Local Persistence of Large Benthic Foraminifera (LBF) under Increasing Urban Development: A Case Study from Zanzibar (Unguja), East Africa

Gita R. Narayan, Natalia Herrán, Claire E. Reymond, Yohanna W. Shaghude, Hildegard Westphal

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Coastal marine management is vital for socio-ecological sustainability of developing, tropical ecosystems, which calls for diverse tools to monitor and assess water quality. The carbonate-dominated habitats off Zanzibar were chosen for study due to potential water quality degradation in a rapidly developing tourist destination heavily reliant on its coral reefs. These reefs are largely unmonitored and subject to local and global stressors. A widely used method for assessing reef health, as an early detection method of ecological changes, is the application of large benthic foraminiferal bioindicators, i.e., the FoRAM Index. We expected to find poor water quality conditions in the unmanaged reefs supported by stress-toelerant (opportunistic) foraminiferal assemblages. The dissolved inorganic nitrogen and phosphate values derived from untreated sewage effluent from Stone Town were highly variable (ranging 0.05–3.77 and 0.05–1.45 µM, respectively), moderate, and occasionally approached or exceeded critical threshold values for oligotrophic ecosystems. The analysis of total assemblages indicated an abundance of symbiont-bearing large benthic foraminifera, dominated by prolific Amphistegina species, comparatively low-moderate diversity, high FI values (7.6 on average), and high coral cover. A water quality gradient was reflected by subtle assemblage differences, suggesting that LBF can provide early warning signals of benthic changes, indicating the importance of long-term monitoring programs in vulnerable, rapidly developing coastal ecosystems exposed to increasing pressures.
Original languageEnglish (US)
JournalJournal of Earth Science
StatePublished - Nov 10 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-11-28
Acknowledgements: This project was carried out within the framework and through funding provided by the Leibniz Graduate School SUTAS (Sustainable Use of Tropical Aquatic Systems) to HW, and the Leibniz Centre for Tropical Marine Research (ZMT) based in Bremen, Germany. All samples were collected under the Revolutionary Government of Zanzibar (S.M.Z) Research/filming Permits issued on 09.09.2014 (Serial No. 1310) and on 09.03.215 (Serial No. 0671). We thank Matern Mtolera and Christopher Muhando of the Institute of Marine Sciences (IMS), University of Dar es Salaam; Uli Kloiber and team from the Chumbe Island Coral Park Ltd. (CHICOP). We especially thank Matthias Birkicht from the ZMT chemistry laboratory, the ZMT scientific diving team and our volunteer field assistants from Germany: Andreas Eich and Jendrik Schroeder. Lastly, we thank the two anonymous reviewers for their constructive comments and edits, which greatly improved this manuscript. Open Access funding enabled and organized by Projekt DEAL.

ASJC Scopus subject areas

  • General Earth and Planetary Sciences


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