Cyanobacteria Composition and Impact of Seasonality on their &lt;i&gt;In Situ&lt;/i&gt; Nitrogen Fixation Rate in a Mangrove Ecosystem Adjacent to Zanzibar Town

Kyaruzi, J.J.; Kyewalyanga,; Muruke, Masoud Hadi

doi:10.4314/wiojms.v2i1.28427

Cited by 17 publications

(13 citation statements)

References 23 publications

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“…The SC sampling location also contained a high level of Scytonema sp., which belongs to the Nostocales (heterocyst-forming) order of cyanobacteria. Another cyanobacterial diazotroph, Pseudoanabaena , was found in all our locations with low abundance; these are frequently detected in mangrove ecosystems ( Kyaruzi et al, 2003 ). Moreover, filamentous non-heterocystous cyanobacteria Microcoleus were detected at all five sampling sites.…”

Section: Discussionmentioning

confidence: 88%

Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

et al. 2015

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Diazotrophs in the mangrove rhizosphere play a major role in providing new nitrogen to the mangrove ecosystem and their composition and activity are strongly influenced by anthropogenic activity and ecological conditions. In this study, the diversity of the diazotroph communities in the rhizosphere sediment of five tropical mangrove sites with different levels of pollution along the north and south coastline of Singapore were studied by pyrosequencing of the nifH gene. Bioinformatics analysis revealed that in all the studied locations, the diazotroph communities comprised mainly of members of the diazotrophic cluster I and cluster III. The detected cluster III diazotrophs, which were composed entirely of sulfate-reducing bacteria, were more abundant in the less polluted locations. The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact. In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location. This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere.

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Section: Discussionmentioning

confidence: 88%

Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

et al. 2015

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“…Lugomela, 2002;Kyaruzi et al, 2003;Sjőling et al, 2005;Hamisi, 2005;. The nitrogen fixation rates recorded at Chwaka Bay and Jambiani fall in the range recorded in similar environments within the region and elsewhere.…”

Section: Discussionmentioning

confidence: 88%

Cyanobacteria Occurrence and Nitrogen Fixation Rates in the Seagrass Meadows of the East Coast of Zanzibar: Comparisons of Sites With and Without Seaweed Farms

Lyimo¹,

Hamisi²

2009

West Ind. Oc. J Mar. Sci.

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Abstract-The occurrence and biological nitrogen fixation rates of epiphytic and benthic diazotrophs were studied in seagrass meadows at sites with seaweed farms and at a control site without seaweed farms from two locations, Chwaka Bay and Jambiani, along the east coast of Zanzibar. Ten species of cyanobacteria were encountered and Lyngbya majuscula and Microcoleus sp. were dominant in Chwaka Bay and Jambiani respectively. Cyanobacterial occurrence was significantly higher in seagrass meadows without seaweed farms (P<0.02), but there was no significant difference (P>0.05) in biomass (chlorophyll a). Biomass averaged 2.96±0.73 and 3.10±1.24 µg Chl a cm -2 in seaweed farms and 3.46±1.72 µg Chl a cm -2 at Chwaka Bay and 3.14±1.31 µg Chl a cm -2 at Jambiani in transects without seaweed farms. Nitrogenase activity showed no significant differences between sites with and without seaweed farms, (P=0.66 Chwaka and 0.75 at Jambiani). Fixation rates in sites without seaweed farms averaged 35.8±39.9 (Chwaka Bay) and 13.1±12.7 (Jambiani) µmol of C 2 H 4 produced/m 2 /hr, while with seaweed farms averaged 22.6±22.5 and 12.8±14.9 µmol C 2 H 4 produced/m 2 /hr at the same sites. There were no significant differences in nutrient levels between locations, sites with and without seaweed farms, or between tidal levels except for nitrate, which was significantly higher (P=0.01) at Jambiani than at Chwaka Bay. It was concluded that diazotrophs contribute a significant amount of exogenous nitrogen to the seagrass ecosystem, but no significant differences could be found between sites with or without seaweed farms.

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“…However, some sequences of DGGE bands were similar to nifH sequences retrieved from uncultured nitrogen-fixing bacteria. Mangrove ecosystems often contain nitrogen fixing cyanobacteria (Kyaruzi et al 2003). However, only the sequence of band H1 and H17 in this study was similar to uncultured cyanobacteria.…”

Section: Discussionmentioning

confidence: 89%

Effects of three different PAHs on nitrogen-fixing bacterial diversity in mangrove sediment

et al. 2012

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Cyanobacteria Composition and Impact of Seasonality on their <i>In Situ</i> Nitrogen Fixation Rate in a Mangrove Ecosystem Adjacent to Zanzibar Town

Cited by 17 publications

References 23 publications

Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

Cyanobacteria Occurrence and Nitrogen Fixation Rates in the Seagrass Meadows of the East Coast of Zanzibar: Comparisons of Sites With and Without Seaweed Farms

Effects of three different PAHs on nitrogen-fixing bacterial diversity in mangrove sediment

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