sandprawns were greater than in the studies of Klosterhaus et al. (2013), Du et al. (2015) and Wilkinson et al. (2018) [38,39,40]. BAFs of 208 and 0.6 were reported for carbamazepine in the ribbed mussel (Geukensia demissa) [38] and in freshwater snails (Planorbid spp.), respectively [39]. Wilkinson et al. (2018) [40] reported BAF values for acetaminophen of 37 in the freshwater snail, Bithynia tentaculata, and 26.4 in the amphipod, Gammarus pulex. However, the BAF values recorded in False Bay [3] were greater (e.g., range of BAF for SMX in mussels Mytilus galloprovincialis: 14,882 to 520,289) than sandprawns in the Zandvlei Estuary. Pharmaceutical uptake by organisms can be species-specific and dependent on lifestyle and trophic position [41,42]. The False Bay invertebrates sampled by Ojemaye and Petrik (2021) [3] were sedentary and epibenthic, whereas the sandprawns used in our study are mobile endobenthic burrowers [11]. Bioaccumulation of acidic pharmaceuticals (such as sulfamethoxazole) can also increase with a decrease in pH due to lowered metabolism with acidification in aquatic environments [43,44,45,46]. Water temperature can similarly alter bioaccumulation due to effects on metabolism [45,46]. The greater bioaccumulation of pharmaceuticals by invertebrates in False Bay despite lower sewage-related pharmaceutical concentrations relative to the Zandvlei Estuary highlights the point that organismal bioaccumulation may be high in spite of low pelagic levels, demonstrating the risk of long-term exposure by epibenthic and endobenthic organisms to multiple persistent contaminants [3].

5. Conclusions

Despite its limited scope, this study has provided valuable knowledge on selected pharmaceutical pollution and bioaccumulation in a temporarily closed urban estuarine environment and on a continent where such information is lacking. The almost 100-fold greater levels of the targeted pharmaceuticals detected in the Zandvlei Estuary relative to False Bay show the potential for temporarily closed, urbanized estuaries to be accumulation sites for pharmaceuticals. Such pharmaceutical levels may impact the physiology of biota, ecosystem processes and people that utilize these systems for recreation and subsistence. Improvements in wastewater treatment facilities and urban sewerage infrastructure are thus necessary to limit pharmaceutical discharges and accumulation in such systems. The calculated bioaccumulation factors for the sandprawns also highlight the assimilative capacity of temporarily closed estuarine environments. The magnitude of differences in concentrations of pharmaceuticals between pelagic samples and sandprawn tissue demonstrates that pelagic samples may not reflect the significant risks to biota of long-term exposure to a plethora of synthetic and persistent pharmaceutical compounds. Further research on pharmaceutical pollution is also key for developing integrative ecosystem management plans, early warning systems for temporarily closed estuaries and public education initiatives. Our finding of sandprawns in the Zandvlei Estuary bioaccumulating some of the selected pharmaceuticals highlights the need to further understand consequences for the physiology of sandprawns and their provision of key ecosystem engineering functions and services, especially considering their wide distribution in Southern Africa, including within temporarily closed estuaries [10,13,15]. In future, temporal replication of sampling will enable assessments of the generality of pharmaceutical pollution in TCEs. It is also recommended that variance in sandprawn contaminant loads be explored to understand whether this variability linked to organism size, sex or other biological factors.

Author Contributions

O.M. and D.P. developed the study design and were responsible for the main body of text. O.M. conducted the field work and experiment and collected all analyzed samples with advice from D.P., L.P. and C.Y.O. O.M. performed the data analyses with advice from D.P., L.P. and C.Y.O. D.P. designed the research program, of which this paper is a component. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by National Research Foundation of South Africa grant number SRUG2204305445.

Institutional Review Board Statement

The research conducted in this paper was approved by the Science Faculty Animal Ethics Committee (Approval number 2022/V6/DP), University of Cape Town.

Data Availability Statement

Dataset available on request from the authors.

Acknowledgments

The City of Cape Town is thanked for granting permission to work in the Zandvlei Estuary. This study was supported financially by the National Research Foundation (NRF) and the University of Cape Town. We are also grateful to several students from the University of Cape Town that assisted with field and laboratory work. Mila Truter is thanked for assistance with data analysis and Megan van Zyl for manuscript formatting.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Chia, M.A.; Lorenzi, A.S.; Ameh, I.; Dauda, S.; Cordeiro-Araújo, M.K.; Agee, J.T.; Okpanachi, I.Y.; Adesalu, A.T. Susceptibility of phytoplankton to the increasing presence of active pharmaceutical ingredients (APIs) in the aquatic environment: A review. Aquat. Toxicol. 2021, 234, 105809. [Google Scholar] [CrossRef]
  2. Gaw, S.; Thomas, K.V.; Hutchinson, T.H. Sources, impacts and trends of pharmaceuticals in the marine and coastal environment. Philos. Trans. R. Soc. 2014, 369, 20130572. [Google Scholar] [CrossRef]
  3. Ojemaye, C.Y.; Petrik, L. Pharmaceuticals and Personal Care Products in the Marine Environment Around False Bay, Cape Town, South Africa: Occurrence and Risk-Assessment Study. Environ. Toxicol. Chem. 2021, 41, 614–634. [Google Scholar] [CrossRef] [PubMed]
  4. Kock, A.; Glanville, H.C.; Law, A.C.; Stanton, T.; Carter, L.J.; Taylor, J.C. Emerging challenges of the impacts of pharmaceuticals on aquatic ecosystems: A diatom perspective. Sci. Total Environ. 2023, 878, 162939. [Google Scholar] [CrossRef]
  5. Fabbri, E.; Franzellitti, S. Human pharmaceuticals in the marine environment: Focus on exposure and biological effects in animal species. Environ. Toxicol. Chem. 2016, 35, 799–812. [Google Scholar] [CrossRef]
  6. Neuparth, T.; Martins, C.; Santos, C.B.; Costa, M.H.; Martins, I.; Costa, P.M.; Santos, M.M. Hypocholesterolaemic pharmaceutical simvastatin disrupts reproduction and population growth of the amphipod Gammarus locusta at the ng/L range. Aquat. Toxicol. 2014, 155, 337–347. [Google Scholar] [CrossRef]
  7. Srain, H.S.; Beazley, K.F.; Walker, T.R. Pharmaceuticals and personal care products and their sublethal and lethal effects in aquatic organisms. Environ. Rev. 2021, 29, 142–181. [Google Scholar] [CrossRef]
  8. Perissinotto, R.; Stretch, D.D.; Whitfield, A.K.; Adams, J.B.; Forbes, A.T.; Demetriades, N.T. Ecosystem functioning of temporarily open/closed estuaries in South Africa. In Estuaries: Types, Movement Patterns; Crane, J.R., Solomon, A.E., Eds.; Nova Science Publishers, Inc.: Hauppauge, NY, USA, 2010; pp. 1–69. [Google Scholar]
  9. Adams, J.B.; Taljaard, S.; van Niekerk, L.; Lemley, D.A. Nutrient enrichment as a threat to the ecological resilience and health of South African microtidal estuaries. Afr. J. Aquat. Sci. 2020, 45, 23–40. [Google Scholar] [CrossRef]
  10. Branch, G.M.; Griffiths, C.L.; Branch, M.; Beckley, L.E. Two Oceans: A Guide to the Marine Life of Southern Africa; Struik Nature: Cape Town, South Africa, 2016. [Google Scholar]
  11. Pillay, D.; Branch, G.M.; Forbes, A.T. Effects of Callianassa kraussi on microbial biofilms and recruitment of macrofauna: A novel hypothesis for adult-juvenile interactions. Mar. Ecol. Prog. Ser. 2007, 347, 1–14. [Google Scholar] [CrossRef]
  12. Pillay, D.; Branch, G.M.; Forbes, A.T. The influence of bioturbation by the sandprawn Callianassa kraussi on feeding and survival of the bivalve Eumarcia paupercula and the gastropod Nassarius kraussianus. J. Exp. Mar. Biol. Ecol. 2007, 344, 1–9. [Google Scholar] [CrossRef]
  13. Pillay, D.; Branch, G.M. Bioengineering effects of burrowing thalassinidean shrimps on marine soft-bottom ecosystems. Oceanogr. Mar. Biol. 2011, 49, 137–192. [Google Scholar]
  14. Pillay, D. Ecosystem engineering by thalassinidean crustaceans: Response variability, contextual dependencies and perspectives on future research. Diversity 2019, 11, 64. [Google Scholar] [CrossRef]
  15. Venter, O.; Pillay, D.; Prayag, K. Water filtration by burrowing sandprawns provides novel insights on endobenthic engineering and solutions for eutrophication. Sci. Rep. 2020, 10, 1913. [Google Scholar] [CrossRef]
  16. Thomas, C.M.; de Cerff, C.; Maniel, G.A.V.; Oyatoye, A.E.; Rocke, E.; Marco, H.G.; Pillay, D. Water filtration by endobenthic sandprawns enhances resilience agaisnnt eutrophication under experimental global change conditions. Sci. Rep. 2023, 13, 19067. [Google Scholar] [CrossRef]
  17. de Cerff, C.; Rocke, E.; Oyatoye, A.E.; Maniel, G.; Pillay, D. Mesocosm evidence for sandprawn-mediated shifts in pelagic resource ratios and phytoplankton traits. Estuar. Coast. Shelf Sci. 2024, 305, 108874. [Google Scholar] [CrossRef]
  18. Van Niekerk, L.; Adams, J.B.; Lamberth, S.J.; MacKay, C.F.; Taljaard, S.; Turpie, J.K.; Weerts, S.P.; Raimondo, D.C. South African National Biodiversity Assessment 2018: Technical Report. CSIR Rep. 2019, 3, 1–30. [Google Scholar]
  19. Archer, E.; Petrie, B.; Kasprzyk-Hordern, B.; Wolfaardt, G.M. The fate of pharmaceuticals and personal care products (PPCPs), endocrine disrupting contaminants (EDCs), metabolites and illicit drugs in a WWTW and environmental waters. Chemosphere 2017, 174, 437–446. [Google Scholar] [CrossRef] [PubMed]
  20. Gqomfa, B.; Maphanga, T.; Shale, K. The impact of informal settlement on water quality of Diep River in Dunoon. Sustain. Water Resour. Manag. 2021, 8, 27. [Google Scholar] [CrossRef]
  21. Swartz, C.; Genthe, B.; Chamier, J.; Petrik, L.F.; Tijani, J.O.; Adeleye, A.; Coomans, C.J.; Ohlin, A.; Falk, D.; Menge, J.G. Emerging Contaminants in Wastewater Treated for Direct Potable Re-Use: The Human Health Risk; Water Research Commission: Pretoria, South Africa, 2016.
  22. Swartz, C.D.; Genthe, B.; Chamier, J.; Petrik, L.F.; Tijani, J.O.; Adeleye, A.; Coomans, C.J.; Ohlin, A.; Falk, D.; Menge, J.G. Emerging Contaminants in Wastewater Treated for Direct Potable Re-Use: The Human Health Risk Priorities in South Africa. In VOLUME III: Occurrence, Fate, Removal and Health Risk Assessment of Chemicals of Emerging Concern in Reclaimed Water for Potable Reuse; Water Research Commission: Pretoria, South Africa, 2018. [Google Scholar]
  23. Harding, W.R. Water quality trends and the influence of salinity in a highly regulated estuary near Cape Town, South Africa. S. Afr. J. Sci. 1994, 90, 240–246. [Google Scholar]
  24. Na, G.; Fang, X.; Cai, Y.; Ge, L.; Zong, H.; Yuan, X.; Yao, Z.; Zhang, Z. Occurance, distribution, and bioaccumulation of antibiotics in coastal environment of Dalian, China. Mar. Pollut. Bull. 2013, 69, 233–237. [Google Scholar] [CrossRef]
  25. Wu, J.; Zhang, Y.; Luo, X.; Wang, J.; Chen, S.; Guan, Y.; Mai, B. Isomer-specific bioaccumulation and trophic transfer of dechlorane plus in the freshwater food web from a highly contaminated site, south China. Environ. Sci. Technol. 2010, 44, 606–611. [Google Scholar] [CrossRef] [PubMed]
  26. Schlacher, T.A.; Wooldridge, T.H. Origin and trophic importance of detritus-evidence from stable isotopes in the benthos of a small, temperate estuary. Oecologia 1996, 106, 382–388. [Google Scholar] [CrossRef]
  27. Osunmakinde, C.S.; Tshabalala, O.S.; Dube, S.; Nindi, M.M. Verification and Validation of Analytical Methods for Testing the Levels of PPHCPs (Pharmaceutical and Personal Health Care Products) in Treated Drinking Water and Sewage; Water Research Commission: Pretoria, South Africa, 2013.
  28. Madikizela, L.M.; Chimuka, L. Occurrence of naproxen, ibuprofen, and diclofenac residues in wastewater and river water of KwaZulu-Natal Province in South Africa. Environ. Monit. Assess. 2017, 189, 348. [Google Scholar] [CrossRef]
  29. Moslah, B.; Hapeshi, E.; Jrad, A.; Fatta-kassinos, D. Pharmaceuticals and illicit drugs in wastewater samples in north-eastern Tunisia. Environ. Sci. Pollut. Res. 2018, 25, 18226–18241. [Google Scholar] [CrossRef]
  30. Ohoro, C.R.; Adeniji, A.O.; Semerjian, L.; Okoh, O.O.; Okoh, A.I. Occurrence and distribution of pharmaceuticals in surface water and sediment of Buffalo and Sundays River estuaries, South Africa and their ecological risk assessment. Emerg. Contam. 2021, 7, 187–195. [Google Scholar] [CrossRef]
  31. Reis-Santos, P.; Pais, M.; Duarte, B.; Cacador, I.; Freitas, A.; Pouca, A.S.V.; Barbosa, J.; Leston, S.; Rosa, J.; Ramos, F.; et al. Screening of human and veterinary pharmaceuticals in estuarine waters: A baseline assessment for the Tejo estuary. Mar. Pollut. Bull. 2018, 135, 1079–1084. [Google Scholar] [CrossRef] [PubMed]
  32. Sun, Q.; Li, Y.; Li, M.; Ashfaq, M.; Lv, M.; Wang, H.; Hu, A.; Yu, C.P. PCPs in Jiulong River estuary (China): Spatiotemporal distributions, fate, and their use as chemical markers of wastewater. Chemosphere 2016, 150, 596–604. [Google Scholar] [CrossRef]
  33. Lara-Martin, P.A.; González-Mazo, E.; Petrovic, M.; Barcelo, D. Occurrence, distribution and partitioning of nonionic surfactants and pharmaceuticals in the urbanized Long Island Sound Estuary (NY). Mar. Pollut. Bull. 2014, 85, 710–719. [Google Scholar] [CrossRef]
  34. Birch, G.F.; Drage, D.S.; Thompson, K.; Eaglesham, G.; Mueller, J.F. Emerging contaminants (pharmaceuticals, personal care products, a food additive and pesticides) in waters of Sydney estuary, Australia. Mar. Pollut. Bull. 2015, 97, 56–66. [Google Scholar] [CrossRef]
  35. Agunbiade, F.O.; Moodley, B. Pharmaceuticals as emerging organic contaminants in Umgeni River water system, KwaZulu-Natal, South Africa. Environ. Monit. Assess. 2014, 186, 7273–7291. [Google Scholar] [CrossRef] [PubMed]
  36. Sigonya, S.; Onwubu, S.C.; Mdluli, P.S. Method optimisation and application based on solid phase extraction of non steriodal anti-inflammatory drugs, antiretroviral drugs, and a lipid regulator from coastal areas of Durban, South Africa. SN Appl. Sci. 2022, 4, 231. [Google Scholar] [CrossRef]
  37. Wanjeri, V.O.W.; Okuku, E.; Gachanja, A.; Ngila, J.C.; Ndungu, P.G. Occurrence, distribution, and environmental risk of pharmaceutical residues in Mombasa peri-urban creeks, Kenya. Chemosphere 2023, 31, 137144. [Google Scholar] [CrossRef]
  38. Klosterhaus, S.L.; Grace, R.; Hamilton, M.C.; Yee, D. Method validation and reconnaissance of pharmaceuticals, personal care products, and alkylphenols in surface waters, sediments, and mussels in an urban estuary. Environ. Int. 2013, 54, 92–99. [Google Scholar] [CrossRef]
  39. Du, B.; Haddad, S.P.; Scott, W.C.; Chambliss, C.K.; Brooks, B.W. Pharmaceutical bioaccumulation by periphyton and snails in an effluent-dependent stream during an extreme drought. Chemosphere 2015, 119, 927–934. [Google Scholar] [CrossRef]
  40. Wilkinson, J.L.; Hooda, P.S.; Swinden, J.; Barker, J.; Barton, S. Spatial (bio) accumulation of pharmaceuticals, illicit drugs, plasticisers, perfluorinated compounds and metabolites in river sediment, aquatic plants and benthic organisms. Environ. Pollut. 2018, 234, 864–875. [Google Scholar] [CrossRef] [PubMed]
  41. Meredith-Williams, M.; Carter, L.J.; Fussell, R.; Raffaelli, D.; Ashauer, R.; Boxall, A.B.A. Uptake and depuration of pharmaceuticals in aquatic invertebrates. Environ. Pollut. 2012, 165, 250–258. [Google Scholar] [CrossRef] [PubMed]
  42. Grabicová, K.; Stañová, A.V.; Švecová, H.; Nováková, P.; Kodeš, V.; Leontovyčová, D.; Brooks, B.W.; Grabic, R. Invertebrates differentially bioaccumulate pharmaceuticals: Implications for routine biomonitoring. Environ. Pollut. 2022, 309, 119715. [Google Scholar] [CrossRef] [PubMed]
  43. Kroeker, K.J.; Kordas, R.L.; Crim, R.N.; Singh, G.G. Meta-analysis reveals negative yet variable effects of ocean acidification. Ecol. Lett. 2010, 13, 1419–1434. [Google Scholar] [CrossRef]
  44. Kroeker, K.J.; Gaylord, B.; Hill, T.M.; Hosfelt, J.D.; Miller, S.H.; Sanford, E. The role of temperature in determining species’ vulnerability to ocean acidification: A case study using Mytilus galloprovincialis. PLoS ONE 2014, 9, e100353. [Google Scholar] [CrossRef]
  45. Serra-Compte, A.; Maulvault, A.L.; Camacho, C.; Álvarez-Muñoz, D.; Barceló, D.; Rodríguez-Mozaz, S.; Margues, A. Effects of water warming and acidification on bioconcentration, metabolization and depuration of pharmaceuticals and endocrine disrupting compounds in marine mussels (Mytilis galloprovincialis). Environ. Pollut. 2018, 236, 824–834. [Google Scholar] [CrossRef]
  46. Bethke, K.; Kropidłowska, K.; Stepnowski, P.; Caban, M. Review of warming and acidification effects to the ecotoxicity of pharmaceuticals on aquatic organisms in the era of climate change. Sci. Total Environ. 2023, 877, 162829. [Google Scholar] [CrossRef] [PubMed]
Water 17 02289 g001
Figure 1. Location of the Zandvlei Estuary and marina within (i) Cape Town (rectangle) and (ii) South Africa (circle) with sampling sites (1–5) shown. The arrowed line near site 5 denotes the sandprawn biotope.
Figure 1. Location of the Zandvlei Estuary and marina within (i) Cape Town (rectangle) and (ii) South Africa (circle) with sampling sites (1–5) shown. The arrowed line near site 5 denotes the sandprawn biotope.
Water 17 02289 g001
Table 1. Chemical and analytical characteristics of pharmaceuticals detected in the Zandvlei Estuary. N-octanol/water partition coefficient = log Kow, retention time = RT, collision energy = CE, limit of detection = LOD, limit of quantification = LOQ.
Table 1. Chemical and analytical characteristics of pharmaceuticals detected in the Zandvlei Estuary. N-octanol/water partition coefficient = log Kow, retention time = RT, collision energy = CE, limit of detection = LOD, limit of quantification = LOQ.
PharmaceuticalTherapeutic ClassMolecular StructureMolecular Weight (g/mol)Log KowRT (min)Ion Transition (m/z)CE (eV)LOD LOQ Recovery (%)
Sandprawn (µg/g)Water (µg/L) Water (µg/L)Sandprawn (µg/g) SandprawnWater
AcetaminophenAnalgesics and antipyreticsWater 17 02289 i001151.161.103.22152 > 93152 > 110240.430.01 1.300.03 98.598.1
AmitriptylineTricyclic antidepressantsWater 17 02289 i002277.404.815.45278 > 117278 > 233200.070.005 0.220.017 98.598.9
BezafibrateFibratesWater 17 02289 i003361.823.819.06360 > 274360 > 274200.800.02 2.500.05 98.999.0
CarbamazepineAnticonvulsantWater 17 02289 i004236.272.676.43237 > 135
237 > 179		237 > 194100.200.01 0.500.02 99.299.7
DiclofenacNonsteroidal anti-inflammatoryWater 17 02289 i005296.154.069.12296 > 215296 > 250150.700.02 2.000.05 99.199.9
Nevirapinenon-nucleoside reverse transcriptase inhibitorsWater 17 02289 i006266.302.54.19267 > 107267 > 226250.160.005 0.480.015 98.298.5
SulfamethoxazoleAntibioticWater 17 02289 i007253.281.314.50254 > 147254 > 156250.300.01 1.000.02 98.999.5
Table 2. Pelagic physico-chemical conditions and pharmaceutical contaminant concentrations (µg/L; mean ± standard error) in water samples measured at sites 1-5 in the Zandvlei Estuary.
Table 2. Pelagic physico-chemical conditions and pharmaceutical contaminant concentrations (µg/L; mean ± standard error) in water samples measured at sites 1-5 in the Zandvlei Estuary.
12345
Physico-chemical dataTemperature (°C)14.3514.2413.7313.5614.60
Salinity (‰)16.7616.8415.3915.9218.19
Dissolved oxygen (mg/L)9.318.249.69.48.95
pH8.528.478.678.708.56
Depth (m)1.21.41.01.70.4
Chl-a (µg/L)81.654.554.451.220.7
Pharmaceuticals (µg/L)Acetaminophen0.121 ± 0.00510.317 ± 0.01341.307 ± 0.05820.329 ± 0.00912.531 ± 0.0762
Amitriptyline0.011 ± 0.00220.012 ± 0.00090.006 ± 0.00030.006 ± 0.00030.09 ± 0.0010
Bezafibrate0.022 ± 0.00550.027 ± 0.00210.019 ± 0.00310.015 ± 0.00330.028 ± 0.0013
Carbamazepine0.071 ± 0.02050.067 ± 0.00960.157 ± 0.05860.100 ± 0.00550.082 ± 0.0144
Diclofenac0.016 ± 0.00570.037 ± 0.01320.040 ± 0.00600.016 ± 0.00320.021 ± 0.0034
Nevirapine0.009 ± 0.00060.009 ± 0.00070.009 ± 0.00060.007 ± 0.00030.008 ± 0.0006
Sulfamethoxazole0.069 ± 0.01290.094 ± 0.00560.093 ± 0.01630.085 ± 0.00380.138 ± 0.0027
Table 3. Concentrations of pharmaceutical contaminants and bioaccumulation in sandprawn tissue samples collected from site 5 in the Zandvlei Estuary. Samples A, B and C represent three samples (1 g) collected randomly from freeze-dried muscle tissue of sandprawns from site 5.
Table 3. Concentrations of pharmaceutical contaminants and bioaccumulation in sandprawn tissue samples collected from site 5 in the Zandvlei Estuary. Samples A, B and C represent three samples (1 g) collected randomly from freeze-dried muscle tissue of sandprawns from site 5.
SampleAcetaminophen
(µg/g) dw		Amitriptyline
(µg/g) dw		Bezafibrate
(µg/g) dw		Carbamazepine
(µg/g) dw		Diclofenac
(µg/g) dw		Nevirapine
(µg/g) dw		Sulfamethoxazole
(µg/g) dw
A14.3980.0030.0052.6120.0180.3592.094
B7.194005.6950.04000.520
C12.334001.8790.01300.480
Bioaccumulation
Factor (L/kg)		4469 *926041,257 **114843,775 **7450 **
Note: ** bioaccumulative compounds, * potentially bioaccumulative compounds.
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Murgatroyd, O.; Petrik, L.; Ojemaye, C.Y.; Pillay, D. Persistent Pharmaceuticals in a South African Urban Estuary and Bioaccumulation in Endobenthic Sandprawns (Kraussillichirus kraussi). Water 2025, 17, 2289. https://doi.org/10.3390/w17152289

AMA Style

Murgatroyd O, Petrik L, Ojemaye CY, Pillay D. Persistent Pharmaceuticals in a South African Urban Estuary and Bioaccumulation in Endobenthic Sandprawns (Kraussillichirus kraussi). Water. 2025; 17(15):2289. https://doi.org/10.3390/w17152289

Chicago/Turabian Style

Murgatroyd, Olivia, Leslie Petrik, Cecilia Y. Ojemaye, and Deena Pillay. 2025. "Persistent Pharmaceuticals in a South African Urban Estuary and Bioaccumulation in Endobenthic Sandprawns (Kraussillichirus kraussi)" Water 17, no. 15: 2289. https://doi.org/10.3390/w17152289

APA Style

Murgatroyd, O., Petrik, L., Ojemaye, C. Y., & Pillay, D. (2025). Persistent Pharmaceuticals in a South African Urban Estuary and Bioaccumulation in Endobenthic Sandprawns (Kraussillichirus kraussi). Water, 17(15), 2289. https://doi.org/10.3390/w17152289

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