Carbon storage in the seagrass meadows of Gazi Bay, Kenya

Vegetated marine habitats are globally important carbon sinks, making a significant contribution towards mitigating climate change, and they provide a wide range of other ecosystem services. However, large gaps in knowledge remain, particularly for seagrass meadows in Africa. The present study estimated biomass and sediment organic carbon (Corg) stocks of four dominant seagrass species in Gazi Bay, Kenya. It compared sediment Corg between seagrass areas in vegetated and un-vegetated ‘controls’, using the naturally patchy occurence of seagrass at this site to test the impacts of seagrass growth on sediment Corg. It also explored relationships between the sediment and above-ground Corg, as well as between the total biomass and above-ground parameters. Sediment Corg was significantly different between species, range: 160.7–233.8 Mg C ha-1 (compared to the global range of 115.3 to 829.2 Mg C ha-1). Vegetated areas in all species had significantly higher sediment Corg compared with un-vegetated controls; the presence of seagrass increased Corg by 4–6 times. Biomass carbon differed significantly between species with means ranging between 4.8–7.1 Mg C ha-1 compared to the global range of 2.5–7.3 Mg C ha-1. To our knowledge, these are among the first results on seagrass sediment Corg to be reported from African seagrass beds; and contribute towards our understanding of the role of seagrass in global carbon dynamics

Biomass and productivity of seagrasses in Africa

There is growing interest in carbon stocks and flows in seagrass ecosystems, but recent global reviews suggest a paucity of studies from Africa. This paper reviews work on seagrass productivity, biomass and sediment carbon in Africa. Most work was conducted in East Africa with a major geographical gap in West Africa. The mean above-ground, below-ground and total biomasses from all studies were 174.4, 474.6 and 514 g DW m-2, respectively with a global range of 461-738 g DW m-2. Mean annual production rate was 913 g DW m-2 yr-1 (global range 816 - 1012 g DW m-2 yr-1). No studies were found giving sediment organic carbon, demonstrating a major gap in seagrass blue carbon work. Given the small numbers of relevant papers and the large geographical areas left undescribed in Africa, any conclusions remain tentative and much remains to be done on seagrass studies in Africa

Sustainable natural resource management must recognise community diversity

Deforestation and overexploitation of mangrove forests are affecting the livelihoods of millions of families that rely on their ecosystem services. Understanding local perceptions about the status and threats to mangroves is therefore crucial in addressing this issue. This research aims to enhance understanding of how sociodemographic factors influence resource use and perceptions of environmental changes through a questionnaire survey (n = 592 households) in five locations in Lamu County, home to 62% of Kenya’s mangroves. The results highlight the variability of mangrove use, ecosystem service recognition, and perceptions and drivers of change across locations, which are influenced by sociodemographic factors such as gender, education, and occupation. Although 89% of respondents reported using mangrove products, only 56% were able to identify mangrove ecosystem services, with those without formal education being less likely to recognize them. Interestingly, 50% of respondents perceived an increase in mangrove cover, contrary to research showing mangrove loss in the area over the last decade. Results show that communities are diverse and perceptions vary between groups, suggesting that implementing uniform management measures may be incomplete or ineffective. Awareness campaigns and capacity-building efforts must be tailored to reduce misperceptions about the state of local resources and to address the specific needs and challenges faced by different groups. Recommendations made here are widely applicable to promote more inclusive and sustainable community engagement in the management of natural resources in developing countries worldwide

Seagrass removal leads to rapid changes in fauna and loss of carbon.

Seagrass habitats are important natural carbon sinks, with an average of ∼14 kg C m−2 buried in their sediments. The fate of this carbon following seagrass removal or damage has major environmental implications but is poorly understood. Using a removal experiment lasting 18 months at Gazi Bay, Kenya, we investigated the impactsof seagrass loss on sediment topography, hydrodynamics, faunal community structure and carbon dynamics. Sediment pins were used to monitor surface elevation. The effects of seagrass removal on water velocity was investigated using Plaster of Paris dissolution. Sediment carbon concentration was measured at the surface and down to 50 cm. Rates of litter decay at three depths in harvested and control treatments were measured using litter bags. Drop samples, cores, and visual counts of faunal mounds and burrows were used to monitor the impact of seagrass removal on the epifaunal and infaunal communities. Whilst control plots showed sediment elevation, harvested plots were eroded (7.6 ± 0.4 and −15.8 ± 0.5mm yr−1 respectively, mean ± 95%CI). Carbon concentration in the surface sediments was significantly reduced with a mean carbon loss of 2.21Mg C ha−1 in the top 5 cm. Because sediment was lost fromharvested plots, with a mean difference in elevation of 3 cm, an additional carbon loss of up to 2.54Mg C ha−1 may have occurred over the 18 months. Seagrass removal had rapid and dramatic impacts on infauna and epifauna. There was a loss of diversity in harvested plots and a shift toward larger bodied, bioturbating species, with a significant increase in mounds and burrows. Buried seagrass litter decomposed significantly faster in the harvested compared with the control plots. Loss of seagrass therefore led to rapid changes in sediment dynamics and chemistry driven in part by significant alterations in the faunal community

Multiple Impact Pathways Of The 2015-2016 El Niño In Coastal Kenya

The 2015-2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a 'non-event'. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015-16 El Niño episode in southern coastal Kenya. By using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather

Public perceptions of mangrove forests matter for their conservation

Abstract not available

Community participatory forestry for the rehabilitation of deforested mangrove areas in Kenya

(keynote speaker)info:eu-repo/semantics/nonPublishe

Mangroves of Kenya

info:eu-repo/semantics/inPres