Untitled

Woitchik, A.F.; Ohowa, Boaz O.; Kazungu, Johnson Michael; Rao, R. G.; Goeyens, Léo; Dehairs, Frank

doi:10.1023/a:1005850032254

Cited by 73 publications

(6 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This chemical reduces the bacterial population of the soil and slows decomposition rate (Steinke et al, 1990). Moreover, other nonchemical factors such as tidal height, rainfall, temperature, and salinity influence decomposition rate (Lewis et al, 2016;Woitchik et al, 1997). The study area has low salinity and high temperature which makes it a tropical estuary (Table 1).…”

Section: Discussionmentioning

confidence: 99%

Natural seedling recruitment and regeneration in deforested and sand‐filled Mangrove forest at Eagle Island, Niger Delta, Nigeria

Numbere

2021

Ecology and Evolution

View full text Add to dashboard Cite

Seed recruitment is a major driver of mangrove restoration globally. It is hypothesized that soil condition and channel hydrology can accelerate seedling recruitment and regeneration after a major disturbance. Species abundance, diversity indices, microbial and chemical concentrations in sand‐filled mangrove forest was studied. Eight plots measuring 487.77 m2 each were established with ten transects in each plot in a random block design to investigate the effect of soil conditions on seedling growth. A total of 1,886 seedlings were counted. Seedling abundance was significantly different between red (Rizophora racemosa), white (Laguncularia racemosa), and black (Avicennia germinans) mangroves, and nypa palm (nypa fruticans). The most dominant species was black mangrove, and the least dominant species was nypa palm. Muddy soils had the most abundant species (n = 994) followed by sandy (n = 457) and semi‐muddy (435) soils. Furthermore, sandy soils had the highest species diversity (H = 0.896) followed by semi‐muddy (H = 0.876) and muddy (H = 0.583) soils. The soil metal concentration has no correlation with seed abundance and occur in the order Iron > Nitrate > Copper > Cadmium. Soil with high species diversity had high soil microbial population; however, seedling abundance was correlated with soil nutrients and not heavy metals. Small seeds are easily recruited while good soil condition plus existing hydrological connection facilitated natural seedling regeneration in the disturbed mangrove forest.

show abstract

Section: Discussionmentioning

confidence: 99%

Natural seedling recruitment and regeneration in deforested and sand‐filled Mangrove forest at Eagle Island, Niger Delta, Nigeria

Numbere

2021

Ecology and Evolution

View full text Add to dashboard Cite

show abstract

“…A common observation with aging macrophyte detritus is the decrease in C:N ratio throughout decomposition which has been linked, with varying extent, to the associated diazotrophic activity (Cundell et al, 1979; Kenworthy and Thayer, 1984; Kenworthy et al, 1987). Additionally, there have also been several studies that directly link BNF observed in these marine detrital systems to N immobilization of the aging detritus, highlighting the importance of diazotrophs in marine detrital food chains (Van der Valk and Attiwill, 1984; Woitchik et al, 1997; Pelegri and Twilley, 1998). Not surprisingly, this trend of decreasing C:N ratio (observed in this study with the 2017 S. horneri decomposition experiment, Figure 5C) has also been reported on several accounts with aging macroalgal detritus but not linked directly to BNF and instead, generally attributed to the buildup of microbial biomass (Smith and Foreman, 1984; Rieper-Kirchner, 1989; Duggins and Eckman, 1997; Banta et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Diazotrophic Macroalgal Associations With Living and Decomposing Sargassum

2018

View full text Add to dashboard Cite

Despite several studies reporting diazotrophic macroalgal associations (DMAs), biological nitrogen fixation (BNF) is still largely overlooked as a potential source of nitrogen (N) for macroalgal productivity. We investigated the role of BNF, via the acetylene reduction method, throughout different life stages of the invasive macroalga, Sargassum horneri, in its non-native Southern California coastal ecosystem. Throughout most of its life cycle, BNF rates were not detectable or yielded insignificant amounts of fixed N to support S. horneri productivity. However, during late summer when nutrient concentrations are usually at their minimum, BNF associated with juvenile S. horneri contributed ∼3–36% of its required N, potentially providing it with a competitive advantage. As DMAs remain poorly understood within macroalgal detrital systems, long term (15–28 days) laboratory decomposition time series were carried out to investigate the role of BNF throughout decomposition of the endemic macroalga, S. palmeri, and the invasive S. horneri. Nitrogenase activity increased drastically during the second phase of decomposition, when increasing microbial populations are typically thought to drive macroalgal degradation, with BNF rates associated with S. palmeri and S. horneri reaching up to 65 and 247 nmol N × g-1(dw) × h-1, respectively. Stimulation of BNF rates by glucose and mannitol additions, up to 42× higher rates observed with S. palmeri, suggest that labile carbon may be limiting at varying degrees in these detrital systems. Comparable, if not higher, dark BNF rates relative to light incubations during S. horneri decomposition suggest an important contribution from heterotrophic N fixers. Inhibition of nitrogenase activity, up to 98%, by sodium molybdate additions also suggest that sulfate reducers may be an important constituent of the detrital diazotrophic community. As labile N can become limiting to the microbial community during macroalgal decomposition, our results suggest that BNF may provide a source of new N, alleviating this limitation. Additionally, while BNF is rarely considered as a source for N enrichment with aging macroalgal detritus, we found it to account for ∼1–11% of N immobilized with decaying S. horneri. Our investigations suggest that DMAs may be globally important with Sargassum and potentially occur within other macroalgal detrital systems.

show abstract

“…Boto and Robertson (1990) reported that nitrogen fixation in sediment, algal mats, aerial roots, and trunks of a mangrove in Australia was almost equal the export of dissolved inorganic nitrogen. Woitchik et al (1997) also found that nitrogen fixation in an African coastal lagoon represents a significant (13-21%), but not the primary source of nitrogen to the mangrove sediment (the litter fall). Nitrogen fixation and a positive sediment balance were considered essential conditions to nutrient outwelling from tropical mangroves .…”

Section: Estimation Of the Role Of Sediments And Mangrovesmentioning

confidence: 93%

Net Ecosystem Metabolism and Nonconservative Fluxes of Organic Matter in a Tropical Mangrove Estuary, Piauí River (NE of Brazil)

Souza

Gomes

Freitas

et al. 2008

Estuaries and Coasts

View full text Add to dashboard Cite

Net ecosystem metabolism (NEM) was measured in the Piauí River estuary, NE Brazil. A mass balance of C, N, and P was used to infer its sources and sinks. Dissolved inorganic carbon (DIC) concentrations and fluxes were measured over a year along this mangrove dominated estuary. DIC concentrations were high in all estuarine sections, particularly at the fluvial end member at the beginning of the rainy season. Carbon dioxide concentrations in the entire estuary were supersaturated throughout the year and highest in the upper estuarine compartment and freshwater, particularly at the rainy season, due to washout effects of carbonaceous soils and different organic anthropogenic effluents. The estuary served as a source of DIC to the atmosphere with an estimated flux of 13 mol CO 2 m −2 year −1 . Input from the river was 46 mol CO 2 m −2 year −1 . The metabolism of the system was heterotrophic, but short periods of autotrophy occurred in the lower more marine portions of the estuary. The pelagic system was more or less balanced between auto-and heterotrophy, whereas the benthic and intertidal mangrove region was heterotrophic. Estimated annual NEM yielded a total DIC production in the order of 18 mol CO 2 m −2 year −1 . The anthropogenic inputs of particulate C, N, and P, dissolved inorganic P (DIP), and DIC were significant. The fluvial loading of particulate organic carbon and dissolved inorganic nitrogen (DIN) was largely retained in two flow regulation and hydroelectric reservoirs, promoting a reduction of C:N and C:P particulate ratios in the estuary. The net nonconservative fluxes obtained by a mass balance approach revealed that the estuary acts as a source of DIP, DIN, and DIC, the latter one being almost equivalent to the losses to the atmosphere. Mangrove forests and tidal mudflats were responsible for most of NEM rates and are the main sites of organic decomposition to sustain net heterotrophy. The main sources for this organic matter are the fluvial and anthropogenic inputs. The mangrove areas are the highest estuarine sources of DIP, DIC, and DIN.

show abstract

Untitled

Cited by 73 publications

References 27 publications

Natural seedling recruitment and regeneration in deforested and sand‐filled Mangrove forest at Eagle Island, Niger Delta, Nigeria

Natural seedling recruitment and regeneration in deforested and sand‐filled Mangrove forest at Eagle Island, Niger Delta, Nigeria

Diazotrophic Macroalgal Associations With Living and Decomposing Sargassum

Net Ecosystem Metabolism and Nonconservative Fluxes of Organic Matter in a Tropical Mangrove Estuary, Piauí River (NE of Brazil)

Contact Info

Product

Resources

About