Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya)

Bouillon, Steven; Moens, Tom; Dehairs, Frank

doi:10.5194/bg-1-71-2004

Cited by 49 publications

(21 citation statements)

References 37 publications

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“…The higher percentage of bacterial biomarkers within the bay suggests a high bacterial biomass in the intertidal and seagrass bed sediments and water column. This is consistent with a previous study carried out in Gazi Bay using δ 13 C analysis of bacteriaspecific PLFAs (phospholipid fatty acids), which found that mangrove carbon was a significant source for bacteria mineralisation in the adjacent seagrass beds (Bouillon et al, 2004). Although branched FAs and 18 : 1 n7 are ascribed to both anaerobic and aerobic bacteria (Kaur et al, 2005;Meziane et al, 2006), the similar spatial patterns indicate similar response to the environmental conditions of Gazi Bay.…”

Section: Contribution Of Other Primary Producers To the Sediment And supporting

confidence: 91%

Small-scale variability in geomorphological settings influences mangrove-derived organic matter export in a tropical bay

et al. 2017

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Abstract. Organic matter (OM) exchanges between adjacent habitats affect the dynamics and functioning of coastal systems, as well as the role of the different primary producers as energy and nutrient sources in food webs. Elemental (C, N, C : N) and isotope (δ 13 C) signatures and fatty acid (FA) profiles were used to assess the influence of geomorphological setting in two climatic seasons on the export and fate of mangrove OM across a tidally influenced tropical area, Gazi Bay (Kenya). The main results indicate that tidal transport, along with riverine runoff, plays a significant role in the distribution of mangrove organic matter. In particular, a marked spatial variability in the export of organic matter from mangroves to adjacent habitats was due to the different settings of the creeks flowing into the bay. Kinondo Creek acted as a mangrove retention site, where export of mangrove material was limited to the contiguous intertidal area, while Kidogoweni Creek acted as a "flow-through" system, from which mangrove material spreads into the bay, especially in the rainy season. This pattern was evident from the isotopic signature of primary producers, which were more 13 C-depleted in the Kinondo Creek and nearby, due to the lower dilution of the dissolved inorganic carbon (DIC) pool, typically depleted as an effect of intense mangrove mineralisation. Despite the trapping efficiency of the seagrass canopy, suspended particulate OM showed the important contribution of mangroves across the whole bay, up to the coral reef, as an effect of the strong ebb tide. Overall, mixing model outcomes indicated a widespread mixed contribution of both allochthonous and autochthonous OM sources across Gazi Bay. Moreover, FAs indicated a notable contribution of brown macroalgae and bacteria in both sediment and suspended pools. These results suggest that ecological connectivity in Gazi Bay is strongly influenced by geomorphological setting, which may have far-reaching consequences for the functioning of the whole ecosystem and the local food webs.

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Section: Contribution Of Other Primary Producers To the Sediment And supporting

confidence: 91%

Small-scale variability in geomorphological settings influences mangrove-derived organic matter export in a tropical bay

et al. 2017

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“…Fontugne and Duplessy, 1981), the DOC pool has δ 13 C values around −16 to −14‰, which is much more enriched than can be expected for marine phytoplankton. However, seagrasses which in our study site are found at the creek mouth and which cover large areas on the slope outside the system, are expected to have δ 13 C values within this range: although δ 13 C signatures for seagrasses were not determined in this particular system, other data from other sites along the east African coast range between −18.6 and −10.7‰ (Bouillon et al, 2004;Macia, 2004). The observed difference in marine end-member δ 13 C signatures and in the timing of local maxima during the tidal cycle results in an offset in δ 13 C signatures between the dissolved and particulate pools.…”

Section: Origin and Exchange Of Organic Mattermentioning

confidence: 77%

“…This had been demonstrated previously based on isotope data of bacterial markers (e.g. Bouillon et al, 2004), yet such data only referred to the upper layers of the sediments, where inputs of non-mangrove sources are likely to be most important (i.e. microphytobenthic production and deposition of suspended matter from the water column).…”

Section: Inorganic Carbon and Ch 4 Dynamicsmentioning

confidence: 90%

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

et al. 2007

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Abstract. We sampled a tidal creek (Ras Dege, Tanzania) during a 24-h cycle to document the variations in a suite of creek water column characteristics and to determine the relative influence of tidal and biological driving forces. Since the creek has no upstream freshwater inputs, highest salinity was observed at low tide, due to evaporation effects and porewater seepage. Total suspended matter (TSM) and particulate organic carbon (POC) showed distinct maxima at periods of highest water flow, indicating that erosion of surface sediments and/or resuspension of bottom sediments were an important source of particulate material. Dissolved organic carbon (DOC), in contrast, varied in phase with water height and was highest at low tide. Stable isotope data of POC and DOC displayed large variations in both pools, and similarly followed the variations in water height. Although the variation of δ 13 C DOC (−23.8 to −13.8‰) was higher than that of δ 13 C POC (−26.2 to −20.5‰), due to the different endmember pool sizes, the δ 13 C signatures of both pools differed only slightly at low tide, but up to 9‰ at high tide. Thus, at low tide both DOC and POC originated from mangrove production. At high tide, however, the DOC pool had signatures consistent with a high contribution of seagrass-derived material, whereas the POC pool was dominated by marine phytoplankton. Daily variations in CH 4 , and partial pressure of CO 2 (pCO 2 ) were similarly governed by tidal influence and were up to 7-and 10-fold higher at low tide, which stresses the importance of exchange of porewater and diffusive fluxes to the water column. When assuming that the high dissolved Correspondence to: S. Bouillon (steven.bouillon@vub.ac.be) inorganic carbon (DIC) levels in the upper parts of the creek (i.e. at low tide) are due to inputs from mineralization, δ 13 C data on DIC indicate that the organic matter source for mineralization had a signature of −22.4‰. Hence, imported POC and DOC from the marine environment contributes strongly to overall mineralization within the mangrove system. Our data demonstrate how biogeochemical processes in the intertidal zone appear to be prominent drivers of element concentrations and isotope signatures in the water column, and how pathways of dissolved and particulate matter transport are fundamentally different.

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“…Due in large part to the productivity of these epiphytes, the primary productivity of seagrass beds is generally several times higher than that of adjacent unvegetated habitats (Moncreiff, Sullivan, & Daehnick, 1992). In addition, seagrass beds get carbon input from nearby coastal systems such as mangrove forests (e.g., Bouillon, Moens, & Dehairs, 2004). Several studies aimed to study the origin of carbon in these systems (e.g., Fleming, Lin, & Sternberg, 1990;Holmer & Bachmann Olsen, 2002;Marguillier, van der Velde, Dehairs, Hemminga, & Rajagopal, 1997) rather than to unravel the effects of total resource availability on consumers.…”

Section: Introductionmentioning

confidence: 99%

Resource availability and meiofauna in sediment of tropical seagrass beds: Local versus global trends

Troch

Gansbeke

Vincx

2006

Marine Environmental Research

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Characterisation of productivity-diversity relationships forms an essential step towards a better understanding of biodiversity. In terrestrial systems this is a topical subject and most studies reported a hump-shaped relationship. For marine systems, however, the number of studies dedicated to this is low despite the high interest in this productivity-diversity relationship.The present study reports on meiofauna density/diversity patterns in relation to resource availability as an indicator for the productivity of the ecosystem. Standardised meiofauna samples were collected in tropical seagrass beds from three localities (Kenya, Mexico, the Philippines) in order to contrast local patterns with a more global scale. Although these sites were physically comparable, a range of resource availabilities was found. These differences between localities were mainly due to different tidal regimes and related input of organic matter. At all sites a significant positive effect of resource increase on meiofauna densities was found. This positive effect was less clear for meiofauna diversity. Highest density and diversity levels were reported for the Kenyan site and this is probably linked to a high tidal range. Pooling all localities together resulted in a significant positive linear relationship between resource availability and meiofauna density/diversity. Caution should be taken when choosing resource indicators. Chlorophyll a concentrations, for example, resulted in a positive density-productivity relationship while organic carbon content, an indicator for more refractory material, showed a negative relationship. In all cases, no hump-shaped relationship could be found suggesting that each ecosystem and each group of organisms may show a particular productivity-diversity/density relationship.

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Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya)

Cited by 49 publications

References 37 publications

Small-scale variability in geomorphological settings influences mangrove-derived organic matter export in a tropical bay

Small-scale variability in geomorphological settings influences mangrove-derived organic matter export in a tropical bay

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

Resource availability and meiofauna in sediment of tropical seagrass beds: Local versus global trends

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