Groundwater enhances above-ground growth in mangroves

Groundwater flow through coastal wetlands plays an important role in the maintenance of productivity of intertidal ecosystems. Groundwater can reduce salinity and increase nutrient availability which can enhance plant growth and alter plant biomass allocation patterns. Here, we used stable isotopes of oxygen and hydrogen to assess how groundwater influences below-ground and above-ground growth in the widespread mangrove species Avicennia marina. We found source water within tree stems varied seasonally, with non-saline water use higher in the wet season when rainwater availability was highest compared to the dry season. Stems with higher proportional contribution of non-saline water had increased above-ground growth but no effect on below-ground growth. Below-ground growth was however influenced by nutrient availability across the intertidal zone which was higher in the high- compared to the low-intertidal zone. Synthesis. This study shows that mangroves use non-saline groundwater and rainwater when available rather than saline water sources. Groundwater flows into the intertidal stimulates organic matter accumulation in above-ground biomass suggesting the availability of non-saline water sources, such as groundwater and rainfall, are important for the growth and productivity of mangrove forests

Data from: Groundwater enhances aboveground growth in mangroves

1. Groundwater flow through coastal wetlands plays an important role in the maintenance of productivity of intertidal ecosystems. Groundwater can reduce salinity and increase nutrient availability which can enhance plant growth and alter plant biomass allocation patterns. 2. Here, we used stable isotopes of oxygen and hydrogen to assess how groundwater influences belowground and aboveground growth in the widespread mangrove species Avicennia marina. 3. We found source water within tree stems varied seasonally, with non-saline water use higher in the wet season when rainwater availability was highest compared to the dry season. Stems with higher proportional contribution of non-saline water had increased aboveground growth but no effect on belowground growth. Belowground growth was however influenced by nutrient availability across the intertidal zone which was higher in the high compared to the low intertidal zone. 4. Synthesis. This study shows that mangroves use non-saline groundwater and rainwater when available rather than saline water sources. Groundwater flows into the intertidal stimulates organic matter accumulation in aboveground biomass suggesting the availability of non-saline water sources, such as groundwater and rainfall, are important for the growth and productivity of mangrove forests

The contrasting effects of nutrient enrichment on growth, biomass allocation and decomposition of plant tissue in coastal wetlands

Aims: Eutrophication of coastal waters can have consequences for the growth, function and soil processes of coastal wetlands. Our aims were to assess how nutrient enrichment affects growth, biomass allocation and decomposition of plant tissues of a common and widespread mangrove, Avicennia marina, and how eutrophication drives changes in below-ground carbon sequestration. Methods: We assessed this through the measurement of above- and belowground growth and decomposition rates of plants and plant tissue in unenriched or nutrient enriched treatments. Results: Nutrient enrichment increased biomass allocation above-ground compared to below-ground in seedlings but not in fully developed, mature trees where we observed the opposite pattern. Experiments to assess root decomposition found that 40–50% of biomass was lost within six months with little change between 12 and 18\ua0months, indicating a high potential for accumulation of organic matter over time. We estimate root-derived carbon sequestration rates of 53, 250 and 94\ua0g C m\ua0year for unenriched control, N and P enriched treatments, respectively. Conclusions: These results show coastal eutrophication can be beneficial and detrimental to ecosystem function of coastal plants. Eutrophication stimulates root growth in fully developed trees, increasing organic matter input to soils. Our data suggests that organic matter accumulation will increase in areas with high nutrient availability where root growth is increased and rates of decomposition are low

Hayes_et_al_2018

This data file contains plant and water data used for the analysis and figure production within our manuscript entitled 'Groundwater enhances aboveground growth in mangroves'

Dynamics of sediment carbon stocks across intertidal wetland habitats of Moreton Bay, Australia

Coastal wetlands are known for high carbon storage within their sediments, but our understanding of the variation in carbon storage among intertidal habitats, particularly over geomorphological settings and along elevation gradients, is limited. Here, we collected 352 cores from 18 sites across Moreton Bay, Australia. We assessed variation in sediment organic carbon (OC) stocks among different geomorphological settings (wetlands within riverine settings along with those with reduced riverine influence located on tide-dominated sand islands), across elevation gradients, with distance from shore and among habitat and vegetation types. We used mid-infrared (MIR) spectroscopy combined with analytical data and partial least squares regression to quantify the carbon content of similar to 2500 sediment samples and provide fine-scale spatial coverage of sediment OC stocks to 150 cm depth. We found sites in river deltas had larger OC stocks (175-504 Mg/ha) than those in nonriverine settings (44-271 Mg/ha). Variation in OC stocks among nonriverine sites was high in comparison with riverine and mixed geomorphic settings, with sites closer to riverine outflow from the east and south of Moreton Bay having higher stocks than those located on the sand islands in the northwest of the bay. Sediment OC stocks increased with elevation within nonriverine settings, but not in riverine geomorphic settings. Sediment OC stocks did not differ between mangrove and saltmarsh habitats. OC stocks did, however, differ between dominant species across the research area and within geomorphic settings. At the landscape scale, the coastal wetlands of the South East Queensland catchments (17,792 ha) are comprised of approximately 4,100,000-5,200,000 Mg of sediment OC. Comparatively high variation in OC storage between riverine and nonriverine geomorphic settings indicates that the availability of mineral sediments and terrestrial derived OC may exert a strong influence over OC storage potential across intertidal wetland systems

Increasing protein content and digestibility in sorghum grain with a synthetic biology approach

Despite great genetic diversity, sorghum grain consistently suffers from poor protein digestibility. The physicochemical packaging of protein bodies which consist of protease-resistant β- and γ-kafirin is considered a major obstacle. A synthetic β-kafirin gene, which shares the endosperm-specific promoter and signal peptide with the native β-kafirin gene (Sobic.009G001600.1), was transformed into sorghum inbred line Tx430. The gene was modified with ten additional proteolytic sites. These sites were designed to be amenable to cleavage by pepsin and/or chymotrypsin proteinases. Five independent transgenic lines were regenerated by microprojectile transformation. Notably, considerably more protein was observed in the peripheral endosperm of transgenic lines under scanning electron microscopy. Microscopy revealed invaginated or irregularly shaped protein bodies in the endosperm of transgenic lines. Grains of transgenic lines contained 11–37% more protein, which was 11–21% more pepsin digestible and 7–25% more chymotrypsin digestible than Tx430. Additionally, the abundant synthetic β-kafirin protein (5.6% of total protein) was detected by mass spectrometry data analysis in the transgenic line 9-1. Field-grown homozygous transgenics retained higher protein content, larger seed size and no reduction in grain number per plant. The results illustrated that plant synthetic biology could play an important role in improving sorghum nutritional value