Isotopic and microbial indicators of sewage pollution from Stone Town, Zanzibar, Tanzania

Moynihan, Molly A.; Baker, David M.; Mmochi, Aviti J.

doi:10.1016/j.marpolbul.2012.05.001

Cited by 45 publications

(32 citation statements)

References 26 publications

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“…These issues are, for instance, the dispersion of sewage pollution or coral larvae, which are of ecological and socioeconomic importance. Dispersion of sewage pollution in the channel is becoming a growing problem that can affect human health [Mohammed, 2002;Moynihan et al, 2012] and biodiversity [Harvell et al, 2004], especially because sewage pollution is considered the most important local factor affecting coral reefs worldwide [Halpern et al, 2008]. Dispersion of coral larvae is important because it represents the connectivity between coral reefs that is crucial for their survival.…”

Section: Application Examplementioning

confidence: 99%

On the dynamics of the Zanzibar Channel

et al. 2015

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The Zanzibar Channel lies between the mainland of Tanzania and Zanzibar Island in the tropical western Indian Ocean, is about 100 km long, 40 km wide, and 40 m deep, and is essential to local socioeconomic activities. This paper presents a model of the seasonal and tidal dynamics of the Zanzibar Channel based on the Regional Ocean Modeling System (ROMS) and a comparison of the model and observations. The seasonal dynamics of the channel is forced by remote processes and the local wind. Remote forcing creates the East African Coastal Current, a portion of which flows through the channel northward with a seasonally varying magnitude. The local wind enhances this seasonality in the surface Ekman layer, resulting in a stronger northward flow during the southwest monsoon season and a weak northward or occasionally southward flow during the northeast monsoon season. The tidal flows converge and diverge in the center of the channel and reduce the transport in the channel. The remotely forced, wind‐forced, and tidal dynamics contain 5%, 3%, and 92% of the total kinetic energy, respectively. Despite their low kinetic energy, the remotely forced and wind‐forced flows are most relevant in advecting channel water to the open ocean, which occurs in 19 days at the peak of the southwest monsoon season. The channel is well mixed, except during brief periods in the two rainy seasons, and temporarily cools between December and February. The dispersion of passive tracers is presented as an example of potential model applications.

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Section: Application Examplementioning

confidence: 99%

On the dynamics of the Zanzibar Channel

et al. 2015

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“…This could be related to local stressors, i.e., land-based pollution and unregulated tourism (Moynihan et al, 2012). Chapwani Reef showed the lowest coral cover (52.4 ± 13.9%), biodiversity (H' = 1.2 ± 0.5) and calcium carbonate production (8.5 ± 4.4 kg CaCO 3 m −2 yr −1 ).…”

Section: Discussion Community Compositionmentioning

confidence: 99%

“…The main outfall, located adjacent to the Port of Stone Town, discharges an estimated 2.2 × 10 6 L d −1 of untreated sewage (Moynihan et al, 2012). Tidal currents distribute the flow of wastewater in a northward direction away from Stone Town toward three nearby reef sites that are important artisanal fishing grounds and tourist destinations (Johnstone et al, 1998;Mohammed and Mgaya, 2001;Mukaka, 2014).…”

Section: Study Sitesmentioning

confidence: 99%

“…Coastal development in particular affects water quality by increasing turbidity and the sediment load in the water column (Mumby et al, 2006) and has been well established to have a direct effect on coral community structure (Fabricius, 2005). Chapwani and Prison already show signs of pollution (Moynihan et al, 2012) and destructive fishing such as dragnets (Muhando, 1998;Mohammed and Mgaya, 2001) have been reported. Both natural and anthropogenic stressors including sedimentation stress, thermal stress, storm damage and overfishing, are constantly affecting reef health and community structure (Dubinsky and Stambler, 1996;Hatcher, 1997;Szmant, 2002).…”

Section: Mpa Relevance and Implication For Managementmentioning

confidence: 99%

“…A range of local stressors have been reported from Zanzibar, from overfishing in Bawe Reef (Lokrantz et al, 2009), pollution in Chapwani and Prison reefs (Moynihan et al, 2012) to mechanical damage by destructive fishing methods such as dragnets (Muhando, 1998; or careless anchoring (Muhando, 1998;. At the same time, Zanzibar has a rapid population growth rate (National Bureau of Statistics, 2012) closely linked to the increase in resource demand and tourist infrastructure (Lange and Jiddawi, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Calcium Carbonate Production, Coral Cover and Diversity along a Distance Gradient from Stone Town: A Case Study from Zanzibar, Tanzania

et al. 2017

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Photosymbiotic scleractinian corals are major bioengineers in tropical coastal waters, where they build structurally complex geological features and provide substrata for a manifold of macro and microhabitats. On a local scale, ecological competition and physical parameters-natural as well as human-derived, alter species richness, biodiversity, and morphological adaptation on tropical coral reefs. Here, we compared four coral reefs in the Zanzibar Archipelago at different distances from Stone Town and under different management regimes. To assess the ecological health of these reefs, calcium carbonate production, structural complexity, and α-diversity were determined. The unprotected reefs in the direct vicinity of Stone Town, which are exposed to fishing pressure, land-derived pollution, unregulated tourism, and careless anchoring, showed the lowest calcium carbonate production (8.47 ± 4.37 kg CaCO 3 m −2 yr −1 ), coral cover (52.4 ± 13.9%), and diversity (H ′ = 0.94 ± 0.37). Conversely, the furthest reef and marine protected area showed the highest net calcium carbonate production (16.90 ± 9.70 kg CaCO 3 m −2 yr −1 ), coral cover (67.4 ± 8.7%), and diversity (H ′ = 1.74 ± 0.20). In comparison to other bioregions and/or reefs of the Indian Ocean, estimates of calcium carbonate production and coral cover (>50%) were relatively high. Moreover, coral community structure differs significantly with distance from Stone Town, in that, the most homogenous reefs dominated by massive and submassive species (Porites lobata and P. rus) occurred the closest to Stone Town.

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High‐resolution imaging sheds new light on a multi‐tier symbiotic partnership between a “walking” solitary coral, a sipunculan, and a bivalve from East Africa

Herran

Narayan

Doo

et al. 2022

Ecology and Evolution

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Marine symbioses are integral to the persistence of ecosystem functioning in coral reefs. Solitary corals of the species Heteropsammia cochlea and Heterocyathus aequicostatus have been observed to live in symbiosis with the sipunculan worm Aspidosiphon muelleri muelleri, which inhabits a cavity within the coral, in Zanzibar (Tanzania). The symbiosis of these photosymbiotic corals enables the coral holobiont to move, in fine to coarse unconsolidated substrata, a process termed as “walking.” This allows the coral to escape sediment cover in turbid conditions which is crucial for these light‐dependent species. An additional commensalistic symbiosis of this coral‐worm holobiont is found between the Aspidosiphon worm and the cryptoendolithic bivalve Jousseaumiella sp., which resides within the cavity of the coral skeleton. To understand the morphological alterations caused by these symbioses, interspecific relationships, with respect to the carbonate structures between these three organisms, are documented using high‐resolution imaging techniques (scanning electron microscopy and µCT scanning). Documenting multi‐layered symbioses can shed light on how morphological plasticity interacts with environmental conditions to contribute to species persistence.

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Isotopic and microbial indicators of sewage pollution from Stone Town, Zanzibar, Tanzania

Cited by 45 publications

References 26 publications

On the dynamics of the Zanzibar Channel

On the dynamics of the Zanzibar Channel

Calcium Carbonate Production, Coral Cover and Diversity along a Distance Gradient from Stone Town: A Case Study from Zanzibar, Tanzania

High‐resolution imaging sheds new light on a multi‐tier symbiotic partnership between a “walking” solitary coral, a sipunculan, and a bivalve from East Africa

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